"PREFACE TO THE SECOND EDITION.\n\nDuring the successive reprints of the first edition of this work, published\nin 1871, I was able to introduce several important corrections; and now\nthat more time has elapsed, I have endeavoured to profit by the fiery\nordeal through which the book has passed, and have taken advantage of all\nthe criticisms which seem to me sound.  I am also greatly indebted to a\nlarge number of correspondents for the communication of a surprising number\nof new facts and remarks.  These have been so numerous, that I have been\nable to use only the more important ones; and of these, as well as of the\nmore important corrections, I will append a list.  Some new illustrations\nhave been introduced, and four of the old drawings have been replaced by\nbetter ones, done from life by Mr. T.W. Wood.  I must especially call\nattention to some observations which I owe to the kindness of Prof. Huxley\n(given as a supplement at the end of Part I.), on the nature of the\ndifferences between the brains of man and the higher apes.  I have been\nparticularly glad to give these observations, because during the last few\nyears several memoirs on the subject have appeared on the Continent, and\ntheir importance has been, in some cases, greatly exaggerated by popular\nwriters.\n\nI may take this opportunity of remarking that my critics frequently assume\nthat I attribute all changes of corporeal structure and mental power\nexclusively to the natural selection of such variations as are often called\nspontaneous; whereas, even in the first edition of the 'Origin of Species,'\nI distinctly stated that great weight must be attributed to the inherited\neffects of use and disuse, with respect both to the body and mind.  I also\nattributed some amount of modification to the direct and prolonged action\nof changed conditions of life.  Some allowance, too, must be made for\noccasional reversions of structure; nor must we forget what I have called\n\"correlated\" growth, meaning, thereby, that various parts of the\norganisation are in some unknown manner so connected, that when one part\nvaries, so do others; and if variations in the one are accumulated by\nselection, other parts will be modified.  Again, it has been said by\nseveral critics, that when I found that many details of structure in man\ncould not be explained through natural selection, I invented sexual\nselection; I gave, however, a tolerably clear sketch of this principle in\nthe first edition of the 'Origin of Species,' and I there stated that it\nwas applicable to man.  This subject of sexual selection has been treated\nat full length in the present work, simply because an opportunity was here\nfirst afforded me.  I have been struck with the likeness of many of the\nhalf-favourable criticisms on sexual selection, with those which appeared\nat first on natural selection; such as, that it would explain some few\ndetails, but certainly was not applicable to the extent to which I have\nemployed it.  My conviction of the power of sexual selection remains\nunshaken; but it is probable, or almost certain, that several of my\nconclusions will hereafter be found erroneous; this can hardly fail to be\nthe case in the first treatment of a subject.  When naturalists have become\nfamiliar with the idea of sexual selection, it will, as I believe, be much\nmore largely accepted; and it has already been fully and favourably\nreceived by several capable judges.\n\nDOWN, BECKENHAM, KENT,\nSeptember, 1874.\n\nFirst Edition February 24, 1871.\nSecond Edition September, 1874.\n\n\nPART I.  THE DESCENT OR ORIGIN OF MAN.\n\n\nCHAPTER I.\n\nThe Evidence of the Descent of Man from some Lower Form.\n\nNature of the evidence bearing on the origin of man--Homologous structures\nin man and the lower animals--Miscellaneous points of correspondence--\nDevelopment--Rudimentary structures, muscles, sense-organs, hair, bones,\nreproductive organs, etc.--The bearing of these three great classes of\nfacts on the origin of man.\n\n\nCHAPTER II.\n\nOn the Manner of Development of Man from some Lower Form.\n\nVariability of body and mind in man--Inheritance--Causes of variability--\nLaws of variation the same in man as in the lower animals--Direct action of\nthe conditions of life--Effects of the increased use and disuse of parts--\nArrested development--Reversion--Correlated variation--Rate of increase--\nChecks to increase--Natural selection--Man the most dominant animal in the\nworld--Importance of his corporeal structure--The causes which have led to\nhis becoming erect--Consequent changes of structure--Decrease in size of\nthe canine teeth--Increased size and altered shape of the skull--Nakedness\n--Absence of a tail--Defenceless condition of man.\n\n\nCHAPTER III.\n\nComparison of the Mental Powers of Man and the Lower Animals.\n\nThe difference in mental power between the highest ape and the lowest\nsavage, immense--Certain instincts in common--The emotions--Curiosity--\nImitation--Attention--Memory--Imagination--Reason--Progressive improvement\n--Tools and weapons used by animals--Abstraction, Self-consciousness--\nLanguage--Sense of beauty--Belief in God, spiritual agencies,\nsuperstitions.\n\n\nCHAPTER IV.\n\nComparison of the Mental Powers of Man and the Lower Animals--continued.\n\nThe moral sense--Fundamental proposition--The qualities of social animals--\nOrigin of sociability--Struggle between opposed instincts--Man a social\nanimal--The more enduring social instincts conquer other less persistent\ninstincts--The social virtues alone regarded by savages--The self-regarding\nvirtues acquired at a later stage of development--The importance of the\njudgment of the members of the same community on conduct--Transmission of\nmoral tendencies--Summary.\n\n\nCHAPTER V.\n\nOn the Development of the Intellectual and Moral Faculties during Primeval\nand Civilised times.\n\nAdvancement of the intellectual powers through natural selection--\nImportance of imitation--Social and moral faculties--Their development\nwithin the limits of the same tribe--Natural selection as affecting\ncivilised nations--Evidence that civilised nations were once barbarous.\n\n\nCHAPTER VI.\n\nOn the Affinities and Genealogy of Man.\n\nPosition of man in the animal series--The natural system genealogical--\nAdaptive characters of slight value--Various small points of resemblance\nbetween man and the Quadrumana--Rank of man in the natural system--\nBirthplace and antiquity of man--Absence of fossil connecting-links--Lower\nstages in the genealogy of man, as inferred firstly from his affinities and\nsecondly from his structure--Early androgynous condition of the Vertebrata\n--Conclusion.\n\n\nCHAPTER VII.\n\nOn the Races of Man.\n\nThe nature and value of specific characters--Application to the races of\nman--Arguments in favour of, and opposed to, ranking the so-called races of\nman as distinct species--Sub-species--Monogenists and polygenists--\nConvergence of character--Numerous points of resemblance in body and mind\nbetween the most distinct races of man--The state of man when he first\nspread over the earth--Each race not descended from a single pair--The\nextinction of races--The formation of races--The effects of crossing--\nSlight influence of the direct action of the conditions of life--Slight or\nno influence of natural selection--Sexual selection.\n\n\nPART II.  SEXUAL SELECTION.\n\n\nCHAPTER VIII.\n\nPrinciples of Sexual Selection.\n\nSecondary sexual characters--Sexual selection--Manner of action--Excess of\nmales--Polygamy--The male alone generally modified through sexual\nselection--Eagerness of the male--Variability of the male--Choice exerted\nby the female--Sexual compared with natural selection--Inheritance at\ncorresponding periods of life, at corresponding seasons of the year, and as\nlimited by sex--Relations between the several forms of inheritance--Causes\nwhy one sex and the young are not modified through sexual selection--\nSupplement on the proportional numbers of the two sexes throughout the\nanimal kingdom-- The proportion of the sexes in relation to natural\nselection.\n\n\nCHAPTER IX.\n\nSecondary Sexual Characters in the Lower Classes of the Animal Kingdom.\n\nThese characters are absent in the lowest classes--Brilliant colours--\nMollusca--Annelids--Crustacea, secondary sexual characters strongly\ndeveloped; dimorphism; colour; characters not acquired before maturity--\nSpiders, sexual colours of; stridulation by the males--Myriapoda.\n\n\nCHAPTER X.\n\nSecondary Sexual Characters of Insects.\n\nDiversified structures possessed by the males for seizing the females--\nDifferences between the sexes, of which the meaning is not understood--\nDifference in size between the sexes--Thysanura--Diptera--Hemiptera--\nHomoptera, musical powers possessed by the males alone--Orthoptera, musical\ninstruments of the males, much diversified in structure; pugnacity;\ncolours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity\nand odours--Coleoptera, colours; furnished with great horns, apparently as\nan ornament; battles; stridulating organs generally common to both sexes.\n\n\nCHAPTER XI.\n\nInsects, continued.--Order Lepidoptera.\n\n(Butterflies and Moths.)\n\nCourtship of Butterflies--Battles--Ticking noise--Colours common to both\nsexes, or more brilliant in the males--Examples--Not due to the direct\naction of the conditions of life--Colours adapted for protection--Colours\nof moths--Display--Perceptive powers of the Lepidoptera--Variability--\nCauses of the difference in colour between the males and females--Mimicry,\nfemale butterflies more brilliantly coloured than the males--Bright colours\nof caterpillars--Summary and concluding remarks on the secondary sexual\ncharacter of insects--Birds and insects compared.\n\n\nCHAPTER XII.\n\nSecondary Sexual Characters of Fishes, Amphibians, and Reptiles.\n\nFishes:  Courtship and battles of the males--Larger size of the females--\nMales, bright colours and ornamental appendages; other strange characters--\nColours and appendages acquired by the males during the breeding-season\nalone--Fishes with both sexes brilliantly coloured--Protective colours--The\nless conspicuous colours of the female cannot be accounted for on the\nprinciple of protection--Male fishes building nests, and taking charge of\nthe ova and young.  AMPHIBIANS:  Differences in structure and colour\nbetween the sexes--Vocal organs.  REPTILES:  Chelonians--Crocodiles--\nSnakes, colours in some cases protective--Lizards, battles of--Ornamental\nappendages--Strange differences in structure between the sexes--Colours--\nSexual differences almost as great as with birds.\n\n\nCHAPTER XIII.\n\nSecondary Sexual Characters of Birds.\n\nSexual differences--Law of battle--Special weapons--Vocal organs--\nInstrumental music--Love-antics and dances--Decorations, permanent and\nseasonal--Double and single annual moults--Display of ornaments by the\nmales.\n\n\nCHAPTER XIV.\n\nBirds--continued.\n\nChoice exerted by the female--Length of courtship--Unpaired birds--Mental\nqualities and taste for the beautiful--Preference or antipathy shewn by the\nfemale for particular males--Variability of birds--Variations sometimes\nabrupt--Laws of variation--Formation of ocelli--Gradations of character--\nCase of Peacock, Argus pheasant, and Urosticte.\n\n\nCHAPTER XV.\n\nBirds--continued.\n\nDiscussion as to why the males alone of some species, and both sexes of\nothers are brightly coloured--On sexually-limited inheritance, as applied\nto various structures and to brightly-coloured plumage--Nidification in\nrelation to colour--Loss of nuptial plumage during the winter.\n\n\nCHAPTER XVI.\n\nBirds--concluded.\n\nThe immature plumage in relation to the character of the plumage in both\nsexes when adult--Six classes of cases--Sexual differences between the\nmales of closely-allied or representative species--The female assuming the\ncharacters of the male--Plumage of the young in relation to the summer and\nwinter plumage of the adults--On the increase of beauty in the birds of the\nworld--Protective colouring--Conspicuously coloured birds--Novelty\nappreciated--Summary of the four chapters on birds.\n\n\nCHAPTER XVII.\n\nSecondary Sexual Characters of Mammals.\n\nThe law of battle--Special weapons, confined to the males--Cause of absence\nof weapons in the female--Weapons common to both sexes, yet primarily\nacquired by the male--Other uses of such weapons--Their high importance--\nGreater size of the male--Means of defence--On the preference shewn by\neither sex in the pairing of quadrupeds.\n\n\nCHAPTER XVIII.\n\nSecondary Sexual Characters of Mammals--continued.\n\nVoice--Remarkable sexual peculiarities in seals--Odour--Development of the\nhair--Colour of the hair and skin--Anomalous case of the female being more\nornamented than the male--Colour and ornaments due to sexual selection--\nColour acquired for the sake of protection--Colour, though common to both\nsexes, often due to sexual selection--On the disappearance of spots and\nstripes in adult quadrupeds--On the colours and ornaments of the\nQuadrumana--Summary.\n\n\nPART III.  SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION.\n\n\nCHAPTER XIX.\n\nSecondary Sexual Characters of Man.\n\nDifferences between man and woman--Causes of such differences, and of\ncertain characters common to both sexes--Law of battle--Differences in\nmental powers, and voice--On the influence of beauty in determining the\nmarriages of mankind--Attention paid by savages to ornaments--Their ideas\nof beauty in women--The tendency to exaggerate each natural peculiarity.\n\n\nCHAPTER XX.\n\nSecondary Sexual Characters of Man--continued.\n\nOn the effects of the continued selection of women according to a different\nstandard of beauty in each race--On the causes which interfere with sexual\nselection in civilised and savage nations--Conditions favourable to sexual\nselection during primeval times--On the manner of action of sexual\nselection with mankind--On the women in savage tribes having some power to\nchoose their husbands--Absence of hair on the body, and development of the\nbeard--Colour of the skin--Summary.\n\n\nCHAPTER XXI.\n\nGeneral Summary and Conclusion.\n\nMain conclusion that man is descended from some lower form--Manner of\ndevelopment--Genealogy of man--Intellectual and moral faculties--Sexual\nselection--Concluding remarks.\n\n\nSUPPLEMENTAL NOTE.\n\n\nINDEX.\n\n\n\nTHE DESCENT OF MAN; AND SELECTION IN RELATION TO SEX.\n\n...\n\nINTRODUCTION.\n\nThe nature of the following work will be best understood by a brief account\nof how it came to be written.  During many years I collected notes on the\norigin or descent of man, without any intention of publishing on the\nsubject, but rather with the determination not to publish, as I thought\nthat I should thus only add to the prejudices against my views.  It seemed\nto me sufficient to indicate, in the first edition of my 'Origin of\nSpecies,' that by this work \"light would be thrown on the origin of man and\nhis history;\" and this implies that man must be included with other organic\nbeings in any general conclusion respecting his manner of appearance on\nthis earth.  Now the case wears a wholly different aspect.  When a\nnaturalist like Carl Vogt ventures to say in his address as President of\nthe National Institution of Geneva (1869), \"personne, en Europe au moins,\nn'ose plus soutenir la creation independante et de toutes pieces, des\nespeces,\" it is manifest that at least a large number of naturalists must\nadmit that species are the modified descendants of other species; and this\nespecially holds good with the younger and rising naturalists.  The greater\nnumber accept the agency of natural selection; though some urge, whether\nwith justice the future must decide, that I have greatly overrated its\nimportance.  Of the older and honoured chiefs in natural science, many\nunfortunately are still opposed to evolution in every form.\n\nIn consequence of the views now adopted by most naturalists, and which will\nultimately, as in every other case, be followed by others who are not\nscientific, I have been led to put together my notes, so as to see how far\nthe general conclusions arrived at in my former works were applicable to\nman.  This seemed all the more desirable, as I had never deliberately\napplied these views to a species taken singly.  When we confine our\nattention to any one form, we are deprived of the weighty arguments derived\nfrom the nature of the affinities which connect together whole groups of\norganisms--their geographical distribution in past and present times, and\ntheir geological succession.  The homological structure, embryological\ndevelopment, and rudimentary organs of a species remain to be considered,\nwhether it be man or any other animal, to which our attention may be\ndirected; but these great classes of facts afford, as it appears to me,\nample and conclusive evidence in favour of the principle of gradual\nevolution.  The strong support derived from the other arguments should,\nhowever, always be kept before the mind.\n\nThe sole object of this work is to consider, firstly, whether man, like\nevery other species, is descended from some pre-existing form; secondly,\nthe manner of his development; and thirdly, the value of the differences\nbetween the so-called races of man.  As I shall confine myself to these\npoints, it will not be necessary to describe in detail the differences\nbetween the several races--an enormous subject which has been fully\ndescribed in many valuable works.  The high antiquity of man has recently\nbeen demonstrated by the labours of a host of eminent men, beginning with\nM. Boucher de Perthes; and this is the indispensable basis for\nunderstanding his origin.  I shall, therefore, take this conclusion for\ngranted, and may refer my readers to the admirable treatises of Sir Charles\nLyell, Sir John Lubbock, and others.  Nor shall I have occasion to do more\nthan to allude to the amount of difference between man and the\nanthropomorphous apes; for Prof. Huxley, in the opinion of most competent\njudges, has conclusively shewn that in every visible character man differs\nless from the higher apes, than these do from the lower members of the same\norder of Primates.\n\nThis work contains hardly any original facts in regard to man; but as the\nconclusions at which I arrived, after drawing up a rough draft, appeared to\nme interesting, I thought that they might interest others.  It has often\nand confidently been asserted, that man's origin can never be known:  but\nignorance more frequently begets confidence than does knowledge:  it is\nthose who know little, and not those who know much, who so positively\nassert that this or that problem will never be solved by science.  The\nconclusion that man is the co-descendant with other species of some\nancient, lower, and extinct form, is not in any degree new.  Lamarck long\nago came to this conclusion, which has lately been maintained by several\neminent naturalists and philosophers; for instance, by Wallace, Huxley,\nLyell, Vogt, Lubbock, Buchner, Rolle, etc. (1.  As the works of the first-\nnamed authors are so well known, I need not give the titles; but as those\nof the latter are less well known in England, I will give them:--'Sechs\nVorlesungen ueber die Darwin'sche Theorie:'  zweite Auflage, 1868, von Dr L.\nBuchner; translated into French under the title 'Conferences sur la Theorie\nDarwinienne,' 1869.  'Der Mensch im Lichte der Darwin'sche Lehre,' 1865,\nvon Dr. F. Rolle.  I will not attempt to give references to all the authors\nwho have taken the same side of the question.  Thus G. Canestrini has\npublished ('Annuario della Soc. d. Nat.,' Modena, 1867, page 81) a very\ncurious paper on rudimentary characters, as bearing on the origin of man.\nAnother work has (1869) been published by Dr. Francesco Barrago, bearing in\nItalian the title of \"Man, made in the image of God, was also made in the\nimage of the ape.\"), and especially by Haeckel.  This last naturalist,\nbesides his great work, 'Generelle Morphologie' (1866), has recently (1868,\nwith a second edition in 1870), published his 'Natuerliche\nSchoepfungsgeschichte,' in which he fully discusses the genealogy of man.\nIf this work had appeared before my essay had been written, I should\nprobably never have completed it.  Almost all the conclusions at which I\nhave arrived I find confirmed by this naturalist, whose knowledge on many\npoints is much fuller than mine.  Wherever I have added any fact or view\nfrom Prof. Haeckel's writings, I give his authority in the text; other\nstatements I leave as they originally stood in my manuscript, occasionally\ngiving in the foot-notes references to his works, as a confirmation of the\nmore doubtful or interesting points.\n\nDuring many years it has seemed to me highly probable that sexual selection\nhas played an important part in differentiating the races of man; but in my\n'Origin of Species' (first edition, page 199) I contented myself by merely\nalluding to this belief.  When I came to apply this view to man, I found it\nindispensable to treat the whole subject in full detail.  (2.  Prof.\nHaeckel was the only author who, at the time when this work first appeared,\nhad discussed the subject of sexual selection, and had seen its full\nimportance, since the publication of the 'Origin'; and this he did in a\nvery able manner in his various works.)  Consequently the second part of\nthe present work, treating of sexual selection, has extended to an\ninordinate length, compared with the first part; but this could not be\navoided.\n\nI had intended adding to the present volumes an essay on the expression of\nthe various emotions by man and the lower animals.  My attention was called\nto this subject many years ago by Sir Charles Bell's admirable work.  This\nillustrious anatomist maintains that man is endowed with certain muscles\nsolely for the sake of expressing his emotions.  As this view is obviously\nopposed to the belief that man is descended from some other and lower form,\nit was necessary for me to consider it.  I likewise wished to ascertain how\nfar the emotions are expressed in the same manner by the different races of\nman.  But owing to the length of the present work, I have thought it better\nto reserve my essay for separate publication.\n\n\nPART I.  THE DESCENT OR ORIGIN OF MAN.\n\n\nCHAPTER I.\n\nTHE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM.\n\nNature of the evidence bearing on the origin of man--Homologous structures\nin man and the lower animals--Miscellaneous points of correspondence--\nDevelopment--Rudimentary structures, muscles, sense-organs, hair, bones,\nreproductive organs, etc.--The bearing of these three great classes of\nfacts on the origin of man.\n\nHe who wishes to decide whether man is the modified descendant of some pre-\nexisting form, would probably first enquire whether man varies, however\nslightly, in bodily structure and in mental faculties; and if so, whether\nthe variations are transmitted to his offspring in accordance with the laws\nwhich prevail with the lower animals.  Again, are the variations the\nresult, as far as our ignorance permits us to judge, of the same general\ncauses, and are they governed by the same general laws, as in the case of\nother organisms; for instance, by correlation, the inherited effects of use\nand disuse, etc.?  Is man subject to similar malconformations, the result\nof arrested development, of reduplication of parts, etc., and does he\ndisplay in any of his anomalies reversion to some former and ancient type\nof structure?  It might also naturally be enquired whether man, like so\nmany other animals, has given rise to varieties and sub-races, differing\nbut slightly from each other, or to races differing so much that they must\nbe classed as doubtful species?  How are such races distributed over the\nworld; and how, when crossed, do they react on each other in the first and\nsucceeding generations?  And so with many other points.\n\nThe enquirer would next come to the important point, whether man tends to\nincrease at so rapid a rate, as to lead to occasional severe struggles for\nexistence; and consequently to beneficial variations, whether in body or\nmind, being preserved, and injurious ones eliminated.  Do the races or\nspecies of men, whichever term may be applied, encroach on and replace one\nanother, so that some finally become extinct?  We shall see that all these\nquestions, as indeed is obvious in respect to most of them, must be\nanswered in the affirmative, in the same manner as with the lower animals.\nBut the several considerations just referred to may be conveniently\ndeferred for a time:  and we will first see how far the bodily structure of\nman shews traces, more or less plain, of his descent from some lower form.\nIn succeeding chapters the mental powers of man, in comparison with those\nof the lower animals, will be considered.\n\nTHE BODILY STRUCTURE OF MAN.\n\nIt is notorious that man is constructed on the same general type or model\nas other mammals.  All the bones in his skeleton can be compared with\ncorresponding bones in a monkey, bat, or seal.  So it is with his muscles,\nnerves, blood-vessels and internal viscera.  The brain, the most important\nof all the organs, follows the same law, as shewn by Huxley and other\nanatomists.  Bischoff (1. 'Grosshirnwindungen des Menschen,' 1868, s. 96.\nThe conclusions of this author, as well as those of Gratiolet and Aeby,\nconcerning the brain, will be discussed by Prof. Huxley in the Appendix\nalluded to in the Preface to this edition.), who is a hostile witness,\nadmits that every chief fissure and fold in the brain of man has its\nanalogy in that of the orang; but he adds that at no period of development\ndo their brains perfectly agree; nor could perfect agreement be expected,\nfor otherwise their mental powers would have been the same.  Vulpian (2.\n'Lec. sur la Phys.' 1866, page 890, as quoted by M. Dally, 'L'Ordre des\nPrimates et le Transformisme,' 1868, page 29.), remarks:  \"Les differences\nreelles qui existent entre l'encephale de l'homme et celui des singes\nsuperieurs, sont bien minimes.  Il ne faut pas se faire d'illusions a cet\negard.  L'homme est bien plus pres des singes anthropomorphes par les\ncaracteres anatomiques de son cerveau que ceux-ci ne le sont non seulement\ndes autres mammiferes, mais meme de certains quadrumanes, des guenons et\ndes macaques.\"  But it would be superfluous here to give further details on\nthe correspondence between man and the higher mammals in the structure of\nthe brain and all other parts of the body.\n\nIt may, however, be worth while to specify a few points, not directly or\nobviously connected with structure, by which this correspondence or\nrelationship is well shewn.\n\nMan is liable to receive from the lower animals, and to communicate to\nthem, certain diseases, as hydrophobia, variola, the glanders, syphilis,\ncholera, herpes, etc. (3.  Dr. W. Lauder Lindsay has treated this subject\nat some length in the 'Journal of Mental Science,' July 1871; and in the\n'Edinburgh Veterinary Review,' July 1858.); and this fact proves the close\nsimilarity (4.  A Reviewer has criticised ('British Quarterly Review,' Oct.\n1st, 1871, page 472) what I have here said with much severity and contempt;\nbut as I do not use the term identity, I cannot see that I am greatly in\nerror.  There appears to me a strong analogy between the same infection or\ncontagion producing the same result, or one closely similar, in two\ndistinct animals, and the testing of two distinct fluids by the same\nchemical reagent.) of their tissues and blood, both in minute structure and\ncomposition, far more plainly than does their comparison under the best\nmicroscope, or by the aid of the best chemical analysis.  Monkeys are\nliable to many of the same non-contagious diseases as we are; thus Rengger\n(5.  'Naturgeschichte der Saeugethiere von Paraguay,' 1830, s. 50.), who\ncarefully observed for a long time the Cebus Azarae in its native land,\nfound it liable to catarrh, with the usual symptoms, and which, when often\nrecurrent, led to consumption.  These monkeys suffered also from apoplexy,\ninflammation of the bowels, and cataract in the eye.  The younger ones when\nshedding their milk-teeth often died from fever.  Medicines produced the\nsame effect on them as on us.  Many kinds of monkeys have a strong taste\nfor tea, coffee, and spiritous liquors:  they will also, as I have myself\nseen, smoke tobacco with pleasure.  (6.  The same tastes are common to some\nanimals much lower in the scale.  Mr. A. Nichols informs me that he kept in\nQueensland, in Australia, three individuals of the Phaseolarctus cinereus;\nand that, without having been taught in any way, they acquired a strong\ntaste for rum, and for smoking tobacco.)  Brehm asserts that the natives of\nnorth-eastern Africa catch the wild baboons by exposing vessels with strong\nbeer, by which they are made drunk.  He has seen some of these animals,\nwhich he kept in confinement, in this state; and he gives a laughable\naccount of their behaviour and strange grimaces.  On the following morning\nthey were very cross and dismal; they held their aching heads with both\nhands, and wore a most pitiable expression:  when beer or wine was offered\nthem, they turned away with disgust, but relished the juice of lemons.  (7.\nBrehm, 'Thierleben,' B. i. 1864, s. 75, 86.  On the Ateles, s. 105.  For\nother analogous statements, see s. 25, 107.)  An American monkey, an\nAteles, after getting drunk on brandy, would never touch it again, and thus\nwas wiser than many men.  These trifling facts prove how similar the nerves\nof taste must be in monkeys and man, and how similarly their whole nervous\nsystem is affected.\n\nMan is infested with internal parasites, sometimes causing fatal effects;\nand is plagued by external parasites, all of which belong to the same\ngenera or families as those infesting other mammals, and in the case of\nscabies to the same species.  (8.  Dr. W. Lauder Lindsay, 'Edinburgh Vet.\nReview,' July 1858, page 13.)  Man is subject, like other mammals, birds,\nand even insects (9.  With respect to insects see Dr. Laycock, \"On a\nGeneral Law of Vital Periodicity,\" 'British Association,' 1842.  Dr.\nMacculloch, 'Silliman's North American Journal of Science,' vol. XVII. page\n305, has seen a dog suffering from tertian ague.  Hereafter I shall return\nto this subject.), to that mysterious law, which causes certain normal\nprocesses, such as gestation, as well as the maturation and duration of\nvarious diseases, to follow lunar periods.  His wounds are repaired by the\nsame process of healing; and the stumps left after the amputation of his\nlimbs, especially during an early embryonic period, occasionally possess\nsome power of regeneration, as in the lowest animals.  (10.  I have given\nthe evidence on this head in my 'Variation of Animals and Plants under\nDomestication,' vol. ii. page 15, and more could be added.)\n\nThe whole process of that most important function, the reproduction of the\nspecies, is strikingly the same in all mammals, from the first act of\ncourtship by the male (11.  Mares e diversis generibus Quadrumanorum sine\ndubio dignoscunt feminas humanas a maribus.  Primum, credo, odoratu, postea\naspectu.  Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus\nanimalium erat, vir in rebus observandis cautus et sagax, hoc mihi\ncertissime probavit, et curatores ejusdem loci et alii e ministris\nconfirmaverunt.  Sir Andrew Smith et Brehm notabant idem in Cynocephalo.\nIllustrissimus Cuvier etiam narrat multa de hac re, qua ut opinor, nihil\nturpius potest indicari inter omnia hominibus et Quadrumanis communia.\nNarrat enim Cynocephalum quendam in furorem incidere aspectu feminarum\naliquarem, sed nequaquam accendi tanto furore ab omnibus.  Semper eligebat\njuniores, et dignoscebat in turba, et advocabat voce gestuque.), to the\nbirth and nurturing of the young.  Monkeys are born in almost as helpless a\ncondition as our own infants; and in certain genera the young differ fully\nas much in appearance from the adults, as do our children from their\nfull-grown parents.  (12.  This remark is made with respect to Cynocephalus\nand the anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier,\n'Histoire Nat. des Mammiferes,' tom. i. 1824.)  It has been urged by some\nwriters, as an important distinction, that with man the young arrive at\nmaturity at a much later age than with any other animal: but if we look to\nthe races of mankind which inhabit tropical countries the difference is not\ngreat, for the orang is believed not to be adult till the age of from ten\nto fifteen years.  (13.  Huxley, 'Man's Place in Nature,' 1863, p. 34.)\nMan differs from woman in size, bodily strength, hairiness, etc., as well\nas in mind, in the same manner as do the two sexes of many mammals.  So\nthat the correspondence in general structure, in the minute structure of\nthe tissues, in chemical composition and in constitution, between man and\nthe higher animals, especially the anthropomorphous apes, is extremely\nclose.\n\nEMBRYONIC DEVELOPMENT.\n\n[Fig. 1.  Shows a human embryo, from Ecker, and a dog embryo, from\nBischoff.  Labelled in each are:\n\na.  Fore-brain, cerebral hemispheres, etc.\nb.  Mid-brain, corpora quadrigemina.\nc.  Hind-brain, cerebellum, medulla oblongata.\nd.  Eye.\ne.  Ear.\nf.  First visceral arch.\ng.  Second visceral arch.\nH.  Vertebral columns and muscles in process of development.\ni.  Anterior extremities.\nK.  Posterior extremities.\nL.  Tail or os coccyx.]\n\nMan is developed from an ovule, about the 125th of an inch in diameter,\nwhich differs in no respect from the ovules of other animals.  The embryo\nitself at a very early period can hardly be distinguished from that of\nother members of the vertebrate kingdom.  At this period the arteries run\nin arch-like branches, as if to carry the blood to branchiae which are not\npresent in the higher Vertebrata, though the slits on the sides of the neck\nstill remain (see f, g, fig. 1), marking their former position.  At a\nsomewhat later period, when the extremities are developed, \"the feet of\nlizards and mammals,\" as the illustrious Von Baer remarks, \"the wings and\nfeet of birds, no less than the hands and feet of man, all arise from the\nsame fundamental form.\"  It is, says Prof. Huxley (14.  'Man's Place in\nNature,' 1863, p. 67.), \"quite in the later stages of development that the\nyoung human being presents marked differences from the young ape, while the\nlatter departs as much from the dog in its developments, as the man does.\nStartling as this last assertion may appear to be, it is demonstrably\ntrue.\"\n\nAs some of my readers may never have seen a drawing of an embryo, I have\ngiven one of man and another of a dog, at about the same early stage of\ndevelopment, carefully copied from two works of undoubted accuracy.  (15.\nThe human embryo (upper fig.) is from Ecker, 'Icones Phys.,' 1851-1859,\ntab. xxx. fig. 2.  This embryo was ten lines in length, so that the drawing\nis much magnified.  The embryo of the dog is from Bischoff,\n'Entwicklungsgeschichte des Hunde-Eies,' 1845, tab. xi. fig. 42B.  This\ndrawing is five times magnified, the embryo being twenty-five days old.\nThe internal viscera have been omitted, and the uterine appendages in both\ndrawings removed.  I was directed to these figures by Prof. Huxley, from\nwhose work, 'Man's Place in Nature,' the idea of giving them was taken.\nHaeckel has also given analogous drawings in his 'Schopfungsgeschichte.')\n\nAfter the foregoing statements made by such high authorities, it would be\nsuperfluous on my part to give a number of borrowed details, shewing that\nthe embryo of man closely resembles that of other mammals.  It may,\nhowever, be added, that the human embryo likewise resembles certain low\nforms when adult in various points of structure.  For instance, the heart\nat first exists as a simple pulsating vessel; the excreta are voided\nthrough a cloacal passage; and the os coccyx projects like a true tail,\n\"extending considerably beyond the rudimentary legs.\"  (16.  Prof. Wyman in\n'Proceedings of the American Academy of Sciences,' vol. iv. 1860, p. 17.)\nIn the embryos of all air-breathing vertebrates, certain glands, called the\ncorpora Wolffiana, correspond with, and act like the kidneys of mature\nfishes.  (17.  Owen, 'Anatomy of Vertebrates,' vol. i. p. 533.)  Even at a\nlater embryonic period, some striking resemblances between man and the\nlower animals may be observed.  Bischoff says that \"the convolutions of the\nbrain in a human foetus at the end of the seventh month reach about the\nsame stage of development as in a baboon when adult.\"  (18.  'Die\nGrosshirnwindungen des Menschen,' 1868, s. 95.)  The great toe, as\nProfessor Owen remarks (19.  'Anatomy of Vertebrates,' vol. ii. p. 553.),\n\"which forms the fulcrum when standing or walking, is perhaps the most\ncharacteristic peculiarity in the human structure;\" but in an embryo, about\nan inch in length, Prof. Wyman (20.  'Proc. Soc. Nat. Hist.' Boston, 1863,\nvol. ix. p. 185.) found \"that the great toe was shorter than the others;\nand, instead of being parallel to them, projected at an angle from the side\nof the foot, thus corresponding with the permanent condition of this part\nin the quadrumana.\"  I will conclude with a quotation from Huxley (21.\n'Man's Place in Nature,' p. 65.) who after asking, does man originate in a\ndifferent way from a dog, bird, frog or fish? says, \"the reply is not\ndoubtful for a moment; without question, the mode of origin, and the early\nstages of the development of man, are identical with those of the animals\nimmediately below him in the scale: without a doubt in these respects, he\nis far nearer to apes than the apes are to the dog.\"\n\nRUDIMENTS.\n\nThis subject, though not intrinsically more important than the two last,\nwill for several reasons be treated here more fully.  (22.  I had written a\nrough copy of this chapter before reading a valuable paper, \"Caratteri\nrudimentali in ordine all' origine dell' uomo\" ('Annuario della Soc. d.\nNaturalisti,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am\nconsiderably indebted.  Haeckel has given admirable discussions on this\nwhole subject, under the title of Dysteleology, in his 'Generelle\nMorphologie' and 'Schoepfungsgeschichte.')  Not one of the higher animals\ncan be named which does not bear some part in a rudimentary condition; and\nman forms no exception to the rule.  Rudimentary organs must be\ndistinguished from those that are nascent; though in some cases the\ndistinction is not easy.  The former are either absolutely useless, such as\nthe mammae of male quadrupeds, or the incisor teeth of ruminants which\nnever cut through the gums; or they are of such slight service to their\npresent possessors, that we can hardly suppose that they were developed\nunder the conditions which now exist.  Organs in this latter state are not\nstrictly rudimentary, but they are tending in this direction.  Nascent\norgans, on the other hand, though not fully developed, are of high service\nto their possessors, and are capable of further development.  Rudimentary\norgans are eminently variable; and this is partly intelligible, as they are\nuseless, or nearly useless, and consequently are no longer subjected to\nnatural selection.  They often become wholly suppressed.  When this occurs,\nthey are nevertheless liable to occasional reappearance through reversion--\na circumstance well worthy of attention.\n\nThe chief agents in causing organs to become rudimentary seem to have been\ndisuse at that period of life when the organ is chiefly used (and this is\ngenerally during maturity), and also inheritance at a corresponding period\nof life.  The term \"disuse\" does not relate merely to the lessened action\nof muscles, but includes a diminished flow of blood to a part or organ,\nfrom being subjected to fewer alternations of pressure, or from becoming in\nany way less habitually active.  Rudiments, however, may occur in one sex\nof those parts which are normally present in the other sex; and such\nrudiments, as we shall hereafter see, have often originated in a way\ndistinct from those here referred to.  In some cases, organs have been\nreduced by means of natural selection, from having become injurious to the\nspecies under changed habits of life.  The process of reduction is probably\noften aided through the two principles of compensation and economy of\ngrowth; but the later stages of reduction, after disuse has done all that\ncan fairly be attributed to it, and when the saving to be effected by the\neconomy of growth would be very small (23.  Some good criticisms on this\nsubject have been given by Messrs. Murie and Mivart, in 'Transact.\nZoological Society,' 1869, vol. vii. p. 92.), are difficult to understand.\nThe final and complete suppression of a part, already useless and much\nreduced in size, in which case neither compensation nor economy can come\ninto play, is perhaps intelligible by the aid of the hypothesis of\npangenesis.  But as the whole subject of rudimentary organs has been\ndiscussed and illustrated in my former works (24.  'Variation of Animals\nand Plants under Domestication,' vol. ii pp. 317 and 397.  See also 'Origin\nof Species,' 5th Edition p. 535.), I need here say no more on this head.\n\nRudiments of various muscles have been observed in many parts of the human\nbody (25.  For instance, M. Richard ('Annales des Sciences Nat.,' 3rd\nseries, Zoolog. 1852, tom. xviii. p. 13) describes and figures rudiments of\nwhat he calls the \"muscle pedieux de la main,\" which he says is sometimes\n\"infiniment petit.\"  Another muscle, called \"le tibial posterieur,\" is\ngenerally quite absent in the hand, but appears from time to time in a more\nor less rudimentary condition.); and not a few muscles, which are regularly\npresent in some of the lower animals can occasionally be detected in man in\na greatly reduced condition.  Every one must have noticed the power which\nmany animals, especially horses, possess of moving or twitching their skin;\nand this is effected by the panniculus carnosus.  Remnants of this muscle\nin an efficient state are found in various parts of our bodies; for\ninstance, the muscle on the forehead, by which the eyebrows are raised.\nThe platysma myoides, which is well developed on the neck, belongs to this\nsystem.  Prof. Turner, of Edinburgh, has occasionally detected, as he\ninforms me, muscular fasciculi in five different situations, namely in the\naxillae, near the scapulae, etc., all of which must be referred to the\nsystem of the panniculus.  He has also shewn (26.  Prof. W. Turner,\n'Proceedings of the Royal Society of Edinburgh,' 1866-67, p. 65.) that the\nmusculus sternalis or sternalis brutorum, which is not an extension of the\nrectus abdominalis, but is closely allied to the panniculus, occurred in\nthe proportion of about three per cent. in upwards of 600 bodies:  he adds,\nthat this muscle affords \"an excellent illustration of the statement that\noccasional and rudimentary structures are especially liable to variation in\narrangement.\"\n\nSome few persons have the power of contracting the superficial muscles on\ntheir scalps; and these muscles are in a variable and partially rudimentary\ncondition.  M. A. de Candolle has communicated to me a curious instance of\nthe long-continued persistence or inheritance of this power, as well as of\nits unusual development.  He knows a family, in which one member, the\npresent head of the family, could, when a youth, pitch several heavy books\nfrom his head by the movement of the scalp alone; and he won wagers by\nperforming this feat.  His father, uncle, grandfather, and his three\nchildren possess the same power to the same unusual degree.  This family\nbecame divided eight generations ago into two branches; so that the head of\nthe above-mentioned branch is cousin in the seventh degree to the head of\nthe other branch.  This distant cousin resides in another part of France;\nand on being asked whether he possessed the same faculty, immediately\nexhibited his power.  This case offers a good illustration how persistent\nmay be the transmission of an absolutely useless faculty, probably derived\nfrom our remote semi-human progenitors; since many monkeys have, and\nfrequently use the power, of largely moving their scalps up and down.  (27.\nSee my 'Expression of the Emotions in Man and Animals,' 1872, p. 144.)\n\nThe extrinsic muscles which serve to move the external ear, and the\nintrinsic muscles which move the different parts, are in a rudimentary\ncondition in man, and they all belong to the system of the panniculus; they\nare also variable in development, or at least in function.  I have seen one\nman who could draw the whole ear forwards; other men can draw it upwards;\nanother who could draw it backwards (28.  Canestrini quotes Hyrtl.\n('Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 97) to the same\neffect.); and from what one of these persons told me, it is probable that\nmost of us, by often touching our ears, and thus directing our attention\ntowards them, could recover some power of movement by repeated trials.  The\npower of erecting and directing the shell of the ears to the various points\nof the compass, is no doubt of the highest service to many animals, as they\nthus perceive the direction of danger; but I have never heard, on\nsufficient evidence, of a man who possessed this power, the one which might\nbe of use to him.  The whole external shell may be considered a rudiment,\ntogether with the various folds and prominences (helix and anti-helix,\ntragus and anti-tragus, etc.) which in the lower animals strengthen and\nsupport the ear when erect, without adding much to its weight.  Some\nauthors, however, suppose that the cartilage of the shell serves to\ntransmit vibrations to the acoustic nerve; but Mr. Toynbee (29.  'The\nDiseases of the Ear,' by J. Toynbee, F.R.S., 1860, p. 12.  A distinguished\nphysiologist, Prof. Preyer, informs me that he had lately been\nexperimenting on the function of the shell of the ear, and has come to\nnearly the same conclusion as that given here.), after collecting all the\nknown evidence on this head, concludes that the external shell is of no\ndistinct use.  The ears of the chimpanzee and orang are curiously like\nthose of man, and the proper muscles are likewise but very slightly\ndeveloped.  (30.  Prof. A. Macalister, 'Annals and Magazine of Natural\nHistory,' vol. vii. 1871, p. 342.)  I am also assured by the keepers in the\nZoological Gardens that these animals never move or erect their ears; so\nthat they are in an equally rudimentary condition with those of man, as far\nas function is concerned.  Why these animals, as well as the progenitors of\nman, should have lost the power of erecting their ears, we cannot say.  It\nmay be, though I am not satisfied with this view, that owing to their\narboreal habits and great strength they were but little exposed to danger,\nand so during a lengthened period moved their ears but little, and thus\ngradually lost the power of moving them.  This would be a parallel case\nwith that of those large and heavy birds, which, from ihabiting oceanic\nislands, have not been exposed to the attacks of beasts of prey, and have\nconsequently lost the power of using their wings for flight.  The inability\nto move the ears in man and several apes is, however, partly compensated by\nthe freedom with which they can move the head in a horizontal plane, so as\nto catch sounds from all directions.  It has been asserted that the ear of\nman alone possesses a lobule; but \"a rudiment of it is found in the\ngorilla\" (31.  Mr. St. George Mivart, 'Elementary Anatomy,' 1873, p. 396.);\nand, as I hear from Prof. Preyer, it is not rarely absent in the negro.\n\n[Fig. 2. Human Ear, modelled and drawn by Mr. Woolner.  The projecting\npoint is labelled a.]\n\nThe celebrated sculptor, Mr. Woolner, informs me of one little peculiarity\nin the external ear, which he has often observed both in men and women, and\nof which he perceived the full significance.  His attention was first\ncalled to the subject whilst at work on his figure of Puck, to which he had\ngiven pointed ears.  He was thus led to examine the ears of various\nmonkeys, and subsequently more carefully those of man.  The peculiarity\nconsists in a little blunt point, projecting from the inwardly folded\nmargin, or helix.  When present, it is developed at birth, and, according\nto Prof. Ludwig Meyer, more frequently in man than in woman.  Mr. Woolner\nmade an exact model of one such case, and sent me the accompanying drawing.\n(Fig. 2).  These points not only project inwards towards the centre of the\near, but often a little outwards from its plane, so as to be visible when\nthe head is viewed from directly in front or behind.  They are variable in\nsize, and somewhat in position, standing either a little higher or lower;\nand they sometimes occur on one ear and not on the other.  They are not\nconfined to mankind, for I observed a case in one of the spider-monkeys\n(Ateles beelzebuth) in our Zoological Gardens; and Mr. E. Ray Lankester\ninforms me of another case in a chimpanzee in the gardens at Hamburg.  The\nhelix obviously consists of the extreme margin of the ear folded inwards;\nand this folding appears to be in some manner connected with the whole\nexternal ear being permanently pressed backwards.  In many monkeys, which\ndo not stand high in the order, as baboons and some species of macacus (32.\nSee also some remarks, and the drawings of the ears of the Lemuroidea, in\nMessrs. Murie and Mivart's excellent paper in 'Transactions of the\nZoological Society,' vol. vii. 1869, pp. 6 and 90.), the upper portion of\nthe ear is slightly pointed, and the margin is not at all folded inwards;\nbut if the margin were to be thus folded, a slight point would necessarily\nproject inwards towards the centre, and probably a little outwards from the\nplane of the ear; and this I believe to be their origin in many cases.  On\nthe other hand, Prof. L. Meyer, in an able paper recently published (33.\n'Ueber das Darwin'sche Spitzohr,' Archiv fur Path. Anat. und Phys., 1871, p.\n485.), maintains that the whole case is one of mere variability; and that\nthe projections are not real ones, but are due to the internal cartilage on\neach side of the points not having been fully developed.  I am quite ready\nto admit that this is the correct explanation in many instances, as in\nthose figured by Prof. Meyer, in which there are several minute points, or\nthe whole margin is sinuous.  I have myself seen, through the kindness of\nDr. L. Down, the ear of a microcephalous idiot, on which there is a\nprojection on the outside of the helix, and not on the inward folded edge,\nso that this point can have no relation to a former apex of the ear.\nNevertheless in some cases, my original view, that the points are vestiges\nof the tips of formerly erect and pointed ears, still seems to me probable.\nI think so from the frequency of their occurrence, and from the general\ncorrespondence in position with that of the tip of a pointed ear.  In one\ncase, of which a photograph has been sent me, the projection is so large,\nthat supposing, in accordance with Prof. Meyer's view, the ear to be made\nperfect by the equal development of the cartilage throughout the whole\nextent of the margin, it would have covered fully one-third of the whole\near.  Two cases have been communicated to me, one in North America, and the\nother in England, in which the upper margin is not at all folded inwards,\nbut is pointed, so that it closely resembles the pointed ear of an ordinary\nquadruped in outline.  In one of these cases, which was that of a young\nchild, the father compared the ear with the drawing which I have given (34.\n'The Expression of the Emotions,' p. 136.) of the ear of a monkey, the\nCynopithecus niger, and says that their outlines are closely similar.  If,\nin these two cases, the margin had been folded inwards in the normal\nmanner, an inward projection must have been formed.  I may add that in two\nother cases the outline still remains somewhat pointed, although the margin\nof the upper part of the ear is normally folded inwards--in one of them,\nhowever, very narrowly.  [Fig.3.  Foetus of an Orang(?).  Exact copy of a\nphotograph, shewing the form of the ear at this early age.]  The following\nwoodcut (No. 3) is an accurate copy of a photograph of the foetus of an\norang (kindly sent me by Dr. Nitsche), in which it may be seen how\ndifferent the pointed outline of the ear is at this period from its adult\ncondition, when it bears a close general resemblance to that of man.  It is\nevident that the folding over of the tip of such an ear, unless it changed\ngreatly during its further development, would give rise to a point\nprojecting inwards.  On the whole, it still seems to me probable that the\npoints in question are in some cases, both in man and apes, vestiges of a\nformer condition.\n\nThe nictitating membrane, or third eyelid, with its accessory muscles and\nother structures, is especially well developed in birds, and is of much\nfunctional importance to them, as it can be rapidly drawn across the whole\neye-ball.  It is found in some reptiles and amphibians, and in certain\nfishes, as in sharks.  It is fairly well developed in the two lower\ndivisions of the mammalian series, namely, in the monotremata and\nmarsupials, and in some few of the higher mammals, as in the walrus.  But\nin man, the quadrumana, and most other mammals, it exists, as is admitted\nby all anatomists, as a mere rudiment, called the semilunar fold.  (35.\nMuller's 'Elements of Physiology,' Eng. translat. 1842, vol. ii. p. 1117.\nOwen, 'Anatomy of Vertebrates,' vol. iii. p. 260; ibid. on the Walrus,\n'Proceedings of the Zoological Society,' November 8, 1854.  See also R.\nKnox, 'Great Artists and Anatomists,' p. 106.  This rudiment apparently is\nsomewhat larger in Negroes and Australians than in Europeans, see Carl\nVogt, 'Lectures on Man,' Eng. translat. p. 129.)\n\nThe sense of smell is of the highest importance to the greater number of\nmammals--to some, as the ruminants, in warning them of danger; to others,\nas the Carnivora, in finding their prey; to others, again, as the wild\nboar, for both purposes combined.  But the sense of smell is of extremely\nslight service, if any, even to the dark coloured races of men, in whom it\nis much more highly developed than in the white and civilised races.  (36.\nThe account given by Humboldt of the power of smell possessed by the\nnatives of South America is well known, and has been confirmed by others.\nM. Houzeau ('Etudes sur les Facultes Mentales,' etc., tom. i. 1872, p. 91)\nasserts that he repeatedly made experiments, and proved that Negroes and\nIndians could recognise persons in the dark by their odour.  Dr. W. Ogle\nhas made some curious observations on the connection between the power of\nsmell and the colouring matter of the mucous membrane of the olfactory\nregion as well as of the skin of the body.  I have, therefore, spoken in\nthe text of the dark-coloured races having a finer sense of smell than the\nwhite races.  See his paper, 'Medico-Chirurgical Transactions,' London,\nvol. liii. 1870, p. 276.)  Nevertheless it does not warn them of danger,\nnor guide them to their food; nor does it prevent the Esquimaux from\nsleeping in the most fetid atmosphere, nor many savages from eating\nhalf-putrid meat.  In Europeans the power differs greatly in different\nindividuals, as I am assured by an eminent naturalist who possesses this\nsense highly developed, and who has attended to the subject.  Those who\nbelieve in the principle of gradual evolution, will not readily admit that\nthe sense of smell in its present state was originally acquired by man, as\nhe now exists.  He inherits the power in an enfeebled and so far\nrudimentary condition, from some early progenitor, to whom it was highly\nserviceable, and by whom it was continually used.  In those animals which\nhave this sense highly developed, such as dogs and horses, the recollection\nof persons and of places is strongly associated with their odour; and we\ncan thus perhaps understand how it is, as Dr. Maudsley has truly remarked\n(37.  'The Physiology and Pathology of Mind,' 2nd ed. 1868, p. 134.), that\nthe sense of smell in man \"is singularly effective in recalling vividly the\nideas and images of forgotten scenes and places.\"\n\nMan differs conspicuously from all the other primates in being almost\nnaked.  But a few short straggling hairs are found over the greater part of\nthe body in the man, and fine down on that of the woman.  The different\nraces differ much in hairiness; and in the individuals of the same race the\nhairs are highly variable, not only in abundance, but likewise in position:\nthus in some Europeans the shoulders are quite naked, whilst in others they\nbear thick tufts of hair.  (38.  Eschricht, Ueber die Richtung der Haare am\nmenschlichen Koerper, Muller's 'Archiv fur Anat. und Phys.' 1837, s. 47.  I\nshall often have to refer to this very curious paper.)  There can be little\ndoubt that the hairs thus scattered over the body are the rudiments of the\nuniform hairy coat of the lower animals.  This view is rendered all the\nmore probable, as it is known that fine, short, and pale-coloured hairs on\nthe limbs and other parts of the body, occasionally become developed into\n\"thickset, long, and rather coarse dark hairs,\" when abnormally nourished\nnear old-standing inflamed surfaces.  (39.  Paget, 'Lectures on Surgical\nPathology,' 1853, vol. i. p. 71.)\n\nI am informed by Sir James Paget that often several members of a family\nhave a few hairs in their eyebrows much longer than the others; so that\neven this slight peculiarity seems to be inherited.  These hairs, too, seem\nto have their representatives; for in the chimpanzee, and in certain\nspecies of Macacus, there are scattered hairs of considerable length rising\nfrom the naked skin above the eyes, and corresponding to our eyebrows;\nsimilar long hairs project from the hairy covering of the superciliary\nridges in some baboons.\n\nThe fine wool-like hair, or so-called lanugo, with which the human foetus\nduring the sixth month is thickly covered, offers a more curious case.  It\nis first developed, during the fifth month, on the eyebrows and face, and\nespecially round the mouth, where it is much longer than that on the head.\nA moustache of this kind was observed by Eschricht (40.  Eschricht, ibid.\ns. 40, 47.) on a female foetus; but this is not so surprising a\ncircumstance as it may at first appear, for the two sexes generally\nresemble each other in all external characters during an early period of\ngrowth.  The direction and arrangement of the hairs on all parts of the\nfoetal body are the same as in the adult, but are subject to much\nvariability.  The whole surface, including even the forehead and ears, is\nthus thickly clothed; but it is a significant fact that the palms of the\nhands and the soles of the feet are quite naked, like the inferior surfaces\nof all four extremities in most of the lower animals.  As this can hardly\nbe an accidental coincidence, the woolly covering of the foetus probably\nrepresents the first permanent coat of hair in those mammals which are born\nhairy.  Three or four cases have been recorded of persons born with their\nwhole bodies and faces thickly covered with fine long hairs; and this\nstrange condition is strongly inherited, and is correlated with an abnormal\ncondition of the teeth.  (41.  See my 'Variation of Animals and Plants\nunder Domestication,' vol. ii. p. 327.  Prof. Alex. Brandt has recently\nsent me an additional case of a father and son, born in Russia, with these\npeculiarities.  I have received drawings of both from Paris.)  Prof. Alex.\nBrandt informs me that he has compared the hair from the face of a man thus\ncharacterised, aged thirty-five, with the lanugo of a foetus, and finds it\nquite similar in texture; therefore, as he remarks, the case may be\nattributed to an arrest of development in the hair, together with its\ncontinued growth.  Many delicate children, as I have been assured by a\nsurgeon to a hospital for children, have their backs covered by rather long\nsilky hairs; and such cases probably come under the same head.\n\nIt appears as if the posterior molar or wisdom-teeth were tending to become\nrudimentary in the more civilised races of man.  These teeth are rather\nsmaller than the other molars, as is likewise the case with the\ncorresponding teeth in the chimpanzee and orang; and they have only two\nseparate fangs.  They do not cut through the gums till about the\nseventeenth year, and I have been assured that they are much more liable to\ndecay, and are earlier lost than the other teeth; but this is denied by\nsome eminent dentists.  They are also much more liable to vary, both in\nstructure and in the period of their development, than the other teeth.\n(42.  Dr. Webb, 'Teeth in Man and the Anthropoid Apes,' as quoted by Dr. C.\nCarter Blake in Anthropological Review, July 1867, p. 299.)  In the\nMelanian races, on the other hand, the wisdom-teeth are usually furnished\nwith three separate fangs, and are generally sound; they also differ from\nthe other molars in size, less than in the Caucasian races. (43.  Owen,\n'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, and 325.)  Prof.\nSchaaffhausen accounts for this difference between the races by \"the\nposterior dental portion of the jaw being always shortened\" in those that\nare civilised (44.  'On the Primitive Form of the Skull,' Eng. translat.,\nin 'Anthropological Review,' Oct. 1868, p. 426), and this shortening may, I\npresume, be attributed to civilised men habitually feeding on soft, cooked\nfood, and thus using their jaws less.  I am informed by Mr. Brace that it\nis becoming quite a common practice in the United States to remove some of\nthe molar teeth of children, as the jaw does not grow large enough for the\nperfect development of the normal number.  (45.  Prof. Montegazza writes to\nme from Florence, that he has lately been studying the last molar teeth in\nthe different races of man, and has come to the same conclusion as that\ngiven in my text, viz., that in the higher or civilised races they are on\nthe road towards atrophy or elimination.)\n\nWith respect to the alimentary canal, I have met with an account of only a\nsingle rudiment, namely the vermiform appendage of the caecum.  The caecum\nis a branch or diverticulum of the intestine, ending in a cul-de-sac, and\nis extremely long in many of the lower vegetable-feeding mammals.  In the\nmarsupial koala it is actually more than thrice as long as the whole body.\n(46.  Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441.)  It is\nsometimes produced into a long gradually-tapering point, and is sometimes\nconstricted in parts.  It appears as if, in consequence of changed diet or\nhabits, the caecum had become much shortened in various animals, the\nvermiform appendage being left as a rudiment of the shortened part.  That\nthis appendage is a rudiment, we may infer from its small size, and from\nthe evidence which Prof. Canestrini (47.  'Annuario della Soc. d. Nat.'\nModena, 1867, p. 94.) has collected of its variability in man.  It is\noccasionally quite absent, or again is largely developed.  The passage is\nsometimes completely closed for half or two-thirds of its length, with the\nterminal part consisting of a flattened solid expansion.  In the orang this\nappendage is long and convoluted:  in man it arises from the end of the\nshort caecum, and is commonly from four to five inches in length, being\nonly about the third of an inch in diameter.  Not only is it useless, but\nit is sometimes the cause of death, of which fact I have lately heard two\ninstances:  this is due to small hard bodies, such as seeds, entering the\npassage, and causing inflammation.  (48.  M. C. Martins (\"De l'Unite\nOrganique,\" in 'Revue des Deux Mondes,' June 15, 1862, p. 16) and Haeckel\n('Generelle Morphologie,' B. ii. s. 278), have both remarked on the\nsingular fact of this rudiment sometimes causing death.)\n\nIn some of the lower Quadrumana, in the Lemuridae and Carnivora, as well as\nin many marsupials, there is a passage near the lower end of the humerus,\ncalled the supra-condyloid foramen, through which the great nerve of the\nfore limb and often the great artery pass.  Now in the humerus of man,\nthere is generally a trace of this passage, which is sometimes fairly well\ndeveloped, being formed by a depending hook-like process of bone, completed\nby a band of ligament.  Dr. Struthers (49.  With respect to inheritance,\nsee Dr. Struthers in the 'Lancet,' Feb. 15, 1873, and another important\npaper, ibid. Jan. 24, 1863, p. 83.  Dr. Knox, as I am informed, was the\nfirst anatomist who drew attention to this peculiar structure in man; see\nhis 'Great Artists and Anatomists,' p. 63.  See also an important memoir on\nthis process by Dr. Gruber, in the 'Bulletin de l'Acad. Imp. de St.\nPetersbourg,' tom. xii. 1867, p. 448.), who has closely attended to the\nsubject, has now shewn that this peculiarity is sometimes inherited, as it\nhas occurred in a father, and in no less than four out of his seven\nchildren.  When present, the great nerve invariably passes through it; and\nthis clearly indicates that it is the homologue and rudiment of the\nsupra-condyloid foramen of the lower animals.  Prof. Turner estimates, as\nhe informs me, that it occurs in about one per cent. of recent skeletons.\nBut if the occasional development of this structure in man is, as seems\nprobable, due to reversion, it is a return to a very ancient state of\nthings, because in the higher Quadrumana it is absent.\n\nThere is another foramen or perforation in the humerus, occasionally\npresent in man, which may be called the inter-condyloid.  This occurs, but\nnot constantly, in various anthropoid and other apes (50.  Mr. St. George\nMivart, 'Transactions Phil. Soc.' 1867, p. 310.), and likewise in many of\nthe lower animals.  It is remarkable that this perforation seems to have\nbeen present in man much more frequently during ancient times than\nrecently.  Mr. Busk (51.  \"On the Caves of Gibraltar,\" 'Transactions of the\nInternational Congress of Prehistoric Archaeology,' Third Session, 1869, p.\n159.  Prof. Wyman has lately shewn (Fourth Annual Report, Peabody Museum,\n1871, p. 20), that this perforation is present in thirty-one per cent. of\nsome human remains from ancient mounds in the Western United States, and in\nFlorida.  It frequently occurs in the negro.) has collected the following\nevidence on this head:  Prof. Broca \"noticed the perforation in four and a\nhalf per cent. of the arm-bones collected in the 'Cimetiere du Sud,' at\nParis; and in the Grotto of Orrony, the contents of which are referred to\nthe Bronze period, as many as eight humeri out of thirty-two were\nperforated; but this extraordinary proportion, he thinks, might be due to\nthe cavern having been a sort of 'family vault.'  Again, M. Dupont found\nthirty per cent. of perforated bones in the caves of the Valley of the\nLesse, belonging to the Reindeer period; whilst M. Leguay, in a sort of\ndolmen at Argenteuil, observed twenty-five per cent. to be perforated; and\nM. Pruner-Bey found twenty-six per cent. in the same condition in bones\nfrom Vaureal.  Nor should it be left unnoticed that M. Pruner-Bey states\nthat this condition is common in Guanche skeletons.\"  It is an interesting\nfact that ancient races, in this and several other cases, more frequently\npresent structures which resemble those of the lower animals than do the\nmodern.  One chief cause seems to be that the ancient races stand somewhat\nnearer in the long line of descent to their remote animal-like progenitors.\n\nIn man, the os coccyx, together with certain other vertebrae hereafter to\nbe described, though functionless as a tail, plainly represent this part in\nother vertebrate animals.  At an early embryonic period it is free, and\nprojects beyond the lower extremities; as may be seen in the drawing (Fig.\n1.) of a human embryo.  Even after birth it has been known, in certain rare\nand anomalous cases (52.  Quatrefages has lately collected the evidence on\nthis subject.  'Revue des Cours Scientifiques,' 1867-1868, p. 625.  In 1840\nFleischmann exhibited a human foetus bearing a free tail, which, as is not\nalways the case, included vertebral bodies; and this tail was critically\nexamined by the many anatomists present at the meeting of naturalists at\nErlangen (see Marshall in Niederlandischen Archiv fuer Zoologie, December\n1871).), to form a small external rudiment of a tail.  The os coccyx is\nshort, usually including only four vertebrae, all anchylosed together:  and\nthese are in a rudimentary condition, for they consist, with the exception\nof the basal one, of the centrum alone.  (53.  Owen, 'On the Nature of\nLimbs,' 1849, p. 114.)  They are furnished with some small muscles; one of\nwhich, as I am informed by Prof. Turner, has been expressly described by\nTheile as a rudimentary repetition of the extensor of the tail, a muscle\nwhich is so largely developed in many mammals.\n\nThe spinal cord in man extends only as far downwards as the last dorsal or\nfirst lumbar vertebra; but a thread-like structure (the filum terminale)\nruns down the axis of the sacral part of the spinal canal, and even along\nthe back of the coccygeal bones.  The upper part of this filament, as Prof.\nTurner informs me, is undoubtedly homologous with the spinal cord; but the\nlower part apparently consists merely of the pia mater, or vascular\ninvesting membrane.  Even in this case the os coccyx may be said to possess\na vestige of so important a structure as the spinal cord, though no longer\nenclosed within a bony canal.  The following fact, for which I am also\nindebted to Prof. Turner, shews how closely the os coccyx corresponds with\nthe true tail in the lower animals:  Luschka has recently discovered at the\nextremity of the coccygeal bones a very peculiar convoluted body, which is\ncontinuous with the middle sacral artery; and this discovery led Krause and\nMeyer to examine the tail of a monkey (Macacus), and of a cat, in both of\nwhich they found a similarly convoluted body, though not at the extremity.\n\nThe reproductive system offers various rudimentary structures; but these\ndiffer in one important respect from the foregoing cases.  Here we are not\nconcerned with the vestige of a part which does not belong to the species\nin an efficient state, but with a part efficient in the one sex, and\nrepresented in the other by a mere rudiment.  Nevertheless, the occurrence\nof such rudiments is as difficult to explain, on the belief of the separate\ncreation of each species, as in the foregoing cases.  Hereafter I shall\nhave to recur to these rudiments, and shall shew that their presence\ngenerally depends merely on inheritance, that is, on parts acquired by one\nsex having been partially transmitted to the other.  I will in this place\nonly give some instances of such rudiments.  It is well known that in the\nmales of all mammals, including man, rudimentary mammae exist.  These in\nseveral instances have become well developed, and have yielded a copious\nsupply of milk.  Their essential identity in the two sexes is likewise\nshewn by their occasional sympathetic enlargement in both during an attack\nof the measles.  The vesicula prostatica, which has been observed in many\nmale mammals, is now universally acknowledged to be the homologue of the\nfemale uterus, together with the connected passage.  It is impossible to\nread Leuckart's able description of this organ, and his reasoning, without\nadmitting the justness of his conclusion.  This is especially clear in the\ncase of those mammals in which the true female uterus bifurcates, for in\nthe males of these the vesicula likewise bifurcates.  (54.  Leuckart, in\nTodd's 'Cyclopaedia of Anatomy' 1849-52, vol. iv. p. 1415. In man this\norgan is only from three to six lines in length, but, like so many other\nrudimentary parts, it is variable in development as well as in other\ncharacters.)  Some other rudimentary structures belonging to the\nreproductive system might have been here adduced.  (55.  See, on this\nsubject, Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 675, 676, 706.)\n\nThe bearing of the three great classes of facts now given is unmistakeable.\nBut it would be superfluous fully to recapitulate the line of argument\ngiven in detail in my 'Origin of Species.'  The homological construction of\nthe whole frame in the members of the same class is intelligible, if we\nadmit their descent from a common progenitor, together with their\nsubsequent adaptation to diversified conditions.  On any other view, the\nsimilarity of pattern between the hand of a man or monkey, the foot of a\nhorse, the flipper of a seal, the wing of a bat, etc., is utterly\ninexplicable.  (56.  Prof. Bianconi, in a recently published work,\nillustrated by admirable engravings ('La Theorie Darwinienne et la creation\ndite independante,' 1874), endeavours to shew that homological structures,\nin the above and other cases, can be fully explained on mechanical\nprinciples, in accordance with their uses.  No one has shewn so well, how\nadmirably such structures are adapted for their final purpose; and this\nadaptation can, as I believe, be explained through natural selection.  In\nconsidering the wing of a bat, he brings forward (p. 218) what appears to\nme (to use Auguste Comte's words) a mere metaphysical principle, namely,\nthe preservation \"in its integrity of the mammalian nature of the animal.\"\nIn only a few cases does he discuss rudiments, and then only those parts\nwhich are partially rudimentary, such as the little hoofs of the pig and\nox, which do not touch the ground; these he shews clearly to be of service\nto the animal.  It is unfortunate that he did not consider such cases as\nthe minute teeth, which never cut through the jaw in the ox, or the mammae\nof male quadrupeds, or the wings of certain beetles, existing under the\nsoldered wing-covers, or the vestiges of the pistil and stamens in various\nflowers, and many other such cases.  Although I greatly admire Prof.\nBianconi's work, yet the belief now held by most naturalists seems to me\nleft unshaken, that homological structures are inexplicable on the\nprinciple of mere adaptation.)  It is no scientific explanation to assert\nthat they have all been formed on the same ideal plan.  With respect to\ndevelopment, we can clearly understand, on the principle of variations\nsupervening at a rather late embryonic period, and being inherited at a\ncorresponding period, how it is that the embryos of wonderfully different\nforms should still retain, more or less perfectly, the structure of their\ncommon progenitor.  No other explanation has ever been given of the\nmarvellous fact that the embryos of a man, dog, seal, bat, reptile, etc.,\ncan at first hardly be distinguished from each other.  In order to\nunderstand the existence of rudimentary organs, we have only to suppose\nthat a former progenitor possessed the parts in question in a perfect\nstate, and that under changed habits of life they became greatly reduced,\neither from simple disuse, or through the natural selection of those\nindividuals which were least encumbered with a superfluous part, aided by\nthe other means previously indicated.\n\nThus we can understand how it has come to pass that man and all other\nvertebrate animals have been constructed on the same general model, why\nthey pass through the same early stages of development, and why they retain\ncertain rudiments in common.  Consequently we ought frankly to admit their\ncommunity of descent:  to take any other view, is to admit that our own\nstructure, and that of all the animals around us, is a mere snare laid to\nentrap our judgment.  This conclusion is greatly strengthened, if we look\nto the members of the whole animal series, and consider the evidence\nderived from their affinities or classification, their geographical\ndistribution and geological succession.  It is only our natural prejudice,\nand that arrogance which made our forefathers declare that they were\ndescended from demi-gods, which leads us to demur to this conclusion.  But\nthe time will before long come, when it will be thought wonderful that\nnaturalists, who were well acquainted with the comparative structure and\ndevelopment of man, and other mammals, should have believed that each was\nthe work of a separate act of creation.\n\n\nCHAPTER II.\n\nON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM.\n\nVariability of body and mind in man--Inheritance--Causes of variability--\nLaws of variation the same in man as in the lower animals--Direct action of\nthe conditions of life--Effects of the increased use and disuse of parts--\nArrested development--Reversion--Correlated variation--Rate of increase--\nChecks to increase--Natural selection--Man the most dominant animal in the\nworld--Importance of his corporeal structure--The causes which have led to\nhis becoming erect--Consequent changes of structure--Decrease in size of\nthe canine teeth--Increased size and altered shape of the skull--Nakedness\n--Absence of a tail--Defenceless condition of man.\n\nIt is manifest that man is now subject to much variability.  No two\nindividuals of the same race are quite alike.  We may compare millions of\nfaces, and each will be distinct.  There is an equally great amount of\ndiversity in the proportions and dimensions of the various parts of the\nbody; the length of the legs being one of the most variable points.  (1.\n'Investigations in Military and Anthropological Statistics of American\nSoldiers,' by B.A. Gould, 1869, p. 256.)  Although in some quarters of the\nworld an elongated skull, and in other quarters a short skull prevails, yet\nthere is great diversity of shape even within the limits of the same race,\nas with the aborigines of America and South Australia--the latter a race\n\"probably as pure and homogeneous in blood, customs, and language as any in\nexistence\"--and even with the inhabitants of so confined an area as the\nSandwich Islands.  (2.  With respect to the \"Cranial forms of the American\naborigines,\" see Dr. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia,\nMay 1868.  On the Australians, see Huxley, in Lyell's 'Antiquity of Man,'\n1863, p. 87.  On the Sandwich Islanders, Prof. J. Wyman, 'Observations on\nCrania,' Boston, 1868, p. 18.)  An eminent dentist assures me that there is\nnearly as much diversity in the teeth as in the features.  The chief\narteries so frequently run in abnormal courses, that it has been found\nuseful for surgical purposes to calculate from 1040 corpses how often each\ncourse prevails.  (3.  'Anatomy of the Arteries,' by R. Quain.  Preface,\nvol. i. 1844.)  The muscles are eminently variable:  thus those of the foot\nwere found by Prof. Turner (4.  'Transactions of the Royal Society of\nEdinburgh,' vol. xxiv. pp. 175, 189.) not to be strictly alike in any two\nout of fifty bodies; and in some the deviations were considerable.  He\nadds, that the power of performing the appropriate movements must have been\nmodified in accordance with the several deviations.  Mr. J. Wood has\nrecorded (5.  'Proceedings Royal Society,' 1867, p. 544; also 1868, pp.\n483, 524.  There is a previous paper, 1866, p. 229.) the occurrence of 295\nmuscular variations in thirty-six subjects, and in another set of the same\nnumber no less than 558 variations, those occurring on both sides of the\nbody being only reckoned as one.  In the last set, not one body out of the\nthirty-six was \"found totally wanting in departures from the standard\ndescriptions of the muscular system given in anatomical text books.\"  A\nsingle body presented the extraordinary number of twenty-five distinct\nabnormalities.  The same muscle sometimes varies in many ways:  thus Prof.\nMacalister describes (6.  'Proc. R. Irish Academy,' vol. x. 1868, p. 141.)\nno less than twenty distinct variations in the palmaris accessorius.\n\nThe famous old anatomist, Wolff (7.  'Act. Acad. St. Petersburg,' 1778,\npart ii. p. 217.), insists that the internal viscera are more variable than\nthe external parts:  Nulla particula est quae non aliter et aliter in aliis\nse habeat hominibus.  He has even written a treatise on the choice of\ntypical examples of the viscera for representation.  A discussion on the\nbeau-ideal of the liver, lungs, kidneys, etc., as of the human face divine,\nsounds strange in our ears.\n\nThe variability or diversity of the mental faculties in men of the same\nrace, not to mention the greater differences between the men of distinct\nraces, is so notorious that not a word need here be said.  So it is with\nthe lower animals.  All who have had charge of menageries admit this fact,\nand we see it plainly in our dogs and other domestic animals.  Brehm\nespecially insists that each individual monkey of those which he kept tame\nin Africa had its own peculiar disposition and temper:  he mentions one\nbaboon remarkable for its high intelligence; and the keepers in the\nZoological Gardens pointed out to me a monkey, belonging to the New World\ndivision, equally remarkable for intelligence.  Rengger, also, insists on\nthe diversity in the various mental characters of the monkeys of the same\nspecies which he kept in Paraguay; and this diversity, as he adds, is\npartly innate, and partly the result of the manner in which they have been\ntreated or educated.  (8.  Brehm, 'Thierleben,' B. i. ss. 58, 87.  Rengger,\n'Saeugethiere von Paraguay,' s. 57.)\n\nI have elsewhere (9.  'Variation of Animals and Plants under\nDomestication,' vol. ii. chap. xii.) so fully discussed the subject of\nInheritance, that I need here add hardly anything.  A greater number of\nfacts have been collected with respect to the transmission of the most\ntrifling, as well as of the most important characters in man, than in any\nof the lower animals; though the facts are copious enough with respect to\nthe latter.  So in regard to mental qualities, their transmission is\nmanifest in our dogs, horses, and other domestic animals.  Besides special\ntastes and habits, general intelligence, courage, bad and good temper,\netc., are certainly transmitted.  With man we see similar facts in almost\nevery family; and we now know, through the admirable labours of Mr. Galton\n(10.  'Hereditary Genius:  an Inquiry into its Laws and Consequences,'\n1869.), that genius which implies a wonderfully complex combination of high\nfaculties, tends to be inherited; and, on the other hand, it is too certain\nthat insanity and deteriorated mental powers likewise run in families.\n\nWith respect to the causes of variability, we are in all cases very\nignorant; but we can see that in man as in the lower animals, they stand in\nsome relation to the conditions to which each species has been exposed,\nduring several generations.  Domesticated animals vary more than those in a\nstate of nature; and this is apparently due to the diversified and changing\nnature of the conditions to which they have been subjected.  In this\nrespect the different races of man resemble domesticated animals, and so do\nthe individuals of the same race, when inhabiting a very wide area, like\nthat of America.  We see the influence of diversified conditions in the\nmore civilised nations; for the members belonging to different grades of\nrank, and following different occupations, present a greater range of\ncharacter than do the members of barbarous nations.  But the uniformity of\nsavages has often been exaggerated, and in some cases can hardly be said to\nexist.  (11.  Mr. Bates remarks ('The Naturalist on the Amazons,' 1863,\nvol. ii p. 159), with respect to the Indians of the same South American\ntribe, \"no two of them were at all similar in the shape of the head; one\nman had an oval visage with fine features, and another was quite Mongolian\nin breadth and prominence of cheek, spread of nostrils, and obliquity of\neyes.\")  It is, nevertheless, an error to speak of man, even if we look\nonly to the conditions to which he has been exposed, as \"far more\ndomesticated\" (12.  Blumenbach, 'Treatises on Anthropology.' Eng.\ntranslat., 1865, p. 205.) than any other animal.  Some savage races, such\nas the Australians, are not exposed to more diversified conditions than are\nmany species which have a wide range.  In another and much more important\nrespect, man differs widely from any strictly domesticated animal; for his\nbreeding has never long been controlled, either by methodical or\nunconscious selection.  No race or body of men has been so completely\nsubjugated by other men, as that certain individuals should be preserved,\nand thus unconsciously selected, from somehow excelling in utility to their\nmasters.  Nor have certain male and female individuals been intentionally\npicked out and matched, except in the well-known case of the Prussian\ngrenadiers; and in this case man obeyed, as might have been expected, the\nlaw of methodical selection; for it is asserted that many tall men were\nreared in the villages inhabited by the grenadiers and their tall wives.\nIn Sparta, also, a form of selection was followed, for it was enacted that\nall children should be examined shortly after birth; the well-formed and\nvigorous being preserved, the others left to perish.  (13.  Mitford's\n'History of Greece,' vol. i. p. 282.  It appears also from a passage in\nXenophon's 'Memorabilia,' B. ii. 4 (to which my attention has been called\nby the Rev. J.N. Hoare), that it was a well recognised principle with the\nGreeks, that men ought to select their wives with a view to the health and\nvigour of their children.  The Grecian poet, Theognis, who lived 550 B.C.,\nclearly saw how important selection, if carefully applied, would be for the\nimprovement of mankind.  He saw, likewise, that wealth often checks the\nproper action of sexual selection.  He thus writes:\n\n    \"With kine and horses, Kurnus! we proceed\n    By reasonable rules, and choose a breed\n    For profit and increase, at any price:\n    Of a sound stock, without defect or vice.\n    But, in the daily matches that we make,\n    The price is everything:  for money's sake,\n    Men marry:  women are in marriage given\n    The churl or ruffian, that in wealth has thriven,\n    May match his offspring with the proudest race:\n    Thus everything is mix'd, noble and base!\n    If then in outward manner, form, and mind,\n    You find us a degraded, motley kind,\n    Wonder no more, my friend! the cause is plain,\n    And to lament the consequence is vain.\"\n\n(The Works of J. Hookham Frere, vol. ii. 1872, p. 334.))\n\nIf we consider all the races of man as forming a single species, his range\nis enormous; but some separate races, as the Americans and Polynesians,\nhave very wide ranges.  It is a well-known law that widely-ranging species\nare much more variable than species with restricted ranges; and the\nvariability of man may with more truth be compared with that of widely-\nranging species, than with that of domesticated animals.\n\nNot only does variability appear to be induced in man and the lower animals\nby the same general causes, but in both the same parts of the body are\naffected in a closely analogous manner.  This has been proved in such full\ndetail by Godron and Quatrefages, that I need here only refer to their\nworks.  (14.  Godron, 'De l'Espece,' 1859, tom. ii. livre 3.  Quatrefages,\n'Unite de l'Espece Humaine,' 1861.  Also Lectures on Anthropology, given in\nthe 'Revue des Cours Scientifiques,' 1866-1868.)  Monstrosities, which\ngraduate into slight variations, are likewise so similar in man and the\nlower animals, that the same classification and the same terms can be used\nfor both, as has been shewn by Isidore Geoffroy St.-Hilaire.  (15.  'Hist.\nGen. et Part. des Anomalies de l'Organisation,' in three volumes, tom. i.\n1832.)  In my work on the variation of domestic animals, I have attempted\nto arrange in a rude fashion the laws of variation under the following\nheads:--The direct and definite action of changed conditions, as exhibited\nby all or nearly all the individuals of the same species, varying in the\nsame manner under the same circumstances.  The effects of the long-\ncontinued use or disuse of parts.  The cohesion of homologous parts.  The\nvariability of multiple parts.  Compensation of growth; but of this law I\nhave found no good instance in the case of man.  The effects of the\nmechanical pressure of one part on another; as of the pelvis on the cranium\nof the infant in the womb.  Arrests of development, leading to the\ndiminution or suppression of parts.  The reappearance of long-lost\ncharacters through reversion.  And lastly, correlated variation.  All these\nso-called laws apply equally to man and the lower animals; and most of them\neven to plants.  It would be superfluous here to discuss all of them (16.\nI have fully discussed these laws in my 'Variation of Animals and Plants\nunder Domestication,' vol. ii. chap. xxii. and xxiii.  M. J.P. Durand has\nlately (1868) published a valuable essay, 'De l'Influence des Milieux,'\netc.  He lays much stress, in the case of plants, on the nature of the\nsoil.);  but several are so important, that they must be treated at\nconsiderable length.\n\nTHE DIRECT AND DEFINITE ACTION OF CHANGED CONDITIONS.\n\nThis is a most perplexing subject.  It cannot be denied that changed\nconditions produce some, and occasionally a considerable effect, on\norganisms of all kinds; and it seems at first probable that if sufficient\ntime were allowed this would be the invariable result.  But I have failed\nto obtain clear evidence in favour of this conclusion; and valid reasons\nmay be urged on the other side, at least as far as the innumerable\nstructures are concerned, which are adapted for special ends.  There can,\nhowever, be no doubt that changed conditions induce an almost indefinite\namount of fluctuating variability, by which the whole organisation is\nrendered in some degree plastic.\n\nIn the United States, above 1,000,000 soldiers, who served in the late war,\nwere measured, and the States in which they were born and reared were\nrecorded.  (17.  'Investigations in Military and Anthrop. Statistics,'\netc., 1869, by B.A. Gould, pp. 93, 107, 126, 131, 134.)  From this\nastonishing number of observations it is proved that local influences of\nsome kind act directly on stature; and we further learn that \"the State\nwhere the physical growth has in great measure taken place, and the State\nof birth, which indicates the ancestry, seem to exert a marked influence on\nthe stature.\"  For instance, it is established, \"that residence in the\nWestern States, during the years of growth, tends to produce increase of\nstature.\"  On the other hand, it is certain that with sailors, their life\ndelays growth, as shewn \"by the great difference between the statures of\nsoldiers and sailors at the ages of seventeen and eighteen years.\"  Mr.\nB.A. Gould endeavoured to ascertain the nature of the influences which thus\nact on stature; but he arrived only at negative results, namely that they\ndid not relate to climate, the elevation of the land, soil, nor even \"in\nany controlling degree\" to the abundance or the need of the comforts of\nlife.  This latter conclusion is directly opposed to that arrived at by\nVillerme, from the statistics of the height of the conscripts in different\nparts of France.  When we compare the differences in stature between the\nPolynesian chiefs and the lower orders within the same islands, or between\nthe inhabitants of the fertile volcanic and low barren coral islands of the\nsame ocean (18.  For the Polynesians, see Prichard's 'Physical History of\nMankind,' vol. v. 1847, pp. 145, 283.  Also Godron, 'De l'Espece,' tom. ii.\np. 289.  There is also a remarkable difference in appearance between the\nclosely-allied Hindoos inhabiting the Upper Ganges and Bengal; see\nElphinstone's 'History of India,' vol. i. p. 324.) or again between the\nFuegians on the eastern and western shores of their country, where the\nmeans of subsistence are very different, it is scarcely possible to avoid\nthe conclusion that better food and greater comfort do influence stature.\nBut the preceding statements shew how difficult it is to arrive at any\nprecise result.  Dr. Beddoe has lately proved that, with the inhabitants of\nBritain, residence in towns and certain occupations have a deteriorating\ninfluence on height; and he infers that the result is to a certain extent\ninherited, as is likewise the case in the United States.  Dr. Beddoe\nfurther believes that wherever a \"race attains its maximum of physical\ndevelopment, it rises highest in energy and moral vigour.\"  (19.  'Memoirs,\nAnthropological Society,' vol. iii. 1867-69, pp. 561, 565, 567.)\n\nWhether external conditions produce any other direct effect on man is not\nknown.  It might have been expected that differences of climate would have\nhad a marked influence, inasmuch as the lungs and kidneys are brought into\nactivity under a low temperature, and the liver and skin under a high one.\n(20.  Dr. Brakenridge, 'Theory of Diathesis,' 'Medical Times,' June 19 and\nJuly 17, 1869.)  It was formerly thought that the colour of the skin and\nthe character of the hair were determined by light or heat; and although it\ncan hardly be denied that some effect is thus produced, almost all\nobservers now agree that the effect has been very small, even after\nexposure during many ages.  But this subject will be more properly\ndiscussed when we treat of the different races of mankind.  With our\ndomestic animals there are grounds for believing that cold and damp\ndirectly affect the growth of the hair; but I have not met with any\nevidence on this head in the case of man.\n\nEFFECTS OF THE INCREASED USE AND DISUSE OF PARTS.\n\nIt is well known that use strengthens the muscles in the individual, and\ncomplete disuse, or the destruction of the proper nerve, weakens them.\nWhen the eye is destroyed, the optic nerve often becomes atrophied.  When\nan artery is tied, the lateral channels increase not only in diameter, but\nin the thickness and strength of their coats.  When one kidney ceases to\nact from disease, the other increases in size, and does double work.  Bones\nincrease not only in thickness, but in length, from carrying a greater\nweight.  (21.  I have given authorities for these several statements in my\n'Variation of Animals and Plants under Domestication,' vol. ii. pp. 297-\n300.  Dr. Jaeger, \"Ueber das Langenwachsthum der Knochen,\" 'Jenaeischen\nZeitschrift,' B. v. Heft. i.)  Different occupations, habitually followed,\nlead to changed proportions in various parts of the body.  Thus it was\nascertained by the United States Commission (22.  'Investigations,' etc.,\nby B.A. Gould, 1869, p. 288.) that the legs of the sailors employed in the\nlate war were longer by 0.217 of an inch than those of the soldiers, though\nthe sailors were on an average shorter men; whilst their arms were shorter\nby 1.09 of an inch, and therefore, out of proportion, shorter in relation\nto their lesser height.  This shortness of the arms is apparently due to\ntheir greater use, and is an unexpected result:  but sailors chiefly use\ntheir arms in pulling, and not in supporting weights.  With sailors, the\ngirth of the neck and the depth of the instep are greater, whilst the\ncircumference of the chest, waist, and hips is less, than in soldiers.\n\nWhether the several foregoing modifications would become hereditary, if the\nsame habits of life were followed during many generations, is not known,\nbut it is probable.  Rengger (23.  'Saeugethiere von Paraguay,' 1830, s. 4.)\nattributes the thin legs and thick arms of the Payaguas Indians to\nsuccessive generations having passed nearly their whole lives in canoes,\nwith their lower extremities motionless.  Other writers have come to a\nsimilar conclusion in analogous cases.  According to Cranz (24.  'History\nof Greenland,' Eng. translat., 1767, vol. i. p. 230.), who lived for a long\ntime with the Esquimaux, \"the natives believe that ingenuity and dexterity\nin seal-catching (their highest art and virtue) is hereditary; there is\nreally something in it, for the son of a celebrated seal-catcher will\ndistinguish himself, though he lost his father in childhood.\"  But in this\ncase it is mental aptitude, quite as much as bodily structure, which\nappears to be inherited.  It is asserted that the hands of English\nlabourers are at birth larger than those of the gentry.  (25.\n'Intermarriage,' by Alex. Walker, 1838, p. 377.)  From the correlation\nwhich exists, at least in some cases (26.  'The Variation of Animals under\nDomestication,' vol. i. p. 173.), between the development of the\nextremities and of the jaws, it is possible that in those classes which do\nnot labour much with their hands and feet, the jaws would be reduced in\nsize from this cause.  That they are generally smaller in refined and\ncivilised men than in hard-working men or savages, is certain.  But with\nsavages, as Mr. Herbert Spencer (27.  'Principles of Biology,' vol. i. p.\n455.) has remarked, the greater use of the jaws in chewing coarse, uncooked\nfood, would act in a direct manner on the masticatory muscles, and on the\nbones to which they are attached.  In infants, long before birth, the skin\non the soles of the feet is thicker than on any other part of the body;\n(28.  Paget, 'Lectures on Surgical Pathology,' vol. ii, 1853, p. 209.) and\nit can hardly be doubted that this is due to the inherited effects of\npressure during a long series of generations.\n\nIt is familiar to every one that watchmakers and engravers are liable to be\nshort-sighted, whilst men living much out of doors, and especially savages,\nare generally long-sighted.  (29.  It is a singular and unexpected fact\nthat sailors are inferior to landsmen in their mean distance of distinct\nvision.  Dr. B.A. Gould ('Sanitary Memoirs of the War of the Rebellion,'\n1869, p. 530), has proved this to be the case; and he accounts for it by\nthe ordinary range of vision in sailors being \"restricted to the length of\nthe vessel and the height of the masts.\")  Short-sight and long-sight\ncertainly tend to be inherited.  (30.  'The Variation of Animals under\nDomestication,' vol. i. p. 8.)  The inferiority of Europeans, in comparison\nwith savages, in eyesight and in the other senses, is no doubt the\naccumulated and transmitted effect of lessened use during many generations;\nfor Rengger (31.  'Saeugethiere von Paraguay,' s. 8, 10.  I have had good\nopportunities for observing the extraordinary power of eyesight in the\nFuegians.  See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404)\non this same subject.  M. Giraud-Teulon has recently collected ('Revue des\nCours Scientifiques,' 1870, p. 625) a large and valuable body of evidence\nproving that the cause of short-sight, \"C'est le travail assidu, de pres.\")\nstates that he has repeatedly observed Europeans, who had been brought up\nand spent their whole lives with the wild Indians, who nevertheless did not\nequal them in the sharpness of their senses.  The same naturalist observes\nthat the cavities in the skull for the reception of the several sense-\norgans are larger in the American aborigines than in Europeans; and this\nprobably indicates a corresponding difference in the dimensions of the\norgans themselves.  Blumenbach has also remarked on the large size of the\nnasal cavities in the skulls of the American aborigines, and connects this\nfact with their remarkably acute power of smell.  The Mongolians of the\nplains of northern Asia, according to Pallas, have wonderfully perfect\nsenses; and Prichard believes that the great breadth of their skulls across\nthe zygomas follows from their highly-developed sense organs.  (32.\nPrichard, 'Physical History of Mankind,' on the authority of Blumenbach,\nvol. i. 1851, p. 311; for the statement by Pallas, vol. iv. 1844, p. 407.)\n\nThe Quechua Indians inhabit the lofty plateaux of Peru; and Alcide\nd'Orbigny states (33.  Quoted by Prichard, 'Researches into the Physical\nHistory of Mankind,' vol. v. p. 463.) that, from continually breathing a\nhighly rarefied atmosphere, they have acquired chests and lungs of\nextraordinary dimensions.  The cells, also, of the lungs are larger and\nmore numerous than in Europeans.  These observations have been doubted, but\nMr. D. Forbes carefully measured many Aymaras, an allied race, living at\nthe height of between 10,000 and 15,000 feet; and he informs me (34.  Mr.\nForbes' valuable paper is now published in the 'Journal of the Ethnological\nSociety of London,' new series, vol. ii. 1870, p.193.) that they differ\nconspicuously from the men of all other races seen by him in the\ncircumference and length of their bodies.  In his table of measurements,\nthe stature of each man is taken at 1000, and the other measurements are\nreduced to this standard.  It is here seen that the extended arms of the\nAymaras are shorter than those of Europeans, and much shorter than those of\nNegroes.  The legs are likewise shorter; and they present this remarkable\npeculiarity, that in every Aymara measured, the femur is actually shorter\nthan the tibia.  On an average, the length of the femur to that of the\ntibia is as 211 to 252; whilst in two Europeans, measured at the same time,\nthe femora to the tibiae were as 244 to 230; and in three Negroes as 258 to\n241.  The humerus is likewise shorter relatively to the forearm.  This\nshortening of that part of the limb which is nearest to the body, appears\nto be, as suggested to me by Mr. Forbes, a case of compensation in relation\nwith the greatly increased length of the trunk.  The Aymaras present some\nother singular points of structure, for instance, the very small projection\nof the heel.\n\nThese men are so thoroughly acclimatised to their cold and lofty abode,\nthat when formerly carried down by the Spaniards to the low eastern plains,\nand when now tempted down by high wages to the gold-washings, they suffer a\nfrightful rate of mortality.  Nevertheless Mr. Forbes found a few pure\nfamilies which had survived during two generations:  and he observed that\nthey still inherited their characteristic peculiarities.  But it was\nmanifest, even without measurement, that these peculiarities had all\ndecreased; and on measurement, their bodies were found not to be so much\nelongated as those of the men on the high plateau; whilst their femora had\nbecome somewhat lengthened, as had their tibiae, although in a less degree.\nThe actual measurements may be seen by consulting Mr. Forbes's memoir.\nFrom these observations, there can, I think, be no doubt that residence\nduring many generations at a great elevation tends, both directly and\nindirectly, to induce inherited modifications in the proportions of the\nbody.  (35.  Dr. Wilckens ('Landwirthschaft.  Wochenblatt,' No. 10, 1869)\nhas lately published an interesting essay shewing how domestic animals,\nwhich live in mountainous regions, have their frames modified.)\n\nAlthough man may not have been much modified during the latter stages of\nhis existence through the increased or decreased use of parts, the facts\nnow given shew that his liability in this respect has not been lost; and we\npositively know that the same law holds good with the lower animals.\nConsequently we may infer that when at a remote epoch the progenitors of\nman were in a transitional state, and were changing from quadrupeds into\nbipeds, natural selection would probably have been greatly aided by the\ninherited effects of the increased or diminished use of the different parts\nof the body.\n\nARRESTS OF DEVELOPMENT.\n\nThere is a difference between arrested development and arrested growth, for\nparts in the former state continue to grow whilst still retaining their\nearly condition.  Various monstrosities come under this head; and some, as\na cleft palate, are known to be occasionally inherited.  It will suffice\nfor our purpose to refer to the arrested brain-development of\nmicrocephalous idiots, as described in Vogt's memoir.  (36.  'Memoire sur\nles Microcephales,' 1867, pp. 50, 125, 169, 171, 184-198.)  Their skulls\nare smaller, and the convolutions of the brain are less complex than in\nnormal men.  The frontal sinus, or the projection over the eye-brows, is\nlargely developed, and the jaws are prognathous to an \"effrayant\" degree;\nso that these idiots somewhat resemble the lower types of mankind.  Their\nintelligence, and most of their mental faculties, are extremely feeble.\nThey cannot acquire the power of speech, and are wholly incapable of\nprolonged attention, but are much given to imitation.  They are strong and\nremarkably active, continually gambolling and jumping about, and making\ngrimaces.  They often ascend stairs on all-fours; and are curiously fond of\nclimbing up furniture or trees.  We are thus reminded of the delight shewn\nby almost all boys in climbing trees; and this again reminds us how lambs\nand kids, originally alpine animals, delight to frisk on any hillock,\nhowever small.  Idiots also resemble the lower animals in some other\nrespects; thus several cases are recorded of their carefully smelling every\nmouthful of food before eating it.  One idiot is described as often using\nhis mouth in aid of his hands, whilst hunting for lice.  They are often\nfilthy in their habits, and have no sense of decency; and several cases\nhave been published of their bodies being remarkably hairy.  (37.  Prof.\nLaycock sums up the character of brute-like idiots by calling them\n\"theroid;\" 'Journal of Mental Science,' July 1863.  Dr. Scott ('The Deaf\nand Dumb,' 2nd ed. 1870, p. 10) has often observed the imbecile smelling\ntheir food.  See, on this same subject, and on the hairiness of idiots, Dr.\nMaudsley, 'Body and Mind,' 1870, pp. 46-51.  Pinel has also given a\nstriking case of hairiness in an idiot.)\n\nREVERSION.\n\nMany of the cases to be here given, might have been introduced under the\nlast heading.  When a structure is arrested in its development, but still\ncontinues growing, until it closely resembles a corresponding structure in\nsome lower and adult member of the same group, it may in one sense be\nconsidered as a case of reversion.  The lower members in a group give us\nsome idea how the common progenitor was probably constructed; and it is\nhardly credible that a complex part, arrested at an early phase of\nembryonic development, should go on growing so as ultimately to perform its\nproper function, unless it had acquired such power during some earlier\nstate of existence, when the present exceptional or arrested structure was\nnormal.  The simple brain of a microcephalous idiot, in as far as it\nresembles that of an ape, may in this sense be said to offer a case of\nreversion.  (38.  In my 'Variation of Animals under Domestication' (vol.\nii. p. 57), I attributed the not very rare cases of supernumerary mammae in\nwomen to reversion.  I was led to this as a probable conclusion, by the\nadditional mammae being generally placed symmetrically on the breast; and\nmore especially from one case, in which a single efficient mamma occurred\nin the inguinal region of a woman, the daughter of another woman with\nsupernumerary mammae.  But I now find (see, for instance, Prof. Preyer,\n'Der Kampf um das Dasein,' 1869, s. 45) that mammae erraticae, occur in\nother situations, as on the back, in the armpit, and on the thigh; the\nmammae in this latter instance having given so much milk that the child was\nthus nourished.  The probability that the additional mammae are due to\nreversion is thus much weakened; nevertheless, it still seems to me\nprobable, because two pairs are often found symmetrically on the breast;\nand of this I myself have received information in several cases.  It is\nwell known that some Lemurs normally have two pairs of mammae on the\nbreast.  Five cases have been recorded of the presence of more than a pair\nof mammae (of course rudimentary) in the male sex of mankind; see 'Journal\nof Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside,\nin which two brothers exhibited this peculiarity; see also a paper by Dr.\nBartels, in 'Reichert's and du Bois-Reymond's Archiv.,' 1872, p. 304.  In\none of the cases alluded to by Dr. Bartels, a man bore five mammae, one\nbeing medial and placed above the navel; Meckel von Hemsbach thinks that\nthis latter case is illustrated by a medial mamma occurring in certain\nCheiroptera.  On the whole, we may well doubt if additional mammae would\never have been developed in both sexes of mankind, had not his early\nprogenitors been provided with more than a single pair.\n\nIn the above work (vol. ii. p. 12), I also attributed, though with much\nhesitation, the frequent cases of polydactylism in men and various animals\nto reversion.  I was partly led to this through Prof. Owen's statement,\nthat some of the Ichthyopterygia possess more than five digits, and\ntherefore, as I supposed, had retained a primordial condition; but Prof.\nGegenbaur ('Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), disputes Owen's\nconclusion.  On the other hand, according to the opinion lately advanced by\nDr. Gunther, on the paddle of Ceratodus, which is provided with articulated\nbony rays on both sides of a central chain of bones, there seems no great\ndifficulty in admitting that six or more digits on one side, or on both\nsides, might reappear through reversion.  I am informed by Dr. Zouteveen\nthat there is a case on record of a man having twenty-four fingers and\ntwenty-four toes!  I was chiefly led to the conclusion that the presence of\nsupernumerary digits might be due to reversion from the fact that such\ndigits, not only are strongly inherited, but, as I then believed, had the\npower of regrowth after amputation, like the normal digits of the lower\nvertebrata.  But I have explained in the second edition of my Variation\nunder Domestication why I now place little reliance on the recorded cases\nof such regrowth.  Nevertheless it deserves notice, inasmuch as arrested\ndevelopment and reversion are intimately related processes; that various\nstructures in an embryonic or arrested condition, such as a cleft palate,\nbifid uterus, etc., are frequently accompanied by polydactylism.  This has\nbeen strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire.  But\nat present it is the safest course to give up altogether the idea that\nthere is any relation between the development of supernumerary digits and\nreversion to some lowly organised progenitor of man.)  There are other\ncases which come more strictly under our present head of reversion.\nCertain structures, regularly occurring in the lower members of the group\nto which man belongs, occasionally make their appearance in him, though not\nfound in the normal human embryo; or, if normally present in the human\nembryo, they become abnormally developed, although in a manner which is\nnormal in the lower members of the group.  These remarks will be rendered\nclearer by the following illustrations.\n\nIn various mammals the uterus graduates from a double organ with two\ndistinct orifices and two passages, as in the marsupials, into a single\norgan, which is in no way double except from having a slight internal fold,\nas in the higher apes and man.  The rodents exhibit a perfect series of\ngradations between these two extreme states.  In all mammals the uterus is\ndeveloped from two simple primitive tubes, the inferior portions of which\nform the cornua; and it is in the words of Dr. Farre, \"by the coalescence\nof the two cornua at their lower extremities that the body of the uterus is\nformed in man; while in those animals in which no middle portion or body\nexists, the cornua remain ununited.  As the development of the uterus\nproceeds, the two cornua become gradually shorter, until at length they are\nlost, or, as it were, absorbed into the body of the uterus.\"  The angles of\nthe uterus are still produced into cornua, even in animals as high up in\nthe scale as the lower apes and lemurs.\n\nNow in women, anomalous cases are not very infrequent, in which the mature\nuterus is furnished with cornua, or is partially divided into two organs;\nand such cases, according to Owen, repeat \"the grade of concentrative\ndevelopment,\" attained by certain rodents.  Here perhaps we have an\ninstance of a simple arrest of embryonic development, with subsequent\ngrowth and perfect functional development; for either side of the partially\ndouble uterus is capable of performing the proper office of gestation.  In\nother and rarer cases, two distinct uterine cavities are formed, each\nhaving its proper orifice and passage.  (39.  See Dr. A. Farre's well-known\narticle in the 'Cyclopaedia of Anatomy and Physiology,' vol. v. 1859, p.\n642.  Owen, 'Anatomy of Vertebrates,' vol. iii. 1868, p. 687.  Professor\nTurner, in 'Edinburgh Medical Journal,' February, 1865.)  No such stage is\npassed through during the ordinary development of the embryo; and it is\ndifficult to believe, though perhaps not impossible, that the two simple,\nminute, primitive tubes should know how (if such an expression may be used)\nto grow into two distinct uteri, each with a well-constructed orifice and\npassage, and each furnished with numerous muscles, nerves, glands and\nvessels, if they had not formerly passed through a similar course of\ndevelopment, as in the case of existing marsupials.  No one will pretend\nthat so perfect a structure as the abnormal double uterus in woman could be\nthe result of mere chance.  But the principle of reversion, by which a\nlong-lost structure is called back into existence, might serve as the guide\nfor its full development, even after the lapse of an enormous interval of\ntime.\n\nProfessor Canestrini, after discussing the foregoing and various analogous\ncases, arrives at the same conclusion as that just given.  He adduces\nanother instance, in the case of the malar bone (40.  'Annuario della Soc.\ndei Naturalisti,' Modena, 1867, p. 83.  Prof. Canestrini gives extracts on\nthis subject from various authorities.  Laurillard remarks, that as he has\nfound a complete similarity in the form, proportions, and connection of the\ntwo malar bones in several human subjects and in certain apes, he cannot\nconsider this disposition of the parts as simply accidental.  Another paper\non this same anomaly has been published by Dr. Saviotti in the 'Gazzetta\ndelle Cliniche,' Turin, 1871, where he says that traces of the division may\nbe detected in about two per cent. of adult skulls; he also remarks that it\nmore frequently occurs in prognathous skulls, not of the Aryan race, than\nin others.  See also G. Delorenzi on the same subject; 'Tre nuovi casi\nd'anomalia dell' osso malare,' Torino, 1872.  Also, E. Morselli, 'Sopra una\nrara anomalia dell' osso malare,' Modena, 1872.  Still more recently Gruber\nhas written a pamphlet on the division of this bone.  I give these\nreferences because a reviewer, without any grounds or scruples, has thrown\ndoubts on my statements.), which, in some of the Quadrumana and other\nmammals, normally consists of two portions.  This is its condition in the\nhuman foetus when two months old; and through arrested development, it\nsometimes remains thus in man when adult, more especially in the lower\nprognathous races.  Hence Canestrini concludes that some ancient progenitor\nof man must have had this bone normally divided into two portions, which\nafterwards became fused together.  In man the frontal bone consists of a\nsingle piece, but in the embryo, and in children, and in almost all the\nlower mammals, it consists of two pieces separated by a distinct suture.\nThis suture occasionally persists more or less distinctly in man after\nmaturity; and more frequently in ancient than in recent crania, especially,\nas Canestrini has observed, in those exhumed from the Drift, and belonging\nto the brachycephalic type.  Here again he comes to the same conclusion as\nin the analogous case of the malar bones.  In this, and other instances\npresently to be given, the cause of ancient races approaching the lower\nanimals in certain characters more frequently than do the modern races,\nappears to be, that the latter stand at a somewhat greater distance in the\nlong line of descent from their early semi-human progenitors.\n\nVarious other anomalies in man, more or less analogous to the foregoing,\nhave been advanced by different authors, as cases of reversion; but these\nseem not a little doubtful, for we have to descend extremely low in the\nmammalian series, before we find such structures normally present.  (41.  A\nwhole series of cases is given by Isidore Geoffroy St.-Hilaire, 'Hist. des\nAnomalies,' tom, iii, p. 437.  A reviewer ('Journal of Anatomy and\nPhysiology,' 1871, p. 366) blames me much for not having discussed the\nnumerous cases, which have been recorded, of various parts arrested in\ntheir development.  He says that, according to my theory, \"every transient\ncondition of an organ, during its development, is not only a means to an\nend, but once was an end in itself.\"  This does not seem to me necessarily\nto hold good.  Why should not variations occur during an early period of\ndevelopment, having no relation to reversion; yet such variations might be\npreserved and accumulated, if in any way serviceable, for instance, in\nshortening and simplifying the course of development?  And again, why\nshould not injurious abnormalities, such as atrophied or hypertrophied\nparts, which have no relation to a former state of existence, occur at an\nearly period, as well as during maturity?)\n\nIn man, the canine teeth are perfectly efficient instruments for\nmastication.  But their true canine character, as Owen (42.  'Anatomy of\nVertebrates,' vol. iii. 1868, p. 323.) remarks, \"is indicated by the\nconical form of the crown, which terminates in an obtuse point, is convex\noutward and flat or sub-concave within, at the base of which surface there\nis a feeble prominence.  The conical form is best expressed in the Melanian\nraces, especially the Australian.  The canine is more deeply implanted, and\nby a stronger fang than the incisors.\"  Nevertheless, this tooth no longer\nserves man as a special weapon for tearing his enemies or prey; it may,\ntherefore, as far as its proper function is concerned, be considered as\nrudimentary.  In every large collection of human skulls some may be found,\nas Haeckel (43.  'Generelle Morphologie,' 1866, B. ii. s. clv.) observes,\nwith the canine teeth projecting considerably beyond the others in the same\nmanner as in the anthropomorphous apes, but in a less degree.  In these\ncases, open spaces between the teeth in the one jaw are left for the\nreception of the canines of the opposite jaw.  An inter-space of this kind\nin a Kaffir skull, figured by Wagner, is surprisingly wide.  (44.  Carl\nVogt's 'Lectures on Man,' Eng. translat., 1864, p. 151.)  Considering how\nfew are the ancient skulls which have been examined, compared to recent\nskulls, it is an interesting fact that in at least three cases the canines\nproject largely; and in the Naulette jaw they are spoken of as enormous.\n(45.  C. Carter Blake, on a jaw from La Naulette, 'Anthropological Review,'\n1867, p. 295. Schaaffhausen, ibid. 1868, p. 426.)\n\nOf the anthropomorphous apes the males alone have their canines fully\ndeveloped; but in the female gorilla, and in a less degree in the female\norang, these teeth project considerably beyond the others; therefore the\nfact, of which I have been assured, that women sometimes have considerably\nprojecting canines, is no serious objection to the belief that their\noccasional great development in man is a case of reversion to an ape-like\nprogenitor.  He who rejects with scorn the belief that the shape of his own\ncanines, and their occasional great development in other men, are due to\nour early forefathers having been provided with these formidable weapons,\nwill probably reveal, by sneering, the line of his descent.  For though he\nno longer intends, nor has the power, to use these teeth as weapons, he\nwill unconsciously retract his \"snarling muscles\" (thus named by Sir C.\nBell) (46.  The Anatomy of Expression, 1844, pp. 110, 131.), so as to\nexpose them ready for action, like a dog prepared to fight.\n\nMany muscles are occasionally developed in man, which are proper to the\nQuadrumana or other mammals.  Professor Vlacovich (47.  Quoted by Prof.\nCanestrini in the 'Annuario della Soc. dei Naturalisti,' 1867, p. 90.)\nexamined forty male subjects, and found a muscle, called by him the ischio-\npubic, in nineteen of them; in three others there was a ligament which\nrepresented this muscle; and in the remaining eighteen no trace of it.  In\nonly two out of thirty female subjects was this muscle developed on both\nsides, but in three others the rudimentary ligament was present.  This\nmuscle, therefore, appears to be much more common in the male than in the\nfemale sex; and on the belief in the descent of man from some lower form,\nthe fact is intelligible; for it has been detected in several of the lower\nanimals, and in all of these it serves exclusively to aid the male in the\nact of reproduction.\n\nMr. J. Wood, in his valuable series of papers (48.  These papers deserve\ncareful study by any one who desires to learn how frequently our muscles\nvary, and in varying come to resemble those of the Quadrumana.  The\nfollowing references relate to the few points touched on in my text:\n'Proc. Royal Soc.' vol. xiv. 1865, pp. 379-384; vol. xv. 1866, pp. 241,\n242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524.  I may here add that\nDr. Murie and Mr. St. George Mivart have shewn in their Memoir on the\nLemuroidea ('Transactions, Zoological Society,' vol. vii. 1869, p. 96), how\nextraordinarily variable some of the muscles are in these animals, the\nlowest members of the Primates.  Gradations, also, in the muscles leading\nto structures found in animals still lower in the scale, are numerous in\nthe Lemuroidea.), has minutely described a vast number of muscular\nvariations in man, which resemble normal structures in the lower animals.\nThe muscles which closely resemble those regularly present in our nearest\nallies, the Quadrumana, are too numerous to be here even specified.  In a\nsingle male subject, having a strong bodily frame, and well-formed skull,\nno less than seven muscular variations were observed, all of which plainly\nrepresented muscles proper to various kinds of apes.  This man, for\ninstance, had on both sides of his neck a true and powerful \"levator\nclaviculae,\" such as is found in all kinds of apes, and which is said to\noccur in about one out of sixty human subjects.  (49.  See also Prof.\nMacalister in 'Proceedings, Royal Irish Academy,' vol. x. 1868, p. 124.)\nAgain, this man had \"a special abductor of the metatarsal bone of the fifth\ndigit, such as Professor Huxley and Mr. Flower have shewn to exist\nuniformly in the higher and lower apes.\"  I will give only two additional\ncases; the acromio-basilar muscle is found in all mammals below man, and\nseems to be correlated with a quadrupedal gait, (50.  Mr. Champneys in\n'Journal of Anatomy and Physiology,' Nov. 1871, p. 178.) and it occurs in\nabout one out of sixty human subjects.  In the lower extremities Mr.\nBradley (51.  Ibid. May 1872, p. 421.) found an abductor ossis metatarsi\nquinti in both feet of man; this muscle had not up to that time been\nrecorded in mankind, but is always present in the anthropomorphous apes.\nThe muscles of the hands and arms--parts which are so eminently\ncharacteristic of man--are extremely liable to vary, so as to resemble the\ncorresponding muscles in the lower animals.  (52.  Prof. Macalister (ibid.\np. 121) has tabulated his observations, and finds that muscular\nabnormalities are most frequent in the fore-arms, secondly, in the face,\nthirdly, in the foot, etc.)  Such resemblances are either perfect or\nimperfect; yet in the latter case they are manifestly of a transitional\nnature.  Certain variations are more common in man, and others in woman,\nwithout our being able to assign any reason.  Mr. Wood, after describing\nnumerous variations, makes the following pregnant remark.  \"Notable\ndepartures from the ordinary type of the muscular structures run in grooves\nor directions, which must be taken to indicate some unknown factor, of much\nimportance to a comprehensive knowledge of general and scientific anatomy.\"\n(53.  The Rev. Dr. Haughton, after giving ('Proc. R. Irish Academy,' June\n27, 1864, p. 715) a remarkable case of variation in the human flexor\npollicis longus, adds, \"This remarkable example shews that man may\nsometimes possess the arrangement of tendons of thumb and fingers\ncharacteristic of the macaque; but whether such a case should be regarded\nas a macaque passing upwards into a man, or a man passing downwards into a\nmacaque, or as a congenital freak of nature, I cannot undertake to say.\"\nIt is satisfactory to hear so capable an anatomist, and so embittered an\nopponent of evolutionism, admitting even the possibility of either of his\nfirst propositions.  Prof. Macalister has also described ('Proceedings\nRoyal Irish Academy,' vol. x. 1864, p. 138) variations in the flexor\npollicis longus, remarkable from their relations to the same muscle in the\nQuadrumana.)\n\nThat this unknown factor is reversion to a former state of existence may be\nadmitted as in the highest degree probable.  (54.  Since the first edition\nof this book appeared, Mr. Wood has published another memoir in the\nPhilosophical Transactions, 1870, p. 83, on the varieties of the muscles of\nthe human neck, shoulder, and chest.  He here shews how extremely variable\nthese muscles are, and how often and how closely the variations resemble\nthe normal muscles of the lower animals.  He sums up by remarking, \"It will\nbe enough for my purpose if I have succeeded in shewing the more important\nforms which, when occurring as varieties in the human subject, tend to\nexhibit in a sufficiently marked manner what may be considered as proofs\nand examples of the Darwinian principle of reversion, or law of\ninheritance, in this department of anatomical science.\")  It is quite\nincredible that a man should through mere accident abnormally resemble\ncertain apes in no less than seven of his muscles, if there had been no\ngenetic connection between them.  On the other hand, if man is descended\nfrom some ape-like creature, no valid reason can be assigned why certain\nmuscles should not suddenly reappear after an interval of many thousand\ngenerations, in the same manner as with horses, asses, and mules, dark-\ncoloured stripes suddenly reappear on the legs, and shoulders, after an\ninterval of hundreds, or more probably of thousands of generations.\n\nThese various cases of reversion are so closely related to those of\nrudimentary organs given in the first chapter, that many of them might have\nbeen indifferently introduced either there or here.  Thus a human uterus\nfurnished with cornua may be said to represent, in a rudimentary condition,\nthe same organ in its normal state in certain mammals.  Some parts which\nare rudimentary in man, as the os coccyx in both sexes, and the mammae in\nthe male sex, are always present; whilst others, such as the supracondyloid\nforamen, only occasionally appear, and therefore might have been introduced\nunder the head of reversion.  These several reversionary structures, as\nwell as the strictly rudimentary ones, reveal the descent of man from some\nlower form in an unmistakable manner.\n\nCORRELATED VARIATION.\n\nIn man, as in the lower animals, many structures are so intimately related,\nthat when one part varies so does another, without our being able, in most\ncases, to assign any reason.  We cannot say whether the one part governs\nthe other, or whether both are governed by some earlier developed part.\nVarious monstrosities, as I. Geoffroy repeatedly insists, are thus\nintimately connected.  Homologous structures are particularly liable to\nchange together, as we see on the opposite sides of the body, and in the\nupper and lower extremities.  Meckel long ago remarked, that when the\nmuscles of the arm depart from their proper type, they almost always\nimitate those of the leg; and so, conversely, with the muscles of the legs.\nThe organs of sight and hearing, the teeth and hair, the colour of the skin\nand of the hair, colour and constitution, are more or less correlated.\n(55.  The authorities for these several statements are given in my\n'Variation of Animals under Domestication,' vol. ii. pp. 320-335.)\nProfessor Schaaffhausen first drew attention to the relation apparently\nexisting between a muscular frame and the strongly-pronounced supra-orbital\nridges, which are so characteristic of the lower races of man.\n\nBesides the variations which can be grouped with more or less probability\nunder the foregoing heads, there is a large class of variations which may\nbe provisionally called spontaneous, for to our ignorance they appear to\narise without any exciting cause.  It can, however, be shewn that such\nvariations, whether consisting of slight individual differences, or of\nstrongly-marked and abrupt deviations of structure, depend much more on the\nconstitution of the organism than on the nature of the conditions to which\nit has been subjected.  (56.  This whole subject has been discussed in\nchap. xxiii. vol. ii. of my 'Variation of Animals and Plants under\nDomestication.')\n\nRATE OF INCREASE.\n\nCivilised populations have been known under favourable conditions, as in\nthe United States, to double their numbers in twenty-five years; and,\naccording to a calculation, by Euler, this might occur in a little over\ntwelve years.  (57.  See the ever memorable 'Essay on the Principle of\nPopulation,' by the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.)  At the\nformer rate, the present population of the United States (thirty millions),\nwould in 657 years cover the whole terraqueous globe so thickly, that four\nmen would have to stand on each square yard of surface.  The primary or\nfundamental check to the continued increase of man is the difficulty of\ngaining subsistence, and of living in comfort.  We may infer that this is\nthe case from what we see, for instance, in the United States, where\nsubsistence is easy, and there is plenty of room.  If such means were\nsuddenly doubled in Great Britain, our number would be quickly doubled.\nWith civilised nations this primary check acts chiefly by restraining\nmarriages.  The greater death-rate of infants in the poorest classes is\nalso very important; as well as the greater mortality, from various\ndiseases, of the inhabitants of crowded and miserable houses, at all ages.\nThe effects of severe epidemics and wars are soon counterbalanced, and more\nthan counterbalanced, in nations placed under favourable conditions.\nEmigration also comes in aid as a temporary check, but, with the extremely\npoor classes, not to any great extent.\n\nThere is reason to suspect, as Malthus has remarked, that the reproductive\npower is actually less in barbarous, than in civilised races.  We know\nnothing positively on this head, for with savages no census has been taken;\nbut from the concurrent testimony of missionaries, and of others who have\nlong resided with such people, it appears that their families are usually\nsmall, and large ones rare.  This may be partly accounted for, as it is\nbelieved, by the women suckling their infants during a long time; but it is\nhighly probable that savages, who often suffer much hardship, and who do\nnot obtain so much nutritious food as civilised men, would be actually less\nprolific.  I have shewn in a former work (58.  'Variation of Animals and\nPlants under Domestication,' vol ii. pp. 111-113, 163.), that all our\ndomesticated quadrupeds and birds, and all our cultivated plants, are more\nfertile than the corresponding species in a state of nature.  It is no\nvalid objection to this conclusion that animals suddenly supplied with an\nexcess of food, or when grown very fat; and that most plants on sudden\nremoval from very poor to very rich soil, are rendered more or less\nsterile.  We might, therefore, expect that civilised men, who in one sense\nare highly domesticated, would be more prolific than wild men.  It is also\nprobable that the increased fertility of civilised nations would become, as\nwith our domestic animals, an inherited character:  it is at least known\nthat with mankind a tendency to produce twins runs in families. (59.  Mr.\nSedgwick, 'British and Foreign Medico-Chirurgical Review,' July 1863, p.\n170.)\n\nNotwithstanding that savages appear to be less prolific than civilised\npeople, they would no doubt rapidly increase if their numbers were not by\nsome means rigidly kept down.  The Santali, or hill-tribes of India, have\nrecently afforded a good illustration of this fact; for, as shewn by Mr.\nHunter (60.  'The Annals of Rural Bengal,' by W.W. Hunter, 1868, p. 259.),\nthey have increased at an extraordinary rate since vaccination has been\nintroduced, other pestilences mitigated, and war sternly repressed.  This\nincrease, however, would not have been possible had not these rude people\nspread into the adjoining districts, and worked for hire.  Savages almost\nalways marry; yet there is some prudential restraint, for they do not\ncommonly marry at the earliest possible age.  The young men are often\nrequired to shew that they can support a wife; and they generally have\nfirst to earn the price with which to purchase her from her parents.  With\nsavages the difficulty of obtaining subsistence occasionally limits their\nnumber in a much more direct manner than with civilised people, for all\ntribes periodically suffer from severe famines.  At such times savages are\nforced to devour much bad food, and their health can hardly fail to be\ninjured.  Many accounts have been published of their protruding stomachs\nand emaciated limbs after and during famines.  They are then, also,\ncompelled to wander much, and, as I was assured in Australia, their infants\nperish in large numbers.  As famines are periodical, depending chiefly on\nextreme seasons, all tribes must fluctuate in number.  They cannot steadily\nand regularly increase, as there is no artificial increase in the supply of\nfood.  Savages, when hard pressed, encroach on each other's territories,\nand war is the result; but they are indeed almost always at war with their\nneighbours.  They are liable to many accidents on land and water in their\nsearch for food; and in some countries they suffer much from the larger\nbeasts of prey.  Even in India, districts have been depopulated by the\nravages of tigers.\n\nMalthus has discussed these several checks, but he does not lay stress\nenough on what is probably the most important of all, namely infanticide,\nespecially of female infants, and the habit of procuring abortion.  These\npractices now prevail in many quarters of the world; and infanticide seems\nformerly to have prevailed, as Mr. M'Lennan (61.  'Primitive Marriage,'\n1865.) has shewn, on a still more extensive scale.  These practices appear\nto have originated in savages recognising the difficulty, or rather the\nimpossibility of supporting all the infants that are born.  Licentiousness\nmay also be added to the foregoing checks; but this does not follow from\nfailing means of subsistence; though there is reason to believe that in\nsome cases (as in Japan) it has been intentionally encouraged as a means of\nkeeping down the population.\n\nIf we look back to an extremely remote epoch, before man had arrived at the\ndignity of manhood, he would have been guided more by instinct and less by\nreason than are the lowest savages at the present time.  Our early semi-\nhuman progenitors would not have practised infanticide or polyandry; for\nthe instincts of the lower animals are never so perverted (62.  A writer in\nthe 'Spectator' (March 12, 1871, p. 320) comments as follows on this\npassage:--\"Mr. Darwin finds himself compelled to reintroduce a new doctrine\nof the fall of man.  He shews that the instincts of the higher animals are\nfar nobler than the habits of savage races of men, and he finds himself,\ntherefore, compelled to re-introduce,--in a form of the substantial\northodoxy of which he appears to be quite unconscious,--and to introduce as\na scientific hypothesis the doctrine that man's gain of KNOWLEDGE was the\ncause of a temporary but long-enduring moral deterioration as indicated by\nthe many foul customs, especially as to marriage, of savage tribes.  What\ndoes the Jewish tradition of the moral degeneration of man through his\nsnatching at a knowledge forbidden him by his highest instinct assert\nbeyond this?\") as to lead them regularly to destroy their own offspring, or\nto be quite devoid of jealousy.  There would have been no prudential\nrestraint from marriage, and the sexes would have freely united at an early\nage.  Hence the progenitors of man would have tended to increase rapidly;\nbut checks of some kind, either periodical or constant, must have kept down\ntheir numbers, even more severely than with existing savages.  What the\nprecise nature of these checks were, we cannot say, any more than with most\nother animals.  We know that horses and cattle, which are not extremely\nprolific animals, when first turned loose in South America, increased at an\nenormous rate.  The elephant, the slowest breeder of all known animals,\nwould in a few thousand years stock the whole world.  The increase of every\nspecies of monkey must be checked by some means; but not, as Brehm remarks,\nby the attacks of beasts of prey.  No one will assume that the actual power\nof reproduction in the wild horses and cattle of America, was at first in\nany sensible degree increased; or that, as each district became fully\nstocked, this same power was diminished.  No doubt, in this case, and in\nall others, many checks concur, and different checks under different\ncircumstances; periodical dearths, depending on unfavourable seasons, being\nprobably the most important of all.  So it will have been with the early\nprogenitors of man.\n\nNATURAL SELECTION.\n\nWe have now seen that man is variable in body and mind; and that the\nvariations are induced, either directly or indirectly, by the same general\ncauses, and obey the same general laws, as with the lower animals.  Man has\nspread widely over the face of the earth, and must have been exposed,\nduring his incessant migrations (63.  See some good remarks to this effect\nby W. Stanley Jevons, \"A Deduction from Darwin's Theory,\" 'Nature,' 1869,\np. 231.), to the most diversified conditions.  The inhabitants of Tierra\ndel Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and\nof the arctic regions in the other, must have passed through many climates,\nand changed their habits many times, before they reached their present\nhomes.  (64.  Latham, 'Man and his Migrations,' 1851, p. 135.)  The early\nprogenitors of man must also have tended, like all other animals, to have\nincreased beyond their means of subsistence; they must, therefore,\noccasionally have been exposed to a struggle for existence, and\nconsequently to the rigid law of natural selection.  Beneficial variations\nof all kinds will thus, either occasionally or habitually, have been\npreserved and injurious ones eliminated.  I do not refer to strongly-marked\ndeviations of structure, which occur only at long intervals of time, but to\nmere individual differences.  We know, for instance, that the muscles of\nour hands and feet, which determine our powers of movement, are liable,\nlike those of the lower animals, (65.  Messrs. Murie and Mivart in their\n'Anatomy of the Lemuroidea' ('Transact. Zoolog. Soc.' vol. vii. 1869, pp.\n96-98) say, \"some muscles are so irregular in their distribution that they\ncannot be well classed in any of the above groups.\"  These muscles differ\neven on the opposite sides of the same individual.) to incessant\nvariability.  If then the progenitors of man inhabiting any district,\nespecially one undergoing some change in its conditions, were divided into\ntwo equal bodies, the one half which included all the individuals best\nadapted by their powers of movement for gaining subsistence, or for\ndefending themselves, would on an average survive in greater numbers, and\nprocreate more offspring than the other and less well endowed half.\n\nMan in the rudest state in which he now exists is the most dominant animal\nthat has ever appeared on this earth.  He has spread more widely than any\nother highly organised form:  and all others have yielded before him.  He\nmanifestly owes this immense superiority to his intellectual faculties, to\nhis social habits, which lead him to aid and defend his fellows, and to his\ncorporeal structure.  The supreme importance of these characters has been\nproved by the final arbitrament of the battle for life.  Through his powers\nof intellect, articulate language has been evolved; and on this his\nwonderful advancement has mainly depended.  As Mr. Chauncey Wright remarks\n(66.  Limits of Natural Selection, 'North American Review,' Oct. 1870, p.\n295.):  \"a psychological analysis of the faculty of language shews, that\neven the smallest proficiency in it might require more brain power than the\ngreatest proficiency in any other direction.\"  He has invented and is able\nto use various weapons, tools, traps, etc., with which he defends himself,\nkills or catches prey, and otherwise obtains food.  He has made rafts or\ncanoes for fishing or crossing over to neighbouring fertile islands.  He\nhas discovered the art of making fire, by which hard and stringy roots can\nbe rendered digestible, and poisonous roots or herbs innocuous.  This\ndiscovery of fire, probably the greatest ever made by man, excepting\nlanguage, dates from before the dawn of history.  These several inventions,\nby which man in the rudest state has become so pre-eminent, are the direct\nresults of the development of his powers of observation, memory, curiosity,\nimagination, and reason.  I cannot, therefore, understand how it is that\nMr. Wallace (67.  'Quarterly Review,' April 1869, p. 392.  This subject is\nmore fully discussed in Mr. Wallace's 'Contributions to the Theory of\nNatural Selection,' 1870, in which all the essays referred to in this work\nare re-published.  The 'Essay on Man,' has been ably criticised by Prof.\nClaparede, one of the most distinguished zoologists in Europe, in an\narticle published in the 'Bibliotheque Universelle,' June 1870.  The remark\nquoted in my text will surprise every one who has read Mr. Wallace's\ncelebrated paper on 'The Origin of Human Races Deduced from the Theory of\nNatural Selection,' originally published in the 'Anthropological Review,'\nMay 1864, p. clviii.  I cannot here resist quoting a most just remark by\nSir J. Lubbock ('Prehistoric Times,' 1865, p. 479) in reference to this\npaper, namely, that Mr. Wallace, \"with characteristic unselfishness,\nascribes it (i.e. the idea of natural selection) unreservedly to Mr.\nDarwin, although, as is well known, he struck out the idea independently,\nand published it, though not with the same elaboration, at the same time.\")\nmaintains, that \"natural selection could only have endowed the savage with\na brain a little superior to that of an ape.\"\n\nAlthough the intellectual powers and social habits of man are of paramount\nimportance to him, we must not underrate the importance of his bodily\nstructure, to which subject the remainder of this chapter will be devoted;\nthe development of the intellectual and social or moral faculties being\ndiscussed in a later chapter.\n\nEven to hammer with precision is no easy matter, as every one who has tried\nto learn carpentry will admit.  To throw a stone with as true an aim as a\nFuegian in defending himself, or in killing birds, requires the most\nconsummate perfection in the correlated action of the muscles of the hand,\narm, and shoulder, and, further, a fine sense of touch.  In throwing a\nstone or spear, and in many other actions, a man must stand firmly on his\nfeet; and this again demands the perfect co-adaptation of numerous muscles.\nTo chip a flint into the rudest tool, or to form a barbed spear or hook\nfrom a bone, demands the use of a perfect hand; for, as a most capable\njudge, Mr. Schoolcraft (68.  Quoted by Mr. Lawson Tait in his 'Law of\nNatural Selection,' 'Dublin Quarterly Journal of Medical Science,' Feb.\n1869.  Dr. Keller is likewise quoted to the same effect.), remarks, the\nshaping fragments of stone into knives, lances, or arrow-heads, shews\n\"extraordinary ability and long practice.\"  This is to a great extent\nproved by the fact that primeval men practised a division of labour; each\nman did not manufacture his own flint tools or rude pottery, but certain\nindividuals appear to have devoted themselves to such work, no doubt\nreceiving in exchange the produce of the chase.  Archaeologists are\nconvinced that an enormous interval of time elapsed before our ancestors\nthought of grinding chipped flints into smooth tools.  One can hardly\ndoubt, that a man-like animal who possessed a hand and arm sufficiently\nperfect to throw a stone with precision, or to form a flint into a rude\ntool, could, with sufficient practice, as far as mechanical skill alone is\nconcerned, make almost anything which a civilised man can make.  The\nstructure of the hand in this respect may be compared with that of the\nvocal organs, which in the apes are used for uttering various signal-cries,\nor, as in one genus, musical cadences; but in man the closely similar vocal\norgans have become adapted through the inherited effects of use for the\nutterance of articulate language.\n\nTurning now to the nearest allies of men, and therefore to the best\nrepresentatives of our early progenitors, we find that the hands of the\nQuadrumana are constructed on the same general pattern as our own, but are\nfar less perfectly adapted for diversified uses.  Their hands do not serve\nfor locomotion so well as the feet of a dog; as may be seen in such monkeys\nas the chimpanzee and orang, which walk on the outer margins of the palms,\nor on the knuckles.  (69.  Owen, 'Anatomy of Vertebrates,' vol. iii. p.\n71.)  Their hands, however, are admirably adapted for climbing trees.\nMonkeys seize thin branches or ropes, with the thumb on one side and the\nfingers and palm on the other, in the same manner as we do.  They can thus\nalso lift rather large objects, such as the neck of a bottle, to their\nmouths.  Baboons turn over stones, and scratch up roots with their hands.\nThey seize nuts, insects, or other small objects with the thumb in\nopposition to the fingers, and no doubt they thus extract eggs and young\nfrom the nests of birds.  American monkeys beat the wild oranges on the\nbranches until the rind is cracked, and then tear it off with the fingers\nof the two hands.  In a wild state they break open hard fruits with stones.\nOther monkeys open mussel-shells with the two thumbs.  With their fingers\nthey pull out thorns and burs, and hunt for each other's parasites.  They\nroll down stones, or throw them at their enemies:  nevertheless, they are\nclumsy in these various actions, and, as I have myself seen, are quite\nunable to throw a stone with precision.\n\nIt seems to me far from true that because \"objects are grasped clumsily\" by\nmonkeys, \"a much less specialised organ of prehension\" would have served\nthem (70.  'Quarterly Review,' April 1869, p. 392.) equally well with their\npresent hands.  On the contrary, I see no reason to doubt that more\nperfectly constructed hands would have been an advantage to them, provided\nthat they were not thus rendered less fitted for climbing trees.  We may\nsuspect that a hand as perfect as that of man would have been\ndisadvantageous for climbing; for the most arboreal monkeys in the world,\nnamely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are\neither thumbless, or their toes partially cohere, so that their limbs are\nconverted into mere grasping hooks.  (71.  In Hylobates syndactylus, as the\nname expresses, two of the toes regularly cohere; and this, as Mr. Blyth\ninforms me, is occasionally the case with the toes of H. agilis, lar, and\nleuciscus.  Colobus is strictly arboreal and extraordinarily active (Brehm,\n'Thierleben,' B. i. s. 50), but whether a better climber than the species\nof the allied genera, I do not know.  It deserves notice that the feet of\nthe sloths, the most arboreal animals in the world, are wonderfully hook-\nlike.\n\nAs soon as some ancient member in the great series of the Primates came to\nbe less arboreal, owing to a change in its manner of procuring subsistence,\nor to some change in the surrounding conditions, its habitual manner of\nprogression would have been modified:  and thus it would have been rendered\nmore strictly quadrupedal or bipedal.  Baboons frequent hilly and rocky\ndistricts, and only from necessity climb high trees (72.  Brehm,\n'Thierleben,' B. i. s. 80.); and they have acquired almost the gait of a\ndog.  Man alone has become a biped; and we can, I think, partly see how he\nhas come to assume his erect attitude, which forms one of his most\nconspicuous characters.  Man could not have attained his present dominant\nposition in the world without the use of his hands, which are so admirably\nadapted to act in obedience to his will.  Sir C. Bell (73.  'The Hand,'\netc., 'Bridgewater Treatise,' 1833, p. 38.) insists that \"the hand supplies\nall instruments, and by its correspondence with the intellect gives him\nuniversal dominion.\"  But the hands and arms could hardly have become\nperfect enough to have manufactured weapons, or to have hurled stones and\nspears with a true aim, as long as they were habitually used for locomotion\nand for supporting the whole weight of the body, or, as before remarked, so\nlong as they were especially fitted for climbing trees.  Such rough\ntreatment would also have blunted the sense of touch, on which their\ndelicate use largely depends.  From these causes alone it would have been\nan advantage to man to become a biped; but for many actions it is\nindispensable that the arms and whole upper part of the body should be\nfree; and he must for this end stand firmly on his feet.  To gain this\ngreat advantage, the feet have been rendered flat; and the great toe has\nbeen peculiarly modified, though this has entailed the almost complete loss\nof its power of prehension.  It accords with the principle of the division\nof physiological labour, prevailing throughout the animal kingdom, that as\nthe hands became perfected for prehension, the feet should have become\nperfected for support and locomotion.  With some savages, however, the foot\nhas not altogether lost its prehensile power, as shewn by their manner of\nclimbing trees, and of using them in other ways.  (74.  Haeckel has an\nexcellent discussion on the steps by which man became a biped:  'Natuerliche\nSchoepfungsgeschichte,' 1868, s. 507.  Dr. Buchner ('Conferences sur la\nTheorie Darwinienne,' 1869, p. 135) has given good cases of the use of the\nfoot as a prehensile organ by man; and has also written on the manner of\nprogression of the higher apes, to which I allude in the following\nparagraph:  see also Owen ('Anatomy of Vertebrates,' vol. iii. p. 71) on\nthis latter subject.\n\nIf it be an advantage to man to stand firmly on his feet and to have his\nhands and arms free, of which, from his pre-eminent success in the battle\nof life there can be no doubt, then I can see no reason why it should not\nhave been advantageous to the progenitors of man to have become more and\nmore erect or bipedal.  They would thus have been better able to defend\nthemselves with stones or clubs, to attack their prey, or otherwise to\nobtain food.  The best built individuals would in the long run have\nsucceeded best, and have survived in larger numbers.  If the gorilla and a\nfew allied forms had become extinct, it might have been argued, with great\nforce and apparent truth, that an animal could not have been gradually\nconverted from a quadruped into a biped, as all the individuals in an\nintermediate condition would have been miserably ill-fitted for\nprogression.  But we know (and this is well worthy of reflection) that the\nanthropomorphous apes are now actually in an intermediate condition; and no\none doubts that they are on the whole well adapted for their conditions of\nlife.  Thus the gorilla runs with a sidelong shambling gait, but more\ncommonly progresses by resting on its bent hands.  The long-armed apes\noccasionally use their arms like crutches, swinging their bodies forward\nbetween them, and some kinds of Hylobates, without having been taught, can\nwalk or run upright with tolerable quickness; yet they move awkwardly, and\nmuch less securely than man.  We see, in short, in existing monkeys a\nmanner of progression intermediate between that of a quadruped and a biped;\nbut, as an unprejudiced judge (75.  Prof. Broca, La Constitution des\nVertebres caudales; 'La Revue d'Anthropologie,' 1872, p. 26, (separate\ncopy).) insists, the anthropomorphous apes approach in structure more\nnearly to the bipedal than to the quadrupedal type.\n\nAs the progenitors of man became more and more erect, with their hands and\narms more and more modified for prehension and other purposes, with their\nfeet and legs at the same time transformed for firm support and\nprogression, endless other changes of structure would have become\nnecessary.  The pelvis would have to be broadened, the spine peculiarly\ncurved, and the head fixed in an altered position, all which changes have\nbeen attained by man.  Prof. Schaaffhausen (76.  'On the Primitive Form of\nthe Skull,' translated in 'Anthropological Review,' Oct. 1868, p. 428.\nOwen ('Anatomy of Vertebrates,' vol. ii. 1866, p. 551) on the mastoid\nprocesses in the higher apes.) maintains that \"the powerful mastoid\nprocesses of the human skull are the result of his erect position;\" and\nthese processes are absent in the orang, chimpanzee, etc., and are smaller\nin the gorilla than in man.  Various other structures, which appear\nconnected with man's erect position, might here have been added.  It is\nvery difficult to decide how far these correlated modifications are the\nresult of natural selection, and how far of the inherited effects of the\nincreased use of certain parts, or of the action of one part on another.\nNo doubt these means of change often co-operate:  thus when certain\nmuscles, and the crests of bone to which they are attached, become enlarged\nby habitual use, this shews that certain actions are habitually performed\nand must be serviceable.  Hence the individuals which performed them best,\nwould tend to survive in greater numbers.\n\nThe free use of the arms and hands, partly the cause and partly the result\nof man's erect position, appears to have led in an indirect manner to other\nmodifications of structure.  The early male forefathers of man were, as\npreviously stated, probably furnished with great canine teeth; but as they\ngradually acquired the habit of using stones, clubs, or other weapons, for\nfighting with their enemies or rivals, they would use their jaws and teeth\nless and less.  In this case, the jaws, together with the teeth, would\nbecome reduced in size, as we may feel almost sure from innumerable\nanalogous cases.  In a future chapter we shall meet with a closely parallel\ncase, in the reduction or complete disappearance of the canine teeth in\nmale ruminants, apparently in relation with the development of their horns;\nand in horses, in relation to their habit of fighting with their incisor\nteeth and hoofs.\n\nIn the adult male anthropomorphous apes, as Rutimeyer (77.  'Die Grenzen\nder Thierwelt, eine Betrachtung zu Darwin's Lehre,' 1868, s. 51.), and\nothers, have insisted, it is the effect on the skull of the great\ndevelopment of the jaw-muscles that causes it to differ so greatly in many\nrespects from that of man, and has given to these animals \"a truly\nfrightful physiognomy.\"  Therefore, as the jaws and teeth in man's\nprogenitors gradually become reduced in size, the adult skull would have\ncome to resemble more and more that of existing man.  As we shall hereafter\nsee, a great reduction of the canine teeth in the males would almost\ncertainly affect the teeth of the females through inheritance.\n\nAs the various mental faculties gradually developed themselves the brain\nwould almost certainly become larger.  No one, I presume, doubts that the\nlarge proportion which the size of man's brain bears to his body, compared\nto the same proportion in the gorilla or orang, is closely connected with\nhis higher mental powers.  We meet with closely analogous facts with\ninsects, for in ants the cerebral ganglia are of extraordinary dimensions,\nand in all the Hymenoptera these ganglia are many times larger than in the\nless intelligent orders, such as beetles.  (78.  Dujardin, 'Annales des\nSciences Nat.' 3rd series, Zoolog., tom. xiv. 1850, p. 203.  See also Mr.\nLowne, 'Anatomy and Phys. of the Musca vomitoria,' 1870, p. 14.  My son,\nMr. F. Darwin, dissected for me the cerebral ganglia of the Formica rufa.)\nOn the other hand, no one supposes that the intellect of any two animals or\nof any two men can be accurately gauged by the cubic contents of their\nskulls.  It is certain that there may be extraordinary mental activity with\nan extremely small absolute mass of nervous matter:  thus the wonderfully\ndiversified instincts, mental powers, and affections of ants are notorious,\nyet their cerebral ganglia are not so large as the quarter of a small pin's\nhead.  Under this point of view, the brain of an ant is one of the most\nmarvellous atoms of matter in the world, perhaps more so than the brain of\na man.\n\nThe belief that there exists in man some close relation between the size of\nthe brain and the development of the intellectual faculties is supported by\nthe comparison of the skulls of savage and civilised races, of ancient and\nmodern people, and by the analogy of the whole vertebrate series.  Dr. J.\nBarnard Davis has proved (79.  'Philosophical Transactions,' 1869, p.\n513.), by many careful measurements, that the mean internal capacity of the\nskull in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics\n87.1; and in Australians only 81.9 cubic inches.  Professor Broca (80.\n'Les Selections,' M. P. Broca, 'Revue d'Anthropologies,' 1873; see also, as\nquoted in C. Vogt's 'Lectures on Man,' Engl. translat., 1864, pp. 88, 90.\nPrichard, 'Physical History of Mankind,' vol. i. 1838, p. 305.) found that\nthe nineteenth century skulls from graves in Paris were larger than those\nfrom vaults of the twelfth century, in the proportion of 1484 to 1426; and\nthat the increased size, as ascertained by measurements, was exclusively in\nthe frontal part of the skull--the seat of the intellectual faculties.\nPrichard is persuaded that the present inhabitants of Britain have \"much\nmore capacious brain-cases\" than the ancient inhabitants.  Nevertheless, it\nmust be admitted that some skulls of very high antiquity, such as the\nfamous one of Neanderthal, are well developed and capacious.  (81.  In the\ninteresting article just referred to, Prof. Broca has well remarked, that\nin civilised nations, the average capacity of the skull must be lowered by\nthe preservation of a considerable number of individuals, weak in mind and\nbody, who would have been promptly eliminated in the savage state.  On the\nother hand, with savages, the average includes only the more capable\nindividuals, who have been able to survive under extremely hard conditions\nof life.  Broca thus explains the otherwise inexplicable fact, that the\nmean capacity of the skull of the ancient Troglodytes of Lozere is greater\nthan that of modern Frenchmen.)  With respect to the lower animals, M.E.\nLartet (82.  'Comptes-rendus des Sciences,' etc., June 1, 1868.), by\ncomparing the crania of tertiary and recent mammals belonging to the same\ngroups, has come to the remarkable conclusion that the brain is generally\nlarger and the convolutions are more complex in the more recent forms.  On\nthe other hand, I have shewn (83.  The 'Variation of Animals and Plants\nunder Domestication,' vol. i. pp. 124-129.) that the brains of domestic\nrabbits are considerably reduced in bulk, in comparison with those of the\nwild rabbit or hare; and this may be attributed to their having been\nclosely confined during many generations, so that they have exerted their\nintellect, instincts, senses and voluntary movements but little.\n\nThe gradually increasing weight of the brain and skull in man must have\ninfluenced the development of the supporting spinal column, more especially\nwhilst he was becoming erect.  As this change of position was being brought\nabout, the internal pressure of the brain will also have influenced the\nform of the skull; for many facts shew how easily the skull is thus\naffected.  Ethnologists believe that it is modified by the kind of cradle\nin which infants sleep.  Habitual spasms of the muscles, and a cicatrix\nfrom a severe burn, have permanently modified the facial bones.  In young\npersons whose heads have become fixed either sideways or backwards, owing\nto disease, one of the two eyes has changed its position, and the shape of\nthe skull has been altered apparently by the pressure of the brain in a new\ndirection.  (84.  Schaaffhausen gives from Blumenbach and Busch, the cases\nof the spasms and cicatrix, in 'Anthropological Review,' Oct. 1868, p. 420.\nDr. Jarrold ('Anthropologia,' 1808, pp. 115, 116) adduces from Camper and\nfrom his own observations, cases of the modification of the skull from the\nhead being fixed in an unnatural position.  He believes that in certain\ntrades, such as that of a shoemaker, where the head is habitually held\nforward, the forehead becomes more rounded and prominent.)  I have shewn\nthat with long-eared rabbits even so trifling a cause as the lopping\nforward of one ear drags forward almost every bone of the skull on that\nside; so that the bones on the opposite side no longer strictly correspond.\nLastly, if any animal were to increase or diminish much in general size,\nwithout any change in its mental powers, or if the mental powers were to be\nmuch increased or diminished, without any great change in the size of the\nbody, the shape of the skull would almost certainly be altered.  I infer\nthis from my observations on domestic rabbits, some kinds of which have\nbecome very much larger than the wild animal, whilst others have retained\nnearly the same size, but in both cases the brain has been much reduced\nrelatively to the size of the body.  Now I was at first much surprised on\nfinding that in all these rabbits the skull had become elongated or\ndolichocephalic; for instance, of two skulls of nearly equal breadth, the\none from a wild rabbit and the other from a large domestic kind, the former\nwas 3.15 and the latter 4.3 inches in length.  (85.  'Variation of Animals\nand Plants under Domestication,' vol. i. p. 117, on the elongation of the\nskull; p. 119, on the effect of the lopping of one ear.)  One of the most\nmarked distinctions in different races of men is that the skull in some is\nelongated, and in others rounded; and here the explanation suggested by the\ncase of the rabbits may hold good; for Welcker finds that short \"men\nincline more to brachycephaly, and tall men to dolichocephaly\" (86.  Quoted\nby Schaaffhausen, in 'Anthropological Review,' Oct. 1868, p. 419.); and\ntall men may be compared with the larger and longer-bodied rabbits, all of\nwhich have elongated skulls or are dolichocephalic.\n\nFrom these several facts we can understand, to a certain extent, the means\nby which the great size and more or less rounded form of the skull have\nbeen acquired by man; and these are characters eminently distinctive of him\nin comparison with the lower animals.\n\nAnother most conspicuous difference between man and the lower animals is\nthe nakedness of his skin.  Whales and porpoises (Cetacea), dugongs\n(Sirenia) and the hippopotamus are naked; and this may be advantageous to\nthem for gliding through the water; nor would it be injurious to them from\nthe loss of warmth, as the species, which inhabit the colder regions, are\nprotected by a thick layer of blubber, serving the same purpose as the fur\nof seals and otters.  Elephants and rhinoceroses are almost hairless; and\nas certain extinct species, which formerly lived under an Arctic climate,\nwere covered with long wool or hair, it would almost appear as if the\nexisting species of both genera had lost their hairy covering from exposure\nto heat.  This appears the more probable, as the elephants in India which\nlive on elevated and cool districts are more hairy (87.  Owen, 'Anatomy of\nVertebrates,' vol. iii. p. 619.) than those on the lowlands.  May we then\ninfer that man became divested of hair from having aboriginally inhabited\nsome tropical land?  That the hair is chiefly retained in the male sex on\nthe chest and face, and in both sexes at the junction of all four limbs\nwith the trunk, favours this inference--on the assumption that the hair was\nlost before man became erect; for the parts which now retain most hair\nwould then have been most protected from the heat of the sun.  The crown of\nthe head, however, offers a curious exception, for at all times it must\nhave been one of the most exposed parts, yet it is thickly clothed with\nhair.  The fact, however, that the other members of the order of Primates,\nto which man belongs, although inhabiting various hot regions, are well\nclothed with hair, generally thickest on the upper surface (88.  Isidore\nGeoffroy St.-Hilaire remarks ('Histoire Nat. Generale,' tom. ii. 1859, pp.\n215-217) on the head of man being covered with long hair; also on the upper\nsurfaces of monkeys and of other mammals being more thickly clothed than\nthe lower surfaces.  This has likewise been observed by various authors.\nProf. P. Gervais ('Histoire Nat. des Mammiferes,' tom. i. 1854, p. 28),\nhowever, states that in the Gorilla the hair is thinner on the back, where\nit is partly rubbed off, than on the lower surface.), is opposed to the\nsupposition that man became naked through the action of the sun.  Mr. Belt\nbelieves (89.  The 'Naturalist in Nicaragua,' 1874, p. 209.  As some\nconfirmation of Mr. Belt's view, I may quote the following passage from Sir\nW. Denison ('Varieties of Vice-Regal Life,' vol. i. 1870, p. 440):  \"It is\nsaid to be a practice with the Australians, when the vermin get\ntroublesome, to singe themselves.\") that within the tropics it is an\nadvantage to man to be destitute of hair, as he is thus enabled to free\nhimself of the multitude of ticks (acari) and other parasites, with which\nhe is often infested, and which sometimes cause ulceration.  But whether\nthis evil is of sufficient magnitude to have led to the denudation of his\nbody through natural selection, may be doubted, since none of the many\nquadrupeds inhabiting the tropics have, as far as I know, acquired any\nspecialised means of relief.  The view which seems to me the most probable\nis that man, or rather primarily woman, became divested of hair for\nornamental purposes, as we shall see under Sexual Selection; and, according\nto this belief, it is not surprising that man should differ so greatly in\nhairiness from all other Primates, for characters, gained through sexual\nselection, often differ to an extraordinary degree in closely related\nforms.\n\nAccording to a popular impression, the absence of a tail is eminently\ndistinctive of man; but as those apes which come nearest to him are\ndestitute of this organ, its disappearance does not relate exclusively to\nman.  The tail often differs remarkably in length within the same genus:\nthus in some species of Macacus it is longer than the whole body, and is\nformed of twenty-four vertebrae; in others it consists of a scarcely\nvisible stump, containing only three or four vertebrae.  In some kinds of\nbaboons there are twenty-five, whilst in the mandrill there are ten very\nsmall stunted caudal vertebrae, or, according to Cuvier (90.  Mr. St.\nGeorge Mivart, 'Proc. Zoolog. Soc.' 1865, pp. 562, 583.  Dr. J.E. Gray,\n'Cat. Brit. Mus.:  'Skeletons.'  Owen, 'Anatomy of Vertebrates,' vol. ii.\np. 517.  Isidore Geoffroy, 'Hist. Nat. Gen.' tom. ii. p. 244.), sometimes\nonly five.  The tail, whether it be long or short, almost always tapers\ntowards the end; and this, I presume, results from the atrophy of the\nterminal muscles, together with their arteries and nerves, through disuse,\nleading to the atrophy of the terminal bones.  But no explanation can at\npresent be given of the great diversity which often occurs in its length.\nHere, however, we are more specially concerned with the complete external\ndisappearance of the tail.  Professor Broca has recently shewn (91.  'Revue\nd'Anthropologie,' 1872; 'La Constitution des vertebres caudales.') that the\ntail in all quadrupeds consists of two portions, generally separated\nabruptly from each other; the basal portion consists of vertebrae, more or\nless perfectly channelled and furnished with apophyses like ordinary\nvertebrae; whereas those of the terminal portion are not channelled, are\nalmost smooth, and scarcely resemble true vertebrae.  A tail, though not\nexternally visible, is really present in man and the anthropomorphous apes,\nand is constructed on exactly the same pattern in both.  In the terminal\nportion the vertebrae, constituting the os coccyx, are quite rudimentary,\nbeing much reduced in size and number.  In the basal portion, the vertebrae\nare likewise few, are united firmly together, and are arrested in\ndevelopment; but they have been rendered much broader and flatter than the\ncorresponding vertebrae in the tails of other animals:  they constitute\nwhat Broca calls the accessory sacral vertebrae.  These are of functional\nimportance by supporting certain internal parts and in other ways; and\ntheir modification is directly connected with the erect or semi-erect\nattitude of man and the anthropomorphous apes.  This conclusion is the more\ntrustworthy, as Broca formerly held a different view, which he has now\nabandoned.  The modification, therefore, of the basal caudal vertebrae in\nman and the higher apes may have been effected, directly or indirectly,\nthrough natural selection.\n\nBut what are we to say about the rudimentary and variable vertebrae of the\nterminal portion of the tail, forming the os coccyx?  A notion which has\noften been, and will no doubt again be ridiculed, namely, that friction has\nhad something to do with the disappearance of the external portion of the\ntail, is not so ridiculous as it at first appears.  Dr. Anderson (92.\n'Proceedings Zoological Society,' 1872, p. 210.) states that the extremely\nshort tail of Macacus brunneus is formed of eleven vertebrae, including the\nimbedded basal ones.  The extremity is tendinous and contains no vertebrae;\nthis is succeeded by five rudimentary ones, so minute that together they\nare only one line and a half in length, and these are permanently bent to\none side in the shape of a hook.  The free part of the tail, only a little\nabove an inch in length, includes only four more small vertebrae.  This\nshort tail is carried erect; but about a quarter of its total length is\ndoubled on to itself to the left; and this terminal part, which includes\nthe hook-like portion, serves \"to fill up the interspace between the upper\ndivergent portion of the callosities;\" so that the animal sits on it, and\nthus renders it rough and callous.  Dr. Anderson thus sums up his\nobservations:  \"These facts seem to me to have only one explanation; this\ntail, from its short size, is in the monkey's way when it sits down, and\nfrequently becomes placed under the animal while it is in this attitude;\nand from the circumstance that it does not extend beyond the extremity of\nthe ischial tuberosities, it seems as if the tail originally had been bent\nround by the will of the animal, into the interspace between the\ncallosities, to escape being pressed between them and the ground, and that\nin time the curvature became permanent, fitting in of itself when the organ\nhappens to be sat upon.\"  Under these circumstances it is not surprising\nthat the surface of the tail should have been roughened and rendered\ncallous, and Dr. Murie (93.  'Proceedings Zoological Society,' 1872, p.\n786.), who carefully observed this species in the Zoological Gardens, as\nwell as three other closely allied forms with slightly longer tails, says\nthat when the animal sits down, the tail \"is necessarily thrust to one side\nof the buttocks; and whether long or short its root is consequently liable\nto be rubbed or chafed.\"  As we now have evidence that mutilations\noccasionally produce an inherited effect (94.  I allude to Dr. Brown-\nSequard's observations on the transmitted effect of an operation causing\nepilepsy in guinea-pigs, and likewise more recently on the analogous\neffects of cutting the sympathetic nerve in the neck.  I shall hereafter\nhave occasion to refer to Mr. Salvin's interesting case of the apparently\ninherited effects of mot-mots biting off the barbs of their own tail-\nfeathers.  See also on the general subject 'Variation of Animals and Plants\nunder Domestication,' vol. ii. pp. 22-24.), it is not very improbable that\nin short-tailed monkeys, the projecting part of the tail, being\nfunctionally useless, should after many generations have become rudimentary\nand distorted, from being continually rubbed and chafed.  We see the\nprojecting part in this condition in the Macacus brunneus, and absolutely\naborted in the M. ecaudatus and in several of the higher apes.  Finally,\nthen, as far as we can judge, the tail has disappeared in man and the\nanthropomorphous apes, owing to the terminal portion having been injured by\nfriction during a long lapse of time; the basal and embedded portion having\nbeen reduced and modified, so as to become suitable to the erect or semi-\nerect position.\n\nI have now endeavoured to shew that some of the most distinctive characters\nof man have in all probability been acquired, either directly, or more\ncommonly indirectly, through natural selection.  We should bear in mind\nthat modifications in structure or constitution which do not serve to adapt\nan organism to its habits of life, to the food which it consumes, or\npassively to the surrounding conditions, cannot have been thus acquired.\nWe must not, however, be too confident in deciding what modifications are\nof service to each being:  we should remember how little we know about the\nuse of many parts, or what changes in the blood or tissues may serve to fit\nan organism for a new climate or new kinds of food.  Nor must we forget the\nprinciple of correlation, by which, as Isidore Geoffroy has shewn in the\ncase of man, many strange deviations of structure are tied together.\nIndependently of correlation, a change in one part often leads, through the\nincreased or decreased use of other parts, to other changes of a quite\nunexpected nature.  It is also well to reflect on such facts, as the\nwonderful growth of galls on plants caused by the poison of an insect, and\non the remarkable changes of colour in the plumage of parrots when fed on\ncertain fishes, or inoculated with the poison of toads (95.  The 'Variation\nof Animals and Plants under Domestication,' vol. ii. pp. 280, 282.); for we\ncan thus see that the fluids of the system, if altered for some special\npurpose, might induce other changes.  We should especially bear in mind\nthat modifications acquired and continually used during past ages for some\nuseful purpose, would probably become firmly fixed, and might be long\ninherited.\n\nThus a large yet undefined extension may safely be given to the direct and\nindirect results of natural selection; but I now admit, after reading the\nessay by Nageli on plants, and the remarks by various authors with respect\nto animals, more especially those recently made by Professor Broca, that in\nthe earlier editions of my 'Origin of Species' I perhaps attributed too\nmuch to the action of natural selection or the survival of the fittest.  I\nhave altered the fifth edition of the 'Origin' so as to confine my remarks\nto adaptive changes of structure; but I am convinced, from the light gained\nduring even the last few years, that very many structures which now appear\nto us useless, will hereafter be proved to be useful, and will therefore\ncome within the range of natural selection.  Nevertheless, I did not\nformerly consider sufficiently the existence of structures, which, as far\nas we can at present judge, are neither beneficial nor injurious; and this\nI believe to be one of the greatest oversights as yet detected in my work.\nI may be permitted to say, as some excuse, that I had two distinct objects\nin view; firstly, to shew that species had not been separately created, and\nsecondly, that natural selection had been the chief agent of change, though\nlargely aided by the inherited effects of habit, and slightly by the direct\naction of the surrounding conditions.  I was not, however, able to annul\nthe influence of my former belief, then almost universal, that each species\nhad been purposely created; and this led to my tacit assumption that every\ndetail of structure, excepting rudiments, was of some special, though\nunrecognised, service.  Any one with this assumption in his mind would\nnaturally extend too far the action of natural selection, either during\npast or present times.  Some of those who admit the principle of evolution,\nbut reject natural selection, seem to forget, when criticising my book,\nthat I had the above two objects in view; hence if I have erred in giving\nto natural selection great power, which I am very far from admitting, or in\nhaving exaggerated its power, which is in itself probable, I have at least,\nas I hope, done good service in aiding to overthrow the dogma of separate\ncreations.\n\nIt is, as I can now see, probable that all organic beings, including man,\npossess peculiarities of structure, which neither are now, nor were\nformerly of any service to them, and which, therefore, are of no\nphysiological importance.  We know not what produces the numberless slight\ndifferences between the individuals of each species, for reversion only\ncarries the problem a few steps backwards, but each peculiarity must have\nhad its efficient cause.  If these causes, whatever they may be, were to\nact more uniformly and energetically during a lengthened period (and\nagainst this no reason can be assigned), the result would probably be not a\nmere slight individual difference, but a well-marked and constant\nmodification, though one of no physiological importance.  Changed\nstructures, which are in no way beneficial, cannot be kept uniform through\nnatural selection, though the injurious will be thus eliminated.\nUniformity of character would, however, naturally follow from the assumed\nuniformity of the exciting causes, and likewise from the free intercrossing\nof many individuals.  During successive periods, the same organism might in\nthis manner acquire successive modifications, which would be transmitted in\na nearly uniform state as long as the exciting causes remained the same and\nthere was free intercrossing.  With respect to the exciting causes we can\nonly say, as when speaking of so-called spontaneous variations, that they\nrelate much more closely to the constitution of the varying organism, than\nto the nature of the conditions to which it has been subjected.\n\nCONCLUSION.\n\nIn this chapter we have seen that as man at the present day is liable, like\nevery other animal, to multiform individual differences or slight\nvariations, so no doubt were the early progenitors of man; the variations\nbeing formerly induced by the same general causes, and governed by the same\ngeneral and complex laws as at present.  As all animals tend to multiply\nbeyond their means of subsistence, so it must have been with the\nprogenitors of man; and this would inevitably lead to a struggle for\nexistence and to natural selection.  The latter process would be greatly\naided by the inherited effects of the increased use of parts, and these two\nprocesses would incessantly react on each other.  It appears, also, as we\nshall hereafter see, that various unimportant characters have been acquired\nby man through sexual selection.  An unexplained residuum of change must be\nleft to the assumed uniform action of those unknown agencies, which\noccasionally induce strongly marked and abrupt deviations of structure in\nour domestic productions.\n\nJudging from the habits of savages and of the greater number of the\nQuadrumana, primeval men, and even their ape-like progenitors, probably\nlived in society.  With strictly social animals, natural selection\nsometimes acts on the individual, through the preservation of variations\nwhich are beneficial to the community.  A community which includes a large\nnumber of well-endowed individuals increases in number, and is victorious\nover other less favoured ones; even although each separate member gains no\nadvantage over the others of the same community.  Associated insects have\nthus acquired many remarkable structures, which are of little or no service\nto the individual, such as the pollen-collecting apparatus, or the sting of\nthe worker-bee, or the great jaws of soldier-ants.  With the higher social\nanimals, I am not aware that any structure has been modified solely for the\ngood of the community, though some are of secondary service to it.  For\ninstance, the horns of ruminants and the great canine teeth of baboons\nappear to have been acquired by the males as weapons for sexual strife, but\nthey are used in defence of the herd or troop.  In regard to certain mental\npowers the case, as we shall see in the fifth chapter, is wholly different;\nfor these faculties have been chiefly, or even exclusively, gained for the\nbenefit of the community, and the individuals thereof have at the same time\ngained an advantage indirectly.\n\nIt has often been objected to such views as the foregoing, that man is one\nof the most helpless and defenceless creatures in the world; and that\nduring his early and less well-developed condition, he would have been\nstill more helpless.  The Duke of Argyll, for instance, insists (96.\n'Primeval Man,' 1869, p. 66.) that \"the human frame has diverged from the\nstructure of brutes, in the direction of greater physical helplessness and\nweakness.  That is to say, it is a divergence which of all others it is\nmost impossible to ascribe to mere natural selection.\"  He adduces the\nnaked and unprotected state of the body, the absence of great teeth or\nclaws for defence, the small strength and speed of man, and his slight\npower of discovering food or of avoiding danger by smell.  To these\ndeficiencies there might be added one still more serious, namely, that he\ncannot climb quickly, and so escape from enemies.  The loss of hair would\nnot have been a great injury to the inhabitants of a warm country.  For we\nknow that the unclothed Fuegians can exist under a wretched climate.  When\nwe compare the defenceless state of man with that of apes, we must remember\nthat the great canine teeth with which the latter are provided, are\npossessed in their full development by the males alone, and are chiefly\nused by them for fighting with their rivals; yet the females, which are not\nthus provided, manage to survive.\n\nIn regard to bodily size or strength, we do not know whether man is\ndescended from some small species, like the chimpanzee, or from one as\npowerful as the gorilla; and, therefore, we cannot say whether man has\nbecome larger and stronger, or smaller and weaker, than his ancestors.  We\nshould, however, bear in mind that an animal possessing great size,\nstrength, and ferocity, and which, like the gorilla, could defend itself\nfrom all enemies, would not perhaps have become social:  and this would\nmost effectually have checked the acquirement of the higher mental\nqualities, such as sympathy and the love of his fellows.  Hence it might\nhave been an immense advantage to man to have sprung from some\ncomparatively weak creature.\n\nThe small strength and speed of man, his want of natural weapons, etc., are\nmore than counterbalanced, firstly, by his intellectual powers, through\nwhich he has formed for himself weapons, tools, etc., though still\nremaining in a barbarous state, and, secondly, by his social qualities\nwhich lead him to give and receive aid from his fellow-men.  No country in\nthe world abounds in a greater degree with dangerous beasts than Southern\nAfrica; no country presents more fearful physical hardships than the Arctic\nregions; yet one of the puniest of races, that of the Bushmen, maintains\nitself in Southern Africa, as do the dwarfed Esquimaux in the Arctic\nregions.  The ancestors of man were, no doubt, inferior in intellect, and\nprobably in social disposition, to the lowest existing savages; but it is\nquite conceivable that they might have existed, or even flourished, if\nthey had advanced in intellect, whilst gradually losing their brute-like\npowers, such as that of climbing trees, etc.  But these ancestors would not\nhave been exposed to any special danger, even if far more helpless and\ndefenceless than any existing savages, had they inhabited some warm\ncontinent or large island, such as Australia, New Guinea, or Borneo, which\nis now the home of the orang.  And natural selection arising from the\ncompetition of tribe with tribe, in some such large area as one of these,\ntogether with the inherited effects of habit, would, under favourable\nconditions, have sufficed to raise man to his present high position in the\norganic scale.\n\n\nCHAPTER III.\n\nCOMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS.\n\nThe difference in mental power between the highest ape and the lowest\nsavage, immense--Certain instincts in common--The emotions--Curiosity--\nImitation--Attention--Memory--Imagination--Reason--Progressive improvement\n--Tools and weapons used by animals--Abstraction, Self-consciousness--\nLanguage--Sense of beauty--Belief in God, spiritual agencies,\nsuperstitions.\n\nWe have seen in the last two chapters that man bears in his bodily\nstructure clear traces of his descent from some lower form; but it may be\nurged that, as man differs so greatly in his mental power from all other\nanimals, there must be some error in this conclusion.  No doubt the\ndifference in this respect is enormous, even if we compare the mind of one\nof the lowest savages, who has no words to express any number higher than\nfour, and who uses hardly any abstract terms for common objects or for the\naffections (1.  See the evidence on those points, as given by Lubbock,\n'Prehistoric Times,' p. 354, etc.), with that of the most highly organised\nape.  The difference would, no doubt, still remain immense, even if one of\nthe higher apes had been improved or civilised as much as a dog has been in\ncomparison with its parent-form, the wolf or jackal.  The Fuegians rank\namongst the lowest barbarians; but I was continually struck with surprise\nhow closely the three natives on board H.M.S. \"Beagle,\" who had lived some\nyears in England, and could talk a little English, resembled us in\ndisposition and in most of our mental faculties.  If no organic being\nexcepting man had possessed any mental power, or if his powers had been of\na wholly different nature from those of the lower animals, then we should\nnever have been able to convince ourselves that our high faculties had been\ngradually developed.  But it can be shewn that there is no fundamental\ndifference of this kind.  We must also admit that there is a much wider\ninterval in mental power between one of the lowest fishes, as a lamprey or\nlancelet, and one of the higher apes, than between an ape and man; yet this\ninterval is filled up by numberless gradations.\n\nNor is the difference slight in moral disposition between a barbarian, such\nas the man described by the old navigator Byron, who dashed his child on\nthe rocks for dropping a basket of sea-urchins, and a Howard or Clarkson;\nand in intellect, between a savage who uses hardly any abstract terms, and\na Newton or Shakspeare.  Differences of this kind between the highest men\nof the highest races and the lowest savages, are connected by the finest\ngradations.  Therefore it is possible that they might pass and be developed\ninto each other.\n\nMy object in this chapter is to shew that there is no fundamental\ndifference between man and the higher mammals in their mental faculties.\nEach division of the subject might have been extended into a separate\nessay, but must here be treated briefly.  As no classification of the\nmental powers has been universally accepted, I shall arrange my remarks in\nthe order most convenient for my purpose; and will select those facts which\nhave struck me most, with the hope that they may produce some effect on the\nreader.\n\nWith respect to animals very low in the scale, I shall give some additional\nfacts under Sexual Selection, shewing that their mental powers are much\nhigher than might have been expected.  The variability of the faculties in\nthe individuals of the same species is an important point for us, and some\nfew illustrations will here be given.  But it would be superfluous to enter\ninto many details on this head, for I have found on frequent enquiry, that\nit is the unanimous opinion of all those who have long attended to animals\nof many kinds, including birds, that the individuals differ greatly in\nevery mental characteristic.  In what manner the mental powers were first\ndeveloped in the lowest organisms, is as hopeless an enquiry as how life\nitself first originated.  These are problems for the distant future, if\nthey are ever to be solved by man.\n\nAs man possesses the same senses as the lower animals, his fundamental\nintuitions must be the same.  Man has also some few instincts in common, as\nthat of self-preservation, sexual love, the love of the mother for her new-\nborn offspring, the desire possessed by the latter to suck, and so forth.\nBut man, perhaps, has somewhat fewer instincts than those possessed by the\nanimals which come next to him in the series.  The orang in the Eastern\nislands, and the chimpanzee in Africa, build platforms on which they sleep;\nand, as both species follow the same habit, it might be argued that this\nwas due to instinct, but we cannot feel sure that it is not the result of\nboth animals having similar wants, and possessing similar powers of\nreasoning.  These apes, as we may assume, avoid the many poisonous fruits\nof the tropics, and man has no such knowledge:  but as our domestic\nanimals, when taken to foreign lands, and when first turned out in the\nspring, often eat poisonous herbs, which they afterwards avoid, we cannot\nfeel sure that the apes do not learn from their own experience or from that\nof their parents what fruits to select.  It is, however, certain, as we\nshall presently see, that apes have an instinctive dread of serpents, and\nprobably of other dangerous animals.\n\nThe fewness and the comparative simplicity of the instincts in the higher\nanimals are remarkable in contrast with those of the lower animals.  Cuvier\nmaintained that instinct and intelligence stand in an inverse ratio to each\nother; and some have thought that the intellectual faculties of the higher\nanimals have been gradually developed from their instincts.  But Pouchet,\nin an interesting essay (2.  'L'Instinct chez les Insectes,' 'Revue des\nDeux Mondes,' Feb. 1870, p. 690.), has shewn that no such inverse ratio\nreally exists.  Those insects which possess the most wonderful instincts\nare certainly the most intelligent.  In the vertebrate series, the least\nintelligent members, namely fishes and amphibians, do not possess complex\ninstincts; and amongst mammals the animal most remarkable for its\ninstincts, namely the beaver, is highly intelligent, as will be admitted by\nevery one who has read Mr. Morgan's excellent work.  (3.  'The American\nBeaver and His Works,' 1868.)\n\nAlthough the first dawnings of intelligence, according to Mr. Herbert\nSpencer (4.  'The Principles of Psychology,' 2nd edit., 1870, pp. 418-\n443.), have been developed through the multiplication and co-ordination of\nreflex actions, and although many of the simpler instincts graduate into\nreflex actions, and can hardly be distinguished from them, as in the case\nof young animals sucking, yet the more complex instincts seem to have\noriginated independently of intelligence.  I am, however, very far from\nwishing to deny that instinctive actions may lose their fixed and untaught\ncharacter, and be replaced by others performed by the aid of the free will.\nOn the other hand, some intelligent actions, after being performed during\nseveral generations, become converted into instincts and are inherited, as\nwhen birds on oceanic islands learn to avoid man.  These actions may then\nbe said to be degraded in character, for they are no longer performed\nthrough reason or from experience.  But the greater number of the more\ncomplex instincts appear to have been gained in a wholly different manner,\nthrough the natural selection of variations of simpler instinctive actions.\nSuch variations appear to arise from the same unknown causes acting on the\ncerebral organisation, which induce slight variations or individual\ndifferences in other parts of the body; and these variations, owing to our\nignorance, are often said to arise spontaneously.  We can, I think, come to\nno other conclusion with respect to the origin of the more complex\ninstincts, when we reflect on the marvellous instincts of sterile worker-\nants and bees, which leave no offspring to inherit the effects of\nexperience and of modified habits.\n\nAlthough, as we learn from the above-mentioned insects and the beaver, a\nhigh degree of intelligence is certainly compatible with complex instincts,\nand although actions, at first learnt voluntarily can soon through habit be\nperformed with the quickness and certainty of a reflex action, yet it is\nnot improbable that there is a certain amount of interference between the\ndevelopment of free intelligence and of instinct,--which latter implies\nsome inherited modification of the brain.  Little is known about the\nfunctions of the brain, but we can perceive that as the intellectual powers\nbecome highly developed, the various parts of the brain must be connected\nby very intricate channels of the freest intercommunication; and as a\nconsequence each separate part would perhaps tend to be less well fitted to\nanswer to particular sensations or associations in a definite and\ninherited--that is instinctive--manner.  There seems even to exist some\nrelation between a low degree of intelligence and a strong tendency to the\nformation of fixed, though not inherited habits; for as a sagacious\nphysician remarked to me, persons who are slightly imbecile tend to act in\neverything by routine or habit; and they are rendered much happier if this\nis encouraged.\n\nI have thought this digression worth giving, because we may easily\nunderrate the mental powers of the higher animals, and especially of man,\nwhen we compare their actions founded on the memory of past events, on\nforesight, reason, and imagination, with exactly similar actions\ninstinctively performed by the lower animals; in this latter case the\ncapacity of performing such actions has been gained, step by step, through\nthe variability of the mental organs and natural selection, without any\nconscious intelligence on the part of the animal during each successive\ngeneration.  No doubt, as Mr. Wallace has argued (5.  'Contributions to the\nTheory of Natural Selection,' 1870, p. 212.), much of the intelligent work\ndone by man is due to imitation and not to reason; but there is this great\ndifference between his actions and many of those performed by the lower\nanimals, namely, that man cannot, on his first trial, make, for instance, a\nstone hatchet or a canoe, through his power of imitation.  He has to learn\nhis work by practice; a beaver, on the other hand, can make its dam or\ncanal, and a bird its nest, as well, or nearly as well, and a spider its\nwonderful web, quite as well (6.  For the evidence on this head, see Mr. J.\nTraherne Moggridge's most interesting work, 'Harvesting Ants and Trap-Door\nSpiders,' 1873, pp. 126, 128.), the first time it tries as when old and\nexperienced.\n\nTo return to our immediate subject:  the lower animals, like man,\nmanifestly feel pleasure and pain, happiness and misery.  Happiness is\nnever better exhibited than by young animals, such as puppies, kittens,\nlambs, etc., when playing together, like our own children.  Even insects\nplay together, as has been described by that excellent observer, P. Huber\n(7.  'Recherches sur les Moeurs des Fourmis,' 1810, p. 173.), who saw ants\nchasing and pretending to bite each other, like so many puppies.\n\nThe fact that the lower animals are excited by the same emotions as\nourselves is so well established, that it will not be necessary to weary\nthe reader by many details.  Terror acts in the same manner on them as on\nus, causing the muscles to tremble, the heart to palpitate, the sphincters\nto be relaxed, and the hair to stand on end.  Suspicion, the offspring of\nfear, is eminently characteristic of most wild animals.  It is, I think,\nimpossible to read the account given by Sir E. Tennent, of the behaviour of\nthe female elephants, used as decoys, without admitting that they\nintentionally practise deceit, and well know what they are about.  Courage\nand timidity are extremely variable qualities in the individuals of the\nsame species, as is plainly seen in our dogs.  Some dogs and horses are\nill-tempered, and easily turn sulky; others are good-tempered; and these\nqualities are certainly inherited.  Every one knows how liable animals are\nto furious rage, and how plainly they shew it.  Many, and probably true,\nanecdotes have been published on the long-delayed and artful revenge of\nvarious animals.  The accurate Rengger, and Brehm (8.  All the following\nstatements, given on the authority of these two naturalists, are taken from\nRengger's 'Naturgesch. der Saeugethiere von Paraguay,' 1830, s. 41-57, and\nfrom Brehm's 'Thierleben,' B. i. s. 10-87.) state that the American and\nAfrican monkeys which they kept tame, certainly revenged themselves.  Sir\nAndrew Smith, a zoologist whose scrupulous accuracy was known to many\npersons, told me the following story of which he was himself an eye-\nwitness; at the Cape of Good Hope an officer had often plagued a certain\nbaboon, and the animal, seeing him approaching one Sunday for parade,\npoured water into a hole and hastily made some thick mud, which he\nskilfully dashed over the officer as he passed by, to the amusement of many\nbystanders.  For long afterwards the baboon rejoiced and triumphed whenever\nhe saw his victim.\n\nThe love of a dog for his master is notorious; as an old writer quaintly\nsays (9.  Quoted by Dr. Lauder Lindsay, in his 'Physiology of Mind in the\nLower Animals,' 'Journal of Mental Science,' April 1871, p. 38.), \"A dog is\nthe only thing on this earth that luvs you more than he luvs himself.\"\n\nIn the agony of death a dog has been known to caress his master, and every\none has heard of the dog suffering under vivisection, who licked the hand\nof the operator; this man, unless the operation was fully justified by an\nincrease of our knowledge, or unless he had a heart of stone, must have\nfelt remorse to the last hour of his life.\n\nAs Whewell (10.  'Bridgewater Treatise,' p. 263.) has well asked, \"who that\nreads the touching instances of maternal affection, related so often of the\nwomen of all nations, and of the females of all animals, can doubt that the\nprinciple of action is the same in the two cases?\"  We see maternal\naffection exhibited in the most trifling details; thus Rengger observed an\nAmerican monkey (a Cebus) carefully driving away the flies which plagued\nher infant; and Duvaucel saw a Hylobates washing the faces of her young\nones in a stream.  So intense is the grief of female monkeys for the loss\nof their young, that it invariably caused the death of certain kinds kept\nunder confinement by Brehm in N. Africa.  Orphan monkeys were always\nadopted and carefully guarded by the other monkeys, both males and females.\nOne female baboon had so capacious a heart that she not only adopted young\nmonkeys of other species, but stole young dogs and cats, which she\ncontinually carried about.  Her kindness, however, did not go so far as to\nshare her food with her adopted offspring, at which Brehm was surprised, as\nhis monkeys always divided everything quite fairly with their own young\nones.  An adopted kitten scratched this affectionate baboon, who certainly\nhad a fine intellect, for she was much astonished at being scratched, and\nimmediately examined the kitten's feet, and without more ado bit off the\nclaws. (11.  A critic, without any grounds ('Quarterly Review,' July 1871,\np. 72), disputes the possibility of this act as described by Brehm, for the\nsake of discrediting my work.  Therefore I tried, and found that I could\nreadily seize with my own teeth the sharp little claws of a kitten nearly\nfive weeks old.)  In the Zoological Gardens, I heard from the keeper that\nan old baboon (C. chacma) had adopted a Rhesus monkey; but when a young\ndrill and mandrill were placed in the cage, she seemed to perceive that\nthese monkeys, though distinct species, were her nearer relatives, for she\nat once rejected the Rhesus and adopted both of them.  The young Rhesus, as\nI saw, was greatly discontented at being thus rejected, and it would, like\na naughty child, annoy and attack the young drill and mandrill whenever it\ncould do so with safety; this conduct exciting great indignation in the old\nbaboon.  Monkeys will also, according to Brehm, defend their master when\nattacked by any one, as well as dogs to whom they are attached, from the\nattacks of other dogs.  But we here trench on the subjects of sympathy and\nfidelity, to which I shall recur.  Some of Brehm's monkeys took much\ndelight in teasing a certain old dog whom they disliked, as well as other\nanimals, in various ingenious ways.\n\nMost of the more complex emotions are common to the higher animals and\nourselves.  Every one has seen how jealous a dog is of his master's\naffection, if lavished on any other creature; and I have observed the same\nfact with monkeys.  This shews that animals not only love, but have desire\nto be loved.  Animals manifestly feel emulation.  They love approbation or\npraise; and a dog carrying a basket for his master exhibits in a high\ndegree self-complacency or pride.  There can, I think, be no doubt that a\ndog feels shame, as distinct from fear, and something very like modesty\nwhen begging too often for food.  A great dog scorns the snarling of a\nlittle dog, and this may be called magnanimity.  Several observers have\nstated that monkeys certainly dislike being laughed at; and they sometimes\ninvent imaginary offences.  In the Zoological Gardens I saw a baboon who\nalways got into a furious rage when his keeper took out a letter or book\nand read it aloud to him; and his rage was so violent that, as I witnessed\non one occasion, he bit his own leg till the blood flowed.  Dogs shew what\nmay be fairly called a sense of humour, as distinct from mere play; if a\nbit of stick or other such object be thrown to one, he will often carry it\naway for a short distance; and then squatting down with it on the ground\nclose before him, will wait until his master comes quite close to take it\naway.  The dog will then seize it and rush away in triumph, repeating the\nsame manoeuvre, and evidently enjoying the practical joke.\n\nWe will now turn to the more intellectual emotions and faculties, which are\nvery important, as forming the basis for the development of the higher\nmental powers.  Animals manifestly enjoy excitement, and suffer from ennui,\nas may be seen with dogs, and, according to Rengger, with monkeys.  All\nanimals feel WONDER, and many exhibit CURIOSITY.  They sometimes suffer\nfrom this latter quality, as when the hunter plays antics and thus attracts\nthem; I have witnessed this with deer, and so it is with the wary chamois,\nand with some kinds of wild-ducks.  Brehm gives a curious account of the\ninstinctive dread, which his monkeys exhibited, for snakes; but their\ncuriosity was so great that they could not desist from occasionally\nsatiating their horror in a most human fashion, by lifting up the lid of\nthe box in which the snakes were kept.  I was so much surprised at his\naccount, that I took a stuffed and coiled-up snake into the monkey-house at\nthe Zoological Gardens, and the excitement thus caused was one of the most\ncurious spectacles which I ever beheld.  Three species of Cercopithecus\nwere the most alarmed; they dashed about their cages, and uttered sharp\nsignal cries of danger, which were understood by the other monkeys.  A few\nyoung monkeys and one old Anubis baboon alone took no notice of the snake.\nI then placed the stuffed specimen on the ground in one of the larger\ncompartments.  After a time all the monkeys collected round it in a large\ncircle, and staring intently, presented a most ludicrous appearance.  They\nbecame extremely nervous; so that when a wooden ball, with which they were\nfamiliar as a plaything, was accidentally moved in the straw, under which\nit was partly hidden, they all instantly started away.  These monkeys\nbehaved very differently when a dead fish, a mouse (12.  I have given a\nshort account of their behaviour on this occasion in my 'Expression of the\nEmotions in Man and Animals,' p. 43.), a living turtle, and other new\nobjects were placed in their cages; for though at first frightened, they\nsoon approached, handled and examined them.  I then placed a live snake in\na paper bag, with the mouth loosely closed, in one of the larger\ncompartments.  One of the monkeys immediately approached, cautiously opened\nthe bag a little, peeped in, and instantly dashed away.  Then I witnessed\nwhat Brehm has described, for monkey after monkey, with head raised high\nand turned on one side, could not resist taking a momentary peep into the\nupright bag, at the dreadful object lying quietly at the bottom.  It would\nalmost appear as if monkeys had some notion of zoological affinities, for\nthose kept by Brehm exhibited a strange, though mistaken, instinctive dread\nof innocent lizards and frogs.  An orang, also, has been known to be much\nalarmed at the first sight of a turtle.  (13.  W.C.L. Martin, 'Natural\nHistory of Mammalia,' 1841, p. 405.)\n\nThe principle of IMITATION is strong in man, and especially, as I have\nmyself observed, with savages.  In certain morbid states of the brain this\ntendency is exaggerated to an extraordinary degree:  some hemiplegic\npatients and others, at the commencement of inflammatory softening of the\nbrain, unconsciously imitate every word which is uttered, whether in their\nown or in a foreign language, and every gesture or action which is\nperformed near them.  (14.  Dr. Bateman, 'On Aphasia,' 1870, p. 110.)\nDesor (15.  Quoted by Vogt, 'Memoire sur les Microcephales,' 1867, p. 168.)\nhas remarked that no animal voluntarily imitates an action performed by\nman, until in the ascending scale we come to monkeys, which are well known\nto be ridiculous mockers.  Animals, however, sometimes imitate each other's\nactions:  thus two species of wolves, which had been reared by dogs,\nlearned to bark, as does sometimes the jackal (16.  The 'Variation of\nAnimals and Plants under Domestication,' vol. i. p. 27.), but whether this\ncan be called voluntary imitation is another question.  Birds imitate the\nsongs of their parents, and sometimes of other birds; and parrots are\nnotorious imitators of any sound which they often hear.  Dureau de la Malle\ngives an account (17.  'Annales des Sciences Nat.' (1st Series), tom. xxii.\np. 397.) of a dog reared by a cat, who learnt to imitate the well-known\naction of a cat licking her paws, and thus washing her ears and face; this\nwas also witnessed by the celebrated naturalist Audouin.  I have received\nseveral confirmatory accounts; in one of these, a dog had not been suckled\nby a cat, but had been brought up with one, together with kittens, and had\nthus acquired the above habit, which he ever afterwards practised during\nhis life of thirteen years.  Dureau de la Malle's dog likewise learnt from\nthe kittens to play with a ball by rolling it about with his fore paws, and\nspringing on it.  A correspondent assures me that a cat in his house used\nto put her paws into jugs of milk having too narrow a mouth for her head.\nA kitten of this cat soon learned the same trick, and practised it ever\nafterwards, whenever there was an opportunity.\n\nThe parents of many animals, trusting to the principle of imitation in\ntheir young, and more especially to their instinctive or inherited\ntendencies, may be said to educate them.  We see this when a cat brings a\nlive mouse to her kittens; and Dureau de la Malle has given a curious\naccount (in the paper above quoted) of his observations on hawks which\ntaught their young dexterity, as well as judgment of distances, by first\ndropping through the air dead mice and sparrows, which the young generally\nfailed to catch, and then bringing them live birds and letting them loose.\n\nHardly any faculty is more important for the intellectual progress of man\nthan ATTENTION.  Animals clearly manifest this power, as when a cat watches\nby a hole and prepares to spring on its prey.  Wild animals sometimes\nbecome so absorbed when thus engaged, that they may be easily approached.\nMr. Bartlett has given me a curious proof how variable this faculty is in\nmonkeys.  A man who trains monkeys to act in plays, used to purchase common\nkinds from the Zoological Society at the price of five pounds for each; but\nhe offered to give double the price, if he might keep three or four of them\nfor a few days, in order to select one.  When asked how he could possibly\nlearn so soon, whether a particular monkey would turn out a good actor, he\nanswered that it all depended on their power of attention.  If when he was\ntalking and explaining anything to a monkey, its attention was easily\ndistracted, as by a fly on the wall or other trifling object, the case was\nhopeless.  If he tried by punishment to make an inattentive monkey act, it\nturned sulky.  On the other hand, a monkey which carefully attended to him\ncould always be trained.\n\nIt is almost superfluous to state that animals have excellent MEMORIES for\npersons and places.  A baboon at the Cape of Good Hope, as I have been\ninformed by Sir Andrew Smith, recognised him with joy after an absence of\nnine months.  I had a dog who was savage and averse to all strangers, and I\npurposely tried his memory after an absence of five years and two days.  I\nwent near the stable where he lived, and shouted to him in my old manner;\nhe shewed no joy, but instantly followed me out walking, and obeyed me,\nexactly as if I had parted with him only half an hour before.  A train of\nold associations, dormant during five years, had thus been instantaneously\nawakened in his mind.  Even ants, as P. Huber (18.  'Les Moeurs des\nFourmis,' 1810, p. 150.) has clearly shewn, recognised their fellow-ants\nbelonging to the same community after a separation of four months.  Animals\ncan certainly by some means judge of the intervals of time between\nrecurrent events.\n\nThe IMAGINATION is one of the highest prerogatives of man.  By this faculty\nhe unites former images and ideas, independently of the will, and thus\ncreates brilliant and novel results.  A poet, as Jean Paul Richter remarks\n(19.  Quoted in Dr. Maudsley's 'Physiology and Pathology of Mind,' 1868,\npp. 19, 220.), \"who must reflect whether he shall make a character say yes\nor no--to the devil with him; he is only a stupid corpse.\"  Dreaming gives\nus the best notion of this power; as Jean Paul again says, \"The dream is an\ninvoluntary art of poetry.\"  The value of the products of our imagination\ndepends of course on the number, accuracy, and clearness of our\nimpressions, on our judgment and taste in selecting or rejecting the\ninvoluntary combinations, and to a certain extent on our power of\nvoluntarily combining them.  As dogs, cats, horses, and probably all the\nhigher animals, even birds (20.  Dr. Jerdon, 'Birds of India,' vol. i.\n1862, p. xxi.  Houzeau says that his parokeets and canary-birds dreamt:\n'Etudes sur les Facultes Mentales des Animaux,' tom. ii. p. 136.) have\nvivid dreams, and this is shewn by their movements and the sounds uttered,\nwe must admit that they possess some power of imagination.  There must be\nsomething special, which causes dogs to howl in the night, and especially\nduring moonlight, in that remarkable and melancholy manner called baying.\nAll dogs do not do so; and, according to Houzeau (21.  ibid. 1872, tom. ii.\np. 181.), they do not then look at the moon, but at some fixed point near\nthe horizon.  Houzeau thinks that their imaginations are disturbed by the\nvague outlines of the surrounding objects, and conjure up before them\nfantastic images:  if this be so, their feelings may almost be called\nsuperstitious.\n\nOf all the faculties of the human mind, it will, I presume, be admitted\nthat REASON stands at the summit.  Only a few persons now dispute that\nanimals possess some power of reasoning.  Animals may constantly be seen to\npause, deliberate, and resolve.  It is a significant fact, that the more\nthe habits of any particular animal are studied by a naturalist, the more\nhe attributes to reason and the less to unlearnt instincts.  (22.  Mr. L.H.\nMorgan's work on 'The American Beaver,' 1868, offers a good illustration of\nthis remark.  I cannot help thinking, however, that he goes too far in\nunderrating the power of instinct.)  In future chapters we shall see that\nsome animals extremely low in the scale apparently display a certain amount\nof reason.  No doubt it is often difficult to distinguish between the power\nof reason and that of instinct.  For instance, Dr. Hayes, in his work on\n'The Open Polar Sea,' repeatedly remarks that his dogs, instead of\ncontinuing to draw the sledges in a compact body, diverged and separated\nwhen they came to thin ice, so that their weight might be more evenly\ndistributed.  This was often the first warning which the travellers\nreceived that the ice was becoming thin and dangerous.  Now, did the dogs\nact thus from the experience of each individual, or from the example of the\nolder and wiser dogs, or from an inherited habit, that is from instinct?\nThis instinct, may possibly have arisen since the time, long ago, when dogs\nwere first employed by the natives in drawing their sledges; or the Arctic\nwolves, the parent-stock of the Esquimaux dog, may have acquired an\ninstinct impelling them not to attack their prey in a close pack, when on\nthin ice.\n\nWe can only judge by the circumstances under which actions are performed,\nwhether they are due to instinct, or to reason, or to the mere association\nof ideas:  this latter principle, however, is intimately connected with\nreason.  A curious case has been given by Prof. Mobius (23.  'Die\nBewegungen der Thiere,' etc., 1873, p. 11.), of a pike, separated by a\nplate of glass from an adjoining aquarium stocked with fish, and who often\ndashed himself with such violence against the glass in trying to catch the\nother fishes, that he was sometimes completely stunned.  The pike went on\nthus for three months, but at last learnt caution, and ceased to do so.\nThe plate of glass was then removed, but the pike would not attack these\nparticular fishes, though he would devour others which were afterwards\nintroduced; so strongly was the idea of a violent shock associated in his\nfeeble mind with the attempt on his former neighbours.  If a savage, who\nhad never seen a large plate-glass window, were to dash himself even once\nagainst it, he would for a long time afterwards associate a shock with a\nwindow-frame; but very differently from the pike, he would probably reflect\non the nature of the impediment, and be cautious under analogous\ncircumstances.  Now with monkeys, as we shall presently see, a painful or\nmerely a disagreeable impression, from an action once performed, is\nsometimes sufficient to prevent the animal from repeating it.  If we\nattribute this difference between the monkey and the pike solely to the\nassociation of ideas being so much stronger and more persistent in the one\nthan the other, though the pike often received much the more severe injury,\ncan we maintain in the case of man that a similar difference implies the\npossession of a fundamentally different mind?\n\nHouzeau relates (24.  'Etudes sur les Facultes Mentales des Animaux,' 1872,\ntom. ii. p. 265.) that, whilst crossing a wide and arid plain in Texas, his\ntwo dogs suffered greatly from thirst, and that between thirty and forty\ntimes they rushed down the hollows to search for water.  These hollows were\nnot valleys, and there were no trees in them, or any other difference in\nthe vegetation, and as they were absolutely dry there could have been no\nsmell of damp earth.  The dogs behaved as if they knew that a dip in the\nground offered them the best chance of finding water, and Houzeau has often\nwitnessed the same behaviour in other animals.\n\nI have seen, as I daresay have others, that when a small object is thrown\non the ground beyond the reach of one of the elephants in the Zoological\nGardens, he blows through his trunk on the ground beyond the object, so\nthat the current reflected on all sides may drive the object within his\nreach.  Again a well-known ethnologist, Mr. Westropp, informs me that he\nobserved in Vienna a bear deliberately making with his paw a current in\nsome water, which was close to the bars of his cage, so as to draw a piece\nof floating bread within his reach.  These actions of the elephant and bear\ncan hardly be attributed to instinct or inherited habit, as they would be\nof little use to an animal in a state of nature.  Now, what is the\ndifference between such actions, when performed by an uncultivated man, and\nby one of the higher animals?\n\nThe savage and the dog have often found water at a low level, and the\ncoincidence under such circumstances has become associated in their minds.\nA cultivated man would perhaps make some general proposition on the\nsubject; but from all that we know of savages it is extremely doubtful\nwhether they would do so, and a dog certainly would not.  But a savage, as\nwell as a dog, would search in the same way, though frequently\ndisappointed; and in both it seems to be equally an act of reason, whether\nor not any general proposition on the subject is consciously placed before\nthe mind.  (25.  Prof. Huxley has analysed with admirable clearness the\nmental steps by which a man, as well as a dog, arrives at a conclusion in a\ncase analogous to that given in my text.  See his article, 'Mr. Darwin's\nCritics,' in the 'Contemporary Review,' Nov. 1871, p. 462, and in his\n'Critiques and Essays,' 1873, p. 279.)  The same would apply to the\nelephant and the bear making currents in the air or water.  The savage\nwould certainly neither know nor care by what law the desired movements\nwere effected; yet his act would be guided by a rude process of reasoning,\nas surely as would a philosopher in his longest chain of deductions.  There\nwould no doubt be this difference between him and one of the higher\nanimals, that he would take notice of much slighter circumstances and\nconditions, and would observe any connection between them after much less\nexperience, and this would be of paramount importance.  I kept a daily\nrecord of the actions of one of my infants, and when he was about eleven\nmonths old, and before he could speak a single word, I was continually\nstruck with the greater quickness, with which all sorts of objects and\nsounds were associated together in his mind, compared with that of the most\nintelligent dogs I ever knew.  But the higher animals differ in exactly the\nsame way in this power of association from those low in the scale, such as\nthe pike, as well as in that of drawing inferences and of observation.\n\nThe promptings of reason, after very short experience, are well shewn by\nthe following actions of American monkeys, which stand low in their order.\nRengger, a most careful observer, states that when he first gave eggs to\nhis monkeys in Paraguay, they smashed them, and thus lost much of their\ncontents; afterwards they gently hit one end against some hard body, and\npicked off the bits of shell with their fingers.  After cutting themselves\nonly ONCE with any sharp tool, they would not touch it again, or would\nhandle it with the greatest caution.  Lumps of sugar were often given them\nwrapped up in paper; and Rengger sometimes put a live wasp in the paper, so\nthat in hastily unfolding it they got stung; after this had ONCE happened,\nthey always first held the packet to their ears to detect any movement\nwithin.  (26.  Mr. Belt, in his most interesting work, 'The Naturalist in\nNicaragua,' 1874, (p. 119), likewise describes various actions of a tamed\nCebus, which, I think, clearly shew that this animal possessed some\nreasoning power.)\n\nThe following cases relate to dogs.  Mr. Colquhoun (27.  'The Moor and the\nLoch,' p. 45.  Col. Hutchinson on 'Dog Breaking,' 1850, p. 46.) winged two\nwild-ducks, which fell on the further side of a stream; his retriever tried\nto bring over both at once, but could not succeed; she then, though never\nbefore known to ruffle a feather, deliberately killed one, brought over the\nother, and returned for the dead bird.  Col. Hutchinson relates that two\npartridges were shot at once, one being killed, the other wounded; the\nlatter ran away, and was caught by the retriever, who on her return came\nacross the dead bird; \"she stopped, evidently greatly puzzled, and after\none or two trials, finding she could not take it up without permitting the\nescape of the winged bird, she considered a moment, then deliberately\nmurdered it by giving it a severe crunch, and afterwards brought away both\ntogether.  This was the only known instance of her ever having wilfully\ninjured any game.\"  Here we have reason though not quite perfect, for the\nretriever might have brought the wounded bird first and then returned for\nthe dead one, as in the case of the two wild-ducks.  I give the above\ncases, as resting on the evidence of two independent witnesses, and because\nin both instances the retrievers, after deliberation, broke through a habit\nwhich is inherited by them (that of not killing the game retrieved), and\nbecause they shew how strong their reasoning faculty must have been to\novercome a fixed habit.\n\nI will conclude by quoting a remark by the illustrious Humboldt.  (28.\n'Personal Narrative,' Eng. translat., vol. iii. p. 106.)  \"The muleteers in\nS. America say, 'I will not give you the mule whose step is easiest, but la\nmas racional,--the one that reasons best'\"; and; as, he adds, \"this popular\nexpression, dictated by long experience, combats the system of animated\nmachines, better perhaps than all the arguments of speculative philosophy.\"\nNevertheless some writers even yet deny that the higher animals possess a\ntrace of reason; and they endeavour to explain away, by what appears to be\nmere verbiage, (29.  I am glad to find that so acute a reasoner as Mr.\nLeslie Stephen ('Darwinism and Divinity, Essays on Free Thinking,' 1873, p.\n80), in speaking of the supposed impassable barrier between the minds of\nman and the lower animals, says, \"The distinctions, indeed, which have been\ndrawn, seem to us to rest upon no better foundation than a great many other\nmetaphysical distinctions; that is, the assumption that because you can\ngive two things different names, they must therefore have different\nnatures.  It is difficult to understand how anybody who has ever kept a\ndog, or seen an elephant, can have any doubt as to an animal's power of\nperforming the essential processes of reasoning.\") all such facts as those\nabove given.\n\nIt has, I think, now been shewn that man and the higher animals, especially\nthe Primates, have some few instincts in common.  All have the same senses,\nintuitions, and sensations,--similar passions, affections, and emotions,\neven the more complex ones, such as jealousy, suspicion, emulation,\ngratitude, and magnanimity; they practise deceit and are revengeful; they\nare sometimes susceptible to ridicule, and even have a sense of humour;\nthey feel wonder and curiosity; they possess the same faculties of\nimitation, attention, deliberation, choice, memory, imagination, the\nassociation of ideas, and reason, though in very different degrees.  The\nindividuals of the same species graduate in intellect from absolute\nimbecility to high excellence.  They are also liable to insanity, though\nfar less often than in the case of man.  (30.  See 'Madness in Animals,' by\nDr. W. Lauder Lindsay, in 'Journal of Mental Science,' July 1871.)\nNevertheless, many authors have insisted that man is divided by an\ninsuperable barrier from all the lower animals in his mental faculties.  I\nformerly made a collection of above a score of such aphorisms, but they are\nalmost worthless, as their wide difference and number prove the difficulty,\nif not the impossibility, of the attempt.  It has been asserted that man\nalone is capable of progressive improvement; that he alone makes use of\ntools or fire, domesticates other animals, or possesses property; that no\nanimal has the power of abstraction, or of forming general concepts, is\nself-conscious and comprehends itself; that no animal employs language;\nthat man alone has a sense of beauty, is liable to caprice, has the feeling\nof gratitude, mystery, etc.; believes in God, or is endowed with a\nconscience.  I will hazard a few remarks on the more important and\ninteresting of these points.\n\nArchbishop Sumner formerly maintained (31.  Quoted by Sir C. Lyell,\n'Antiquity of Man,' p. 497.) that man alone is capable of progressive\nimprovement.  That he is capable of incomparably greater and more rapid\nimprovement than is any other animal, admits of no dispute; and this is\nmainly due to his power of speaking and handing down his acquired\nknowledge.  With animals, looking first to the individual, every one who\nhas had any experience in setting traps, knows that young animals can be\ncaught much more easily than old ones; and they can be much more easily\napproached by an enemy.  Even with respect to old animals, it is impossible\nto catch many in the same place and in the same kind of trap, or to destroy\nthem by the same kind of poison; yet it is improbable that all should have\npartaken of the poison, and impossible that all should have been caught in\na trap.  They must learn caution by seeing their brethren caught or\npoisoned.  In North America, where the fur-bearing animals have long been\npursued, they exhibit, according to the unanimous testimony of all\nobservers, an almost incredible amount of sagacity, caution and cunning;\nbut trapping has been there so long carried on, that inheritance may\npossibly have come into play.  I have received several accounts that when\ntelegraphs are first set up in any district, many birds kill themselves by\nflying against the wires, but that in the course of a very few years they\nlearn to avoid this danger, by seeing, as it would appear, their comrades\nkilled.  (32.  For additional evidence, with details, see M. Houzeau,\n'Etudes sur les Facultes Mentales des Animaux,' tom. ii. 1872, p. 147.)\n\nIf we look to successive generations, or to the race, there is no doubt\nthat birds and other animals gradually both acquire and lose caution in\nrelation to man or other enemies (33.  See, with respect to birds on\noceanic islands, my 'Journal of Researches during the Voyage of the\n\"Beagle,\"' 1845, p. 398.  'Origin of Species,' 5th ed. p. 260.); and this\ncaution is certainly in chief part an inherited habit or instinct, but in\npart the result of individual experience.  A good observer, Leroy (34.\n'Lettres Phil. sur l'Intelligence des Animaux,' nouvelle edit., 1802, p.\n86.), states, that in districts where foxes are much hunted, the young, on\nfirst leaving their burrows, are incontestably much more wary than the old\nones in districts where they are not much disturbed.\n\nOur domestic dogs are descended from wolves and jackals (35.  See the\nevidence on this head in chap. i. vol. i., 'On the Variation of Animals and\nPlants under Domestication.'), and though they may not have gained in\ncunning, and may have lost in wariness and suspicion, yet they have\nprogressed in certain moral qualities, such as in affection, trust-\nworthiness, temper, and probably in general intelligence.  The common rat\nhas conquered and beaten several other species throughout Europe, in parts\nof North America, New Zealand, and recently in Formosa, as well as on the\nmainland of China.  Mr. Swinhoe (36.  'Proceedings Zoological Society,'\n1864, p. 186.), who describes these two latter cases, attributes the\nvictory of the common rat over the large Mus coninga to its superior\ncunning; and this latter quality may probably be attributed to the habitual\nexercise of all its faculties in avoiding extirpation by man, as well as to\nnearly all the less cunning or weak-minded rats having been continuously\ndestroyed by him.  It is, however, possible that the success of the common\nrat may be due to its having possessed greater cunning than its fellow-\nspecies, before it became associated with man.  To maintain, independently\nof any direct evidence, that no animal during the course of ages has\nprogressed in intellect or other mental faculties, is to beg the question\nof the evolution of species.  We have seen that, according to Lartet,\nexisting mammals belonging to several orders have larger brains than their\nancient tertiary prototypes.\n\nIt has often been said that no animal uses any tool; but the chimpanzee in\na state of nature cracks a native fruit, somewhat like a walnut, with a\nstone.  (37.  Savage and Wyman in 'Boston Journal of Natural History,' vol.\niv. 1843-44, p. 383.)  Rengger (38.  'Saeugethiere von Paraguay,' 1830, s.\n51-56.) easily taught an American monkey thus to break open hard palm-nuts;\nand afterwards of its own accord, it used stones to open other kinds of\nnuts, as well as boxes.  It thus also removed the soft rind of fruit that\nhad a disagreeable flavour.  Another monkey was taught to open the lid of a\nlarge box with a stick, and afterwards it used the stick as a lever to move\nheavy bodies; and I have myself seen a young orang put a stick into a\ncrevice, slip his hand to the other end, and use it in the proper manner as\na lever.  The tamed elephants in India are well known to break off branches\nof trees and use them to drive away the flies; and this same act has been\nobserved in an elephant in a state of nature.  (39.  The Indian Field,\nMarch 4, 1871.)  I have seen a young orang, when she thought she was going\nto be whipped, cover and protect herself with a blanket or straw.  In these\nseveral cases stones and sticks were employed as implements; but they are\nlikewise used as weapons.  Brehm (40.  'Thierleben,' B. i. s. 79, 82.)\nstates, on the authority of the well-known traveller Schimper, that in\nAbyssinia when the baboons belonging to one species (C. gelada) descend in\ntroops from the mountains to plunder the fields, they sometimes encounter\ntroops of another species (C. hamadryas), and then a fight ensues.  The\nGeladas roll down great stones, which the Hamadryas try to avoid, and then\nboth species, making a great uproar, rush furiously against each other.\nBrehm, when accompanying the Duke of Coburg-Gotha, aided in an attack with\nfire-arms on a troop of baboons in the pass of Mensa in Abyssinia.  The\nbaboons in return rolled so many stones down the mountain, some as large as\na man's head, that the attackers had to beat a hasty retreat; and the pass\nwas actually closed for a time against the caravan.  It deserves notice\nthat these baboons thus acted in concert.  Mr. Wallace (41.  'The Malay\nArchipelago,' vol. i. 1869, p. 87.) on three occasions saw female orangs,\naccompanied by their young, \"breaking off branches and the great spiny\nfruit of the Durian tree, with every appearance of rage; causing such a\nshower of missiles as effectually kept us from approaching too near the\ntree.\"  As I have repeatedly seen, a chimpanzee will throw any object at\nhand at a person who offends him; and the before-mentioned baboon at the\nCape of Good Hope prepared mud for the purpose.\n\nIn the Zoological Gardens, a monkey, which had weak teeth, used to break\nopen nuts with a stone; and I was assured by the keepers that after using\nthe stone, he hid it in the straw, and would not let any other monkey touch\nit.  Here, then, we have the idea of property; but this idea is common to\nevery dog with a bone, and to most or all birds with their nests.\n\nThe Duke of Argyll (42.  'Primeval Man,' 1869, pp. 145, 147.) remarks, that\nthe fashioning of an implement for a special purpose is absolutely peculiar\nto man; and he considers that this forms an immeasurable gulf between him\nand the brutes.  This is no doubt a very important distinction; but there\nappears to me much truth in Sir J. Lubbock's suggestion (43.  'Prehistoric\nTimes,' 1865, p. 473, etc.), that when primeval man first used flint-stones\nfor any purpose, he would have accidentally splintered them, and would then\nhave used the sharp fragments.  From this step it would be a small one to\nbreak the flints on purpose, and not a very wide step to fashion them\nrudely.  This latter advance, however, may have taken long ages, if we may\njudge by the immense interval of time which elapsed before the men of the\nneolithic period took to grinding and polishing their stone tools.  In\nbreaking the flints, as Sir J. Lubbock likewise remarks, sparks would have\nbeen emitted, and in grinding them heat would have been evolved:  thus the\ntwo usual methods of \"obtaining fire may have originated.\"  The nature of\nfire would have been known in the many volcanic regions where lava\noccasionally flows through forests.  The anthropomorphous apes, guided\nprobably by instinct, build for themselves temporary platforms; but as many\ninstincts are largely controlled by reason, the simpler ones, such as this\nof building a platform, might readily pass into a voluntary and conscious\nact.  The orang is known to cover itself at night with the leaves of the\nPandanus; and Brehm states that one of his baboons used to protect itself\nfrom the heat of the sun by throwing a straw-mat over its head.  In these\nseveral habits, we probably see the first steps towards some of the simpler\narts, such as rude architecture and dress, as they arose amongst the early\nprogenitors of man.\n\nABSTRACTION, GENERAL CONCEPTIONS, SELF-CONSCIOUSNESS, MENTAL INDIVIDUALITY.\n\nIt would be very difficult for any one with even much more knowledge than I\npossess, to determine how far animals exhibit any traces of these high\nmental powers.  This difficulty arises from the impossibility of judging\nwhat passes through the mind of an animal; and again, the fact that writers\ndiffer to a great extent in the meaning which they attribute to the above\nterms, causes a further difficulty.  If one may judge from various articles\nwhich have been published lately, the greatest stress seems to be laid on\nthe supposed entire absence in animals of the power of abstraction, or of\nforming general concepts.  But when a dog sees another dog at a distance,\nit is often clear that he perceives that it is a dog in the abstract; for\nwhen he gets nearer his whole manner suddenly changes, if the other dog be\na friend.  A recent writer remarks, that in all such cases it is a pure\nassumption to assert that the mental act is not essentially of the same\nnature in the animal as in man.  If either refers what he perceives with\nhis senses to a mental concept, then so do both.  (44.  Mr. Hookham, in a\nletter to Prof. Max Muller, in the 'Birmingham News,' May 1873.)  When I\nsay to my terrier, in an eager voice (and I have made the trial many\ntimes), \"Hi, hi, where is it?\" she at once takes it as a sign that\nsomething is to be hunted, and generally first looks quickly all around,\nand then rushes into the nearest thicket, to scent for any game, but\nfinding nothing, she looks up into any neighbouring tree for a squirrel.\nNow do not these actions clearly shew that she had in her mind a general\nidea or concept that some animal is to be discovered and hunted?\n\nIt may be freely admitted that no animal is self-conscious, if by this term\nit is implied, that he reflects on such points, as whence he comes or\nwhither he will go, or what is life and death, and so forth.  But how can\nwe feel sure that an old dog with an excellent memory and some power of\nimagination, as shewn by his dreams, never reflects on his past pleasures\nor pains in the chase?  And this would be a form of self-consciousness.  On\nthe other hand, as Buchner (45.  'Conferences sur la Theorie Darwinienne,'\nFrench translat. 1869, p. 132.) has remarked, how little can the hard-\nworked wife of a degraded Australian savage, who uses very few abstract\nwords, and cannot count above four, exert her self-consciousness, or\nreflect on the nature of her own existence.  It is generally admitted, that\nthe higher animals possess memory, attention, association, and even some\nimagination and reason.  If these powers, which differ much in different\nanimals, are capable of improvement, there seems no great improbability in\nmore complex faculties, such as the higher forms of abstraction, and self-\nconsciousness, etc., having been evolved through the development and\ncombination of the simpler ones.  It has been urged against the views here\nmaintained that it is impossible to say at what point in the ascending\nscale animals become capable of abstraction, etc.; but who can say at what\nage this occurs in our young children?  We see at least that such powers\nare developed in children by imperceptible degrees.\n\nThat animals retain their mental individuality is unquestionable.  When my\nvoice awakened a train of old associations in the mind of the before-\nmentioned dog, he must have retained his mental individuality, although\nevery atom of his brain had probably undergone change more than once during\nthe interval of five years.  This dog might have brought forward the\nargument lately advanced to crush all evolutionists, and said, \"I abide\namid all mental moods and all material changes...The teaching that atoms\nleave their impressions as legacies to other atoms falling into the places\nthey have vacated is contradictory of the utterance of consciousness, and\nis therefore false; but it is the teaching necessitated by evolutionism,\nconsequently the hypothesis is a false one.\"  (46.  The Rev. Dr. J. M'Cann,\n'Anti-Darwinism,' 1869, p. 13.)\n\nLANGUAGE.\n\nThis faculty has justly been considered as one of the chief distinctions\nbetween man and the lower animals.  But man, as a highly competent judge,\nArchbishop Whately remarks, \"is not the only animal that can make use of\nlanguage to express what is passing in his mind, and can understand, more\nor less, what is so expressed by another.\"  (47.  Quoted in\n'Anthropological Review,' 1864, p. 158.)  In Paraguay the Cebus azarae when\nexcited utters at least six distinct sounds, which excite in other monkeys\nsimilar emotions.  (48.  Rengger, ibid. s. 45.)  The movements of the\nfeatures and gestures of monkeys are understood by us, and they partly\nunderstand ours, as Rengger and others declare.  It is a more remarkable\nfact that the dog, since being domesticated, has learnt to bark (49.  See\nmy 'Variation of Animals and Plants under Domestication,' vol. i. p. 27.)\nin at least four or five distinct tones.  Although barking is a new art, no\ndoubt the wild parent-species of the dog expressed their feelings by cries\nof various kinds.  With the domesticated dog we have the bark of eagerness,\nas in the chase; that of anger, as well as growling; the yelp or howl of\ndespair, as when shut up; the baying at night; the bark of joy, as when\nstarting on a walk with his master; and the very distinct one of demand or\nsupplication, as when wishing for a door or window to be opened.  According\nto Houzeau, who paid particular attention to the subject, the domestic fowl\nutters at least a dozen significant sounds.  (50.  'Facultes Mentales des\nAnimaux,' tom. ii. 1872, p. 346-349.)\n\nThe habitual use of articulate language is, however, peculiar to man; but\nhe uses, in common with the lower animals, inarticulate cries to express\nhis meaning, aided by gestures and the movements of the muscles of the\nface.  (51.  See a discussion on this subject in Mr. E.B. Tylor's very\ninteresting work, 'Researches into the Early History of Mankind,' 1865,\nchaps. ii. to iv.)  This especially holds good with the more simple and\nvivid feelings, which are but little connected with our higher\nintelligence.  Our cries of pain, fear, surprise, anger, together with\ntheir appropriate actions, and the murmur of a mother to her beloved child\nare more expressive than any words.  That which distinguishes man from the\nlower animals is not the understanding of articulate sounds, for, as every\none knows, dogs understand many words and sentences.  In this respect they\nare at the same stage of development as infants, between the ages of ten\nand twelve months, who understand many words and short sentences, but\ncannot yet utter a single word.  It is not the mere articulation which is\nour distinguishing character, for parrots and other birds possess this\npower.  Nor is it the mere capacity of connecting definite sounds with\ndefinite ideas; for it is certain that some parrots, which have been taught\nto speak, connect unerringly words with things, and persons with events.\n(52.  I have received several detailed accounts to this effect.  Admiral\nSir B.J. Sulivan, whom I know to be a careful observer, assures me that an\nAfrican parrot, long kept in his father's house, invariably called certain\npersons of the household, as well as visitors, by their names.  He said\n\"good morning\" to every one at breakfast, and \"good night\" to each as they\nleft the room at night, and never reversed these salutations.  To Sir B.J.\nSulivan's father, he used to add to the \" good morning\" a short sentence,\nwhich was never once repeated after his father's death.  He scolded\nviolently a strange dog which came into the room through the open window;\nand he scolded another parrot (saying \"you naughty polly\") which had got\nout of its cage, and was eating apples on the kitchen table.  See also, to\nthe same effect, Houzeau on parrots, 'Facultes Mentales,' tom. ii. p. 309.\nDr. A. Moschkau informs me that he knew a starling which never made a\nmistake in saying in German \"good morning\" to persons arriving, and \"good\nbye, old fellow,\" to those departing.  I could add several other such\ncases.)  The lower animals differ from man solely in his almost infinitely\nlarger power of associating together the most diversified sounds and ideas;\nand this obviously depends on the high development of his mental powers.\n\nAs Horne Tooke, one of the founders of the noble science of philology,\nobserves, language is an art, like brewing or baking; but writing would\nhave been a better simile.  It certainly is not a true instinct, for every\nlanguage has to be learnt.  It differs, however, widely from all ordinary\narts, for man has an instinctive tendency to speak, as we see in the babble\nof our young children; whilst no child has an instinctive tendency to brew,\nbake, or write.  Moreover, no philologist now supposes that any language\nhas been deliberately invented; it has been slowly and unconsciously\ndeveloped by many steps.  (53.  See some good remarks on this head by Prof.\nWhitney, in his 'Oriental and Linguistic Studies,' 1873, p. 354.  He\nobserves that the desire of communication between man is the living force,\nwhich, in the development of language, \"works both consciously and\nunconsciously; consciously as regards the immediate end to be attained;\nunconsciously as regards the further consequences of the act.\")  The sounds\nuttered by birds offer in several respects the nearest analogy to language,\nfor all the members of the same species utter the same instinctive cries\nexpressive of their emotions; and all the kinds which sing, exert their\npower instinctively; but the actual song, and even the call-notes, are\nlearnt from their parents or foster-parents.  These sounds, as Daines\nBarrington (54.  Hon. Daines Barrington in 'Philosoph. Transactions,' 1773,\np. 262.  See also Dureau de la Malle, in 'Ann. des. Sc. Nat.' 3rd series,\nZoolog., tom. x. p. 119.) has proved, \"are no more innate than language is\nin man.\"  The first attempts to sing \"may be compared to the imperfect\nendeavour in a child to babble.\"  The young males continue practising, or\nas the bird-catchers say, \"recording,\" for ten or eleven months.  Their\nfirst essays shew hardly a rudiment of the future song; but as they grow\nolder we can perceive what they are aiming at; and at last they are said\n\"to sing their song round.\"  Nestlings which have learnt the song of a\ndistinct species, as with the canary-birds educated in the Tyrol, teach and\ntransmit their new song to their offspring.  The slight natural differences\nof song in the same species inhabiting different districts may be\nappositely compared, as Barrington remarks, \"to provincial dialects\"; and\nthe songs of allied, though distinct species may be compared with the\nlanguages of distinct races of man.  I have given the foregoing details to\nshew that an instinctive tendency to acquire an art is not peculiar to man.\n\nWith respect to the origin of articulate language, after having read on the\none side the highly interesting works of Mr. Hensleigh Wedgwood, the Rev.\nF. Farrar, and Prof. Schleicher (55.  'On the Origin of Language,' by H.\nWedgwood, 1866.  'Chapters on Language,' by the Rev. F.W. Farrar, 1865.\nThese works are most interesting.  See also 'De la Phys. et de Parole,' par\nAlbert Lemoine, 1865, p. 190.  The work on this subject, by the late Prof.\nAug. Schleicher, has been translated by Dr. Bikkers into English, under the\ntitle of 'Darwinism tested by the Science of Language,' 1869.), and the\ncelebrated lectures of Prof. Max Muller on the other side, I cannot doubt\nthat language owes its origin to the imitation and modification of various\nnatural sounds, the voices of other animals, and man's own instinctive\ncries, aided by signs and gestures.  When we treat of sexual selection we\nshall see that primeval man, or rather some early progenitor of man,\nprobably first used his voice in producing true musical cadences, that is\nin singing, as do some of the gibbon-apes at the present day; and we may\nconclude from a widely-spread analogy, that this power would have been\nespecially exerted during the courtship of the sexes,--would have expressed\nvarious emotions, such as love, jealousy, triumph,--and would have served\nas a challenge to rivals.  It is, therefore, probable that the imitation of\nmusical cries by articulate sounds may have given rise to words expressive\nof various complex emotions.  The strong tendency in our nearest allies,\nthe monkeys, in microcephalous idiots (56.  Vogt, 'Memoire sur les\nMicrocephales,' 1867, p. 169.  With respect to savages, I have given some\nfacts in my 'Journal of Researches,' etc., 1845, p. 206.), and in the\nbarbarous races of mankind, to imitate whatever they hear deserves notice,\nas bearing on the subject of imitation.  Since monkeys certainly understand\nmuch that is said to them by man, and when wild, utter signal-cries of\ndanger to their fellows (57.  See clear evidence on this head in the two\nworks so often quoted, by Brehm and Rengger.); and since fowls give\ndistinct warnings for danger on the ground, or in the sky from hawks (both,\nas well as a third cry, intelligible to dogs) (58.  Houzeau gives a very\ncurious account of his observations on this subject in his 'Facultes\nMentales des Animaux,' tom. ii. p. 348.), may not some unusually wise ape-\nlike animal have imitated the growl of a beast of prey, and thus told his\nfellow-monkeys the nature of the expected danger?  This would have been a\nfirst step in the formation of a language.\n\nAs the voice was used more and more, the vocal organs would have been\nstrengthened and perfected through the principle of the inherited effects\nof use; and this would have reacted on the power of speech.  But the\nrelation between the continued use of language and the development of the\nbrain, has no doubt been far more important.  The mental powers in some\nearly progenitor of man must have been more highly developed than in any\nexisting ape, before even the most imperfect form of speech could have come\ninto use; but we may confidently believe that the continued use and\nadvancement of this power would have reacted on the mind itself, by\nenabling and encouraging it to carry on long trains of thought.  A complex\ntrain of thought can no more be carried on without the aid of words,\nwhether spoken or silent, than a long calculation without the use of\nfigures or algebra.  It appears, also, that even an ordinary train of\nthought almost requires, or is greatly facilitated by some form of\nlanguage, for the dumb, deaf, and blind girl, Laura Bridgman, was observed\nto use her fingers whilst dreaming.  (59.  See remarks on this head by Dr.\nMaudsley, 'The Physiology and Pathology of Mind,' 2nd ed., 1868, p. 199.)\nNevertheless, a long succession of vivid and connected ideas may pass\nthrough the mind without the aid of any form of language, as we may infer\nfrom the movements of dogs during their dreams.  We have, also, seen that\nanimals are able to reason to a certain extent, manifestly without the aid\nof language.  The intimate connection between the brain, as it is now\ndeveloped in us, and the faculty of speech, is well shewn by those curious\ncases of brain-disease in which speech is specially affected, as when the\npower to remember substantives is lost, whilst other words can be correctly\nused, or where substantives of a certain class, or all except the initial\nletters of substantives and proper names are forgotten.  (60.  Many curious\ncases have been recorded.  See, for instance, Dr. Bateman 'On Aphasia,'\n1870, pp. 27, 31, 53, 100, etc.  Also, 'Inquiries Concerning the\nIntellectual Powers,' by Dr. Abercrombie, 1838, p. 150.)  There is no more\nimprobability in the continued use of the mental and vocal organs leading\nto inherited changes in their structure and functions, than in the case of\nhand-writing, which depends partly on the form of the hand and partly on\nthe disposition of the mind; and handwriting is certainly inherited.  (61.\n'The Variation of Animals and Plants under Domestication,' vol. ii. p. 6.'\n\nSeveral writers, more especially Prof. Max Muller (62.  Lectures on 'Mr.\nDarwin's Philosophy of Language,' 1873.), have lately insisted that the use\nof language implies the power of forming general concepts; and that as no\nanimals are supposed to possess this power, an impassable barrier is formed\nbetween them and man.  (63.  The judgment of a distinguished philologist,\nsuch as Prof. Whitney, will have far more weight on this point than\nanything that I can say.  He remarks ('Oriental and Linguistic Studies,'\n1873, p. 297), in speaking of Bleek's views:  \"Because on the grand scale\nlanguage is the necessary auxiliary of thought, indispensable to the\ndevelopment of the power of thinking, to the distinctness and variety and\ncomplexity of cognitions to the full mastery of consciousness; therefore he\nwould fain make thought absolutely impossible without speech, identifying\nthe faculty with its instrument.  He might just as reasonably assert that\nthe human hand cannot act without a tool.  With such a doctrine to start\nfrom, he cannot stop short of Max Muller's worst paradoxes, that an infant\n(in fans, not speaking) is not a human being, and that deaf-mutes do not\nbecome possessed of reason until they learn to twist their fingers into\nimitation of spoken words.\"  Max Muller gives in italics ('Lectures on Mr.\nDarwin's Philosophy of Language,' 1873, third lecture) this aphorism:\n\"There is no thought without words, as little as there are words without\nthought.\"  What a strange definition must here be given to the word\nthought!)  With respect to animals, I have already endeavoured to shew that\nthey have this power, at least in a rude and incipient degree.  As far as\nconcerns infants of from ten to eleven months old, and deaf-mutes, it seems\nto me incredible, that they should be able to connect certain sounds with\ncertain general ideas as quickly as they do, unless such ideas were already\nformed in their minds.  The same remark may be extended to the more\nintelligent animals; as Mr. Leslie Stephen observes (64.  'Essays on Free\nThinking,' etc., 1873, p. 82.), \"A dog frames a general concept of cats or\nsheep, and knows the corresponding words as well as a philosopher.  And the\ncapacity to understand is as good a proof of vocal intelligence, though in\nan inferior degree, as the capacity to speak.\"\n\nWhy the organs now used for speech should have been originally perfected\nfor this purpose, rather than any other organs, it is not difficult to see.\nAnts have considerable powers of intercommunication by means of their\nantennae, as shewn by Huber, who devotes a whole chapter to their language.\nWe might have used our fingers as efficient instruments, for a person with\npractice can report to a deaf man every word of a speech rapidly delivered\nat a public meeting; but the loss of our hands, whilst thus employed, would\nhave been a serious inconvenience.  As all the higher mammals possess vocal\norgans, constructed on the same general plan as ours, and used as a means\nof communication, it was obviously probable that these same organs would be\nstill further developed if the power of communication had to be improved;\nand this has been effected by the aid of adjoining and well adapted parts,\nnamely the tongue and lips.  (65.  See some good remarks to this effect by\nDr. Maudsley, 'The Physiology and Pathology of Mind,' 1868, p. 199.)  The\nfact of the higher apes not using their vocal organs for speech, no doubt\ndepends on their intelligence not having been sufficiently advanced.  The\npossession by them of organs, which with long-continued practice might have\nbeen used for speech, although not thus used, is paralleled by the case of\nmany birds which possess organs fitted for singing, though they never sing.\nThus, the nightingale and crow have vocal organs similarly constructed,\nthese being used by the former for diversified song, and by the latter only\nfor croaking.  (66.  Macgillivray, 'Hist. of British Birds,' vol. ii. 1839,\np. 29.  An excellent observer, Mr. Blackwall, remarks that the magpie\nlearns to pronounce single words, and even short sentences, more readily\nthan almost any other British bird; yet, as he adds, after long and closely\ninvestigating its habits, he has never known it, in a state of nature,\ndisplay any unusual capacity for imitation.  'Researches in Zoology,' 1834,\np. 158.)  If it be asked why apes have not had their intellects developed\nto the same degree as that of man, general causes only can be assigned in\nanswer, and it is unreasonable to expect any thing more definite,\nconsidering our ignorance with respect to the successive stages of\ndevelopment through which each creature has passed.\n\nThe formation of different languages and of distinct species, and the\nproofs that both have been developed through a gradual process, are\ncuriously parallel.  (67.  See the very interesting parallelism between the\ndevelopment of species and languages, given by Sir C. Lyell in 'The\nGeological Evidences of the Antiquity of Man,' 1863, chap. xxiii.)  But we\ncan trace the formation of many words further back than that of species,\nfor we can perceive how they actually arose from the imitation of various\nsounds.  We find in distinct languages striking homologies due to community\nof descent, and analogies due to a similar process of formation.  The\nmanner in which certain letters or sounds change when others change is very\nlike correlated growth.  We have in both cases the reduplication of parts,\nthe effects of long-continued use, and so forth.  The frequent presence of\nrudiments, both in languages and in species, is still more remarkable.  The\nletter m in the word am, means I; so that in the expression I am, a\nsuperfluous and useless rudiment has been retained.  In the spelling also\nof words, letters often remain as the rudiments of ancient forms of\npronunciation.  Languages, like organic beings, can be classed in groups\nunder groups; and they can be classed either naturally according to\ndescent, or artificially by other characters.  Dominant languages and\ndialects spread widely, and lead to the gradual extinction of other\ntongues.  A language, like a species, when once extinct, never, as Sir C.\nLyell remarks, reappears.  The same language never has two birth-places.\nDistinct languages may be crossed or blended together.  (68.  See remarks\nto this effect by the Rev. F.W. Farrar, in an interesting article, entitled\n'Philology and Darwinism,' in 'Nature,' March 24th, 1870, p. 528.)  We see\nvariability in every tongue, and new words are continually cropping up; but\nas there is a limit to the powers of the memory, single words, like whole\nlanguages, gradually become extinct.  As Max Muller (69.  'Nature,' January\n6th, 1870, p. 257.) has well remarked:--\"A struggle for life is constantly\ngoing on amongst the words and grammatical forms in each language.  The\nbetter, the shorter, the easier forms are constantly gaining the upper\nhand, and they owe their success to their own inherent virtue.\"  To these\nmore important causes of the survival of certain words, mere novelty and\nfashion may be added; for there is in the mind of man a strong love for\nslight changes in all things.  The survival or preservation of certain\nfavoured words in the struggle for existence is natural selection.\n\nThe perfectly regular and wonderfully complex construction of the languages\nof many barbarous nations has often been advanced as a proof, either of the\ndivine origin of these languages, or of the high art and former\ncivilisation of their founders.  Thus F. von Schlegel writes:  \"In those\nlanguages which appear to be at the lowest grade of intellectual culture,\nwe frequently observe a very high and elaborate degree of art in their\ngrammatical structure.  This is especially the case with the Basque and the\nLapponian, and many of the American languages.\"  (70.  Quoted by C.S. Wake,\n'Chapters on Man,' 1868, p. 101.)  But it is assuredly an error to speak of\nany language as an art, in the sense of its having been elaborately and\nmethodically formed.  Philologists now admit that conjugations,\ndeclensions, etc., originally existed as distinct words, since joined\ntogether; and as such words express the most obvious relations between\nobjects and persons, it is not surprising that they should have been used\nby the men of most races during the earliest ages.  With respect to\nperfection, the following illustration will best shew how easily we may\nerr:  a Crinoid sometimes consists of no less than 150,000 pieces of shell\n(71.  Buckland, 'Bridgewater Treatise,' p. 411.), all arranged with perfect\nsymmetry in radiating lines; but a naturalist does not consider an animal\nof this kind as more perfect than a bilateral one with comparatively few\nparts, and with none of these parts alike, excepting on the opposite sides\nof the body.  He justly considers the differentiation and specialisation of\norgans as the test of perfection.  So with languages:  the most symmetrical\nand complex ought not to be ranked above irregular, abbreviated, and\nbastardised languages, which have borrowed expressive words and useful\nforms of construction from various conquering, conquered, or immigrant\nraces.\n\nFrom these few and imperfect remarks I conclude that the extremely complex\nand regular construction of many barbarous languages, is no proof that they\nowe their origin to a special act of creation.  (72.  See some good remarks\non the simplification of languages, by Sir J. Lubbock, 'Origin of\nCivilisation,' 1870, p. 278.)  Nor, as we have seen, does the faculty of\narticulate speech in itself offer any insuperable objection to the belief\nthat man has been developed from some lower form.\n\nSENSE OF BEAUTY.\n\nThis sense has been declared to be peculiar to man.  I refer here only to\nthe pleasure given by certain colours, forms, and sounds, and which may\nfairly be called a sense of the beautiful; with cultivated men such\nsensations are, however, intimately associated with complex ideas and\ntrains of thought.  When we behold a male bird elaborately displaying his\ngraceful plumes or splendid colours before the female, whilst other birds,\nnot thus decorated, make no such display, it is impossible to doubt that\nshe admires the beauty of her male partner.  As women everywhere deck\nthemselves with these plumes, the beauty of such ornaments cannot be\ndisputed.  As we shall see later, the nests of humming-birds, and the\nplaying passages of bower-birds are tastefully ornamented with gaily-\ncoloured objects; and this shews that they must receive some kind of\npleasure from the sight of such things.  With the great majority of\nanimals, however, the taste for the beautiful is confined, as far as we can\njudge, to the attractions of the opposite sex.  The sweet strains poured\nforth by many male birds during the season of love, are certainly admired\nby the females, of which fact evidence will hereafter be given.  If female\nbirds had been incapable of appreciating the beautiful colours, the\nornaments, and voices of their male partners, all the labour and anxiety\nexhibited by the latter in displaying their charms before the females would\nhave been thrown away; and this it is impossible to admit.  Why certain\nbright colours should excite pleasure cannot, I presume, be explained, any\nmore than why certain flavours and scents are agreeable; but habit has\nsomething to do with the result, for that which is at first unpleasant to\nour senses, ultimately becomes pleasant, and habits are inherited.  With\nrespect to sounds, Helmholtz has explained to a certain extent on\nphysiological principles, why harmonies and certain cadences are agreeable.\nBut besides this, sounds frequently recurring at irregular intervals are\nhighly disagreeable, as every one will admit who has listened at night to\nthe irregular flapping of a rope on board ship.  The same principle seems\nto come into play with vision, as the eye prefers symmetry or figures with\nsome regular recurrence.  Patterns of this kind are employed by even the\nlowest savages as ornaments; and they have been developed through sexual\nselection for the adornment of some male animals.  Whether we can or not\ngive any reason for the pleasure thus derived from vision and hearing, yet\nman and many of the lower animals are alike pleased by the same colours,\ngraceful shading and forms, and the same sounds.\n\nThe taste for the beautiful, at least as far as female beauty is concerned,\nis not of a special nature in the human mind; for it differs widely in the\ndifferent races of man, and is not quite the same even in the different\nnations of the same race.  Judging from the hideous ornaments, and the\nequally hideous music admired by most savages, it might be urged that their\naesthetic faculty was not so highly developed as in certain animals, for\ninstance, as in birds.  Obviously no animal would be capable of admiring\nsuch scenes as the heavens at night, a beautiful landscape, or refined\nmusic; but such high tastes are acquired through culture, and depend on\ncomplex associations; they are not enjoyed by barbarians or by uneducated\npersons.\n\nMany of the faculties, which have been of inestimable service to man for\nhis progressive advancement, such as the powers of the imagination, wonder,\ncuriosity, an undefined sense of beauty, a tendency to imitation, and the\nlove of excitement or novelty, could hardly fail to lead to capricious\nchanges of customs and fashions.  I have alluded to this point, because a\nrecent writer (73.  'The Spectator,' Dec. 4th, 1869, p. 1430.) has oddly\nfixed on Caprice \"as one of the most remarkable and typical differences\nbetween savages and brutes.\"  But not only can we partially understand how\nit is that man is from various conflicting influences rendered capricious,\nbut that the lower animals are, as we shall hereafter see, likewise\ncapricious in their affections, aversions, and sense of beauty.  There is\nalso reason to suspect that they love novelty, for its own sake.\n\nBELIEF IN GOD--RELIGION.\n\nThere is no evidence that man was aboriginally endowed with the ennobling\nbelief in the existence of an Omnipotent God.  On the contrary there is\nample evidence, derived not from hasty travellers, but from men who have\nlong resided with savages, that numerous races have existed, and still\nexist, who have no idea of one or more gods, and who have no words in their\nlanguages to express such an idea.  (74.  See an excellent article on this\nsubject by the Rev. F.W. Farrar, in the 'Anthropological Review,' Aug.\n1864, p. ccxvii.  For further facts see Sir J. Lubbock, 'Prehistoric\nTimes,' 2nd edit., 1869, p. 564; and especially the chapters on Religion in\nhis 'Origin of Civilisation,' 1870.)  The question is of course wholly\ndistinct from that higher one, whether there exists a Creator and Ruler of\nthe universe; and this has been answered in the affirmative by some of the\nhighest intellects that have ever existed.\n\nIf, however, we include under the term \"religion\" the belief in unseen or\nspiritual agencies, the case is wholly different; for this belief seems to\nbe universal with the less civilised races.  Nor is it difficult to\ncomprehend how it arose.  As soon as the important faculties of the\nimagination, wonder, and curiosity, together with some power of reasoning,\nhad become partially developed, man would naturally crave to understand\nwhat was passing around him, and would have vaguely speculated on his own\nexistence.  As Mr. M'Lennan (75.  'The Worship of Animals and Plants,' in\nthe 'Fortnightly Review,' Oct. 1, 1869, p. 422.) has remarked, \"Some\nexplanation of the phenomena of life, a man must feign for himself, and to\njudge from the universality of it, the simplest hypothesis, and the first\nto occur to men, seems to have been that natural phenomena are ascribable\nto the presence in animals, plants, and things, and in the forces of\nnature, of such spirits prompting to action as men are conscious they\nthemselves possess.\"  It is also probable, as Mr. Tylor has shewn, that\ndreams may have first given rise to the notion of spirits; for savages do\nnot readily distinguish between subjective and objective impressions.  When\na savage dreams, the figures which appear before him are believed to have\ncome from a distance, and to stand over him; or \"the soul of the dreamer\ngoes out on its travels, and comes home with a remembrance of what it has\nseen.\"  (76.  Tylor, 'Early History of Mankind,' 1865, p. 6.  See also the\nthree striking chapters on the 'Development of Religion,' in Lubbock's\n'Origin of Civilisation,' 1870.  In a like manner Mr. Herbert Spencer, in\nhis ingenious essay in the 'Fortnightly Review' (May 1st, 1870, p. 535),\naccounts for the earliest forms of religious belief throughout the world,\nby man being led through dreams, shadows, and other causes, to look at\nhimself as a double essence, corporeal and spiritual.  As the spiritual\nbeing is supposed to exist after death and to be powerful, it is\npropitiated by various gifts and ceremonies, and its aid invoked.  He then\nfurther shews that names or nicknames given from some animal or other\nobject, to the early progenitors or founders of a tribe, are supposed after\na long interval to represent the real progenitor of the tribe; and such\nanimal or object is then naturally believed still to exist as a spirit, is\nheld sacred, and worshipped as a god.  Nevertheless I cannot but suspect\nthat there is a still earlier and ruder stage, when anything which\nmanifests power or movement is thought to be endowed with some form of\nlife, and with mental faculties analogous to our own.)  But until the\nfaculties of imagination, curiosity, reason, etc., had been fairly well\ndeveloped in the mind of man, his dreams would not have led him to believe\nin spirits, any more than in the case of a dog.\n\nThe tendency in savages to imagine that natural objects and agencies are\nanimated by spiritual or living essences, is perhaps illustrated by a\nlittle fact which I once noticed:  my dog, a full-grown and very sensible\nanimal, was lying on the lawn during a hot and still day; but at a little\ndistance a slight breeze occasionally moved an open parasol, which would\nhave been wholly disregarded by the dog, had any one stood near it.  As it\nwas, every time that the parasol slightly moved, the dog growled fiercely\nand barked.  He must, I think, have reasoned to himself in a rapid and\nunconscious manner, that movement without any apparent cause indicated the\npresence of some strange living agent, and that no stranger had a right to\nbe on his territory.\n\nThe belief in spiritual agencies would easily pass into the belief in the\nexistence of one or more gods.  For savages would naturally attribute to\nspirits the same passions, the same love of vengeance or simplest form of\njustice, and the same affections which they themselves feel.  The Fuegians\nappear to be in this respect in an intermediate condition, for when the\nsurgeon on board the \"Beagle\" shot some young ducklings as specimens, York\nMinster declared in the most solemn manner, \"Oh, Mr. Bynoe, much rain, much\nsnow, blow much\"; and this was evidently a retributive punishment for\nwasting human food.  So again he related how, when his brother killed a\n\"wild man,\" storms long raged, much rain and snow fell.  Yet we could never\ndiscover that the Fuegians believed in what we should call a God, or\npractised any religious rites; and Jemmy Button, with justifiable pride,\nstoutly maintained that there was no devil in his land.  This latter\nassertion is the more remarkable, as with savages the belief in bad spirits\nis far more common than that in good ones.\n\nThe feeling of religious devotion is a highly complex one, consisting of\nlove, complete submission to an exalted and mysterious superior, a strong\nsense of dependence (77.  See an able article on the 'Physical Elements of\nReligion,' by Mr. L. Owen Pike, in 'Anthropological Review,' April 1870, p.\nlxiii.), fear, reverence, gratitude, hope for the future, and perhaps other\nelements.  No being could experience so complex an emotion until advanced\nin his intellectual and moral faculties to at least a moderately high\nlevel.  Nevertheless, we see some distant approach to this state of mind in\nthe deep love of a dog for his master, associated with complete submission,\nsome fear, and perhaps other feelings.  The behaviour of a dog when\nreturning to his master after an absence, and, as I may add, of a monkey to\nhis beloved keeper, is widely different from that towards their fellows.\nIn the latter case the transports of joy appear to be somewhat less, and\nthe sense of equality is shewn in every action.  Professor Braubach goes so\nfar as to maintain that a dog looks on his master as on a god.  (78.\n'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53.  It is\nsaid (Dr. W. Lauder Lindsay, 'Journal of Mental Science,' 1871, p. 43),\nthat Bacon long ago, and the poet Burns, held the same notion.)\n\nThe same high mental faculties which first led man to believe in unseen\nspiritual agencies, then in fetishism, polytheism, and ultimately in\nmonotheism, would infallibly lead him, as long as his reasoning powers\nremained poorly developed, to various strange superstitions and customs.\nMany of these are terrible to think of--such as the sacrifice of human\nbeings to a blood-loving god; the trial of innocent persons by the ordeal\nof poison or fire; witchcraft, etc.--yet it is well occasionally to reflect\non these superstitions, for they shew us what an infinite debt of gratitude\nwe owe to the improvement of our reason, to science, and to our accumulated\nknowledge.  As Sir J. Lubbock (79.  'Prehistoric Times,' 2nd edit., p. 571.\nIn this work (p. 571) there will be found an excellent account of the many\nstrange and capricious customs of savages.) has well observed, \"it is not\ntoo much to say that the horrible dread of unknown evil hangs like a thick\ncloud over savage life, and embitters every pleasure.\"  These miserable and\nindirect consequences of our highest faculties may be compared with the\nincidental and occasional mistakes of the instincts of the lower animals.\n\n\nCHAPTER IV.\n\nCOMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS--continued.\n\nThe moral sense--Fundamental proposition--The qualities of social animals--\nOrigin of sociability--Struggle between opposed instincts--Man a social\nanimal--The more enduring social instincts conquer other less persistent\ninstincts--The social virtues alone regarded by savages--The self-regarding\nvirtues acquired at a later stage of development--The importance of the\njudgment of the members of the same community on conduct--Transmission of\nmoral tendencies--Summary.\n\nI fully subscribe to the judgment of those writers (1.  See, for instance,\non this subject, Quatrefages, 'Unite de l'Espece Humaine,' 1861, p. 21,\netc.) who maintain that of all the differences between man and the lower\nanimals, the moral sense or conscience is by far the most important.  This\nsense, as Mackintosh (2.  'Dissertation on Ethical Philosophy,' 1837, p.\n231, etc.) remarks, \"has a rightful supremacy over every other principle of\nhuman action\"; it is summed up in that short but imperious word \"ought,\" so\nfull of high significance.  It is the most noble of all the attributes of\nman, leading him without a moment's hesitation to risk his life for that of\na fellow-creature; or after due deliberation, impelled simply by the deep\nfeeling of right or duty, to sacrifice it in some great cause.  Immanuel\nKant exclaims, \"Duty!  Wondrous thought, that workest neither by fond\ninsinuation, flattery, nor by any threat, but merely by holding up thy\nnaked law in the soul, and so extorting for thyself always reverence, if\nnot always obedience; before whom all appetites are dumb, however secretly\nthey rebel; whence thy original?\"  (3.  'Metaphysics of Ethics,' translated\nby J.W. Semple, Edinburgh, 1836, p. 136.)\n\nThis great question has been discussed by many writers (4.  Mr. Bain gives\na list ('Mental and Moral Science,' 1868, pp. 543-725) of twenty-six\nBritish authors who have written on this subject, and whose names are\nfamiliar to every reader; to these, Mr. Bain's own name, and those of Mr.\nLecky, Mr. Shadworth Hodgson, Sir J. Lubbock, and others, might be added.)\nof consummate ability; and my sole excuse for touching on it, is the\nimpossibility of here passing it over; and because, as far as I know, no\none has approached it exclusively from the side of natural history.  The\ninvestigation possesses, also, some independent interest, as an attempt to\nsee how far the study of the lower animals throws light on one of the\nhighest psychical faculties of man.\n\nThe following proposition seems to me in a high degree probable--namely,\nthat any animal whatever, endowed with well-marked social instincts (5.\nSir B. Brodie, after observing that man is a social animal ('Psychological\nEnquiries,' 1854, p. 192), asks the pregnant question, \"ought not this to\nsettle the disputed question as to the existence of a moral sense?\"\nSimilar ideas have probably occurred to many persons, as they did long ago\nto Marcus Aurelius.  Mr. J.S. Mill speaks, in his celebrated work,\n'Utilitarianism,' (1864, pp. 45, 46), of the social feelings as a \"powerful\nnatural sentiment,\" and as \"the natural basis of sentiment for utilitarian\nmorality.\"  Again he says, \"Like the other acquired capacities above\nreferred to, the moral faculty, if not a part of our nature, is a natural\nout-growth from it; capable, like them, in a certain small degree of\nspringing up spontaneously.\"  But in opposition to all this, he also\nremarks, \"if, as in my own belief, the moral feelings are not innate, but\nacquired, they are not for that reason less natural.\"  It is with\nhesitation that I venture to differ at all from so profound a thinker, but\nit can hardly be disputed that the social feelings are instinctive or\ninnate in the lower animals; and why should they not be so in man?  Mr.\nBain (see, for instance, 'The Emotions and the Will,' 1865, p. 481) and\nothers believe that the moral sense is acquired by each individual during\nhis lifetime.  On the general theory of evolution this is at least\nextremely improbable.  The ignoring of all transmitted mental qualities\nwill, as it seems to me, be hereafter judged as a most serious blemish in\nthe works of Mr. Mill.), the parental and filial affections being here\nincluded, would inevitably acquire a moral sense or conscience, as soon as\nits intellectual powers had become as well, or nearly as well developed, as\nin man.  For, FIRSTLY, the social instincts lead an animal to take pleasure\nin the society of its fellows, to feel a certain amount of sympathy with\nthem, and to perform various services for them.  The services may be of a\ndefinite and evidently instinctive nature; or there may be only a wish and\nreadiness, as with most of the higher social animals, to aid their fellows\nin certain general ways.  But these feelings and services are by no means\nextended to all the individuals of the same species, only to those of the\nsame association.  SECONDLY, as soon as the mental faculties had become\nhighly developed, images of all past actions and motives would be\nincessantly passing through the brain of each individual:  and that feeling\nof dissatisfaction, or even misery, which invariably results, as we shall\nhereafter see, from any unsatisfied instinct, would arise, as often as it\nwas perceived that the enduring and always present social instinct had\nyielded to some other instinct, at the time stronger, but neither enduring\nin its nature, nor leaving behind it a very vivid impression.  It is clear\nthat many instinctive desires, such as that of hunger, are in their nature\nof short duration; and after being satisfied, are not readily or vividly\nrecalled.  THIRDLY, after the power of language had been acquired, and the\nwishes of the community could be expressed, the common opinion how each\nmember ought to act for the public good, would naturally become in a\nparamount degree the guide to action.  But it should be borne in mind that\nhowever great weight we may attribute to public opinion, our regard for the\napprobation and disapprobation of our fellows depends on sympathy, which,\nas we shall see, forms an essential part of the social instinct, and is\nindeed its foundation-stone.  LASTLY, habit in the individual would\nultimately play a very important part in guiding the conduct of each\nmember; for the social instinct, together with sympathy, is, like any other\ninstinct, greatly strengthened by habit, and so consequently would be\nobedience to the wishes and judgment of the community.  These several\nsubordinate propositions must now be discussed, and some of them at\nconsiderable length.\n\nIt may be well first to premise that I do not wish to maintain that any\nstrictly social animal, if its intellectual faculties were to become as\nactive and as highly developed as in man, would acquire exactly the same\nmoral sense as ours.  In the same manner as various animals have some sense\nof beauty, though they admire widely-different objects, so they might have\na sense of right and wrong, though led by it to follow widely different\nlines of conduct.  If, for instance, to take an extreme case, men were\nreared under precisely the same conditions as hive-bees, there can hardly\nbe a doubt that our unmarried females would, like the worker-bees, think it\na sacred duty to kill their brothers, and mothers would strive to kill\ntheir fertile daughters; and no one would think of interfering.  (6.  Mr.\nH. Sidgwick remarks, in an able discussion on this subject (the 'Academy,'\nJune 15, 1872, p. 231), \"a superior bee, we may feel sure, would aspire to\na milder solution of the population question.\"  Judging, however, from the\nhabits of many or most savages, man solves the problem by female\ninfanticide, polyandry and promiscuous intercourse; therefore it may well\nbe doubted whether it would be by a milder method.  Miss Cobbe, in\ncommenting ('Darwinism in Morals,' 'Theological Review,' April 1872, pp.\n188-191) on the same illustration, says, the PRINCIPLES of social duty\nwould be thus reversed; and by this, I presume, she means that the\nfulfilment of a social duty would tend to the injury of individuals; but\nshe overlooks the fact, which she would doubtless admit, that the instincts\nof the bee have been acquired for the good of the community.  She goes so\nfar as to say that if the theory of ethics advocated in this chapter were\never generally accepted, \"I cannot but believe that in the hour of their\ntriumph would be sounded the knell of the virtue of mankind!\"  It is to be\nhoped that the belief in the permanence of virtue on this earth is not held\nby many persons on so weak a tenure.)  Nevertheless, the bee, or any other\nsocial animal, would gain in our supposed case, as it appears to me, some\nfeeling of right or wrong, or a conscience.  For each individual would have\nan inward sense of possessing certain stronger or more enduring instincts,\nand others less strong or enduring; so that there would often be a struggle\nas to which impulse should be followed; and satisfaction, dissatisfaction,\nor even misery would be felt, as past impressions were compared during\ntheir incessant passage through the mind.  In this case an inward monitor\nwould tell the animal that it would have been better to have followed the\none impulse rather than the other.  The one course ought to have been\nfollowed, and the other ought not; the one would have been right and the\nother wrong; but to these terms I shall recur.\n\n\nSOCIABILITY.\n\nAnimals of many kinds are social; we find even distinct species living\ntogether; for example, some American monkeys; and united flocks of rooks,\njackdaws, and starlings.  Man shews the same feeling in his strong love for\nthe dog, which the dog returns with interest.  Every one must have noticed\nhow miserable horses, dogs, sheep, etc., are when separated from their\ncompanions, and what strong mutual affection the two former kinds, at\nleast, shew on their reunion.  It is curious to speculate on the feelings\nof a dog, who will rest peacefully for hours in a room with his master or\nany of the family, without the least notice being taken of him; but if left\nfor a short time by himself, barks or howls dismally.  We will confine our\nattention to the higher social animals; and pass over insects, although\nsome of these are social, and aid one another in many important ways.  The\nmost common mutual service in the higher animals is to warn one another of\ndanger by means of the united senses of all.  Every sportsman knows, as Dr.\nJaeger remarks (7.  'Die Darwin'sche Theorie,' s. 101.), how difficult it\nis to approach animals in a herd or troop.  Wild horses and cattle do not,\nI believe, make any danger-signal; but the attitude of any one of them who\nfirst discovers an enemy, warns the others.  Rabbits stamp loudly on the\nground with their hind-feet as a signal:  sheep and chamois do the same\nwith their forefeet, uttering likewise a whistle.  Many birds, and some\nmammals, post sentinels, which in the case of seals are said (8.  Mr. R.\nBrown in 'Proc. Zoolog. Soc.' 1868, p. 409.) generally to be the females.\nThe leader of a troop of monkeys acts as the sentinel, and utters cries\nexpressive both of danger and of safety.  (9.  Brehm, 'Thierleben,' B. i.\n1864, s. 52, 79.  For the case of the monkeys extracting thorns from each\nother, see s. 54.  With respect to the Hamadryas turning over stones, the\nfact is given (s. 76), on the evidence of Alvarez, whose observations Brehm\nthinks quite trustworthy.  For the cases of the old male baboons attacking\nthe dogs, see s. 79; and with respect to the eagle, s. 56.)  Social animals\nperform many little services for each other:  horses nibble, and cows lick\neach other, on any spot which itches:  monkeys search each other for\nexternal parasites; and Brehm states that after a troop of the\nCercopithecus griseo-viridis has rushed through a thorny brake, each monkey\nstretches itself on a branch, and another monkey sitting by,\n\"conscientiously\" examines its fur, and extracts every thorn or burr.\n\nAnimals also render more important services to one another:  thus wolves\nand some other beasts of prey hunt in packs, and aid one another in\nattacking their victims.  Pelicans fish in concert.  The Hamadryas baboons\nturn over stones to find insects, etc.; and when they come to a large one,\nas many as can stand round, turn it over together and share the booty.\nSocial animals mutually defend each other.  Bull bisons in N. America, when\nthere is danger, drive the cows and calves into the middle of the herd,\nwhilst they defend the outside.  I shall also in a future chapter give an\naccount of two young wild bulls at Chillingham attacking an old one in\nconcert, and of two stallions together trying to drive away a third\nstallion from a troop of mares.  In Abyssinia, Brehm encountered a great\ntroop of baboons who were crossing a valley:  some had already ascended the\nopposite mountain, and some were still in the valley; the latter were\nattacked by the dogs, but the old males immediately hurried down from the\nrocks, and with mouths widely opened, roared so fearfully, that the dogs\nquickly drew back.  They were again encouraged to the attack; but by this\ntime all the baboons had reascended the heights, excepting a young one,\nabout six months old, who, loudly calling for aid, climbed on a block of\nrock, and was surrounded.  Now one of the largest males, a true hero, came\ndown again from the mountain, slowly went to the young one, coaxed him, and\ntriumphantly led him away--the dogs being too much astonished to make an\nattack.  I cannot resist giving another scene which was witnessed by this\nsame naturalist; an eagle seized a young Cercopithecus, which, by clinging\nto a branch, was not at once carried off; it cried loudly for assistance,\nupon which the other members of the troop, with much uproar, rushed to the\nrescue, surrounded the eagle, and pulled out so many feathers, that he no\nlonger thought of his prey, but only how to escape.  This eagle, as Brehm\nremarks, assuredly would never again attack a single monkey of a troop.\n(10.  Mr. Belt gives the case of a spider-monkey (Ateles) in Nicaragua,\nwhich was heard screaming for nearly two hours in the forest, and was found\nwith an eagle perched close by it.  The bird apparently feared to attack as\nlong as it remained face to face; and Mr. Belt believes, from what he has\nseen of the habits of these monkeys, that they protect themselves from\neagles by keeping two or three together.  'The Naturalist in Nicaragua,'\n1874, p. 118.)\n\nIt is certain that associated animals have a feeling of love for each\nother, which is not felt by non-social adult animals.  How far in most\ncases they actually sympathise in the pains and pleasures of others, is\nmore doubtful, especially with respect to pleasures.  Mr. Buxton, however,\nwho had excellent means of observation (11.  'Annals and Magazine of\nNatural History,' November 1868, p. 382.), states that his macaws, which\nlived free in Norfolk, took \"an extravagant interest\" in a pair with a\nnest; and whenever the female left it, she was surrounded by a troop\n\"screaming horrible acclamations in her honour.\"  It is often difficult to\njudge whether animals have any feeling for the sufferings of others of\ntheir kind.  Who can say what cows feel, when they surround and stare\nintently on a dying or dead companion; apparently, however, as Houzeau\nremarks, they feel no pity.  That animals sometimes are far from feeling\nany sympathy is too certain; for they will expel a wounded animal from the\nherd, or gore or worry it to death.  This is almost the blackest fact in\nnatural history, unless, indeed, the explanation which has been suggested\nis true, that their instinct or reason leads them to expel an injured\ncompanion, lest beasts of prey, including man, should be tempted to follow\nthe troop.  In this case their conduct is not much worse than that of the\nNorth American Indians, who leave their feeble comrades to perish on the\nplains; or the Fijians, who, when their parents get old, or fall ill, bury\nthem alive.  (12.  Sir J. Lubbock, 'Prehistoric Times,' 2nd ed., p. 446.)\n\nMany animals, however, certainly sympathise with each other's distress or\ndanger.  This is the case even with birds.  Captain Stansbury (13.  As\nquoted by Mr. L.H. Morgan, 'The American Beaver,' 1868, p. 272.  Capt.\nStansbury also gives an interesting account of the manner in which a very\nyoung pelican, carried away by a strong stream, was guided and encouraged\nin its attempts to reach the shore by half a dozen old birds.) found on a\nsalt lake in Utah an old and completely blind pelican, which was very fat,\nand must have been well fed for a long time by his companions.  Mr. Blyth,\nas he informs me, saw Indian crows feeding two or three of their companions\nwhich were blind; and I have heard of an analogous case with the domestic\ncock.  We may, if we choose, call these actions instinctive; but such cases\nare much too rare for the development of any special instinct.  (14.  As\nMr. Bain states, \"effective aid to a sufferer springs from sympathy\nproper:\"  'Mental and Moral Science,' 1868, p. 245.)  I have myself seen a\ndog, who never passed a cat who lay sick in a basket, and was a great\nfriend of his, without giving her a few licks with his tongue, the surest\nsign of kind feeling in a dog.\n\nIt must be called sympathy that leads a courageous dog to fly at any one\nwho strikes his master, as he certainly will.  I saw a person pretending to\nbeat a lady, who had a very timid little dog on her lap, and the trial had\nnever been made before; the little creature instantly jumped away, but\nafter the pretended beating was over, it was really pathetic to see how\nperseveringly he tried to lick his mistress's face, and comfort her.  Brehm\n(15.  'Thierleben,' B. i. s. 85.) states that when a baboon in confinement\nwas pursued to be punished, the others tried to protect him.  It must have\nbeen sympathy in the cases above given which led the baboons and\nCercopitheci to defend their young comrades from the dogs and the eagle.  I\nwill give only one other instance of sympathetic and heroic conduct, in the\ncase of a little American monkey.  Several years ago a keeper at the\nZoological Gardens shewed me some deep and scarcely healed wounds on the\nnape of his own neck, inflicted on him, whilst kneeling on the floor, by a\nfierce baboon.  The little American monkey, who was a warm friend of this\nkeeper, lived in the same large compartment, and was dreadfully afraid of\nthe great baboon.  Nevertheless, as soon as he saw his friend in peril, he\nrushed to the rescue, and by screams and bites so distracted the baboon\nthat the man was able to escape, after, as the surgeon thought, running\ngreat risk of his life.\n\nBesides love and sympathy, animals exhibit other qualities connected with\nthe social instincts, which in us would be called moral; and I agree with\nAgassiz (16.  'De l'Espece et de la Classe,' 1869, p. 97.) that dogs\npossess something very like a conscience.\n\nDogs possess some power of self-command, and this does not appear to be\nwholly the result of fear.  As Braubach (17.  'Die Darwin'sche Art-Lehre,'\n1869, s. 54.) remarks, they will refrain from stealing food in the absence\nof their master.  They have long been accepted as the very type of fidelity\nand obedience.  But the elephant is likewise very faithful to his driver or\nkeeper, and probably considers him as the leader of the herd.  Dr. Hooker\ninforms me that an elephant, which he was riding in India, became so deeply\nbogged that he remained stuck fast until the next day, when he was\nextricated by men with ropes.  Under such circumstances elephants will\nseize with their trunks any object, dead or alive, to place under their\nknees, to prevent their sinking deeper in the mud; and the driver was\ndreadfully afraid lest the animal should have seized Dr. Hooker and crushed\nhim to death.  But the driver himself, as Dr. Hooker was assured, ran no\nrisk.  This forbearance under an emergency so dreadful for a heavy animal,\nis a wonderful proof of noble fidelity.  (18.  See also Hooker's 'Himalayan\nJournals,' vol. ii. 1854, p. 333.)\n\nAll animals living in a body, which defend themselves or attack their\nenemies in concert, must indeed be in some degree faithful to one another;\nand those that follow a leader must be in some degree obedient.  When the\nbaboons in Abyssinia (19.  Brehm, 'Thierleben,' B. i. s. 76.) plunder a\ngarden, they silently follow their leader; and if an imprudent young animal\nmakes a noise, he receives a slap from the others to teach him silence and\nobedience.  Mr. Galton, who has had excellent opportunities for observing\nthe half-wild cattle in S. Africa, says (20.  See his extremely interesting\npaper on 'Gregariousness in Cattle, and in Man,' 'Macmillan's Magazine,'\nFeb. 1871, p. 353.), that they cannot endure even a momentary separation\nfrom the herd.  They are essentially slavish, and accept the common\ndetermination, seeking no better lot than to be led by any one ox who has\nenough self-reliance to accept the position.  The men who break in these\nanimals for harness, watch assiduously for those who, by grazing apart,\nshew a self-reliant disposition, and these they train as fore-oxen.  Mr.\nGalton adds that such animals are rare and valuable; and if many were born\nthey would soon be eliminated, as lions are always on the look-out for the\nindividuals which wander from the herd.\n\nWith respect to the impulse which leads certain animals to associate\ntogether, and to aid one another in many ways, we may infer that in most\ncases they are impelled by the same sense of satisfaction or pleasure which\nthey experience in performing other instinctive actions; or by the same\nsense of dissatisfaction as when other instinctive actions are checked.  We\nsee this in innumerable instances, and it is illustrated in a striking\nmanner by the acquired instincts of our domesticated animals; thus a young\nshepherd-dog delights in driving and running round a flock of sheep, but\nnot in worrying them; a young fox-hound delights in hunting a fox, whilst\nsome other kinds of dogs, as I have witnessed, utterly disregard foxes.\nWhat a strong feeling of inward satisfaction must impel a bird, so full of\nactivity, to brood day after day over her eggs.  Migratory birds are quite\nmiserable if stopped from migrating; perhaps they enjoy starting on their\nlong flight; but it is hard to believe that the poor pinioned goose,\ndescribed by Audubon, which started on foot at the proper time for its\njourney of probably more than a thousand miles, could have felt any joy in\ndoing so.  Some instincts are determined solely by painful feelings, as by\nfear, which leads to self-preservation, and is in some cases directed\ntowards special enemies.  No one, I presume, can analyse the sensations of\npleasure or pain.  In many instances, however, it is probable that\ninstincts are persistently followed from the mere force of inheritance,\nwithout the stimulus of either pleasure or pain.  A young pointer, when it\nfirst scents game, apparently cannot help pointing.  A squirrel in a cage\nwho pats the nuts which it cannot eat, as if to bury them in the ground,\ncan hardly be thought to act thus, either from pleasure or pain.  Hence the\ncommon assumption that men must be impelled to every action by experiencing\nsome pleasure or pain may be erroneous.  Although a habit may be blindly\nand implicitly followed, independently of any pleasure or pain felt at the\nmoment, yet if it be forcibly and abruptly checked, a vague sense of\ndissatisfaction is generally experienced.\n\nIt has often been assumed that animals were in the first place rendered\nsocial, and that they feel as a consequence uncomfortable when separated\nfrom each other, and comfortable whilst together; but it is a more probable\nview that these sensations were first developed, in order that those\nanimals which would profit by living in society, should be induced to live\ntogether, in the same manner as the sense of hunger and the pleasure of\neating were, no doubt, first acquired in order to induce animals to eat.\nThe feeling of pleasure from society is probably an extension of the\nparental or filial affections, since the social instinct seems to be\ndeveloped by the young remaining for a long time with their parents; and\nthis extension may be attributed in part to habit, but chiefly to natural\nselection.  With those animals which were benefited by living in close\nassociation, the individuals which took the greatest pleasure in society\nwould best escape various dangers, whilst those that cared least for their\ncomrades, and lived solitary, would perish in greater numbers.  With\nrespect to the origin of the parental and filial affections, which\napparently lie at the base of the social instincts, we know not the steps\nby which they have been gained; but we may infer that it has been to a\nlarge extent through natural selection.  So it has almost certainly been\nwith the unusual and opposite feeling of hatred between the nearest\nrelations, as with the worker-bees which kill their brother drones, and\nwith the queen-bees which kill their daughter-queens; the desire to destroy\ntheir nearest relations having been in this case of service to the\ncommunity.  Parental affection, or some feeling which replaces it, has been\ndeveloped in certain animals extremely low in the scale, for example, in\nstar-fishes and spiders.  It is also occasionally present in a few members\nalone in a whole group of animals, as in the genus Forficula, or earwigs.\n\nThe all-important emotion of sympathy is distinct from that of love.  A\nmother may passionately love her sleeping and passive infant, but she can\nhardly at such times be said to feel sympathy for it.  The love of a man\nfor his dog is distinct from sympathy, and so is that of a dog for his\nmaster.  Adam Smith formerly argued, as has Mr. Bain recently, that the\nbasis of sympathy lies in our strong retentiveness of former states of pain\nor pleasure.  Hence, \"the sight of another person enduring hunger, cold,\nfatigue, revives in us some recollection of these states, which are painful\neven in idea.\"  We are thus impelled to relieve the sufferings of another,\nin order that our own painful feelings may be at the same time relieved.\nIn like manner we are led to participate in the pleasures of others.  (21.\nSee the first and striking chapter in Adam Smith's 'Theory of Moral\nSentiments.'  Also 'Mr. Bain's Mental and Moral Science,' 1868, pp. 244,\nand 275-282.  Mr. Bain states, that, \"sympathy is, indirectly, a source of\npleasure to the sympathiser\"; and he accounts for this through reciprocity.\nHe remarks that \"the person benefited, or others in his stead, may make up,\nby sympathy and good offices returned, for all the sacrifice.\"  But if, as\nappears to be the case, sympathy is strictly an instinct, its exercise\nwould give direct pleasure, in the same manner as the exercise, as before\nremarked, of almost every other instinct.)  But I cannot see how this view\nexplains the fact that sympathy is excited, in an immeasurably stronger\ndegree, by a beloved, than by an indifferent person.  The mere sight of\nsuffering, independently of love, would suffice to call up in us vivid\nrecollections and associations.  The explanation may lie in the fact that,\nwith all animals, sympathy is directed solely towards the members of the\nsame community, and therefore towards known, and more or less beloved\nmembers, but not to all the individuals of the same species.  This fact is\nnot more surprising than that the fears of many animals should be directed\nagainst special enemies.  Species which are not social, such as lions and\ntigers, no doubt feel sympathy for the suffering of their own young, but\nnot for that of any other animal.  With mankind, selfishness, experience,\nand imitation, probably add, as Mr. Bain has shewn, to the power of\nsympathy; for we are led by the hope of receiving good in return to perform\nacts of sympathetic kindness to others; and sympathy is much strengthened\nby habit.  In however complex a manner this feeling may have originated, as\nit is one of high importance to all those animals which aid and defend one\nanother, it will have been increased through natural selection; for those\ncommunities, which included the greatest number of the most sympathetic\nmembers, would flourish best, and rear the greatest number of offspring.\n\nIt is, however, impossible to decide in many cases whether certain social\ninstincts have been acquired through natural selection, or are the indirect\nresult of other instincts and faculties, such as sympathy, reason,\nexperience, and a tendency to imitation; or again, whether they are simply\nthe result of long-continued habit.  So remarkable an instinct as the\nplacing sentinels to warn the community of danger, can hardly have been the\nindirect result of any of these faculties; it must, therefore, have been\ndirectly acquired.  On the other hand, the habit followed by the males of\nsome social animals of defending the community, and of attacking their\nenemies or their prey in concert, may perhaps have originated from mutual\nsympathy; but courage, and in most cases strength, must have been\npreviously acquired, probably through natural selection.\n\nOf the various instincts and habits, some are much stronger than others;\nthat is, some either give more pleasure in their performance, and more\ndistress in their prevention, than others; or, which is probably quite as\nimportant, they are, through inheritance, more persistently followed,\nwithout exciting any special feeling of pleasure or pain.  We are ourselves\nconscious that some habits are much more difficult to cure or change than\nothers.  Hence a struggle may often be observed in animals between\ndifferent instincts, or between an instinct and some habitual disposition;\nas when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues\nagain, or returns ashamed to his master; or as between the love of a female\ndog for her young puppies and for her master,--for she may be seen to slink\naway to them, as if half ashamed of not accompanying her master.  But the\nmost curious instance known to me of one instinct getting the better of\nanother, is the migratory instinct conquering the maternal instinct.  The\nformer is wonderfully strong; a confined bird will at the proper season\nbeat her breast against the wires of her cage, until it is bare and bloody.\nIt causes young salmon to leap out of the fresh water, in which they could\ncontinue to exist, and thus unintentionally to commit suicide.  Every one\nknows how strong the maternal instinct is, leading even timid birds to face\ngreat danger, though with hesitation, and in opposition to the instinct of\nself-preservation.  Nevertheless, the migratory instinct is so powerful,\nthat late in the autumn swallows, house-martins, and swifts frequently\ndesert their tender young, leaving them to perish miserably in their nests.\n(22.  This fact, the Rev. L. Jenyns states (see his edition of 'White's\nNat. Hist. of Selborne,' 1853, p. 204) was first recorded by the\nillustrious Jenner, in 'Phil. Transact.' 1824, and has since been confirmed\nby several observers, especially by Mr. Blackwall.  This latter careful\nobserver examined, late in the autumn, during two years, thirty-six nests;\nhe found that twelve contained young dead birds, five contained eggs on the\npoint of being hatched, and three, eggs not nearly hatched.  Many birds,\nnot yet old enough for a prolonged flight, are likewise deserted and left\nbehind.  See Blackwall, 'Researches in Zoology,' 1834, pp. 108, 118.  For\nsome additional evidence, although this is not wanted, see Leroy, 'Lettres\nPhil.' 1802, p. 217.  For Swifts, Gould's 'Introduction to the Birds of\nGreat Britain,' 1823, p. 5.  Similar cases have been observed in Canada by\nMr. Adams; 'Pop. Science Review,' July 1873, p. 283.)\n\nWe can perceive that an instinctive impulse, if it be in any way more\nbeneficial to a species than some other or opposed instinct, would be\nrendered the more potent of the two through natural selection; for the\nindividuals which had it most strongly developed would survive in larger\nnumbers.  Whether this is the case with the migratory in comparison with\nthe maternal instinct, may be doubted.  The great persistence, or steady\naction of the former at certain seasons of the year during the whole day,\nmay give it for a time paramount force.\n\nMAN A SOCIAL ANIMAL.\n\nEvery one will admit that man is a social being.  We see this in his\ndislike of solitude, and in his wish for society beyond that of his own\nfamily.  Solitary confinement is one of the severest punishments which can\nbe inflicted.  Some authors suppose that man primevally lived in single\nfamilies; but at the present day, though single families, or only two or\nthree together, roam the solitudes of some savage lands, they always, as\nfar as I can discover, hold friendly relations with other families\ninhabiting the same district.  Such families occasionally meet in council,\nand unite for their common defence.  It is no argument against savage man\nbeing a social animal, that the tribes inhabiting adjacent districts are\nalmost always at war with each other; for the social instincts never extend\nto all the individuals of the same species.  Judging from the analogy of\nthe majority of the Quadrumana, it is probable that the early ape-like\nprogenitors of man were likewise social; but this is not of much importance\nfor us.  Although man, as he now exists, has few special instincts, having\nlost any which his early progenitors may have possessed, this is no reason\nwhy he should not have retained from an extremely remote period some degree\nof instinctive love and sympathy for his fellows.  We are indeed all\nconscious that we do possess such sympathetic feelings (23.  Hume remarks\n('An Enquiry Concerning the Principles of Morals,' edit. of 1751, p. 132),\n\"There seems a necessity for confessing that the happiness and misery of\nothers are not spectacles altogether indifferent to us, but that the view\nof the former...communicates a secret joy; the appearance of the latter...\nthrows a melancholy damp over the imagination.\"); but our consciousness\ndoes not tell us whether they are instinctive, having originated long ago\nin the same manner as with the lower animals, or whether they have been\nacquired by each of us during our early years.  As man is a social animal,\nit is almost certain that he would inherit a tendency to be faithful to his\ncomrades, and obedient to the leader of his tribe; for these qualities are\ncommon to most social animals.  He would consequently possess some capacity\nfor self-command.  He would from an inherited tendency be willing to\ndefend, in concert with others, his fellow-men; and would be ready to aid\nthem in any way, which did not too greatly interfere with his own welfare\nor his own strong desires.\n\nThe social animals which stand at the bottom of the scale are guided almost\nexclusively, and those which stand higher in the scale are largely guided,\nby special instincts in the aid which they give to the members of the same\ncommunity; but they are likewise in part impelled by mutual love and\nsympathy, assisted apparently by some amount of reason.  Although man, as\njust remarked, has no special instincts to tell him how to aid his fellow-\nmen, he still has the impulse, and with his improved intellectual faculties\nwould naturally be much guided in this respect by reason and experience.\nInstinctive sympathy would also cause him to value highly the approbation\nof his fellows; for, as Mr. Bain has clearly shewn (24.  'Mental and Moral\nScience,' 1868, p. 254.), the love of praise and the strong feeling of\nglory, and the still stronger horror of scorn and infamy, \"are due to the\nworkings of sympathy.\"  Consequently man would be influenced in the highest\ndegree by the wishes, approbation, and blame of his fellow-men, as\nexpressed by their gestures and language.  Thus the social instincts, which\nmust have been acquired by man in a very rude state, and probably even by\nhis early ape-like progenitors, still give the impulse to some of his best\nactions; but his actions are in a higher degree determined by the expressed\nwishes and judgment of his fellow-men, and unfortunately very often by his\nown strong selfish desires.  But as love, sympathy and self-command become\nstrengthened by habit, and as the power of reasoning becomes clearer, so\nthat man can value justly the judgments of his fellows, he will feel\nhimself impelled, apart from any transitory pleasure or pain, to certain\nlines of conduct.  He might then declare--not that any barbarian or\nuncultivated man could thus think--I am the supreme judge of my own\nconduct, and in the words of Kant, I will not in my own person violate the\ndignity of humanity.\n\nTHE MORE ENDURING SOCIAL INSTINCTS CONQUER THE LESS PERSISTENT INSTINCTS.\n\nWe have not, however, as yet considered the main point, on which, from our\npresent point of view, the whole question of the moral sense turns.  Why\nshould a man feel that he ought to obey one instinctive desire rather than\nanother?  Why is he bitterly regretful, if he has yielded to a strong sense\nof self-preservation, and has not risked his life to save that of a fellow-\ncreature? or why does he regret having stolen food from hunger?\n\nIt is evident in the first place, that with mankind the instinctive\nimpulses have different degrees of strength; a savage will risk his own\nlife to save that of a member of the same community, but will be wholly\nindifferent about a stranger:  a young and timid mother urged by the\nmaternal instinct will, without a moment's hesitation, run the greatest\ndanger for her own infant, but not for a mere fellow-creature.\nNevertheless many a civilised man, or even boy, who never before risked his\nlife for another, but full of courage and sympathy, has disregarded the\ninstinct of self-preservation, and plunged at once into a torrent to save a\ndrowning man, though a stranger.  In this case man is impelled by the same\ninstinctive motive, which made the heroic little American monkey, formerly\ndescribed, save his keeper, by attacking the great and dreaded baboon.\nSuch actions as the above appear to be the simple result of the greater\nstrength of the social or maternal instincts rather than that of any other\ninstinct or motive; for they are performed too instantaneously for\nreflection, or for pleasure or pain to be felt at the time; though, if\nprevented by any cause, distress or even misery might be felt.  In a timid\nman, on the other hand, the instinct of self-preservation might be so\nstrong, that he would be unable to force himself to run any such risk,\nperhaps not even for his own child.\n\nI am aware that some persons maintain that actions performed impulsively,\nas in the above cases, do not come under the dominion of the moral sense,\nand cannot be called moral.  They confine this term to actions done\ndeliberately, after a victory over opposing desires, or when prompted by\nsome exalted motive.  But it appears scarcely possible to draw any clear\nline of distinction of this kind.  (25.  I refer here to the distinction\nbetween what has been called MATERIAL and FORMAL morality.  I am glad to\nfind that Professor Huxley ('Critiques and Addresses,' 1873, p. 287) takes\nthe same view on this subject as I do.  Mr. Leslie Stephen remarks ('Essays\non Freethinking and Plain Speaking,' 1873, p. 83), \"the metaphysical\ndistinction, between material and formal morality is as irrelevant as other\nsuch distinctions.\")  As far as exalted motives are concerned, many\ninstances have been recorded of savages, destitute of any feeling of\ngeneral benevolence towards mankind, and not guided by any religious\nmotive, who have deliberately sacrificed their lives as prisoners(26.  I\nhave given one such case, namely of three Patagonian Indians who preferred\nbeing shot, one after the other, to betraying the plans of their companions\nin war ('Journal of Researches,' 1845, p. 103).), rather than betray their\ncomrades; and surely their conduct ought to be considered as moral.  As far\nas deliberation, and the victory over opposing motives are concerned,\nanimals may be seen doubting between opposed instincts, in rescuing their\noffspring or comrades from danger; yet their actions, though done for the\ngood of others, are not called moral.  Moreover, anything performed very\noften by us, will at last be done without deliberation or hesitation, and\ncan then hardly be distinguished from an instinct; yet surely no one will\npretend that such an action ceases to be moral.  On the contrary, we all\nfeel that an act cannot be considered as perfect, or as performed in the\nmost noble manner, unless it be done impulsively, without deliberation or\neffort, in the same manner as by a man in whom the requisite qualities are\ninnate.  He who is forced to overcome his fear or want of sympathy before\nhe acts, deserves, however, in one way higher credit than the man whose\ninnate disposition leads him to a good act without effort.  As we cannot\ndistinguish between motives, we rank all actions of a certain class as\nmoral, if performed by a moral being.  A moral being is one who is capable\nof comparing his past and future actions or motives, and of approving or\ndisapproving of them.  We have no reason to suppose that any of the lower\nanimals have this capacity; therefore, when a Newfoundland dog drags a\nchild out of the water, or a monkey faces danger to rescue its comrade, or\ntakes charge of an orphan monkey, we do not call its conduct moral.  But in\nthe case of man, who alone can with certainty be ranked as a moral being,\nactions of a certain class are called moral, whether performed\ndeliberately, after a struggle with opposing motives, or impulsively\nthrough instinct, or from the effects of slowly-gained habit.\n\nBut to return to our more immediate subject.  Although some instincts are\nmore powerful than others, and thus lead to corresponding actions, yet it\nis untenable, that in man the social instincts (including the love of\npraise and fear of blame) possess greater strength, or have, through long\nhabit, acquired greater strength than the instincts of self-preservation,\nhunger, lust, vengeance, etc.  Why then does man regret, even though trying\nto banish such regret, that he has followed the one natural impulse rather\nthan the other; and why does he further feel that he ought to regret his\nconduct?  Man in this respect differs profoundly from the lower animals.\nNevertheless we can, I think, see with some degree of clearness the reason\nof this difference.\n\nMan, from the activity of his mental faculties, cannot avoid reflection:\npast impressions and images are incessantly and clearly passing through his\nmind.  Now with those animals which live permanently in a body, the social\ninstincts are ever present and persistent.  Such animals are always ready\nto utter the danger-signal, to defend the community, and to give aid to\ntheir fellows in accordance with their habits; they feel at all times,\nwithout the stimulus of any special passion or desire, some degree of love\nand sympathy for them; they are unhappy if long separated from them, and\nalways happy to be again in their company.  So it is with ourselves.  Even\nwhen we are quite alone, how often do we think with pleasure or pain of\nwhat others think of us,--of their imagined approbation or disapprobation;\nand this all follows from sympathy, a fundamental element of the social\ninstincts.  A man who possessed no trace of such instincts would be an\nunnatural monster.  On the other hand, the desire to satisfy hunger, or any\npassion such as vengeance, is in its nature temporary, and can for a time\nbe fully satisfied.  Nor is it easy, perhaps hardly possible, to call up\nwith complete vividness the feeling, for instance, of hunger; nor indeed,\nas has often been remarked, of any suffering.  The instinct of self-\npreservation is not felt except in the presence of danger; and many a\ncoward has thought himself brave until he has met his enemy face to face.\nThe wish for another man's property is perhaps as persistent a desire as\nany that can be named; but even in this case the satisfaction of actual\npossession is generally a weaker feeling than the desire:  many a thief, if\nnot a habitual one, after success has wondered why he stole some article.\n(27. Enmity or hatred seems also to be a highly persistent feeling, perhaps\nmore so than any other that can be named.  Envy is defined as hatred of\nanother for some excellence or success; and Bacon insists (Essay ix.), \"Of\nall other affections envy is the most importune and continual.\"  Dogs are\nvery apt to hate both strange men and strange dogs, especially if they live\nnear at hand, but do not belong to the same family, tribe, or clan; this\nfeeling would thus seem to be innate, and is certainly a most persistent\none.  It seems to be the complement and converse of the true social\ninstinct.  From what we hear of savages, it would appear that something of\nthe same kind holds good with them.  If this be so, it would be a small\nstep in any one to transfer such feelings to any member of the same tribe\nif he had done him an injury and had become his enemy.  Nor is it probable\nthat the primitive conscience would reproach a man for injuring his enemy;\nrather it would reproach him, if he had not revenged himself.  To do good\nin return for evil, to love your enemy, is a height of morality to which it\nmay be doubted whether the social instincts would, by themselves, have ever\nled us.  It is necessary that these instincts, together with sympathy,\nshould have been highly cultivated and extended by the aid of reason,\ninstruction, and the love or fear of God, before any such golden rule would\never be thought of and obeyed.)\n\nA man cannot prevent past impressions often repassing through his mind; he\nwill thus be driven to make a comparison between the impressions of past\nhunger, vengeance satisfied, or danger shunned at other men's cost, with\nthe almost ever-present instinct of sympathy, and with his early knowledge\nof what others consider as praiseworthy or blameable.  This knowledge\ncannot be banished from his mind, and from instinctive sympathy is esteemed\nof great moment.  He will then feel as if he had been baulked in following\na present instinct or habit, and this with all animals causes\ndissatisfaction, or even misery.\n\nThe above case of the swallow affords an illustration, though of a reversed\nnature, of a temporary though for the time strongly persistent instinct\nconquering another instinct, which is usually dominant over all others.  At\nthe proper season these birds seem all day long to be impressed with the\ndesire to migrate; their habits change; they become restless, are noisy and\ncongregate in flocks.  Whilst the mother-bird is feeding, or brooding over\nher nestlings, the maternal instinct is probably stronger than the\nmigratory; but the instinct which is the more persistent gains the victory,\nand at last, at a moment when her young ones are not in sight, she takes\nflight and deserts them.  When arrived at the end of her long journey, and\nthe migratory instinct has ceased to act, what an agony of remorse the bird\nwould feel, if, from being endowed with great mental activity, she could\nnot prevent the image constantly passing through her mind, of her young\nones perishing in the bleak north from cold and hunger.\n\nAt the moment of action, man will no doubt be apt to follow the stronger\nimpulse; and though this may occasionally prompt him to the noblest deeds,\nit will more commonly lead him to gratify his own desires at the expense of\nother men.  But after their gratification when past and weaker impressions\nare judged by the ever-enduring social instinct, and by his deep regard for\nthe good opinion of his fellows, retribution will surely come.  He will\nthen feel remorse, repentance, regret, or shame; this latter feeling,\nhowever, relates almost exclusively to the judgment of others.  He will\nconsequently resolve more or less firmly to act differently for the future;\nand this is conscience; for conscience looks backwards, and serves as a\nguide for the future.\n\nThe nature and strength of the feelings which we call regret, shame,\nrepentance or remorse, depend apparently not only on the strength of the\nviolated instinct, but partly on the strength of the temptation, and often\nstill more on the judgment of our fellows.  How far each man values the\nappreciation of others, depends on the strength of his innate or acquired\nfeeling of sympathy; and on his own capacity for reasoning out the remote\nconsequences of his acts.  Another element is most important, although not\nnecessary, the reverence or fear of the Gods, or Spirits believed in by\neach man:  and this applies especially in cases of remorse.  Several\ncritics have objected that though some slight regret or repentance may be\nexplained by the view advocated in this chapter, it is impossible thus to\naccount for the soul-shaking feeling of remorse.  But I can see little\nforce in this objection.  My critics do not define what they mean by\nremorse, and I can find no definition implying more than an overwhelming\nsense of repentance.  Remorse seems to bear the same relation to\nrepentance, as rage does to anger, or agony to pain.  It is far from\nstrange that an instinct so strong and so generally admired, as maternal\nlove, should, if disobeyed, lead to the deepest misery, as soon as the\nimpression of the past cause of disobedience is weakened.  Even when an\naction is opposed to no special instinct, merely to know that our friends\nand equals despise us for it is enough to cause great misery.  Who can\ndoubt that the refusal to fight a duel through fear has caused many men an\nagony of shame?  Many a Hindoo, it is said, has been stirred to the bottom\nof his soul by having partaken of unclean food.  Here is another case of\nwhat must, I think, be called remorse.  Dr. Landor acted as a magistrate in\nWest Australia, and relates (28.  'Insanity in Relation to Law,' Ontario,\nUnited States, 1871, p. 1.), that a native on his farm, after losing one of\nhis wives from disease, came and said that, \"he was going to a distant\ntribe to spear a woman, to satisfy his sense of duty to his wife.  I told\nhim that if he did so, I would send him to prison for life.  He remained\nabout the farm for some months, but got exceedingly thin, and complained\nthat he could not rest or eat, that his wife's spirit was haunting him,\nbecause he had not taken a life for hers.  I was inexorable, and assured\nhim that nothing should save him if he did.\"  Nevertheless the man\ndisappeared for more than a year, and then returned in high condition; and\nhis other wife told Dr. Landor that her husband had taken the life of a\nwoman belonging to a distant tribe; but it was impossible to obtain legal\nevidence of the act.  The breach of a rule held sacred by the tribe, will\nthus, as it seems, give rise to the deepest feelings,--and this quite apart\nfrom the social instincts, excepting in so far as the rule is grounded on\nthe judgment of the community.  How so many strange superstitions have\narisen throughout the world we know not; nor can we tell how some real and\ngreat crimes, such as incest, have come to be held in an abhorrence (which\nis not however quite universal) by the lowest savages.  It is even doubtful\nwhether in some tribes incest would be looked on with greater horror, than\nwould the marriage of a man with a woman bearing the same name, though not\na relation.  \"To violate this law is a crime which the Australians hold in\nthe greatest abhorrence, in this agreeing exactly with certain tribes of\nNorth America.  When the question is put in either district, is it worse to\nkill a girl of a foreign tribe, or to marry a girl of one's own, an answer\njust opposite to ours would be given without hesitation.\"  (29.  E.B.\nTylor, in 'Contemporary Review,' April 1873, p. 707.)  We may, therefore,\nreject the belief, lately insisted on by some writers, that the abhorrence\nof incest is due to our possessing a special God-implanted conscience.  On\nthe whole it is intelligible, that a man urged by so powerful a sentiment\nas remorse, though arising as above explained, should be led to act in a\nmanner, which he has been taught to believe serves as an expiation, such as\ndelivering himself up to justice.\n\nMan prompted by his conscience, will through long habit acquire such\nperfect self-command, that his desires and passions will at last yield\ninstantly and without a struggle to his social sympathies and instincts,\nincluding his feeling for the judgment of his fellows.  The still hungry,\nor the still revengeful man will not think of stealing food, or of wreaking\nhis vengeance.  It is possible, or as we shall hereafter see, even\nprobable, that the habit of self-command may, like other habits, be\ninherited.  Thus at last man comes to feel, through acquired and perhaps\ninherited habit, that it is best for him to obey his more persistent\nimpulses.  The imperious word \"ought\" seems merely to imply the\nconsciousness of the existence of a rule of conduct, however it may have\noriginated.  Formerly it must have been often vehemently urged that an\ninsulted gentleman OUGHT to fight a duel.  We even say that a pointer OUGHT\nto point, and a retriever to retrieve game.  If they fail to do so, they\nfail in their duty and act wrongly.\n\nIf any desire or instinct leading to an action opposed to the good of\nothers still appears, when recalled to mind, as strong as, or stronger\nthan, the social instinct, a man will feel no keen regret at having\nfollowed it; but he will be conscious that if his conduct were known to his\nfellows, it would meet with their disapprobation; and few are so destitute\nof sympathy as not to feel discomfort when this is realised.  If he has no\nsuch sympathy, and if his desires leading to bad actions are at the time\nstrong, and when recalled are not over-mastered by the persistent social\ninstincts, and the judgment of others, then he is essentially a bad man\n(30.  Dr. Prosper Despine, in his Psychologie Naturelle, 1868 (tom. i. p.\n243; tom. ii. p. 169) gives many curious cases of the worst criminals, who\napparently have been entirely destitute of conscience.); and the sole\nrestraining motive left is the fear of punishment, and the conviction that\nin the long run it would be best for his own selfish interests to regard\nthe good of others rather than his own.\n\nIt is obvious that every one may with an easy conscience gratify his own\ndesires, if they do not interfere with his social instincts, that is with\nthe good of others; but in order to be quite free from self-reproach, or at\nleast of anxiety, it is almost necessary for him to avoid the\ndisapprobation, whether reasonable or not, of his fellow-men.  Nor must he\nbreak through the fixed habits of his life, especially if these are\nsupported by reason; for if he does, he will assuredly feel\ndissatisfaction.  He must likewise avoid the reprobation of the one God or\ngods in whom, according to his knowledge or superstition, he may believe;\nbut in this case the additional fear of divine punishment often supervenes.\n\nTHE STRICTLY SOCIAL VIRTUES AT FIRST ALONE REGARDED.\n\nThe above view of the origin and nature of the moral sense, which tells us\nwhat we ought to do, and of the conscience which reproves us if we disobey\nit, accords well with what we see of the early and undeveloped condition of\nthis faculty in mankind.  The virtues which must be practised, at least\ngenerally, by rude men, so that they may associate in a body, are those\nwhich are still recognised as the most important.  But they are practised\nalmost exclusively in relation to the men of the same tribe; and their\nopposites are not regarded as crimes in relation to the men of other\ntribes.  No tribe could hold together if murder, robbery, treachery, etc.,\nwere common; consequently such crimes within the limits of the same tribe\n\"are branded with everlasting infamy\" (31.  See an able article in the\n'North British Review,' 1867, p. 395.  See also Mr. W. Bagehot's articles\non the Importance of Obedience and Coherence to Primitive Man, in the\n'Fortnightly Review,' 1867, p. 529, and 1868, p. 457, etc.); but excite no\nsuch sentiment beyond these limits.  A North-American Indian is well\npleased with himself, and is honoured by others, when he scalps a man of\nanother tribe; and a Dyak cuts off the head of an unoffending person, and\ndries it as a trophy.  The murder of infants has prevailed on the largest\nscale throughout the world (32.  The fullest account which I have met with\nis by Dr. Gerland, in his 'Ueber den Aussterben der Naturvoelker,' 1868; but\nI shall have to recur to the subject of infanticide in a future chapter.),\nand has met with no reproach; but infanticide, especially of females, has\nbeen thought to be good for the tribe, or at least not injurious.  Suicide\nduring former times was not generally considered as a crime (33.  See the\nvery interesting discussion on suicide in Lecky's 'History of European\nMorals,' vol. i. 1869, p. 223.  With respect to savages, Mr. Winwood Reade\ninforms me that the negroes of West Africa often commit suicide.  It is\nwell known how common it was amongst the miserable aborigines of South\nAmerica after the Spanish conquest.  For New Zealand, see the voyage of the\nNovara, and for the Aleutian Islands, Mueller, as quoted by Houzeau, 'Les\nFacultes Mentales,' etc., tom. ii. p. 136.), but rather, from the courage\ndisplayed, as an honourable act; and it is still practised by some semi-\ncivilised and savage nations without reproach, for it does not obviously\nconcern others of the tribe.  It has been recorded that an Indian Thug\nconscientiously regretted that he had not robbed and strangled as many\ntravellers as did his father before him.  In a rude state of civilisation\nthe robbery of strangers is, indeed, generally considered as honourable.\n\n\nSlavery, although in some ways beneficial during ancient times (34.  See\nMr. Bagehot, 'Physics and Politics,' 1872, p. 72.), is a great crime; yet\nit was not so regarded until quite recently, even by the most civilised\nnations.  And this was especially the case, because the slaves belonged in\ngeneral to a race different from that of their masters.  As barbarians do\nnot regard the opinion of their women, wives are commonly treated like\nslaves.  Most savages are utterly indifferent to the sufferings of\nstrangers, or even delight in witnessing them.  It is well known that the\nwomen and children of the North-American Indians aided in torturing their\nenemies.  Some savages take a horrid pleasure in cruelty to animals (35.\nSee, for instance, Mr. Hamilton's account of the Kaffirs, 'Anthropological\nReview,' 1870, p. xv.), and humanity is an unknown virtue.  Nevertheless,\nbesides the family affections, kindness is common, especially during\nsickness, between the members of the same tribe, and is sometimes extended\nbeyond these limits.  Mungo Park's touching account of the kindness of the\nnegro women of the interior to him is well known.  Many instances could be\ngiven of the noble fidelity of savages towards each other, but not to\nstrangers; common experience justifies the maxim of the Spaniard, \"Never,\nnever trust an Indian.\"  There cannot be fidelity without truth; and this\nfundamental virtue is not rare between the members of the same tribe:  thus\nMungo Park heard the negro women teaching their young children to love the\ntruth.  This, again, is one of the virtues which becomes so deeply rooted\nin the mind, that it is sometimes practised by savages, even at a high\ncost, towards strangers; but to lie to your enemy has rarely been thought a\nsin, as the history of modern diplomacy too plainly shews.  As soon as a\ntribe has a recognised leader, disobedience becomes a crime, and even\nabject submission is looked at as a sacred virtue.\n\nAs during rude times no man can be useful or faithful to his tribe without\ncourage, this quality has universally been placed in the highest rank; and\nalthough in civilised countries a good yet timid man may be far more useful\nto the community than a brave one, we cannot help instinctively honouring\nthe latter above a coward, however benevolent.  Prudence, on the other\nhand, which does not concern the welfare of others, though a very useful\nvirtue, has never been highly esteemed.  As no man can practise the virtues\nnecessary for the welfare of his tribe without self-sacrifice, self-\ncommand, and the power of endurance, these qualities have been at all times\nhighly and most justly valued.  The American savage voluntarily submits to\nthe most horrid tortures without a groan, to prove and strengthen his\nfortitude and courage; and we cannot help admiring him, or even an Indian\nFakir, who, from a foolish religious motive, swings suspended by a hook\nburied in his flesh.\n\nThe other so-called self-regarding virtues, which do not obviously, though\nthey may really, affect the welfare of the tribe, have never been esteemed\nby savages, though now highly appreciated by civilised nations.  The\ngreatest intemperance is no reproach with savages.  Utter licentiousness,\nand unnatural crimes, prevail to an astounding extent.  (36.  Mr. M'Lennan\nhas given ('Primitive Marriage,' 1865, p. 176) a good collection of facts\non this head.)  As soon, however, as marriage, whether polygamous, or\nmonogamous, becomes common, jealousy will lead to the inculcation of female\nvirtue; and this, being honoured, will tend to spread to the unmarried\nfemales.  How slowly it spreads to the male sex, we see at the present day.\nChastity eminently requires self-command; therefore it has been honoured\nfrom a very early period in the moral history of civilised man.  As a\nconsequence of this, the senseless practice of celibacy has been ranked\nfrom a remote period as a virtue. (38.  Lecky, 'History of European\nMorals,' vol. i. 1869, p. 109.)  The hatred of indecency, which appears to\nus so natural as to be thought innate, and which is so valuable an aid to\nchastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton\nremarks (38.  'Embassy to China,' vol. ii. p. 348.), to civilised life.\nThis is shewn by the ancient religious rites of various nations, by the\ndrawings on the walls of Pompeii, and by the practices of many savages.\n\nWe have now seen that actions are regarded by savages, and were probably so\nregarded by primeval man, as good or bad, solely as they obviously affect\nthe welfare of the tribe,--not that of the species, nor that of an\nindividual member of the tribe.  This conclusion agrees well with the\nbelief that the so-called moral sense is aboriginally derived from the\nsocial instincts, for both relate at first exclusively to the community.\n\nThe chief causes of the low morality of savages, as judged by our standard,\nare, firstly, the confinement of sympathy to the same tribe.  Secondly,\npowers of reasoning insufficient to recognise the bearing of many virtues,\nespecially of the self-regarding virtues, on the general welfare of the\ntribe.  Savages, for instance, fail to trace the multiplied evils\nconsequent on a want of temperance, chastity, etc.  And, thirdly, weak\npower of self-command; for this power has not been strengthened through\nlong-continued, perhaps inherited, habit, instruction and religion.\n\nI have entered into the above details on the immorality of savages (39.\nSee on this subject copious evidence in Chap. vii. of Sir J. Lubbock,\n'Origin of Civilisation,' 1870.), because some authors have recently taken\na high view of their moral nature, or have attributed most of their crimes\nto mistaken benevolence. (40.  For instance Lecky, 'History of European\nMorals,' vol. i. p. 124.)  These authors appear to rest their conclusion on\nsavages possessing those virtues which are serviceable, or even necessary,\nfor the existence of the family and of the tribe,--qualities which they\nundoubtedly do possess, and often in a high degree.\n\nCONCLUDING REMARKS.\n\nIt was assumed formerly by philosophers of the derivative (41.  This term\nis used in an able article in the 'Westminster Review,' Oct. 1869, p. 498.\nFor the \"Greatest happiness principle,\" see J.S. Mill, 'Utilitarianism,' p.\n17.) school of morals that the foundation of morality lay in a form of\nSelfishness; but more recently the \"Greatest happiness principle\" has been\nbrought prominently forward.  It is, however, more correct to speak of the\nlatter principle as the standard, and not as the motive of conduct.\nNevertheless, all the authors whose works I have consulted, with a few\nexceptions (42.  Mill recognises ('System of Logic,' vol. ii. p. 422) in\nthe clearest manner, that actions may be performed through habit without\nthe anticipation of pleasure.  Mr. H. Sidgwick also, in his Essay on\nPleasure and Desire ('The Contemporary Review,' April 1872, p. 671),\nremarks:  \"To sum up, in contravention of the doctrine that our conscious\nactive impulses are always directed towards the production of agreeable\nsensations in ourselves, I would maintain that we find everywhere in\nconsciousness extra-regarding impulse, directed towards something that is\nnot pleasure; that in many cases the impulse is so far incompatible with\nthe self-regarding that the two do not easily co-exist in the same moment\nof consciousness.\"  A dim feeling that our impulses do not by any means\nalways arise from any contemporaneous or anticipated pleasure, has, I\ncannot but think, been one chief cause of the acceptance of the intuitive\ntheory of morality, and of the rejection of the utilitarian or \"Greatest\nhappiness\" theory.  With respect to the latter theory the standard and the\nmotive of conduct have no doubt often been confused, but they are really in\nsome degree blended.), write as if there must be a distinct motive for\nevery action, and that this must be associated with some pleasure or\ndispleasure.  But man seems often to act impulsively, that is from instinct\nor long habit, without any consciousness of pleasure, in the same manner as\ndoes probably a bee or ant, when it blindly follows its instincts.  Under\ncircumstances of extreme peril, as during a fire, when a man endeavours to\nsave a fellow-creature without a moment's hesitation, he can hardly feel\npleasure; and still less has he time to reflect on the dissatisfaction\nwhich he might subsequently experience if he did not make the attempt.\nShould he afterwards reflect over his own conduct, he would feel that there\nlies within him an impulsive power widely different from a search after\npleasure or happiness; and this seems to be the deeply planted social\ninstinct.\n\nIn the case of the lower animals it seems much more appropriate to speak of\ntheir social instincts, as having been developed for the general good\nrather than for the general happiness of the species.  The term, general\ngood, may be defined as the rearing of the greatest number of individuals\nin full vigour and health, with all their faculties perfect, under the\nconditions to which they are subjected.  As the social instincts both of\nman and the lower animals have no doubt been developed by nearly the same\nsteps, it would be advisable, if found practicable, to use the same\ndefinition in both cases, and to take as the standard of morality, the\ngeneral good or welfare of the community, rather than the general\nhappiness; but this definition would perhaps require some limitation on\naccount of political ethics.\n\nWhen a man risks his life to save that of a fellow-creature, it seems also\nmore correct to say that he acts for the general good, rather than for the\ngeneral happiness of mankind.  No doubt the welfare and the happiness of\nthe individual usually coincide; and a contented, happy tribe will flourish\nbetter than one that is discontented and unhappy.  We have seen that even\nat an early period in the history of man, the expressed wishes of the\ncommunity will have naturally influenced to a large extent the conduct of\neach member; and as all wish for happiness, the \"greatest happiness\nprinciple\" will have become a most important secondary guide and object;\nthe social instinct, however, together with sympathy (which leads to our\nregarding the approbation and disapprobation of others), having served as\nthe primary impulse and guide.  Thus the reproach is removed of laying the\nfoundation of the noblest part of our nature in the base principle of\nselfishness; unless, indeed, the satisfaction which every animal feels,\nwhen it follows its proper instincts, and the dissatisfaction felt when\nprevented, be called selfish.\n\nThe wishes and opinions of the members of the same community, expressed at\nfirst orally, but later by writing also, either form the sole guides of our\nconduct, or greatly reinforce the social instincts; such opinions, however,\nhave sometimes a tendency directly opposed to these instincts.  This latter\nfact is well exemplified by the LAW OF HONOUR, that is, the law of the\nopinion of our equals, and not of all our countrymen.  The breach of this\nlaw, even when the breach is known to be strictly accordant with true\nmorality, has caused many a man more agony than a real crime.  We recognise\nthe same influence in the burning sense of shame which most of us have\nfelt, even after the interval of years, when calling to mind some\naccidental breach of a trifling, though fixed, rule of etiquette.  The\njudgment of the community will generally be guided by some rude experience\nof what is best in the long run for all the members; but this judgment will\nnot rarely err from ignorance and weak powers of reasoning.  Hence the\nstrangest customs and superstitions, in complete opposition to the true\nwelfare and happiness of mankind, have become all-powerful throughout the\nworld.  We see this in the horror felt by a Hindoo who breaks his caste,\nand in many other such cases.  It would be difficult to distinguish between\nthe remorse felt by a Hindoo who has yielded to the temptation of eating\nunclean food, from that felt after committing a theft; but the former would\nprobably be the more severe.\n\nHow so many absurd rules of conduct, as well as so many absurd religious\nbeliefs, have originated, we do not know; nor how it is that they have\nbecome, in all quarters of the world, so deeply impressed on the mind of\nmen; but it is worthy of remark that a belief constantly inculcated during\nthe early years of life, whilst the brain is impressible, appears to\nacquire almost the nature of an instinct; and the very essence of an\ninstinct is that it is followed independently of reason.  Neither can we\nsay why certain admirable virtues, such as the love of truth, are much more\nhighly appreciated by some savage tribes than by others (43.  Good\ninstances are given by Mr. Wallace in 'Scientific Opinion,' Sept. 15, 1869;\nand more fully in his 'Contributions to the Theory of Natural Selection,'\n1870, p. 353.); nor, again, why similar differences prevail even amongst\nhighly civilised nations.  Knowing how firmly fixed many strange customs\nand superstitions have become, we need feel no surprise that the self-\nregarding virtues, supported as they are by reason, should now appear to us\nso natural as to be thought innate, although they were not valued by man in\nhis early condition.\n\nNot withstanding many sources of doubt, man can generally and readily\ndistinguish between the higher and lower moral rules.  The higher are\nfounded on the social instincts, and relate to the welfare of others.  They\nare supported by the approbation of our fellow-men and by reason.  The\nlower rules, though some of them when implying self-sacrifice hardly\ndeserve to be called lower, relate chiefly to self, and arise from public\nopinion, matured by experience and cultivation; for they are not practised\nby rude tribes.\n\nAs man advances in civilisation, and small tribes are united into larger\ncommunities, the simplest reason would tell each individual that he ought\nto extend his social instincts and sympathies to all the members of the\nsame nation, though personally unknown to him.  This point being once\nreached, there is only an artificial barrier to prevent his sympathies\nextending to the men of all nations and races.  If, indeed, such men are\nseparated from him by great differences in appearance or habits, experience\nunfortunately shews us how long it is, before we look at them as our\nfellow-creatures.  Sympathy beyond the confines of man, that is, humanity\nto the lower animals, seems to be one of the latest moral acquisitions.  It\nis apparently unfelt by savages, except towards their pets.  How little the\nold Romans knew of it is shewn by their abhorrent gladiatorial exhibitions.\nThe very idea of humanity, as far as I could observe, was new to most of\nthe Gauchos of the Pampas.  This virtue, one of the noblest with which man\nis endowed, seems to arise incidentally from our sympathies becoming more\ntender and more widely diffused, until they are extended to all sentient\nbeings.  As soon as this virtue is honoured and practised by some few men,\nit spreads through instruction and example to the young, and eventually\nbecomes incorporated in public opinion.\n\nThe highest possible stage in moral culture is when we recognise that we\nought to control our thoughts, and \"not even in inmost thought to think\nagain the sins that made the past so pleasant to us.\"  (44.  Tennyson,\nIdylls of the King, p. 244.)  Whatever makes any bad action familiar to the\nmind, renders its performance by so much the easier.  As Marcus Aurelius\nlong ago said, \"Such as are thy habitual thoughts, such also will be the\ncharacter of thy mind; for the soul is dyed by the thoughts.\"  (45.  'The\nThoughts of the Emperor M. Aurelius Antoninus,'  English translation, 2nd\nedit., 1869. p. 112.  Marcus Aurelius was born A.D. 121.)\n\nOur great philosopher, Herbert Spencer, has recently explained his views on\nthe moral sense.  He says (46.  Letter to Mr. Mill in Bain's 'Mental and\nMoral Science,' 1868, p. 722.), \"I believe that the experiences of utility\norganised and consolidated through all past generations of the human race,\nhave been producing corresponding modifications, which, by continued\ntransmission and accumulation, have become in us certain faculties of moral\nintuition--certain emotions responding to right and wrong conduct, which\nhave no apparent basis in the individual experiences of utility.\"  There is\nnot the least inherent improbability, as it seems to me, in virtuous\ntendencies being more or less strongly inherited; for, not to mention the\nvarious dispositions and habits transmitted by many of our domestic animals\nto their offspring, I have heard of authentic cases in which a desire to\nsteal and a tendency to lie appeared to run in families of the upper ranks;\nand as stealing is a rare crime in the wealthy classes, we can hardly\naccount by accidental coincidence for the tendency occurring in two or\nthree members of the same family.  If bad tendencies are transmitted, it is\nprobable that good ones are likewise transmitted.  That the state of the\nbody by affecting the brain, has great influence on the moral tendencies is\nknown to most of those who have suffered from chronic derangements of the\ndigestion or liver.  The same fact is likewise shewn by the \"perversion or\ndestruction of the moral sense being often one of the earliest symptoms of\nmental derangement\" (47.  Maudsley, 'Body and Mind,' 1870, p. 60.); and\ninsanity is notoriously often inherited.  Except through the principle of\nthe transmission of moral tendencies, we cannot understand the differences\nbelieved to exist in this respect between the various races of mankind.\n\nEven the partial transmission of virtuous tendencies would be an immense\nassistance to the primary impulse derived directly and indirectly from the\nsocial instincts.  Admitting for a moment that virtuous tendencies are\ninherited, it appears probable, at least in such cases as chastity,\ntemperance, humanity to animals, etc., that they become first impressed on\nthe mental organization through habit, instruction and example, continued\nduring several generations in the same family, and in a quite subordinate\ndegree, or not at all, by the individuals possessing such virtues having\nsucceeded best in the struggle for life.  My chief source of doubt with\nrespect to any such inheritance, is that senseless customs, superstitions,\nand tastes, such as the horror of a Hindoo for unclean food, ought on the\nsame principle to be transmitted.  I have not met with any evidence in\nsupport of the transmission of superstitious customs or senseless habits,\nalthough in itself it is perhaps not less probable than that animals should\nacquire inherited tastes for certain kinds of food or fear of certain foes.\n\nFinally the social instincts, which no doubt were acquired by man as by the\nlower animals for the good of the community, will from the first have given\nto him some wish to aid his fellows, some feeling of sympathy, and have\ncompelled him to regard their approbation and disapprobation.  Such\nimpulses will have served him at a very early period as a rude rule of\nright and wrong.  But as man gradually advanced in intellectual power, and\nwas enabled to trace the more remote consequences of his actions; as he\nacquired sufficient knowledge to reject baneful customs and superstitions;\nas he regarded more and more, not only the welfare, but the happiness of\nhis fellow-men; as from habit, following on beneficial experience,\ninstruction and example, his sympathies became more tender and widely\ndiffused, extending to men of all races, to the imbecile, maimed, and other\nuseless members of society, and finally to the lower animals,--so would the\nstandard of his morality rise higher and higher.  And it is admitted by\nmoralists of the derivative school and by some intuitionists, that the\nstandard of morality has risen since an early period in the history of man.\n(48.  A writer in the 'North British Review' (July 1869, p. 531), well\ncapable of forming a sound judgment, expresses himself strongly in favour\nof this conclusion.  Mr. Lecky ('History of Morals,' vol. i. p. 143) seems\nto a certain extent to coincide therein.)\n\nAs a struggle may sometimes be seen going on between the various instincts\nof the lower animals, it is not surprising that there should be a struggle\nin man between his social instincts, with their derived virtues, and his\nlower, though momentarily stronger impulses or desires.  This, as Mr.\nGalton (49.  See his remarkable work on 'Hereditary Genius,' 1869, p. 349.\nThe Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good remarks on\nthe contest in man's nature between right and wrong.) has remarked, is all\nthe less surprising, as man has emerged from a state of barbarism within a\ncomparatively recent period.  After having yielded to some temptation we\nfeel a sense of dissatisfaction, shame, repentance, or remorse, analogous\nto the feelings caused by other powerful instincts or desires, when left\nunsatisfied or baulked.  We compare the weakened impression of a past\ntemptation with the ever present social instincts, or with habits, gained\nin early youth and strengthened during our whole lives, until they have\nbecome almost as strong as instincts.  If with the temptation still before\nus we do not yield, it is because either the social instinct or some custom\nis at the moment predominant, or because we have learnt that it will appear\nto us hereafter the stronger, when compared with the weakened impression of\nthe temptation, and we realise that its violation would cause us suffering.\nLooking to future generations, there is no cause to fear that the social\ninstincts will grow weaker, and we may expect that virtuous habits will\ngrow stronger, becoming perhaps fixed by inheritance.  In this case the\nstruggle between our higher and lower impulses will be less severe, and\nvirtue will be triumphant.\n\nSUMMARY OF THE LAST TWO CHAPTERS.\n\nThere can be no doubt that the difference between the mind of the lowest\nman and that of the highest animal is immense.  An anthropomorphous ape, if\nhe could take a dispassionate view of his own case, would admit that though\nhe could form an artful plan to plunder a garden--though he could use\nstones for fighting or for breaking open nuts, yet that the thought of\nfashioning a stone into a tool was quite beyond his scope.  Still less, as\nhe would admit, could he follow out a train of metaphysical reasoning, or\nsolve a mathematical problem, or reflect on God, or admire a grand natural\nscene.  Some apes, however, would probably declare that they could and did\nadmire the beauty of the coloured skin and fur of their partners in\nmarriage.  They would admit, that though they could make other apes\nunderstand by cries some of their perceptions and simpler wants, the notion\nof expressing definite ideas by definite sounds had never crossed their\nminds.  They might insist that they were ready to aid their fellow-apes of\nthe same troop in many ways, to risk their lives for them, and to take\ncharge of their orphans; but they would be forced to acknowledge that\ndisinterested love for all living creatures, the most noble attribute of\nman, was quite beyond their comprehension.\n\nNevertheless the difference in mind between man and the higher animals,\ngreat as it is, certainly is one of degree and not of kind.  We have seen\nthat the senses and intuitions, the various emotions and faculties, such as\nlove, memory, attention, curiosity, imitation, reason, etc., of which man\nboasts, may be found in an incipient, or even sometimes in a well-developed\ncondition, in the lower animals.  They are also capable of some inherited\nimprovement, as we see in the domestic dog compared with the wolf or\njackal.  If it could be proved that certain high mental powers, such as the\nformation of general concepts, self-consciousness, etc., were absolutely\npeculiar to man, which seems extremely doubtful, it is not improbable that\nthese qualities are merely the incidental results of other highly-advanced\nintellectual faculties; and these again mainly the result of the continued\nuse of a perfect language.  At what age does the new-born infant possess\nthe power of abstraction, or become self-conscious, and reflect on its own\nexistence?  We cannot answer; nor can we answer in regard to the ascending\norganic scale.  The half-art, half-instinct of language still bears the\nstamp of its gradual evolution.  The ennobling belief in God is not\nuniversal with man; and the belief in spiritual agencies naturally follows\nfrom other mental powers.  The moral sense perhaps affords the best and\nhighest distinction between man and the lower animals; but I need say\nnothing on this head, as I have so lately endeavoured to shew that the\nsocial instincts,--the prime principle of man's moral constitution (50.\n'The Thoughts of Marcus Aurelius,' etc., p. 139.)--with the aid of active\nintellectual powers and the effects of habit, naturally lead to the golden\nrule, \"As ye would that men should do to you, do ye to them likewise;\" and\nthis lies at the foundation of morality.\n\nIn the next chapter I shall make some few remarks on the probable steps and\nmeans by which the several mental and moral faculties of man have been\ngradually evolved.  That such evolution is at least possible, ought not to\nbe denied, for we daily see these faculties developing in every infant; and\nwe may trace a perfect gradation from the mind of an utter idiot, lower\nthan that of an animal low in the scale, to the mind of a Newton.\n\n\nCHAPTER V.\n\nON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL\nAND CIVILISED TIMES.\n\nAdvancement of the intellectual powers through natural selection--\nImportance of imitation--Social and moral faculties--Their development\nwithin the limits of the same tribe--Natural selection as affecting\ncivilised nations--Evidence that civilised nations were once barbarous.\n\nThe subjects to be discussed in this chapter are of the highest interest,\nbut are treated by me in an imperfect and fragmentary manner.  Mr. Wallace,\nin an admirable paper before referred to (1.  Anthropological Review, May\n1864, p. clviii.), argues that man, after he had partially acquired those\nintellectual and moral faculties which distinguish him from the lower\nanimals, would have been but little liable to bodily modifications through\nnatural selection or any other means.  For man is enabled through his\nmental faculties \"to keep with an unchanged body in harmony with the\nchanging universe.\"  He has great power of adapting his habits to new\nconditions of life.  He invents weapons, tools, and various stratagems to\nprocure food and to defend himself.  When he migrates into a colder climate\nhe uses clothes, builds sheds, and makes fires; and by the aid of fire\ncooks food otherwise indigestible.  He aids his fellow-men in many ways,\nand anticipates future events.  Even at a remote period he practised some\ndivision of labour.\n\nThe lower animals, on the other hand, must have their bodily structure\nmodified in order to survive under greatly changed conditions.  They must\nbe rendered stronger, or acquire more effective teeth or claws, for defence\nagainst new enemies; or they must be reduced in size, so as to escape\ndetection and danger.  When they migrate into a colder climate, they must\nbecome clothed with thicker fur, or have their constitutions altered.  If\nthey fail to be thus modified, they will cease to exist.\n\nThe case, however, is widely different, as Mr. Wallace has with justice\ninsisted, in relation to the intellectual and moral faculties of man.\nThese faculties are variable; and we have every reason to believe that the\nvariations tend to be inherited.  Therefore, if they were formerly of high\nimportance to primeval man and to his ape-like progenitors, they would have\nbeen perfected or advanced through natural selection.  Of the high\nimportance of the intellectual faculties there can be no doubt, for man\nmainly owes to them his predominant position in the world.  We can see,\nthat in the rudest state of society, the individuals who were the most\nsagacious, who invented and used the best weapons or traps, and who were\nbest able to defend themselves, would rear the greatest number of\noffspring.  The tribes, which included the largest number of men thus\nendowed, would increase in number and supplant other tribes.  Numbers\ndepend primarily on the means of subsistence, and this depends partly on\nthe physical nature of the country, but in a much higher degree on the arts\nwhich are there practised.  As a tribe increases and is victorious, it is\noften still further increased by the absorption of other tribes.  (2.\nAfter a time the members or tribes which are absorbed into another tribe\nassume, as Sir Henry Maine remarks ('Ancient Law,' 1861, p. 131), that they\nare the co-descendants of the same ancestors.)  The stature and strength of\nthe men of a tribe are likewise of some importance for its success, and\nthese depend in part on the nature and amount of the food which can be\nobtained.  In Europe the men of the Bronze period were supplanted by a race\nmore powerful, and, judging from their sword-handles, with larger hands (3.\nMorlot, 'Soc. Vaud. Sc. Nat.' 1860, p. 294.); but their success was\nprobably still more due to their superiority in the arts.\n\nAll that we know about savages, or may infer from their traditions and from\nold monuments, the history of which is quite forgotten by the present\ninhabitants, shew that from the remotest times successful tribes have\nsupplanted other tribes.  Relics of extinct or forgotten tribes have been\ndiscovered throughout the civilised regions of the earth, on the wild\nplains of America, and on the isolated islands in the Pacific Ocean.  At\nthe present day civilised nations are everywhere supplanting barbarous\nnations, excepting where the climate opposes a deadly barrier; and they\nsucceed mainly, though not exclusively, through their arts, which are the\nproducts of the intellect.  It is, therefore, highly probable that with\nmankind the intellectual faculties have been mainly and gradually perfected\nthrough natural selection; and this conclusion is sufficient for our\npurpose.  Undoubtedly it would be interesting to trace the development of\neach separate faculty from the state in which it exists in the lower\nanimals to that in which it exists in man; but neither my ability nor\nknowledge permits the attempt.\n\nIt deserves notice that, as soon as the progenitors of man became social\n(and this probably occurred at a very early period), the principle of\nimitation, and reason, and experience would have increased, and much\nmodified the intellectual powers in a way, of which we see only traces in\nthe lower animals.  Apes are much given to imitation, as are the lowest\nsavages; and the simple fact previously referred to, that after a time no\nanimal can be caught in the same place by the same sort of trap, shews that\nanimals learn by experience, and imitate the caution of others.  Now, if\nsome one man in a tribe, more sagacious than the others, invented a new\nsnare or weapon, or other means of attack or defence, the plainest self-\ninterest, without the assistance of much reasoning power, would prompt the\nother members to imitate him; and all would thus profit.  The habitual\npractice of each new art must likewise in some slight degree strengthen the\nintellect.  If the new invention were an important one, the tribe would\nincrease in number, spread, and supplant other tribes.  In a tribe thus\nrendered more numerous there would always be a rather greater chance of the\nbirth of other superior and inventive members.  If such men left children\nto inherit their mental superiority, the chance of the birth of still more\ningenious members would be somewhat better, and in a very small tribe\ndecidedly better.  Even if they left no children, the tribe would still\ninclude their blood-relations; and it has been ascertained by\nagriculturists (4.  I have given instances in my Variation of Animals under\nDomestication, vol. ii. p. 196.) that by preserving and breeding from the\nfamily of an animal, which when slaughtered was found to be valuable, the\ndesired character has been obtained.\n\nTurning now to the social and moral faculties.  In order that primeval men,\nor the ape-like progenitors of man, should become social, they must have\nacquired the same instinctive feelings, which impel other animals to live\nin a body; and they no doubt exhibited the same general disposition.  They\nwould have felt uneasy when separated from their comrades, for whom they\nwould have felt some degree of love; they would have warned each other of\ndanger, and have given mutual aid in attack or defence.  All this implies\nsome degree of sympathy, fidelity, and courage.  Such social qualities, the\nparamount importance of which to the lower animals is disputed by no one,\nwere no doubt acquired by the progenitors of man in a similar manner,\nnamely, through natural selection, aided by inherited habit.  When two\ntribes of primeval man, living in the same country, came into competition,\nif (other circumstances being equal) the one tribe included a great number\nof courageous, sympathetic and faithful members, who were always ready to\nwarn each other of danger, to aid and defend each other, this tribe would\nsucceed better and conquer the other.  Let it be borne in mind how all-\nimportant in the never-ceasing wars of savages, fidelity and courage must\nbe.  The advantage which disciplined soldiers have over undisciplined\nhordes follows chiefly from the confidence which each man feels in his\ncomrades.  Obedience, as Mr. Bagehot has well shewn (5.  See a remarkable\nseries of articles on 'Physics and Politics,' in the 'Fortnightly Review,'\nNov. 1867; April 1, 1868; July 1, 1869, since separately published.), is of\nthe highest value, for any form of government is better than none.  Selfish\nand contentious people will not cohere, and without coherence nothing can\nbe effected.  A tribe rich in the above qualities would spread and be\nvictorious over other tribes:  but in the course of time it would, judging\nfrom all past history, be in its turn overcome by some other tribe still\nmore highly endowed.  Thus the social and moral qualities would tend slowly\nto advance and be diffused throughout the world.\n\nBut it may be asked, how within the limits of the same tribe did a large\nnumber of members first become endowed with these social and moral\nqualities, and how was the standard of excellence raised?  It is extremely\ndoubtful whether the offspring of the more sympathetic and benevolent\nparents, or of those who were the most faithful to their comrades, would be\nreared in greater numbers than the children of selfish and treacherous\nparents belonging to the same tribe.  He who was ready to sacrifice his\nlife, as many a savage has been, rather than betray his comrades, would\noften leave no offspring to inherit his noble nature.  The bravest men, who\nwere always willing to come to the front in war, and who freely risked\ntheir lives for others, would on an average perish in larger numbers than\nother men.  Therefore, it hardly seems probable, that the number of men\ngifted with such virtues, or that the standard of their excellence, could\nbe increased through natural selection, that is, by the survival of the\nfittest; for we are not here speaking of one tribe being victorious over\nanother.\n\nAlthough the circumstances, leading to an increase in the number of those\nthus endowed within the same tribe, are too complex to be clearly followed\nout, we can trace some of the probable steps.  In the first place, as the\nreasoning powers and foresight of the members became improved, each man\nwould soon learn that if he aided his fellow-men, he would commonly receive\naid in return.  From this low motive he might acquire the habit of aiding\nhis fellows; and the habit of performing benevolent actions certainly\nstrengthens the feeling of sympathy which gives the first impulse to\nbenevolent actions.  Habits, moreover, followed during many generations\nprobably tend to be inherited.\n\nBut another and much more powerful stimulus to the development of the\nsocial virtues, is afforded by the praise and the blame of our fellow-men.\nTo the instinct of sympathy, as we have already seen, it is primarily due,\nthat we habitually bestow both praise and blame on others, whilst we love\nthe former and dread the latter when applied to ourselves; and this\ninstinct no doubt was originally acquired, like all the other social\ninstincts, through natural selection.  At how early a period the\nprogenitors of man in the course of their development, became capable of\nfeeling and being impelled by, the praise or blame of their fellow-\ncreatures, we cannot of course say.  But it appears that even dogs\nappreciate encouragement, praise, and blame.  The rudest savages feel the\nsentiment of glory, as they clearly shew by preserving the trophies of\ntheir prowess, by their habit of excessive boasting, and even by the\nextreme care which they take of their personal appearance and decorations;\nfor unless they regarded the opinion of their comrades, such habits would\nbe senseless.\n\nThey certainly feel shame at the breach of some of their lesser rules, and\napparently remorse, as shewn by the case of the Australian who grew thin\nand could not rest from having delayed to murder some other woman, so as to\npropitiate his dead wife's spirit.  Though I have not met with any other\nrecorded case, it is scarcely credible that a savage, who will sacrifice\nhis life rather than betray his tribe, or one who will deliver himself up\nas a prisoner rather than break his parole (6.  Mr. Wallace gives cases in\nhis 'Contributions to the Theory of Natural Selection,' 1870, p. 354.),\nwould not feel remorse in his inmost soul, if he had failed in a duty,\nwhich he held sacred.\n\nWe may therefore conclude that primeval man, at a very remote period, was\ninfluenced by the praise and blame of his fellows.  It is obvious, that the\nmembers of the same tribe would approve of conduct which appeared to them\nto be for the general good, and would reprobate that which appeared evil.\nTo do good unto others--to do unto others as ye would they should do unto\nyou--is the foundation-stone of morality.  It is, therefore, hardly\npossible to exaggerate the importance during rude times of the love of\npraise and the dread of blame.  A man who was not impelled by any deep,\ninstinctive feeling, to sacrifice his life for the good of others, yet was\nroused to such actions by a sense of glory, would by his example excite the\nsame wish for glory in other men, and would strengthen by exercise the\nnoble feeling of admiration.  He might thus do far more good to his tribe\nthan by begetting offspring with a tendency to inherit his own high\ncharacter.\n\nWith increased experience and reason, man perceives the more remote\nconsequences of his actions, and the self-regarding virtues, such as\ntemperance, chastity, etc., which during early times are, as we have before\nseen, utterly disregarded, come to be highly esteemed or even held sacred.\nI need not, however, repeat what I have said on this head in the fourth\nchapter.  Ultimately our moral sense or conscience becomes a highly complex\nsentiment--originating in the social instincts, largely guided by the\napprobation of our fellow-men, ruled by reason, self-interest, and in later\ntimes by deep religious feelings, and confirmed by instruction and habit.\n\nIt must not be forgotten that although a high standard of morality gives\nbut a slight or no advantage to each individual man and his children over\nthe other men of the same tribe, yet that an increase in the number of\nwell-endowed men and an advancement in the standard of morality will\ncertainly give an immense advantage to one tribe over another.  A tribe\nincluding many members who, from possessing in a high degree the spirit of\npatriotism, fidelity, obedience, courage, and sympathy, were always ready\nto aid one another, and to sacrifice themselves for the common good, would\nbe victorious over most other tribes; and this would be natural selection.\nAt all times throughout the world tribes have supplanted other tribes; and\nas morality is one important element in their success, the standard of\nmorality and the number of well-endowed men will thus everywhere tend to\nrise and increase.\n\nIt is, however, very difficult to form any judgment why one particular\ntribe and not another has been successful and has risen in the scale of\ncivilisation.  Many savages are in the same condition as when first\ndiscovered several centuries ago.  As Mr. Bagehot has remarked, we are apt\nto look at progress as normal in human society; but history refutes this.\nThe ancients did not even entertain the idea, nor do the Oriental nations\nat the present day.  According to another high authority, Sir Henry Maine\n(7.  'Ancient Law,' 1861, p. 22.  For Mr. Bagehot's remarks, 'Fortnightly\nReview,' April 1, 1868, p. 452.), \"the greatest part of mankind has never\nshewn a particle of desire that its civil institutions should be improved.\"\nProgress seems to depend on many concurrent favourable conditions, far too\ncomplex to be followed out.  But it has often been remarked, that a cool\nclimate, from leading to industry and to the various arts, has been highly\nfavourable thereto.  The Esquimaux, pressed by hard necessity, have\nsucceeded in many ingenious inventions, but their climate has been too\nsevere for continued progress.  Nomadic habits, whether over wide plains,\nor through the dense forests of the tropics, or along the shores of the\nsea, have in every case been highly detrimental.  Whilst observing the\nbarbarous inhabitants of Tierra del Fuego, it struck me that the possession\nof some property, a fixed abode, and the union of many families under a\nchief, were the indispensable requisites for civilisation.  Such habits\nalmost necessitate the cultivation of the ground; and the first steps in\ncultivation would probably result, as I have elsewhere shewn (8.  'The\nVariation of Animals and Plants under Domestication,' vol. i. p. 309.),\nfrom some such accident as the seeds of a fruit-tree falling on a heap of\nrefuse, and producing an unusually fine variety.  The problem, however, of\nthe first advance of savages towards civilisation is at present much too\ndifficult to be solved.\n\nNATURAL SELECTION AS AFFECTING CIVILISED NATIONS.\n\nI have hitherto only considered the advancement of man from a semi-human\ncondition to that of the modern savage.  But some remarks on the action of\nnatural selection on civilised nations may be worth adding.  This subject\nhas been ably discussed by Mr. W.R. Greg (9.  'Fraser's Magazine,' Sept.\n1868, p. 353.  This article seems to have struck many persons, and has\ngiven rise to two remarkable essays and a rejoinder in the 'Spectator,'\nOct. 3rd and 17th, 1868.  It has also been discussed in the 'Quarterly\nJournal of Science,' 1869, p. 152, and by Mr. Lawson Tait in the 'Dublin\nQuarterly Journal of Medical Science,' Feb. 1869, and by Mr. E. Ray\nLankester in his 'Comparative Longevity,' 1870, p. 128.  Similar views\nappeared previously in the 'Australasian,' July 13, 1867.  I have borrowed\nideas from several of these writers.), and previously by Mr. Wallace and\nMr. Galton.  (10.  For Mr. Wallace, see 'Anthropological Review,' as before\ncited.  Mr. Galton in 'Macmillan's Magazine,' Aug. 1865, p. 318; also his\ngreat work, 'Hereditary Genius,' 1870.)  Most of my remarks are taken from\nthese three authors.  With savages, the weak in body or mind are soon\neliminated; and those that survive commonly exhibit a vigorous state of\nhealth.  We civilised men, on the other hand, do our utmost to check the\nprocess of elimination; we build asylums for the imbecile, the maimed, and\nthe sick; we institute poor-laws; and our medical men exert their utmost\nskill to save the life of every one to the last moment.  There is reason to\nbelieve that vaccination has preserved thousands, who from a weak\nconstitution would formerly have succumbed to small-pox.  Thus the weak\nmembers of civilised societies propagate their kind.  No one who has\nattended to the breeding of domestic animals will doubt that this must be\nhighly injurious to the race of man.  It is surprising how soon a want of\ncare, or care wrongly directed, leads to the degeneration of a domestic\nrace; but excepting in the case of man himself, hardly any one is so\nignorant as to allow his worst animals to breed.\n\nThe aid which we feel impelled to give to the helpless is mainly an\nincidental result of the instinct of sympathy, which was originally\nacquired as part of the social instincts, but subsequently rendered, in the\nmanner previously indicated, more tender and more widely diffused.  Nor\ncould we check our sympathy, even at the urging of hard reason, without\ndeterioration in the noblest part of our nature.  The surgeon may harden\nhimself whilst performing an operation, for he knows that he is acting for\nthe good of his patient; but if we were intentionally to neglect the weak\nand helpless, it could only be for a contingent benefit, with an\noverwhelming present evil.  We must therefore bear the undoubtedly bad\neffects of the weak surviving and propagating their kind; but there appears\nto be at least one check in steady action, namely that the weaker and\ninferior members of society do not marry so freely as the sound; and this\ncheck might be indefinitely increased by the weak in body or mind\nrefraining from marriage, though this is more to be hoped for than\nexpected.\n\nIn every country in which a large standing army is kept up, the finest\nyoung men are taken by the conscription or are enlisted.  They are thus\nexposed to early death during war, are often tempted into vice, and are\nprevented from marrying during the prime of life.  On the other hand the\nshorter and feebler men, with poor constitutions, are left at home, and\nconsequently have a much better chance of marrying and propagating their\nkind.  (11. Prof. H. Fick ('Einfluss der Naturwissenschaft auf das Recht,'\nJune 1872) has some good remarks on this head, and on other such points.)\n\nMan accumulates property and bequeaths it to his children, so that the\nchildren of the rich have an advantage over the poor in the race for\nsuccess, independently of bodily or mental superiority.  On the other hand,\nthe children of parents who are short-lived, and are therefore on an\naverage deficient in health and vigour, come into their property sooner\nthan other children, and will be likely to marry earlier, and leave a\nlarger number of offspring to inherit their inferior constitutions.  But\nthe inheritance of property by itself is very far from an evil; for without\nthe accumulation of capital the arts could not progress; and it is chiefly\nthrough their power that the civilised races have extended, and are now\neverywhere extending their range, so as to take the place of the lower\nraces.  Nor does the moderate accumulation of wealth interfere with the\nprocess of selection.  When a poor man becomes moderately rich, his\nchildren enter trades or professions in which there is struggle enough, so\nthat the able in body and mind succeed best.  The presence of a body of\nwell-instructed men, who have not to labour for their daily bread, is\nimportant to a degree which cannot be over-estimated; as all high\nintellectual work is carried on by them, and on such work, material\nprogress of all kinds mainly depends, not to mention other and higher\nadvantages.  No doubt wealth when very great tends to convert men into\nuseless drones, but their number is never large; and some degree of\nelimination here occurs, for we daily see rich men, who happen to be fools\nor profligate, squandering away their wealth.\n\nPrimogeniture with entailed estates is a more direct evil, though it may\nformerly have been a great advantage by the creation of a dominant class,\nand any government is better than none.  Most eldest sons, though they may\nbe weak in body or mind, marry, whilst the younger sons, however superior\nin these respects, do not so generally marry.  Nor can worthless eldest\nsons with entailed estates squander their wealth.  But here, as elsewhere,\nthe relations of civilised life are so complex that some compensatory\nchecks intervene.  The men who are rich through primogeniture are able to\nselect generation after generation the more beautiful and charming women;\nand these must generally be healthy in body and active in mind.  The evil\nconsequences, such as they may be, of the continued preservation of the\nsame line of descent, without any selection, are checked by men of rank\nalways wishing to increase their wealth and power; and this they effect by\nmarrying heiresses.  But the daughters of parents who have produced single\nchildren, are themselves, as Mr. Galton (12. 'Hereditary Genius,' 1870, pp.\n132-140.) has shewn, apt to be sterile; and thus noble families are\ncontinually cut off in the direct line, and their wealth flows into some\nside channel; but unfortunately this channel is not determined by\nsuperiority of any kind.\n\nAlthough civilisation thus checks in many ways the action of natural\nselection, it apparently favours the better development of the body, by\nmeans of good food and the freedom from occasional hardships.  This may be\ninferred from civilised men having been found, wherever compared, to be\nphysically stronger than savages.  (13. Quatrefages, 'Revue des Cours\nScientifiques,' 1867-68, p. 659.)  They appear also to have equal powers of\nendurance, as has been proved in many adventurous expeditions.  Even the\ngreat luxury of the rich can be but little detrimental; for the expectation\nof life of our aristocracy, at all ages and of both sexes, is very little\ninferior to that of healthy English lives in the lower classes.   (14.\nSee the fifth and sixth columns, compiled from good authorities, in the\ntable given in Mr. E.R. Lankester's 'Comparative Longevity,' 1870, p. 115.)\n\nWe will now look to the intellectual faculties.  If in each grade of\nsociety the members were divided into two equal bodies, the one including\nthe intellectually superior and the other the inferior, there can be little\ndoubt that the former would succeed best in all occupations, and rear a\ngreater number of children.  Even in the lowest walks of life, skill and\nability must be of some advantage; though in many occupations, owing to the\ngreat division of labour, a very small one.  Hence in civilised nations\nthere will be some tendency to an increase both in the number and in the\nstandard of the intellectually able.  But I do not wish to assert that this\ntendency may not be more than counterbalanced in other ways, as by the\nmultiplication of the reckless and improvident; but even to such as these,\nability must be some advantage.\n\nIt has often been objected to views like the foregoing, that the most\neminent men who have ever lived have left no offspring to inherit their\ngreat intellect.  Mr. Galton says, \"I regret I am unable to solve the\nsimple question whether, and how far, men and women who are prodigies of\ngenius are infertile.  I have, however, shewn that men of eminence are by\nno means so.\"  (15.  'Hereditary Genius,' 1870, p. 330.)  Great lawgivers,\nthe founders of beneficent religions, great philosophers and discoverers in\nscience, aid the progress of mankind in a far higher degree by their works\nthan by leaving a numerous progeny.  In the case of corporeal structures,\nit is the selection of the slightly better-endowed and the elimination of\nthe slightly less well-endowed individuals, and not the preservation of\nstrongly-marked and rare anomalies, that leads to the advancement of a\nspecies.  (16.  'Origin of Species' (fifth edition, 1869), p. 104.)  So it\nwill be with the intellectual faculties, since the somewhat abler men in\neach grade of society succeed rather better than the less able, and\nconsequently increase in number, if not otherwise prevented.  When in any\nnation the standard of intellect and the number of intellectual men have\nincreased, we may expect from the law of the deviation from an average,\nthat prodigies of genius will, as shewn by Mr. Galton, appear somewhat more\nfrequently than before.\n\nIn regard to the moral qualities, some elimination of the worst\ndispositions is always in progress even in the most civilised nations.\nMalefactors are executed, or imprisoned for long periods, so that they\ncannot freely transmit their bad qualities.  Melancholic and insane persons\nare confined, or commit suicide.  Violent and quarrelsome men often come to\na bloody end.  The restless who will not follow any steady occupation--and\nthis relic of barbarism is a great check to civilisation (17.  'Hereditary\nGenius,' 1870, p. 347.)--emigrate to newly-settled countries; where they\nprove useful pioneers.  Intemperance is so highly destructive, that the\nexpectation of life of the intemperate, at the age of thirty for instance,\nis only 13.8 years; whilst for the rural labourers of England at the same\nage it is 40.59 years.  (18.  E. Ray Lankester, 'Comparative Longevity,'\n1870, p. 115.  The table of the intemperate is from Neison's 'Vital\nStatistics.'  In regard to profligacy, see Dr. Farr, 'Influence of Marriage\non Mortality,' 'Nat. Assoc. for the Promotion of Social Science,' 1858.)\nProfligate women bear few children, and profligate men rarely marry; both\nsuffer from disease.  In the breeding of domestic animals, the elimination\nof those individuals, though few in number, which are in any marked manner\ninferior, is by no means an unimportant element towards success.  This\nespecially holds good with injurious characters which tend to reappear\nthrough reversion, such as blackness in sheep; and with mankind some of the\nworst dispositions, which occasionally without any assignable cause make\ntheir appearance in families, may perhaps be reversions to a savage state,\nfrom which we are not removed by very many generations.  This view seems\nindeed recognised in the common expression that such men are the black\nsheep of the family.\n\nWith civilised nations, as far as an advanced standard of morality, and an\nincreased number of fairly good men are concerned, natural selection\napparently effects but little; though the fundamental social instincts were\noriginally thus gained.  But I have already said enough, whilst treating of\nthe lower races, on the causes which lead to the advance of morality,\nnamely, the approbation of our fellow-men--the strengthening of our\nsympathies by habit--example and imitation--reason--experience, and even\nself-interest--instruction during youth, and religious feelings.\n\nA most important obstacle in civilised countries to an increase in the\nnumber of men of a superior class has been strongly insisted on by Mr. Greg\nand Mr. Galton (19.  'Fraser's Magazine,' Sept. 1868, p. 353.  'Macmillan's\nMagazine,' Aug. 1865, p. 318.  The Rev. F.W. Farrar ('Fraser's Magazine,'\nAug. 1870, p. 264) takes a different view.), namely, the fact that the very\npoor and reckless, who are often degraded by vice, almost invariably marry\nearly, whilst the careful and frugal, who are generally otherwise virtuous,\nmarry late in life, so that they may be able to support themselves and\ntheir children in comfort.  Those who marry early produce within a given\nperiod not only a greater number of generations, but, as shewn by Dr.\nDuncan (20.  'On the Laws of the Fertility of Women,' in 'Transactions of\nthe Royal Society,' Edinburgh, vol. xxiv. p. 287; now published separately\nunder the title of 'Fecundity, Fertility, and Sterility,' 1871.  See, also,\nMr. Galton, 'Hereditary Genius,' pp. 352-357, for observations to the above\neffect.), they produce many more children.  The children, moreover, that\nare borne by mothers during the prime of life are heavier and larger, and\ntherefore probably more vigorous, than those born at other periods.  Thus\nthe reckless, degraded, and often vicious members of society, tend to\nincrease at a quicker rate than the provident and generally virtuous\nmembers.  Or as Mr. Greg puts the case:  \"The careless, squalid, unaspiring\nIrishman multiplies like rabbits:  the frugal, foreseeing, self-respecting,\nambitious Scot, stern in his morality, spiritual in his faith, sagacious\nand disciplined in his intelligence, passes his best years in struggle and\nin celibacy, marries late, and leaves few behind him.  Given a land\noriginally peopled by a thousand Saxons and a thousand Celts--and in a\ndozen generations five-sixths of the population would be Celts, but five-\nsixths of the property, of the power, of the intellect, would belong to the\none-sixth of Saxons that remained.  In the eternal 'struggle for\nexistence,' it would be the inferior and LESS favoured race that had\nprevailed--and prevailed by virtue not of its good qualities but of its\nfaults.\"\n\nThere are, however, some checks to this downward tendency.  We have seen\nthat the intemperate suffer from a high rate of mortality, and the\nextremely profligate leave few offspring.  The poorest classes crowd into\ntowns, and it has been proved by Dr. Stark from the statistics of ten years\nin Scotland (21.  'Tenth Annual Report of Births, Deaths, etc., in\nScotland,' 1867, p. xxix.), that at all ages the death-rate is higher in\ntowns than in rural districts, \"and during the first five years of life the\ntown death-rate is almost exactly double that of the rural districts.\"  As\nthese returns include both the rich and the poor, no doubt more than twice\nthe number of births would be requisite to keep up the number of the very\npoor inhabitants in the towns, relatively to those in the country.  With\nwomen, marriage at too early an age is highly injurious; for it has been\nfound in France that, \"Twice as many wives under twenty die in the year, as\ndied out of the same number of the unmarried.\"  The mortality, also, of\nhusbands under twenty is \"excessively high\" (22.  These quotations are\ntaken from our highest authority on such questions, namely, Dr. Farr, in\nhis paper 'On the Influence of Marriage on the Mortality of the French\nPeople,' read before the Nat. Assoc. for the Promotion of Social Science,\n1858.), but what the cause of this may be, seems doubtful.  Lastly, if the\nmen who prudently delay marrying until they can bring up their families in\ncomfort, were to select, as they often do, women in the prime of life, the\nrate of increase in the better class would be only slightly lessened.\n\nIt was established from an enormous body of statistics, taken during 1853,\nthat the unmarried men throughout France, between the ages of twenty and\neighty, die in a much larger proportion than the married:  for instance,\nout of every 1000 unmarried men, between the ages of twenty and thirty,\n11.3 annually died, whilst of the married, only 6.5 died.  (23.  Dr. Farr,\nibid.  The quotations given below are extracted from the same striking\npaper.)  A similar law was proved to hold good, during the years 1863 and\n1864, with the entire population above the age of twenty in Scotland:  for\ninstance, out of every 1000 unmarried men, between the ages of twenty and\nthirty, 14.97 annually died, whilst of the married only 7.24 died, that is\nless than half.  (24. I have taken the mean of the quinquennial means,\ngiven in 'The Tenth Annual Report of Births, Deaths, etc., in Scotland,'\n1867.  The quotation from Dr. Stark is copied from an article in the 'Daily\nNews,' Oct. 17, 1868, which Dr. Farr considers very carefully written.)\nDr. Stark remarks on this, \"Bachelorhood is more destructive to life than\nthe most unwholesome trades, or than residence in an unwholesome house or\ndistrict where there has never been the most distant attempt at sanitary\nimprovement.\"  He considers that the lessened mortality is the direct\nresult of \"marriage, and the more regular domestic habits which attend that\nstate.\"  He admits, however, that the intemperate, profligate, and criminal\nclasses, whose duration of life is low, do not commonly marry; and it must\nlikewise be admitted that men with a weak constitution, ill health, or any\ngreat infirmity in body or mind, will often not wish to marry, or will be\nrejected.  Dr. Stark seems to have come to the conclusion that marriage in\nitself is a main cause of prolonged life, from finding that aged married\nmen still have a considerable advantage in this respect over the unmarried\nof the same advanced age; but every one must have known instances of men,\nwho with weak health during youth did not marry, and yet have survived to\nold age, though remaining weak, and therefore always with a lessened chance\nof life or of marrying.  There is another remarkable circumstance which\nseems to support Dr. Stark's conclusion, namely, that widows and widowers\nin France suffer in comparison with the married a very heavy rate of\nmortality; but Dr. Farr attributes this to the poverty and evil habits\nconsequent on the disruption of the family, and to grief.  On the whole we\nmay conclude with Dr. Farr that the lesser mortality of married than of\nunmarried men, which seems to be a general law, \"is mainly due to the\nconstant elimination of imperfect types, and to the skilful selection of\nthe finest individuals out of each successive generation;\" the selection\nrelating only to the marriage state, and acting on all corporeal,\nintellectual, and moral qualities.  (25.  Dr. Duncan remarks ('Fecundity,\nFertility, etc.' 1871, p. 334) on this subject:  \"At every age the healthy\nand beautiful go over from the unmarried side to the married, leaving the\nunmarried columns crowded with the sickly and unfortunate.\")  We may,\ntherefore, infer that sound and good men who out of prudence remain for a\ntime unmarried, do not suffer a high rate of mortality.\n\nIf the various checks specified in the two last paragraphs, and perhaps\nothers as yet unknown, do not prevent the reckless, the vicious and\notherwise inferior members of society from increasing at a quicker rate\nthan the better class of men, the nation will retrograde, as has too often\noccurred in the history of the world.  We must remember that progress is no\ninvariable rule.  It is very difficult to say why one civilised nation\nrises, becomes more powerful, and spreads more widely, than another; or why\nthe same nation progresses more quickly at one time than at another.  We\ncan only say that it depends on an increase in the actual number of the\npopulation, on the number of men endowed with high intellectual and moral\nfaculties, as well as on their standard of excellence.  Corporeal structure\nappears to have little influence, except so far as vigour of body leads to\nvigour of mind.\n\nIt has been urged by several writers that as high intellectual powers are\nadvantageous to a nation, the old Greeks, who stood some grades higher in\nintellect than any race that has ever existed (26.  See the ingenious and\noriginal argument on this subject by Mr. Galton, 'Hereditary Genius,' pp.\n340-342.), ought, if the power of natural selection were real, to have\nrisen still higher in the scale, increased in number, and stocked the whole\nof Europe.  Here we have the tacit assumption, so often made with respect\nto corporeal structures, that there is some innate tendency towards\ncontinued development in mind and body.  But development of all kinds\ndepends on many concurrent favourable circumstances.  Natural selection\nacts only tentatively.  Individuals and races may have acquired certain\nindisputable advantages, and yet have perished from failing in other\ncharacters.  The Greeks may have retrograded from a want of coherence\nbetween the many small states, from the small size of their whole country,\nfrom the practice of slavery, or from extreme sensuality; for they did not\nsuccumb until \"they were enervated and corrupt to the very core.\"  (27.\nMr. Greg, 'Fraser's Magazine,' Sept. 1868, p. 357.)  The western nations of\nEurope, who now so immeasurably surpass their former savage progenitors,\nand stand at the summit of civilisation, owe little or none of their\nsuperiority to direct inheritance from the old Greeks, though they owe much\nto the written works of that wonderful people.\n\nWho can positively say why the Spanish nation, so dominant at one time, has\nbeen distanced in the race.  The awakening of the nations of Europe from\nthe dark ages is a still more perplexing problem.  At that early period, as\nMr. Galton has remarked, almost all the men of a gentle nature, those given\nto meditation or culture of the mind, had no refuge except in the bosom of\na Church which demanded celibacy (28.  'Hereditary Genius,' 1870, pp. 357-\n359.  The Rev. F.W. Farrar ('Fraser's Magazine,' Aug. 1870, p. 257)\nadvances arguments on the other side.  Sir C. Lyell had already\n('Principles of Geology,' vol. ii. 1868, p. 489), in a striking passage\ncalled attention to the evil influence of the Holy Inquisition in having,\nthrough selection, lowered the general standard of intelligence in\nEurope.); and this could hardly fail to have had a deteriorating influence\non each successive generation.  During this same period the Holy\nInquisition selected with extreme care the freest and boldest men in order\nto burn or imprison them.  In Spain alone some of the best men--those who\ndoubted and questioned, and without doubting there can be no progress--were\neliminated during three centuries at the rate of a thousand a year.  The\nevil which the Catholic Church has thus effected is incalculable, though no\ndoubt counterbalanced to a certain, perhaps to a large, extent in other\nways; nevertheless, Europe has progressed at an unparalleled rate.\n\nThe remarkable success of the English as colonists, compared to other\nEuropean nations, has been ascribed to their \"daring and persistent\nenergy\"; a result which is well illustrated by comparing the progress of\nthe Canadians of English and French extraction; but who can say how the\nEnglish gained their energy?  There is apparently much truth in the belief\nthat the wonderful progress of the United States, as well as the character\nof the people, are the results of natural selection; for the more\nenergetic, restless, and courageous men from all parts of Europe have\nemigrated during the last ten or twelve generations to that great country,\nand have there succeeded best.  (29.  Mr. Galton, 'Macmillan's Magazine,'\nAugust 1865, p. 325.  See also, 'Nature,' 'On Darwinism and National Life,'\nDec. 1869, p. 184.)  Looking to the distant future, I do not think that the\nRev. Mr. Zincke takes an exaggerated view when he says (30.  'Last Winter\nin the United States,' 1868, p. 29.):  \"All other series of events--as that\nwhich resulted in the culture of mind in Greece, and that which resulted in\nthe empire of Rome--only appear to have purpose and value when viewed in\nconnection with, or rather as subsidiary to...the great stream of Anglo-\nSaxon emigration to the west.\"  Obscure as is the problem of the advance of\ncivilisation, we can at least see that a nation which produced during a\nlengthened period the greatest number of highly intellectual, energetic,\nbrave, patriotic, and benevolent men, would generally prevail over less\nfavoured nations.\n\nNatural selection follows from the struggle for existence; and this from a\nrapid rate of increase.  It is impossible not to regret bitterly, but\nwhether wisely is another question, the rate at which man tends to\nincrease; for this leads in barbarous tribes to infanticide and many other\nevils, and in civilised nations to abject poverty, celibacy, and to the\nlate marriages of the prudent.  But as man suffers from the same physical\nevils as the lower animals, he has no right to expect an immunity from the\nevils consequent on the struggle for existence.  Had he not been subjected\nduring primeval times to natural selection, assuredly he would never have\nattained to his present rank.  Since we see in many parts of the world\nenormous areas of the most fertile land capable of supporting numerous\nhappy homes, but peopled only by a few wandering savages, it might be\nargued that the struggle for existence had not been sufficiently severe to\nforce man upwards to his highest standard.  Judging from all that we know\nof man and the lower animals, there has always been sufficient variability\nin their intellectual and moral faculties, for a steady advance through\nnatural selection.  No doubt such advance demands many favourable\nconcurrent circumstances; but it may well be doubted whether the most\nfavourable would have sufficed, had not the rate of increase been rapid,\nand the consequent struggle for existence extremely severe.  It even\nappears from what we see, for instance, in parts of S. America, that a\npeople which may be called civilised, such as the Spanish settlers, is\nliable to become indolent and to retrograde, when the conditions of life\nare very easy.  With highly civilised nations continued progress depends in\na subordinate degree on natural selection; for such nations do not supplant\nand exterminate one another as do savage tribes.  Nevertheless the more\nintelligent members within the same community will succeed better in the\nlong run than the inferior, and leave a more numerous progeny, and this is\na form of natural selection.  The more efficient causes of progress seem to\nconsist of a good education during youth whilst the brain is impressible,\nand of a high standard of excellence, inculcated by the ablest and best\nmen, embodied in the laws, customs and traditions of the nation, and\nenforced by public opinion.  It should, however, be borne in mind, that the\nenforcement of public opinion depends on our appreciation of the\napprobation and disapprobation of others; and this appreciation is founded\non our sympathy, which it can hardly be doubted was originally developed\nthrough natural selection as one of the most important elements of the\nsocial instincts.  (31.  I am much indebted to Mr. John Morley for some\ngood criticisms on this subject:  see, also Broca, 'Les Selections,' 'Revue\nd'Anthropologie,' 1872.)\n\nON THE EVIDENCE THAT ALL CIVILISED NATIONS WERE ONCE BARBAROUS.\n\nThe present subject has been treated in so full and admirable a manner by\nSir J. Lubbock (32.  'On the Origin of Civilisation,' 'Proceedings of the\nEthnological Society,' Nov. 26, 1867.),  Mr. Tylor, Mr. M'Lennan, and\nothers, that I need here give only the briefest summary of their results.\nThe arguments recently advanced by the Duke of Argyll (33.  'Primeval Man,'\n1869.) and formerly by Archbishop Whately, in favour of the belief that man\ncame into the world as a civilised being, and that all savages have since\nundergone degradation, seem to me weak in comparison with those advanced on\nthe other side.  Many nations, no doubt, have fallen away in civilisation,\nand some may have lapsed into utter barbarism, though on this latter head I\nhave met with no evidence.  The Fuegians were probably compelled by other\nconquering hordes to settle in their inhospitable country, and they may\nhave become in consequence somewhat more degraded; but it would be\ndifficult to prove that they have fallen much below the Botocudos, who\ninhabit the finest parts of Brazil.\n\nThe evidence that all civilised nations are the descendants of barbarians,\nconsists, on the one side, of clear traces of their former low condition in\nstill-existing customs, beliefs, language, etc.; and on the other side, of\nproofs that savages are independently able to raise themselves a few steps\nin the scale of civilisation, and have actually thus risen.  The evidence\non the first head is extremely curious, but cannot be here given:  I refer\nto such cases as that of the art of enumeration, which, as Mr. Tylor\nclearly shews by reference to the words still used in some places,\noriginated in counting the fingers, first of one hand and then of the\nother, and lastly of the toes.  We have traces of this in our own decimal\nsystem, and in the Roman numerals, where, after the V, which is supposed to\nbe an abbreviated picture of a human hand, we pass on to VI, etc., when the\nother hand no doubt was used.  So again, \"when we speak of three-score and\nten, we are counting by the vigesimal system, each score thus ideally made,\nstanding for 20--for 'one man' as a Mexican or Carib would put it.\"  (34.\n'Royal Institution of Great Britain,' March 15, 1867.  Also, 'Researches\ninto the Early History of Mankind,' 1865.)  According to a large and\nincreasing school of philologists, every language bears the marks of its\nslow and gradual evolution.  So it is with the art of writing, for letters\nare rudiments of pictorial representations.  It is hardly possible to read\nMr. M'Lennan's work (35.  'Primitive Marriage,' 1865.  See, likewise, an\nexcellent article, evidently by the same author, in the 'North British\nReview,' July 1869.  Also, Mr. L.H. Morgan, 'A Conjectural Solution of the\nOrigin of the Class. System of Relationship,' in 'Proc. American Acad. of\nSciences,' vol. vii. Feb. 1868.  Prof. Schaaffhausen ('Anthropolog.\nReview,' Oct. 1869, p. 373) remarks on \"the vestiges of human sacrifices\nfound both in Homer and the Old Testament.\") and not admit that almost all\ncivilised nations still retain traces of such rude habits as the forcible\ncapture of wives.  What ancient nation, as the same author asks, can be\nnamed that was originally monogamous?  The primitive idea of justice, as\nshewn by the law of battle and other customs of which vestiges still\nremain, was likewise most rude.  Many existing superstitions are the\nremnants of former false religious beliefs.  The highest form of religion--\nthe grand idea of God hating sin and loving righteousness--was unknown\nduring primeval times.\n\nTurning to the other kind of evidence:  Sir J. Lubbock has shewn that some\nsavages have recently improved a little in some of their simpler arts.\nFrom the extremely curious account which he gives of the weapons, tools,\nand arts, in use amongst savages in various parts of the world, it cannot\nbe doubted that these have nearly all been independent discoveries,\nexcepting perhaps the art of making fire.  (36.  Sir J. Lubbock,\n'Prehistoric Times,' 2nd edit. 1869, chaps. xv. and xvi. et passim.  See\nalso the excellent 9th Chapter in Tylor's 'Early History of Mankind,' 2nd\nedit., 1870.)  The Australian boomerang is a good instance of one such\nindependent discovery.  The Tahitians when first visited had advanced in\nmany respects beyond the inhabitants of most of the other Polynesian\nislands.  There are no just grounds for the belief that the high culture of\nthe native Peruvians and Mexicans was derived from abroad (37.  Dr. F.\nMueller has made some good remarks to this effect in the 'Reise der Novara:\nAnthropolog. Theil,' Abtheil. iii. 1868, s. 127.); many native plants were\nthere cultivated, and a few native animals domesticated.  We should bear in\nmind that, judging from the small influence of most missionaries, a\nwandering crew from some semi-civilised land, if washed to the shores of\nAmerica, would not have produced any marked effect on the natives, unless\nthey had already become somewhat advanced.  Looking to a very remote period\nin the history of the world, we find, to use Sir J. Lubbock's well-known\nterms, a paleolithic and neolithic period; and no one will pretend that the\nart of grinding rough flint tools was a borrowed one.  In all parts of\nEurope, as far east as Greece, in Palestine, India, Japan, New Zealand, and\nAfrica, including Egypt, flint tools have been discovered in abundance; and\nof their use the existing inhabitants retain no tradition.  There is also\nindirect evidence of their former use by the Chinese and ancient Jews.\nHence there can hardly be a doubt that the inhabitants of these countries,\nwhich include nearly the whole civilised world, were once in a barbarous\ncondition.  To believe that man was aboriginally civilised and then\nsuffered utter degradation in so many regions, is to take a pitiably low\nview of human nature.  It is apparently a truer and more cheerful view that\nprogress has been much more general than retrogression; that man has risen,\nthough by slow and interrupted steps, from a lowly condition to the highest\nstandard as yet attained by him in knowledge, morals and religion.\n\n\nCHAPTER VI.\n\nON THE AFFINITIES AND GENEALOGY OF MAN.\n\nPosition of man in the animal series--The natural system genealogical--\nAdaptive characters of slight value--Various small points of resemblance\nbetween man and the Quadrumana--Rank of man in the natural system--\nBirthplace and antiquity of man--Absence of fossil connecting links--Lower\nstages in the genealogy of man, as inferred, firstly from his affinities\nand secondly from his structure--Early androgynous condition of the\nVertebrata--Conclusion.\n\nEven if it be granted that the difference between man and his nearest\nallies is as great in corporeal structure as some naturalists maintain, and\nalthough we must grant that the difference between them is immense in\nmental power, yet the facts given in the earlier chapters appear to\ndeclare, in the plainest manner, that man is descended from some lower\nform, notwithstanding that connecting-links have not hitherto been\ndiscovered.\n\nMan is liable to numerous, slight, and diversified variations, which are\ninduced by the same general causes, are governed and transmitted in\naccordance with the same general laws, as in the lower animals.  Man has\nmultiplied so rapidly, that he has necessarily been exposed to struggle for\nexistence, and consequently to natural selection.  He has given rise to\nmany races, some of which differ so much from each other, that they have\noften been ranked by naturalists as distinct species.  His body is\nconstructed on the same homological plan as that of other mammals.  He\npasses through the same phases of embryological development.  He retains\nmany rudimentary and useless structures, which no doubt were once\nserviceable.  Characters occasionally make their re-appearance in him,\nwhich we have reason to believe were possessed by his early progenitors.\nIf the origin of man had been wholly different from that of all other\nanimals, these various appearances would be mere empty deceptions; but such\nan admission is incredible.  These appearances, on the other hand, are\nintelligible, at least to a large extent, if man is the co-descendant with\nother mammals of some unknown and lower form.\n\nSome naturalists, from being deeply impressed with the mental and spiritual\npowers of man, have divided the whole organic world into three kingdoms,\nthe Human, the Animal, and the Vegetable, thus giving to man a separate\nkingdom.  (1.  Isidore Geoffroy St.-Hilaire gives a detailed account of the\nposition assigned to man by various naturalists in their classifications:\n'Hist. Nat. Gen.' tom. ii. 1859, pp. 170-189.)  Spiritual powers cannot be\ncompared or classed by the naturalist:  but he may endeavour to shew, as I\nhave done, that the mental faculties of man and the lower animals do not\ndiffer in kind, although immensely in degree.  A difference in degree,\nhowever great, does not justify us in placing man in a distinct kingdom, as\nwill perhaps be best illustrated by comparing the mental powers of two\ninsects, namely, a coccus or scale-insect and an ant, which undoubtedly\nbelong to the same class.  The difference is here greater than, though of a\nsomewhat different kind from, that between man and the highest mammal.  The\nfemale coccus, whilst young, attaches itself by its proboscis to a plant;\nsucks the sap, but never moves again; is fertilised and lays eggs; and this\nis its whole history.  On the other hand, to describe the habits and mental\npowers of worker-ants, would require, as Pierre Huber has shewn, a large\nvolume; I may, however, briefly specify a few points.  Ants certainly\ncommunicate information to each other, and several unite for the same work,\nor for games of play.  They recognise their fellow-ants after months of\nabsence, and feel sympathy for each other.  They build great edifices, keep\nthem clean, close the doors in the evening, and post sentries.  They make\nroads as well as tunnels under rivers, and temporary bridges over them, by\nclinging together.  They collect food for the community, and when an\nobject, too large for entrance, is brought to the nest, they enlarge the\ndoor, and afterwards build it up again.  They store up seeds, of which they\nprevent the germination, and which, if damp, are brought up to the surface\nto dry.  They keep aphides and other insects as milch-cows.  They go out to\nbattle in regular bands, and freely sacrifice their lives for the common\nweal.  They emigrate according to a preconcerted plan.  They capture\nslaves.  They move the eggs of their aphides, as well as their own eggs and\ncocoons, into warm parts of the nest, in order that they may be quickly\nhatched; and endless similar facts could be given.  (2.  Some of the most\ninteresting facts ever published on the habits of ants are given by Mr.\nBelt, in his 'Naturalist in Nicaragua,' 1874.  See also Mr. Moggridge's\nadmirable work, 'Harvesting Ants,' etc., 1873, also 'L'Instinct chez les\nInsectes,' by M. George Pouchet, 'Revue des Deux Mondes,' Feb. 1870, p.\n682.)  On the whole, the difference in mental power between an ant and a\ncoccus is immense; yet no one has ever dreamed of placing these insects in\ndistinct classes, much less in distinct kingdoms.  No doubt the difference\nis bridged over by other insects; and this is not the case with man and the\nhigher apes.  But we have every reason to believe that the breaks in the\nseries are simply the results of many forms having become extinct.\n\nProfessor Owen, relying chiefly on the structure of the brain, has divided\nthe mammalian series into four sub-classes.  One of these he devotes to\nman; in another he places both the marsupials and the Monotremata; so that\nhe makes man as distinct from all other mammals as are these two latter\ngroups conjoined.  This view has not been accepted, as far as I am aware,\nby any naturalist capable of forming an independent judgment, and therefore\nneed not here be further considered.\n\nWe can understand why a classification founded on any single character or\norgan--even an organ so wonderfully complex and important as the brain--or\non the high development of the mental faculties, is almost sure to prove\nunsatisfactory.  This principle has indeed been tried with hymenopterous\ninsects; but when thus classed by their habits or instincts, the\narrangement proved thoroughly artificial.  (3.  Westwood, 'Modern\nClassification of Insects,' vol. ii. 1840, p. 87.)  Classifications may, of\ncourse, be based on any character whatever, as on size, colour, or the\nelement inhabited; but naturalists have long felt a profound conviction\nthat there is a natural system.  This system, it is now generally admitted,\nmust be, as far as possible, genealogical in arrangement,--that is, the co-\ndescendants of the same form must be kept together in one group, apart from\nthe co-descendants of any other form; but if the parent-forms are related,\nso will be their descendants, and the two groups together will form a\nlarger group.  The amount of difference between the several groups--that is\nthe amount of modification which each has undergone--is expressed by such\nterms as genera, families, orders, and classes.  As we have no record of\nthe lines of descent, the pedigree can be discovered only by observing the\ndegrees of resemblance between the beings which are to be classed.  For\nthis object numerous points of resemblance are of much more importance than\nthe amount of similarity or dissimilarity in a few points.  If two\nlanguages were found to resemble each other in a multitude of words and\npoints of construction, they would be universally recognised as having\nsprung from a common source, notwithstanding that they differed greatly in\nsome few words or points of construction.  But with organic beings the\npoints of resemblance must not consist of adaptations to similar habits of\nlife:  two animals may, for instance, have had their whole frames modified\nfor living in the water, and yet they will not be brought any nearer to\neach other in the natural system.  Hence we can see how it is that\nresemblances in several unimportant structures, in useless and rudimentary\norgans, or not now functionally active, or in an embryological condition,\nare by far the most serviceable for classification; for they can hardly be\ndue to adaptations within a late period; and thus they reveal the old lines\nof descent or of true affinity.\n\nWe can further see why a great amount of modification in some one character\nought not to lead us to separate widely any two organisms.  A part which\nalready differs much from the same part in other allied forms has already,\naccording to the theory of evolution, varied much; consequently it would\n(as long as the organism remained exposed to the same exciting conditions)\nbe liable to further variations of the same kind; and these, if beneficial,\nwould be preserved, and thus be continually augmented.  In many cases the\ncontinued development of a part, for instance, of the beak of a bird, or of\nthe teeth of a mammal, would not aid the species in gaining its food, or\nfor any other object; but with man we can see no definite limit to the\ncontinued development of the brain and mental faculties, as far as\nadvantage is concerned.  Therefore in determining the position of man in\nthe natural or genealogical system, the extreme development of his brain\nought not to outweigh a multitude of resemblances in other less important\nor quite unimportant points.\n\nThe greater number of naturalists who have taken into consideration the\nwhole structure of man, including his mental faculties, have followed\nBlumenbach and Cuvier, and have placed man in a separate Order, under the\ntitle of the Bimana, and therefore on an equality with the orders of the\nQuadrumana, Carnivora, etc.  Recently many of our best naturalists have\nrecurred to the view first propounded by Linnaeus, so remarkable for his\nsagacity, and have placed man in the same Order with the Quadrumana, under\nthe title of the Primates.  The justice of this conclusion will be\nadmitted:  for in the first place, we must bear in mind the comparative\ninsignificance for classification of the great development of the brain in\nman, and that the strongly-marked differences between the skulls of man and\nthe Quadrumana (lately insisted upon by Bischoff, Aeby, and others)\napparently follow from their differently developed brains.  In the second\nplace, we must remember that nearly all the other and more important\ndifferences between man and the Quadrumana are manifestly adaptive in their\nnature, and relate chiefly to the erect position of man; such as the\nstructure of his hand, foot, and pelvis, the curvature of his spine, and\nthe position of his head.  The family of Seals offers a good illustration\nof the small importance of adaptive characters for classification.  These\nanimals differ from all other Carnivora in the form of their bodies and in\nthe structure of their limbs, far more than does man from the higher apes;\nyet in most systems, from that of Cuvier to the most recent one by Mr.\nFlower (4.  'Proceedings Zoological Society,' 1863, p. 4.), seals are\nranked as a mere family in the Order of the Carnivora.  If man had not been\nhis own classifier, he would never have thought of founding a separate\norder for his own reception.\n\nIt would be beyond my limits, and quite beyond my knowledge, even to name\nthe innumerable points of structure in which man agrees with the other\nPrimates.  Our great anatomist and philosopher, Prof. Huxley, has fully\ndiscussed this subject (5.  'Evidence as to Man's Place in Nature,' 1863,\np. 70, et passim.), and concludes that man in all parts of his organization\ndiffers less from the higher apes, than these do from the lower members of\nthe same group.  Consequently there \"is no justification for placing man in\na distinct order.\"\n\nIn an early part of this work I brought forward various facts, shewing how\nclosely man agrees in constitution with the higher mammals; and this\nagreement must depend on our close similarity in minute structure and\nchemical composition.  I gave, as instances, our liability to the same\ndiseases, and to the attacks of allied parasites; our tastes in common for\nthe same stimulants, and the similar effects produced by them, as well as\nby various drugs, and other such facts.\n\nAs small unimportant points of resemblance between man and the Quadrumana\nare not commonly noticed in systematic works, and as, when numerous, they\nclearly reveal our relationship, I will specify a few such points.  The\nrelative position of our features is manifestly the same; and the various\nemotions are displayed by nearly similar movements of the muscles and skin,\nchiefly above the eyebrows and round the mouth.  Some few expressions are,\nindeed, almost the same, as in the weeping of certain kinds of monkeys and\nin the laughing noise made by others, during which the corners of the mouth\nare drawn backwards, and the lower eyelids wrinkled.  The external ears are\ncuriously alike.  In man the nose is much more prominent than in most\nmonkeys; but we may trace the commencement of an aquiline curvature in the\nnose of the Hoolock Gibbon; and this in the Semnopithecus nasica is carried\nto a ridiculous extreme.\n\nThe faces of many monkeys are ornamented with beards, whiskers, or\nmoustaches.  The hair on the head grows to a great length in some species\nof Semnopithecus (6.  Isidore Geoffroy St.-Hilaire, 'Hist. Nat. Gen.' tom.\nii. 1859, p. 217.); and in the Bonnet monkey (Macacus radiatus) it radiates\nfrom a point on the crown, with a parting down the middle.  It is commonly\nsaid that the forehead gives to man his noble and intellectual appearance;\nbut the thick hair on the head of the Bonnet monkey terminates downwards\nabruptly, and is succeeded by hair so short and fine that at a little\ndistance the forehead, with the exception of the eyebrows, appears quite\nnaked.  It has been erroneously asserted that eyebrows are not present in\nany monkey.  In the species just named the degree of nakedness of the\nforehead differs in different individuals; and Eschricht states (7.  'Ueber\ndie Richtung der Haare,' etc., Mueller's 'Archiv fur Anat. und Phys.' 1837,\ns. 51.) that in our children the limit between the hairy scalp and the\nnaked forehead is sometimes not well defined; so that here we seem to have\na trifling case of reversion to a progenitor, in whom the forehead had not\nas yet become quite naked.\n\nIt is well known that the hair on our arms tends to converge from above and\nbelow to a point at the elbow.  This curious arrangement, so unlike that in\nmost of the lower mammals, is common to the gorilla, chimpanzee, orang,\nsome species of Hylobates, and even to some few American monkeys.  But in\nHylobates agilis the hair on the fore-arm is directed downwards or towards\nthe wrist in the ordinary manner; and in H. lar it is nearly erect, with\nonly a very slight forward inclination; so that in this latter species it\nis in a transitional state.  It can hardly be doubted that with most\nmammals the thickness of the hair on the back and its direction, is adapted\nto throw off the rain; even the transverse hairs on the fore-legs of a dog\nmay serve for this end when he is coiled up asleep.  Mr. Wallace, who has\ncarefully studied the habits of the orang, remarks that the convergence of\nthe hair towards the elbow on the arms of the orang may be explained as\nserving to throw off the rain, for this animal during rainy weather sits\nwith its arms bent, and with the hands clasped round a branch or over its\nhead.  According to Livingstone, the gorilla also \"sits in pelting rain\nwith his hands over his head.\"  (8.  Quoted by Reade, 'The African Sketch\nBook,' vol i. 1873, p. 152.)  If the above explanation is correct, as seems\nprobable, the direction of the hair on our own arms offers a curious record\nof our former state; for no one supposes that it is now of any use in\nthrowing off the rain; nor, in our present erect condition, is it properly\ndirected for this purpose.\n\nIt would, however, be rash to trust too much to the principle of adaptation\nin regard to the direction of the hair in man or his early progenitors; for\nit is impossible to study the figures given by Eschricht of the arrangement\nof the hair on the human foetus (this being the same as in the adult) and\nnot agree with this excellent observer that other and more complex causes\nhave intervened.  The points of convergence seem to stand in some relation\nto those points in the embryo which are last closed in during development.\nThere appears, also, to exist some relation between the arrangement of the\nhair on the limbs, and the course of the medullary arteries. (9.  On the\nhair in Hylobates, see 'Natural History of Mammals,' by C.L. Martin, 1841,\np. 415.  Also, Isidore Geoffroy on the American monkeys and other kinds,\n'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243.  Eschricht, ibid. s. 46, 55,\n61.  Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619.  Wallace,\n'Contributions to the Theory of Natural Selection,' 1870, p. 344.)\n\nIt must not be supposed that the resemblances between man and certain apes\nin the above and in many other points--such as in having a naked forehead,\nlong tresses on the head, etc.,--are all necessarily the result of unbroken\ninheritance from a common progenitor, or of subsequent reversion.  Many of\nthese resemblances are more probably due to analogous variation, which\nfollows, as I have elsewhere attempted to shew (10.  'Origin of Species,'\n5th edit. 1869, p.194.  'The Variation of Animals and Plants under\nDomestication,' vol. ii. 1868, p. 348.), from co-descended organisms having\na similar constitution, and having been acted on by like causes inducing\nsimilar modifications.  With respect to the similar direction of the hair\non the fore-arms of man and certain monkeys, as this character is common to\nalmost all the anthropomorphous apes, it may probably be attributed to\ninheritance; but this is not certain, as some very distinct American\nmonkeys are thus characterised.\n\nAlthough, as we have now seen, man has no just right to form a separate\nOrder for his own reception, he may perhaps claim a distinct Sub-order or\nFamily.  Prof. Huxley, in his last work (11.  'An Introduction to the\nClassification of Animals,' 1869, p. 99.), divides the primates into three\nSub-orders; namely, the Anthropidae with man alone, the Simiadae including\nmonkeys of all kinds, and the Lemuridae with the diversified genera of\nlemurs.  As far as differences in certain important points of structure are\nconcerned, man may no doubt rightly claim the rank of a Sub-order; and this\nrank is too low, if we look chiefly to his mental faculties.  Nevertheless,\nfrom a genealogical point of view it appears that this rank is too high,\nand that man ought to form merely a Family, or possibly even only a Sub-\nfamily.  If we imagine three lines of descent proceeding from a common\nstock, it is quite conceivable that two of them might after the lapse of\nages be so slightly changed as still to remain as species of the same\ngenus, whilst the third line might become so greatly modified as to deserve\nto rank as a distinct Sub-family, Family, or even Order.  But in this case\nit is almost certain that the third line would still retain through\ninheritance numerous small points of resemblance with the other two.  Here,\nthen, would occur the difficulty, at present insoluble, how much weight we\nought to assign in our classifications to strongly-marked differences in\nsome few points,--that is, to the amount of modification undergone; and how\nmuch to close resemblance in numerous unimportant points, as indicating the\nlines of descent or genealogy.  To attach much weight to the few but strong\ndifferences is the most obvious and perhaps the safest course, though it\nappears more correct to pay great attention to the many small resemblances,\nas giving a truly natural classification.\n\nIn forming a judgment on this head with reference to man, we must glance at\nthe classification of the Simiadae.  This family is divided by almost all\nnaturalists into the Catarrhine group, or Old World monkeys, all of which\nare characterised (as their name expresses) by the peculiar structure of\ntheir nostrils, and by having four premolars in each jaw; and into the\nPlatyrrhine group or New World monkeys (including two very distinct sub-\ngroups), all of which are characterised by differently constructed\nnostrils, and by having six premolars in each jaw.  Some other small\ndifferences might be mentioned.  Now man unquestionably belongs in his\ndentition, in the structure of his nostrils, and some other respects, to\nthe Catarrhine or Old World division; nor does he resemble the Platyrrhines\nmore closely than the Catarrhines in any characters, excepting in a few of\nnot much importance and apparently of an adaptive nature.  It is therefore\nagainst all probability that some New World species should have formerly\nvaried and produced a man-like creature, with all the distinctive\ncharacters proper to the Old World division; losing at the same time all\nits own distinctive characters.  There can, consequently, hardly be a doubt\nthat man is an off-shoot from the Old World Simian stem; and that under a\ngenealogical point of view he must be classed with the Catarrhine division.\n(12.  This is nearly the same classification as that provisionally adopted\nby Mr. St. George Mivart, ('Transactions, Philosophical Society,\" 1867, p.\n300), who, after separating the Lemuridae, divides the remainder of the\nPrimates into the Hominidae, the Simiadae which answer to the Catarrhines,\nthe Cebidae, and the Hapalidae,--these two latter groups answering to the\nPlatyrrhines.  Mr. Mivart still abides by the same view; see 'Nature,'\n1871, p. 481.)\n\nThe anthropomorphous apes, namely the gorilla, chimpanzee, orang, and\nhylobates, are by most naturalists separated from the other Old World\nmonkeys, as a distinct sub-group.  I am aware that Gratiolet, relying on\nthe structure of the brain, does not admit the existence of this sub-group,\nand no doubt it is a broken one.  Thus the orang, as Mr. St. G. Mivart\nremarks, \"is one of the most peculiar and aberrant forms to be found in the\nOrder.\"  (13.  'Transactions, Zoolog. Soc.' vol. vi. 1867, p. 214.)  The\nremaining non-anthropomorphous Old World monkeys, are again divided by some\nnaturalists into two or three smaller sub-groups; the genus Semnopithecus,\nwith its peculiar sacculated stomach, being the type of one sub-group.  But\nit appears from M. Gaudry's wonderful discoveries in Attica, that during\nthe Miocene period a form existed there, which connected Semnopithecus and\nMacacus; and this probably illustrates the manner in which the other and\nhigher groups were once blended together.\n\nIf the anthropomorphous apes be admitted to form a natural sub-group, then\nas man agrees with them, not only in all those characters which he\npossesses in common with the whole Catarrhine group, but in other peculiar\ncharacters, such as the absence of a tail and of callosities, and in\ngeneral appearance, we may infer that some ancient member of the\nanthropomorphous sub-group gave birth to man.  It is not probable that,\nthrough the law of analogous variation, a member of one of the other lower\nsub-groups should have given rise to a man-like creature, resembling the\nhigher anthropomorphous apes in so many respects.  No doubt man, in\ncomparison with most of his allies, has undergone an extraordinary amount\nof modification, chiefly in consequence of the great development of his\nbrain and his erect position; nevertheless, we should bear in mind that he\n\"is but one of several exceptional forms of Primates.\"  (14.  Mr. St. G.\nMivart, 'Transactions of the Philosophical Society,' 1867, p. 410.)\n\nEvery naturalist, who believes in the principle of evolution, will grant\nthat the two main divisions of the Simiadae, namely the Catarrhine and\nPlatyrrhine monkeys, with their sub-groups, have all proceeded from some\none extremely ancient progenitor.  The early descendants of this\nprogenitor, before they had diverged to any considerable extent from each\nother, would still have formed a single natural group; but some of the\nspecies or incipient genera would have already begun to indicate by their\ndiverging characters the future distinctive marks of the Catarrhine and\nPlatyrrhine divisions.  Hence the members of this supposed ancient group\nwould not have been so uniform in their dentition, or in the structure of\ntheir nostrils, as are the existing Catarrhine monkeys in one way and the\nPlatyrrhines in another way, but would have resembled in this respect the\nallied Lemuridae, which differ greatly from each other in the form of their\nmuzzles (15.  Messrs. Murie and Mivart on the Lemuroidea, 'Transactions,\nZoological Society,' vol. vii, 1869, p. 5.), and to an extraordinary degree\nin their dentition.\n\nThe Catarrhine and Platyrrhine monkeys agree in a multitude of characters,\nas is shewn by their unquestionably belonging to one and the same Order.\nThe many characters which they possess in common can hardly have been\nindependently acquired by so many distinct species; so that these\ncharacters must have been inherited.  But a naturalist would undoubtedly\nhave ranked as an ape or a monkey, an ancient form which possessed many\ncharacters common to the Catarrhine and Platyrrhine monkeys, other\ncharacters in an intermediate condition, and some few, perhaps, distinct\nfrom those now found in either group.  And as man from a genealogical point\nof view belongs to the Catarrhine or Old World stock, we must conclude,\nhowever much the conclusion may revolt our pride, that our early\nprogenitors would have been properly thus designated.  (16.  Haeckel has\ncome to this same conclusion.  See 'Ueber die Entstehung des\nMenschengeschlechts,' in Virchow's 'Sammlung. gemein. wissen. Vortraege,'\n1868, s. 61.  Also his 'Natuerliche Schoepfungsgeschichte,' 1868, in which he\ngives in detail his views on the genealogy of man.)  But we must not fall\ninto the error of supposing that the early progenitor of the whole Simian\nstock, including man, was identical with, or even closely resembled, any\nexisting ape or monkey.\n\nON THE BIRTHPLACE AND ANTIQUITY OF MAN.\n\nWe are naturally led to enquire, where was the birthplace of man at that\nstage of descent when our progenitors diverged from the Catarrhine stock?\nThe fact that they belonged to this stock clearly shews that they inhabited\nthe Old World; but not Australia nor any oceanic island, as we may infer\nfrom the laws of geographical distribution.  In each great region of the\nworld the living mammals are closely related to the extinct species of the\nsame region.  It is therefore probable that Africa was formerly inhabited\nby extinct apes closely allied to the gorilla and chimpanzee; and as these\ntwo species are now man's nearest allies, it is somewhat more probable that\nour early progenitors lived on the African continent than elsewhere.  But\nit is useless to speculate on this subject; for two or three\nanthropomorphous apes, one the Dryopithecus (17.  Dr. C. Forsyth Major,\n'Sur les Singes fossiles trouves en Italie:' 'Soc. Ital. des Sc. Nat.' tom.\nxv. 1872.) of Lartet, nearly as large as a man, and closely allied to\nHylobates, existed in Europe during the Miocene age; and since so remote a\nperiod the earth has certainly undergone many great revolutions, and there\nhas been ample time for migration on the largest scale.\n\nAt the period and place, whenever and wherever it was, when man first lost\nhis hairy covering, he probably inhabited a hot country; a circumstance\nfavourable for the frugiferous diet on which, judging from analogy, he\nsubsisted.  We are far from knowing how long ago it was when man first\ndiverged from the Catarrhine stock; but it may have occurred at an epoch as\nremote as the Eocene period; for that the higher apes had diverged from the\nlower apes as early as the Upper Miocene period is shewn by the existence\nof the Dryopithecus.  We are also quite ignorant at how rapid a rate\norganisms, whether high or low in the scale, may be modified under\nfavourable circumstances; we know, however, that some have retained the\nsame form during an enormous lapse of time.  From what we see going on\nunder domestication, we learn that some of the co-descendants of the same\nspecies may be not at all, some a little, and some greatly changed, all\nwithin the same period.  Thus it may have been with man, who has undergone\na great amount of modification in certain characters in comparison with the\nhigher apes.\n\nThe great break in the organic chain between man and his nearest allies,\nwhich cannot be bridged over by any extinct or living species, has often\nbeen advanced as a grave objection to the belief that man is descended from\nsome lower form; but this objection will not appear of much weight to those\nwho, from general reasons, believe in the general principle of evolution.\nBreaks often occur in all parts of the series, some being wide, sharp and\ndefined, others less so in various degrees; as between the orang and its\nnearest allies--between the Tarsius and the other Lemuridae--between the\nelephant, and in a more striking manner between the Ornithorhynchus or\nEchidna, and all other mammals.  But these breaks depend merely on the\nnumber of related forms which have become extinct.  At some future period,\nnot very distant as measured by centuries, the civilised races of man will\nalmost certainly exterminate, and replace, the savage races throughout the\nworld.  At the same time the anthropomorphous apes, as Professor\nSchaaffhausen has remarked (18.  'Anthropological Review,' April 1867, p.\n236.), will no doubt be exterminated.  The break between man and his\nnearest allies will then be wider, for it will intervene between man in a\nmore civilised state, as we may hope, even than the Caucasian, and some ape\nas low as a baboon, instead of as now between the negro or Australian and\nthe gorilla.\n\nWith respect to the absence of fossil remains, serving to connect man with\nhis ape-like progenitors, no one will lay much stress on this fact who\nreads Sir C. Lyell's discussion (19.  'Elements of Geology,' 1865, pp. 583-\n585.  'Antiquity of Man,' 1863, p. 145.), where he shews that in all the\nvertebrate classes the discovery of fossil remains has been a very slow and\nfortuitous process.  Nor should it be forgotten that those regions which\nare the most likely to afford remains connecting man with some extinct ape-\nlike creature, have not as yet been searched by geologists.\n\nLOWER STAGES IN THE GENEALOGY OF MAN.\n\nWe have seen that man appears to have diverged from the Catarrhine or Old\nWorld division of the Simiadae, after these had diverged from the New World\ndivision.  We will now endeavour to follow the remote traces of his\ngenealogy, trusting principally to the mutual affinities between the\nvarious classes and orders, with some slight reference to the periods, as\nfar as ascertained, of their successive appearance on the earth.  The\nLemuridae stand below and near to the Simiadae, and constitute a very\ndistinct family of the primates, or, according to Haeckel and others, a\ndistinct Order.  This group is diversified and broken to an extraordinary\ndegree, and includes many aberrant forms.  It has, therefore, probably\nsuffered much extinction.  Most of the remnants survive on islands, such as\nMadagascar and the Malayan archipelago, where they have not been exposed to\nso severe a competition as they would have been on well-stocked continents.\nThis group likewise presents many gradations, leading, as Huxley remarks\n(20.  'Man's Place in Nature,' p. 105.), \"insensibly from the crown and\nsummit of the animal creation down to creatures from which there is but a\nstep, as it seems, to the lowest, smallest, and least intelligent of the\nplacental mammalia.\"  From these various considerations it is probable that\nthe Simiadae were originally developed from the progenitors of the existing\nLemuridae; and these in their turn from forms standing very low in the\nmammalian series.\n\nThe Marsupials stand in many important characters below the placental\nmammals.  They appeared at an earlier geological period, and their range\nwas formerly much more extensive than at present.  Hence the Placentata are\ngenerally supposed to have been derived from the Implacentata or\nMarsupials; not, however, from forms closely resembling the existing\nMarsupials, but from their early progenitors.  The Monotremata are plainly\nallied to the Marsupials, forming a third and still lower division in the\ngreat mammalian series.  They are represented at the present day solely by\nthe Ornithorhynchus and Echidna; and these two forms may be safely\nconsidered as relics of a much larger group, representatives of which have\nbeen preserved in Australia through some favourable concurrence of\ncircumstances.  The Monotremata are eminently interesting, as leading in\nseveral important points of structure towards the class of reptiles.\n\nIn attempting to trace the genealogy of the Mammalia, and therefore of man,\nlower down in the series, we become involved in greater and greater\nobscurity; but as a most capable judge, Mr. Parker, has remarked, we have\ngood reason to believe, that no true bird or reptile intervenes in the\ndirect line of descent.  He who wishes to see what ingenuity and knowledge\ncan effect, may consult Prof. Haeckel's works.  (21.  Elaborate tables are\ngiven in his 'Generelle Morphologie' (B. ii. s. cliii. and s. 425); and\nwith more especial reference to man in his 'Natuerliche\nSchoepfungsgeschichte,' 1868.  Prof. Huxley, in reviewing this latter work\n('The Academy,' 1869, p. 42) says, that he considers the phylum or lines of\ndescent of the Vertebrata to be admirably discussed by Haeckel, although he\ndiffers on some points.  He expresses, also, his high estimate of the\ngeneral tenor and spirit of the whole work.)  I will content myself with a\nfew general remarks.  Every evolutionist will admit that the five great\nvertebrate classes, namely, mammals, birds, reptiles, amphibians, and\nfishes, are descended from some one prototype; for they have much in\ncommon, especially during their embryonic state.  As the class of fishes is\nthe most lowly organised, and appeared before the others, we may conclude\nthat all the members of the vertebrate kingdom are derived from some\nfishlike animal.  The belief that animals so distinct as a monkey, an\nelephant, a humming-bird, a snake, a frog, and a fish, etc., could all have\nsprung from the same parents, will appear monstrous to those who have not\nattended to the recent progress of natural history.  For this belief\nimplies the former existence of links binding closely together all these\nforms, now so utterly unlike.\n\nNevertheless, it is certain that groups of animals have existed, or do now\nexist, which serve to connect several of the great vertebrate classes more\nor less closely.  We have seen that the Ornithorhynchus graduates towards\nreptiles; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and\nothers, that the Dinosaurians are in many important characters intermediate\nbetween certain reptiles and certain birds--the birds referred to being the\nostrich-tribe (itself evidently a widely-diffused remnant of a larger\ngroup) and the Archeopteryx, that strange Secondary bird, with a long\nlizard-like tail.  Again, according to Prof. Owen (22.  'Palaeontology'\n1860, p. 199.), the Ichthyosaurians--great sea-lizards furnished with\npaddles--present many affinities with fishes, or rather, according to\nHuxley, with amphibians; a class which, including in its highest division\nfrogs and toads, is plainly allied to the Ganoid fishes.  These latter\nfishes swarmed during the earlier geological periods, and were constructed\non what is called a generalised type, that is, they presented diversified\naffinities with other groups of organisms.  The Lepidosiren is also so\nclosely allied to amphibians and fishes, that naturalists long disputed in\nwhich of these two classes to rank it; it, and also some few Ganoid fishes,\nhave been preserved from utter extinction by inhabiting rivers, which are\nharbours of refuge, and are related to the great waters of the ocean in the\nsame way that islands are to continents.\n\nLastly, one single member of the immense and diversified class of fishes,\nnamely, the lancelet or amphioxus, is so different from all other fishes,\nthat Haeckel maintains that it ought to form a distinct class in the\nvertebrate kingdom.  This fish is remarkable for its negative characters;\nit can hardly be said to possess a brain, vertebral column, or heart, etc.;\nso that it was classed by the older naturalists amongst the worms.  Many\nyears ago Prof. Goodsir perceived that the lancelet presented some\naffinities with the Ascidians, which are invertebrate, hermaphrodite,\nmarine creatures permanently attached to a support.  They hardly appear\nlike animals, and consist of a simple, tough, leathery sack, with two small\nprojecting orifices.  They belong to the Mulluscoida of Huxley--a lower\ndivision of the great kingdom of the Mollusca; but they have recently been\nplaced by some naturalists amongst the Vermes or worms.  Their larvae\nsomewhat resemble tadpoles in shape (23.  At the Falkland Islands I had the\nsatisfaction of seeing, in April, 1833, and therefore some years before any\nother naturalist, the locomotive larvae of a compound Ascidian, closely\nallied to Synoicum, but apparently generically distinct from it.  The tail\nwas about five times as long as the oblong head, and terminated in a very\nfine filament.  It was, as sketched by me under a simple microscope,\nplainly divided by transverse opaque partitions, which I presume represent\nthe great cells figured by Kovalevsky.  At an early stage of development\nthe tail was closely coiled round the head of the larva.), and have the\npower of swimming freely about.  Mr. Kovalevsky (24.  'Memoires de l'Acad.\ndes Sciences de St. Petersbourg,' tom. x. No. 15, 1866.) has lately\nobserved that the larvae of Ascidians are related to the Vertebrata, in\ntheir manner of development, in the relative position of the nervous\nsystem, and in possessing a structure closely like the chorda dorsalis of\nvertebrate animals; and in this he has been since confirmed by Prof.\nKupffer.  M. Kovalevsky writes to me from Naples, that he has now carried\nthese observations yet further, and should his results be well established,\nthe whole will form a discovery of the very greatest value.  Thus, if we\nmay rely on embryology, ever the safest guide in classification, it seems\nthat we have at last gained a clue to the source whence the Vertebrata were\nderived.  (25.  But I am bound to add that some competent judges dispute\nthis conclusion; for instance, M. Giard, in a series of papers in the\n'Archives de Zoologie Experimentale,' for 1872.  Nevertheless, this\nnaturalist remarks, p. 281, \"L'organisation de la larve ascidienne en\ndehors de toute hypothese et de toute theorie, nous montre comment la\nnature peut produire la disposition fondamentale du type vertebre\n(l'existence d'une corde dorsale) chez un invertebre par la seule condition\nvitale de l'adaptation, et cette simple possibilite du passage supprime\nl'abime entre les deux sous-regnes, encore bien qu'en ignore par ou le\npassage s'est fait en realite.\")  We should then be justified in believing\nthat at an extremely remote period a group of animals existed, resembling\nin many respects the larvae of our present Ascidians, which diverged into\ntwo great branches--the one retrograding in development and producing the\npresent class of Ascidians, the other rising to the crown and summit of the\nanimal kingdom by giving birth to the Vertebrata.\n\nWe have thus far endeavoured rudely to trace the genealogy of the\nVertebrata by the aid of their mutual affinities.  We will now look to man\nas he exists; and we shall, I think, be able partially to restore the\nstructure of our early progenitors, during successive periods, but not in\ndue order of time.  This can be effected by means of the rudiments which\nman still retains, by the characters which occasionally make their\nappearance in him through reversion, and by the aid of the principles of\nmorphology and embryology.  The various facts, to which I shall here\nallude, have been given in the previous chapters.\n\nThe early progenitors of man must have been once covered with hair, both\nsexes having beards; their ears were probably pointed, and capable of\nmovement; and their bodies were provided with a tail, having the proper\nmuscles.  Their limbs and bodies were also acted on by many muscles which\nnow only occasionally reappear, but are normally present in the Quadrumana.\nAt this or some earlier period, the great artery and nerve of the humerus\nran through a supra-condyloid foramen.  The intestine gave forth a much\nlarger diverticulum or caecum than that now existing.  The foot was then\nprehensile, judging from the condition of the great toe in the foetus; and\nour progenitors, no doubt, were arboreal in their habits, and frequented\nsome warm, forest-clad land.  The males had great canine teeth, which\nserved them as formidable weapons.  At a much earlier period the uterus was\ndouble; the excreta were voided through a cloaca; and the eye was protected\nby a third eyelid or nictitating membrane.  At a still earlier period the\nprogenitors of man must have been aquatic in their habits; for morphology\nplainly tells us that our lungs consist of a modified swim-bladder, which\nonce served as a float.  The clefts on the neck in the embryo of man shew\nwhere the branchiae once existed.  In the lunar or weekly recurrent periods\nof some of our functions we apparently still retain traces of our\nprimordial birthplace, a shore washed by the tides.  At about this same\nearly period the true kidneys were replaced by the corpora wolffiana.  The\nheart existed as a simple pulsating vessel; and the chorda dorsalis took\nthe place of a vertebral column.  These early ancestors of man, thus seen\nin the dim recesses of time, must have been as simply, or even still more\nsimply organised than the lancelet or amphioxus.\n\nThere is one other point deserving a fuller notice.  It has long been known\nthat in the vertebrate kingdom one sex bears rudiments of various accessory\nparts, appertaining to the reproductive system, which properly belong to\nthe opposite sex; and it has now been ascertained that at a very early\nembryonic period both sexes possess true male and female glands.  Hence\nsome remote progenitor of the whole vertebrate kingdom appears to have been\nhermaphrodite or androgynous.  (26.  This is the conclusion of Prof.\nGegenbaur, one of the highest authorities in comparative anatomy:  see\n'Grundzuege der vergleich. Anat.' 1870, s. 876.  The result has been arrived\nat chiefly from the study of the Amphibia; but it appears from the\nresearches of Waldeyer (as quoted in 'Journal of Anat. and Phys.' 1869, p.\n161), that the sexual organs of even \"the higher vertebrata are, in their\nearly condition, hermaphrodite.\"  Similar views have long been held by some\nauthors, though until recently without a firm basis.)  But here we\nencounter a singular difficulty.  In the mammalian class the males possess\nrudiments of a uterus with the adjacent passage, in their vesiculae\nprostaticae; they bear also rudiments of mammae, and some male Marsupials\nhave traces of a marsupial sack.  (27.  The male Thylacinus offers the best\ninstance.  Owen, 'Anatomy of Vertebrates,' vol. iii. p. 771.)  Other\nanalogous facts could be added.  Are we, then, to suppose that some\nextremely ancient mammal continued androgynous, after it had acquired the\nchief distinctions of its class, and therefore after it had diverged from\nthe lower classes of the vertebrate kingdom?  This seems very improbable,\nfor we have to look to fishes, the lowest of all the classes, to find any\nstill existent androgynous forms.  (28.  Hermaphroditism has been observed\nin several species of Serranus, as well as in some other fishes, where it\nis either normal and symmetrical, or abnormal and unilateral.  Dr.\nZouteveen has given me references on this subject, more especially to a\npaper by Prof. Halbertsma, in the 'Transact. of the Dutch Acad. of\nSciences,' vol. xvi.  Dr. Gunther doubts the fact, but it has now been\nrecorded by too many good observers to be any longer disputed.  Dr. M.\nLessona writes to me, that he has verified the observations made by\nCavolini on Serranus.  Prof. Ercolani has recently shewn ('Accad. delle\nScienze,' Bologna, Dec. 28, 1871) that eels are androgynous.)  That various\naccessory parts, proper to each sex, are found in a rudimentary condition\nin the opposite sex, may be explained by such organs having been gradually\nacquired by the one sex, and then transmitted in a more or less imperfect\nstate to the other.  When we treat of sexual selection, we shall meet with\ninnumerable instances of this form of transmission,--as in the case of the\nspurs, plumes, and brilliant colours, acquired for battle or ornament by\nmale birds, and inherited by the females in an imperfect or rudimentary\ncondition.\n\nThe possession by male mammals of functionally imperfect mammary organs is,\nin some respects, especially curious.  The Monotremata have the proper\nmilk-secreting glands with orifices, but no nipples; and as these animals\nstand at the very base of the mammalian series, it is probable that the\nprogenitors of the class also had milk-secreting glands, but no nipples.\nThis conclusion is supported by what is known of their manner of\ndevelopment; for Professor Turner informs me, on the authority of Kolliker\nand Langer, that in the embryo the mammary glands can be distinctly traced\nbefore the nipples are in the least visible; and the development of\nsuccessive parts in the individual generally represents and accords with\nthe development of successive beings in the same line of descent.  The\nMarsupials differ from the Monotremata by possessing nipples; so that\nprobably these organs were first acquired by the Marsupials, after they had\ndiverged from, and risen above, the Monotremata, and were then transmitted\nto the placental mammals.  (29.  Prof. Gegenbaur has shewn ('Jenaeische\nZeitschrift,' Bd. vii. p. 212) that two distinct types of nipples prevail\nthroughout the several mammalian orders, but that it is quite intelligible\nhow both could have been derived from the nipples of the Marsupials, and\nthe latter from those of the Monotremata.  See, also, a memoir by Dr. Max\nHuss, on the mammary glands, ibid. B. viii. p. 176.)  No one will suppose\nthat the marsupials still remained androgynous, after they had\napproximately acquired their present structure.  How then are we to account\nfor male mammals possessing mammae?  It is possible that they were first\ndeveloped in the females and then transferred to the males, but from what\nfollows this is hardly probable.\n\nIt may be suggested, as another view, that long after the progenitors of\nthe whole mammalian class had ceased to be androgynous, both sexes yielded\nmilk, and thus nourished their young; and in the case of the Marsupials,\nthat both sexes carried their young in marsupial sacks.  This will not\nappear altogether improbable, if we reflect that the males of existing\nsyngnathous fishes receive the eggs of the females in their abdominal\npouches, hatch them, and afterwards, as some believe, nourish the young\n(30.  Mr. Lockwood believes (as quoted in 'Quart. Journal of Science,'\nApril 1868, p. 269), from what he has observed of the development of\nHippocampus, that the walls of the abdominal pouch of the male in some way\nafford nourishment.  On male fishes hatching the ova in their mouths, see a\nvery interesting paper by Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.'\nSept. 15, 1857; also Prof. Turner, in 'Journal of Anatomy and Physiology,'\nNov. 1, 1866, p. 78.  Dr. Gunther has likewise described similar cases.);--\nthat certain other male fishes hatch the eggs within their mouths or\nbranchial cavities;--that certain male toads take the chaplets of eggs from\nthe females, and wind them round their own thighs, keeping them there until\nthe tadpoles are born;--that certain male birds undertake the whole duty of\nincubation, and that male pigeons, as well as the females, feed their\nnestlings with a secretion from their crops.  But the above suggestion\nfirst occurred to me from mammary glands of male mammals being so much more\nperfectly developed than the rudiments of the other accessory reproductive\nparts, which are found in the one sex though proper to the other.  The\nmammary glands and nipples, as they exist in male mammals, can indeed\nhardly be called rudimentary; they are merely not fully developed, and not\nfunctionally active.  They are sympathetically affected under the influence\nof certain diseases, like the same organs in the female.  They often\nsecrete a few drops of milk at birth and at puberty:  this latter fact\noccurred in the curious case, before referred to, where a young man\npossessed two pairs of mammae.  In man and some other male mammals these\norgans have been known occasionally to become so well developed during\nmaturity as to yield a fair supply of milk.  Now if we suppose that during\na former prolonged period male mammals aided the females in nursing their\noffspring (31.  Mlle. C. Royer has suggested a similar view in her 'Origine\nde l'homme,' etc., 1870.), and that afterwards from some cause (as from the\nproduction of a smaller number of young) the males ceased to give this aid,\ndisuse of the organs during maturity would lead to their becoming inactive;\nand from two well-known principles of inheritance, this state of inactivity\nwould probably be transmitted to the males at the corresponding age of\nmaturity.  But at an earlier age these organs would be left unaffected, so\nthat they would be almost equally well developed in the young of both\nsexes.\n\nCONCLUSION.\n\nVon Baer has defined advancement or progress in the organic scale better\nthan any one else, as resting on the amount of differentiation and\nspecialisation of the several parts of a being,--when arrived at maturity,\nas I should be inclined to add.  Now as organisms have become slowly\nadapted to diversified lines of life by means of natural selection, their\nparts will have become more and more differentiated and specialised for\nvarious functions from the advantage gained by the division of\nphysiological labour.  The same part appears often to have been modified\nfirst for one purpose, and then long afterwards for some other and quite\ndistinct purpose; and thus all the parts are rendered more and more\ncomplex.  But each organism still retains the general type of structure of\nthe progenitor from which it was aboriginally derived.  In accordance with\nthis view it seems, if we turn to geological evidence, that organisation on\nthe whole has advanced throughout the world by slow and interrupted steps.\nIn the great kingdom of the Vertebrata it has culminated in man.  It must\nnot, however, be supposed that groups of organic beings are always\nsupplanted, and disappear as soon as they have given birth to other and\nmore perfect groups.  The latter, though victorious over their\npredecessors, may not have become better adapted for all places in the\neconomy of nature.  Some old forms appear to have survived from inhabiting\nprotected sites, where they have not been exposed to very severe\ncompetition; and these often aid us in constructing our genealogies, by\ngiving us a fair idea of former and lost populations.  But we must not fall\ninto the error of looking at the existing members of any lowly-organised\ngroup as perfect representatives of their ancient predecessors.\n\nThe most ancient progenitors in the kingdom of the Vertebrata, at which we\nare able to obtain an obscure glance, apparently consisted of a group of\nmarine animals (32.  The inhabitants of the seashore must be greatly\naffected by the tides; animals living either about the MEAN high-water\nmark, or about the MEAN low-water mark, pass through a complete cycle of\ntidal changes in a fortnight.  Consequently, their food supply will undergo\nmarked changes week by week.  The vital functions of such animals, living\nunder these conditions for many generations, can hardly fail to run their\ncourse in regular weekly periods.  Now it is a mysterious fact that in the\nhigher and now terrestrial Vertebrata, as well as in other classes, many\nnormal and abnormal processes have one or more whole weeks as their\nperiods; this would be rendered intelligible if the Vertebrata are\ndescended from an animal allied to the existing tidal Ascidians.  Many\ninstances of such periodic processes might be given, as the gestation of\nmammals, the duration of fevers, etc.  The hatching of eggs affords also a\ngood example, for, according to Mr. Bartlett ('Land and Water,' Jan. 7,\n1871), the eggs of the pigeon are hatched in two weeks; those of the fowl\nin three; those of the duck in four; those of the goose in five; and those\nof the ostrich in seven weeks.  As far as we can judge, a recurrent period,\nif approximately of the right duration for any process or function, would\nnot, when once gained, be liable to change; consequently it might be thus\ntransmitted through almost any number of generations.  But if the function\nchanged, the period would have to change, and would be apt to change almost\nabruptly by a whole week.  This conclusion, if sound, is highly remarkable;\nfor the period of gestation in each mammal, and the hatching of each bird's\neggs, and many other vital processes, thus betray to us the primordial\nbirthplace of these animals.), resembling the larvae of existing Ascidians.\nThese animals probably gave rise to a group of fishes, as lowly organised\nas the lancelet; and from these the Ganoids, and other fishes like the\nLepidosiren, must have been developed.  From such fish a very small advance\nwould carry us on to the Amphibians.  We have seen that birds and reptiles\nwere once intimately connected together; and the Monotremata now connect\nmammals with reptiles in a slight degree.  But no one can at present say by\nwhat line of descent the three higher and related classes, namely, mammals,\nbirds, and reptiles, were derived from the two lower vertebrate classes,\nnamely, amphibians and fishes.  In the class of mammals the steps are not\ndifficult to conceive which led from the ancient Monotremata to the ancient\nMarsupials; and from these to the early progenitors of the placental\nmammals.  We may thus ascend to the Lemuridae; and the interval is not very\nwide from these to the Simiadae.  The Simiadae then branched off into two\ngreat stems, the New World and Old World monkeys; and from the latter, at a\nremote period, Man, the wonder and glory of the Universe, proceeded.\n\nThus we have given to man a pedigree of prodigious length, but not, it may\nbe said, of noble quality.  The world, it has often been remarked, appears\nas if it had long been preparing for the advent of man:  and this, in one\nsense is strictly true, for he owes his birth to a long line of\nprogenitors.  If any single link in this chain had never existed, man would\nnot have been exactly what he now is.  Unless we wilfully close our eyes,\nwe may, with our present knowledge, approximately recognise our parentage;\nnor need we feel ashamed of it.  The most humble organism is something much\nhigher than the inorganic dust under our feet; and no one with an unbiassed\nmind can study any living creature, however humble, without being struck\nwith enthusiasm at its marvellous structure and properties.\n\n\nCHAPTER VII.\n\nON THE RACES OF MAN.\n\nThe nature and value of specific characters--Application to the races of\nman--Arguments in favour of, and opposed to, ranking the so-called races of\nman as distinct species--Sub-species--Monogenists and polygenists--\nConvergence of character--Numerous points of resemblance in body and mind\nbetween the most distinct races of man--The state of man when he first\nspread over the earth--Each race not descended from a single pair--The\nextinction of races--The formation of races--The effects of crossing--\nSlight influence of the direct action of the conditions of life--Slight or\nno influence of natural selection--Sexual selection.\n\nIt is not my intention here to describe the several so-called races of men;\nbut I am about to enquire what is the value of the differences between them\nunder a classificatory point of view, and how they have originated.  In\ndetermining whether two or more allied forms ought to be ranked as species\nor varieties, naturalists are practically guided by the following\nconsiderations; namely, the amount of difference between them, and whether\nsuch differences relate to few or many points of structure, and whether\nthey are of physiological importance; but more especially whether they are\nconstant.  Constancy of character is what is chiefly valued and sought for\nby naturalists.  Whenever it can be shewn, or rendered probable, that the\nforms in question have remained distinct for a long period, this becomes an\nargument of much weight in favour of treating them as species.  Even a\nslight degree of sterility between any two forms when first crossed, or in\ntheir offspring, is generally considered as a decisive test of their\nspecific distinctness; and their continued persistence without blending\nwithin the same area, is usually accepted as sufficient evidence, either of\nsome degree of mutual sterility, or in the case of animals of some mutual\nrepugnance to pairing.\n\nIndependently of fusion from intercrossing, the complete absence, in a\nwell-investigated region, of varieties linking together any two closely-\nallied forms, is probably the most important of all the criterions of their\nspecific distinctness; and this is a somewhat different consideration from\nmere constancy of character, for two forms may be highly variable and yet\nnot yield intermediate varieties.  Geographical distribution is often\nbrought into play unconsciously and sometimes consciously; so that forms\nliving in two widely separated areas, in which most of the other\ninhabitants are specifically distinct, are themselves usually looked at as\ndistinct; but in truth this affords no aid in distinguishing geographical\nraces from so-called good or true species.\n\nNow let us apply these generally-admitted principles to the races of man,\nviewing him in the same spirit as a naturalist would any other animal.  In\nregard to the amount of difference between the races, we must make some\nallowance for our nice powers of discrimination gained by the long habit of\nobserving ourselves.  In India, as Elphinstone remarks, although a newly-\narrived European cannot at first distinguish the various native races, yet\nthey soon appear to him extremely dissimilar (1.  'History of India,' 1841,\nvol. i. p. 323.  Father Ripa makes exactly the same remark with respect to\nthe Chinese.); and the Hindoo cannot at first perceive any difference\nbetween the several European nations.  Even the most distinct races of man\nare much more like each other in form than would at first be supposed;\ncertain negro tribes must be excepted, whilst others, as Dr. Rohlfs writes\nto me, and as I have myself seen, have Caucasian features.  This general\nsimilarity is well shewn by the French photographs in the Collection\nAnthropologique du Museum de Paris of the men belonging to various races,\nthe greater number of which might pass for Europeans, as many persons to\nwhom I have shewn them have remarked.  Nevertheless, these men, if seen\nalive, would undoubtedly appear very distinct, so that we are clearly much\ninfluenced in our judgment by the mere colour of the skin and hair, by\nslight differences in the features, and by expression.\n\nThere is, however, no doubt that the various races, when carefully compared\nand measured, differ much from each other,--as in the texture of the hair,\nthe relative proportions of all parts of the body (2.  A vast number of\nmeasurements of Whites, Blacks, and Indians, are given in the\n'Investigations in the Military and Anthropolog. Statistics of American\nSoldiers,' by B.A. Gould, 1869, pp. 298-358; 'On the capacity of the\nlungs,' p. 471.  See also the numerous and valuable tables, by Dr.\nWeisbach, from the observations of Dr. Scherzer and Dr. Schwarz, in the\n'Reise der Novara:  Anthropolog. Theil,' 1867.), the capacity of the lungs,\nthe form and capacity of the skull, and even in the convolutions of the\nbrain.  (3.  See, for instance, Mr. Marshall's account of the brain of a\nBushwoman, in 'Philosophical Transactions,' 1864, p. 519.)  But it would be\nan endless task to specify the numerous points of difference.  The races\ndiffer also in constitution, in acclimatisation and in liability to certain\ndiseases.  Their mental characteristics are likewise very distinct; chiefly\nas it would appear in their emotional, but partly in their intellectual\nfaculties.  Every one who has had the opportunity of comparison, must have\nbeen struck with the contrast between the taciturn, even morose, aborigines\nof S. America and the light-hearted, talkative negroes.  There is a nearly\nsimilar contrast between the Malays and the Papuans (4.  Wallace, 'The\nMalay Archipelago,' vol. ii. 1869, p. 178.), who live under the same\nphysical conditions, and are separated from each other only by a narrow\nspace of sea.\n\nWe will first consider the arguments which may be advanced in favour of\nclassing the races of man as distinct species, and then the arguments on\nthe other side.  If a naturalist, who had never before seen a Negro,\nHottentot, Australian, or Mongolian, were to compare them, he would at once\nperceive that they differed in a multitude of characters, some of slight\nand some of considerable importance.  On enquiry he would find that they\nwere adapted to live under widely different climates, and that they\ndiffered somewhat in bodily constitution and mental disposition.  If he\nwere then told that hundreds of similar specimens could be brought from the\nsame countries, he would assuredly declare that they were as good species\nas many to which he had been in the habit of affixing specific names.  This\nconclusion would be greatly strengthened as soon as he had ascertained that\nthese forms had all retained the same character for many centuries; and\nthat negroes, apparently identical with existing negroes, had lived at\nleast 4000 years ago.  (5.  With respect to the figures in the famous\nEgyptian caves of Abou-Simbel, M. Pouchet says ('The Plurality of the Human\nRaces,' Eng. translat., 1864, p. 50), that he was far from finding\nrecognisable representations of the dozen or more nations which some\nauthors believe that they can recognise.  Even some of the most strongly-\nmarked races cannot be identified with that degree of unanimity which might\nhave been expected from what has been written on the subject.  Thus Messrs.\nNott and Gliddon ('Types of Mankind,' p. 148), state that Rameses II., or\nthe Great, has features superbly European; whereas Knox, another firm\nbeliever in the specific distinctness of the races of man ('Races of Man,'\n1850, p. 201), speaking of young Memnon (the same as Rameses II., as I am\ninformed by Mr. Birch), insists in the strongest manner that he is\nidentical in character with the Jews of Antwerp.  Again, when I looked at\nthe statue of Amunoph III., I agreed with two officers of the\nestablishment, both competent judges, that he had a strongly-marked negro\ntype of features; but Messrs. Nott and Gliddon (ibid. p. 146, fig. 53),\ndescribe him as a hybrid, but not of \"negro intermixture.\")  He would also\nhear, on the authority of an excellent observer, Dr. Lund (6.  As quoted by\nNott and Gliddon, 'Types of Mankind,' 1854, p. 439.  They give also\ncorroborative evidence; but C. Vogt thinks that the subject requires\nfurther investigation.), that the human skulls found in the caves of\nBrazil, entombed with many extinct mammals, belonged to the same type as\nthat now prevailing throughout the American Continent.\n\nOur naturalist would then perhaps turn to geographical distribution, and he\nwould probably declare that those forms must be distinct species, which\ndiffer not only in appearance, but are fitted for hot, as well as damp or\ndry countries, and for the Arctic regions.  He might appeal to the fact that\nno species in the group next to man--namely, the Quadrumana, can resist a\nlow temperature, or any considerable change of climate; and that the\nspecies which come nearest to man have never been reared to maturity, even\nunder the temperate climate of Europe.  He would be deeply impressed with\nthe fact, first noticed by Agassiz (7.  'Diversity of Origin of the Human\nRaces,' in the 'Christian Examiner,' July 1850.), that the different races\nof man are distributed over the world in the same zoological provinces, as\nthose inhabited by undoubtedly distinct species and genera of mammals.\nThis is manifestly the case with the Australian, Mongolian, and Negro races\nof man; in a less well-marked manner with the Hottentots; but plainly with\nthe Papuans and Malays, who are separated, as Mr. Wallace has shewn, by\nnearly the same line which divides the great Malayan and Australian\nzoological provinces.  The Aborigines of America range throughout the\nContinent; and this at first appears opposed to the above rule, for most of\nthe productions of the Southern and Northern halves differ widely:  yet\nsome few living forms, as the opossum, range from the one into the other,\nas did formerly some of the gigantic Edentata.  The Esquimaux, like other\nArctic animals, extend round the whole polar regions.  It should be\nobserved that the amount of difference between the mammals of the several\nzoological provinces does not correspond with the degree of separation\nbetween the latter; so that it can hardly be considered as an anomaly that\nthe Negro differs more, and the American much less from the other races of\nman, than do the mammals of the African and American continents from the\nmammals of the other provinces.  Man, it may be added, does not appear to\nhave aboriginally inhabited any oceanic island; and in this respect, he\nresembles the other members of his class.\n\nIn determining whether the supposed varieties of the same kind of domestic\nanimal should be ranked as such, or as specifically distinct, that is,\nwhether any of them are descended from distinct wild species, every\nnaturalist would lay much stress on the fact of their external parasites\nbeing specifically distinct.  All the more stress would be laid on this\nfact, as it would be an exceptional one; for I am informed by Mr. Denny\nthat the most different kinds of dogs, fowls, and pigeons, in England, are\ninfested by the same species of Pediculi or lice.  Now Mr. A. Murray has\ncarefully examined the Pediculi collected in different countries from the\ndifferent races of man (8.  'Transactions of the Royal Society of\nEdinburgh,' vol. xxii, 1861, p. 567.); and he finds that they differ, not\nonly in colour, but in the structure of their claws and limbs.  In every\ncase in which many specimens were obtained the differences were constant.\nThe surgeon of a whaling ship in the Pacific assured me that when the\nPediculi, with which some Sandwich Islanders on board swarmed, strayed on\nto the bodies of the English sailors, they died in the course of three or\nfour days.  These Pediculi were darker coloured, and appeared different\nfrom those proper to the natives of Chiloe in South America, of which he\ngave me specimens.  These, again, appeared larger and much softer than\nEuropean lice.  Mr. Murray procured four kinds from Africa, namely, from\nthe Negroes of the Eastern and Western coasts, from the Hottentots and\nKaffirs; two kinds from the natives of Australia; two from North and two\nfrom South America.  In these latter cases it may be presumed that the\nPediculi came from natives inhabiting different districts.  With insects\nslight structural differences, if constant, are generally esteemed of\nspecific value:  and the fact of the races of man being infested by\nparasites, which appear to be specifically distinct, might fairly be urged\nas an argument that the races themselves ought to be classed as distinct\nspecies.\n\nOur supposed naturalist having proceeded thus far in his investigation,\nwould next enquire whether the races of men, when crossed, were in any\ndegree sterile.  He might consult the work (9.  'On the Phenomena of\nHybridity in the Genus Homo,' Eng. translat., 1864.) of Professor Broca, a\ncautious and philosophical observer, and in this he would find good\nevidence that some races were quite fertile together, but evidence of an\nopposite nature in regard to other races.  Thus it has been asserted that\nthe native women of Australia and Tasmania rarely produce children to\nEuropean men; the evidence, however, on this head has now been shewn to be\nalmost valueless.  The half-castes are killed by the pure blacks:  and an\naccount has lately been published of eleven half-caste youths murdered and\nburnt at the same time, whose remains were found by the police.  (10.  See\nthe interesting letter by Mr. T.A. Murray, in the 'Anthropological Review,'\nApril 1868, p. liii.  In this letter Count Strzelecki's statement that\nAustralian women who have borne children to a white man, are afterwards\nsterile with their own race, is disproved.  M. A. de Quatrefages has also\ncollected (Revue des Cours Scientifiques, March, 1869, p. 239), much\nevidence that Australians and Europeans are not sterile when crossed.)\nAgain, it has often been said that when mulattoes intermarry, they produce\nfew children; on the other hand, Dr. Bachman, of Charleston (11.  'An\nExamination of Prof. Agassiz's Sketch of the Nat. Provinces of the Animal\nWorld,' Charleston, 1855, p. 44.), positively asserts that he has known\nmulatto families which have intermarried for several generations, and have\ncontinued on an average as fertile as either pure whites or pure blacks.\nEnquiries formerly made by Sir C. Lyell on this subject led him, as he\ninforms me, to the same conclusion.  (12.  Dr. Rohlfs writes to me that he\nfound the mixed races in the Great Sahara, derived from Arabs, Berbers, and\nNegroes of three tribes, extraordinarily fertile.  On the other hand, Mr.\nWinwood Reade informs me that the Negroes on the Gold Coast, though\nadmiring white men and mulattoes, have a maxim that mulattoes should not\nintermarry, as the children are few and sickly.  This belief, as Mr. Reade\nremarks, deserves attention, as white men have visited and resided on the\nGold Coast for four hundred years, so that the natives have had ample time\nto gain knowledge through experience.)  In the United States the census for\nthe year 1854 included, according to Dr. Bachman, 405,751 mulattoes; and\nthis number, considering all the circumstances of the case, seems small;\nbut it may partly be accounted for by the degraded and anomalous position\nof the class, and by the profligacy of the women.  A certain amount of\nabsorption of mulattoes into negroes must always be in progress; and this\nwould lead to an apparent diminution of the former.  The inferior vitality\nof mulattoes is spoken of in a trustworthy work (13.  'Military and\nAnthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p.\n319.) as a well-known phenomenon; and this, although a different\nconsideration from their lessened fertility, may perhaps be advanced as a\nproof of the specific distinctness of the parent races.  No doubt both\nanimal and vegetable hybrids, when produced from extremely distinct\nspecies, are liable to premature death; but the parents of mulattoes cannot\nbe put under the category of extremely distinct species.  The common Mule,\nso notorious for long life and vigour, and yet so sterile, shews how little\nnecessary connection there is in hybrids between lessened fertility and\nvitality; other analogous cases could be cited.\n\nEven if it should hereafter be proved that all the races of men were\nperfectly fertile together, he who was inclined from other reasons to rank\nthem as distinct species, might with justice argue that fertility and\nsterility are not safe criterions of specific distinctness.  We know that\nthese qualities are easily affected by changed conditions of life, or by\nclose inter-breeding, and that they are governed by highly complex laws,\nfor instance, that of the unequal fertility of converse crosses between the\nsame two species.  With forms which must be ranked as undoubted species, a\nperfect series exists from those which are absolutely sterile when crossed,\nto those which are almost or completely fertile.  The degrees of sterility\ndo not coincide strictly with the degrees of difference between the parents\nin external structure or habits of life.  Man in many respects may be\ncompared with those animals which have long been domesticated, and a large\nbody of evidence can be advanced in favour of the Pallasian doctrine (14.\nThe 'Variation of Animals and Plants under Domestication,' vol. ii. p. 109.\nI may here remind the reader that the sterility of species when crossed is\nnot a specially-acquired quality, but, like the incapacity of certain trees\nto be grafted together, is incidental on other acquired differences.  The\nnature of these differences is unknown, but they relate more especially to\nthe reproductive system, and much less so to external structure or to\nordinary differences in constitution.  One important element in the\nsterility of crossed species apparently lies in one or both having been\nlong habituated to fixed conditions; for we know that changed conditions\nhave a special influence on the reproductive system, and we have good\nreason to believe (as before remarked) that the fluctuating conditions of\ndomestication tend to eliminate that sterility which is so general with\nspecies, in a natural state, when crossed.  It has elsewhere been shewn by\nme (ibid. vol. ii. p. 185, and 'Origin of Species,' 5th edit. p. 317), that\nthe sterility of crossed species has not been acquired through natural\nselection:  we can see that when two forms have already been rendered very\nsterile, it is scarcely possible that their sterility should be augmented\nby the preservation or survival of the more and more sterile individuals;\nfor, as the sterility increases, fewer and fewer offspring will be produced\nfrom which to breed, and at last only single individuals will be produced\nat the rarest intervals.  But there is even a higher grade of sterility\nthan this.  Both Gartner and Kolreuter have proved that in genera of\nplants, including many species, a series can be formed from species which,\nwhen crossed, yield fewer and fewer seeds, to species which never produce a\nsingle seed, but yet are affected by the pollen of the other species, as\nshewn by the swelling of the germen.  It is here manifestly impossible to\nselect the more sterile individuals, which have already ceased to yield\nseeds; so that the acme of sterility, when the germen alone is affected,\ncannot have been gained through selection.  This acme, and no doubt the\nother grades of sterility, are the incidental results of certain unknown\ndifferences in the constitution of the reproductive system of the species\nwhich are crossed.), that domestication tends to eliminate the sterility\nwhich is so general a result of the crossing of species in a state of\nnature.  From these several considerations, it may be justly urged that the\nperfect fertility of the intercrossed races of man, if established, would\nnot absolutely preclude us from ranking them as distinct species.\n\nIndependently of fertility, the characters presented by the offspring from\na cross have been thought to indicate whether or not the parent-forms ought\nto be ranked as species or varieties; but after carefully studying the\nevidence, I have come to the conclusion that no general rules of this kind\ncan be trusted.  The ordinary result of a cross is the production of a\nblended or intermediate form; but in certain cases some of the offspring\ntake closely after one parent-form, and some after the other.  This is\nespecially apt to occur when the parents differ in characters which first\nappeared as sudden variations or monstrosities.  (15.  'The Variation of\nAnimals,' etc., vol. ii. p. 92.)  I refer to this point, because Dr. Rohlfs\ninforms me that he has frequently seen in Africa the offspring of negroes\ncrossed with members of other races, either completely black or completely\nwhite, or rarely piebald.  On the other hand, it is notorious that in\nAmerica mulattoes commonly present an intermediate appearance.\n\nWe have now seen that a naturalist might feel himself fully justified in\nranking the races of man as distinct species; for he has found that they\nare distinguished by many differences in structure and constitution, some\nbeing of importance.  These differences have, also, remained nearly\nconstant for very long periods of time.  Our naturalist will have been in\nsome degree influenced by the enormous range of man, which is a great\nanomaly in the class of mammals, if mankind be viewed as a single species.\nHe will have been struck with the distribution of the several so-called\nraces, which accords with that of other undoubtedly distinct species of\nmammals.  Finally, he might urge that the mutual fertility of all the races\nhas not as yet been fully proved, and even if proved would not be an\nabsolute proof of their specific identity.\n\nOn the other side of the question, if our supposed naturalist were to\nenquire whether the forms of man keep distinct like ordinary species, when\nmingled together in large numbers in the same country, he would immediately\ndiscover that this was by no means the case.  In Brazil he would behold an\nimmense mongrel population of Negroes and Portuguese; in Chiloe, and other\nparts of South America, he would behold the whole population consisting of\nIndians and Spaniards blended in various degrees.  (16.  M. de Quatrefages\nhas given ('Anthropological Review,' Jan. 1869, p. 22), an interesting\naccount of the success and energy of the Paulistas in Brazil, who are a\nmuch crossed race of Portuguese and Indians, with a mixture of the blood of\nother races.)  In many parts of the same continent he would meet with the\nmost complex crosses between Negroes, Indians, and Europeans; and judging\nfrom the vegetable kingdom, such triple crosses afford the severest test of\nthe mutual fertility of the parent forms.  In one island of the Pacific he\nwould find a small population of mingled Polynesian and English blood; and\nin the Fiji Archipelago a population of Polynesian and Negritos crossed in\nall degrees.  Many analogous cases could be added; for instance, in Africa.\nHence the races of man are not sufficiently distinct to inhabit the same\ncountry without fusion; and the absence of fusion affords the usual and\nbest test of specific distinctness.\n\nOur naturalist would likewise be much disturbed as soon as he perceived\nthat the distinctive characters of all the races were highly variable.\nThis fact strikes every one on first beholding the negro slaves in Brazil,\nwho have been imported from all parts of Africa.  The same remark holds\ngood with the Polynesians, and with many other races.  It may be doubted\nwhether any character can be named which is distinctive of a race and is\nconstant.  Savages, even within the limits of the same tribe, are not\nnearly so uniform in character, as has been often asserted.  Hottentot\nwomen offer certain peculiarities, more strongly marked than those\noccurring in any other race, but these are known not to be of constant\noccurrence.  In the several American tribes, colour and hairiness differ\nconsiderably; as does colour to a certain degree, and the shape of the\nfeatures greatly, in the Negroes of Africa.  The shape of the skull varies\nmuch in some races (17.  For instance, with the aborigines of America and\nAustralia, Prof. Huxley says ('Transact. Internat. Congress of Prehist.\nArch.' 1868, p. 105), that the skulls of many South Germans and Swiss are\n\"as short and as broad as those of the Tartars,\" etc.); and so it is with\nevery other character.  Now all naturalists have learnt by dearly bought\nexperience, how rash it is to attempt to define species by the aid of\ninconstant characters.\n\nBut the most weighty of all the arguments against treating the races of man\nas distinct species, is that they graduate into each other, independently\nin many cases, as far as we can judge, of their having intercrossed.  Man\nhas been studied more carefully than any other animal, and yet there is the\ngreatest possible diversity amongst capable judges whether he should be\nclassed as a single species or race, or as two (Virey), as three\n(Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven\n(Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent),\nsixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-\nthree, according to Burke.  (18.  See a good discussion on this subject in\nWaitz, 'Introduction to Anthropology,' Eng. translat., 1863, pp. 198-208,\n227.  I have taken some of the above statements from H. Tuttle's 'Origin\nand Antiquity of Physical Man,' Boston, 1866, p. 35.)  This diversity of\njudgment does not prove that the races ought not to be ranked as species,\nbut it shews that they graduate into each other, and that it is hardly\npossible to discover clear distinctive characters between them.\n\nEvery naturalist who has had the misfortune to undertake the description of\na group of highly varying organisms, has encountered cases (I speak after\nexperience) precisely like that of man; and if of a cautious disposition,\nhe will end by uniting all the forms which graduate into each other, under\na single species; for he will say to himself that he has no right to give\nnames to objects which he cannot define.  Cases of this kind occur in the\nOrder which includes man, namely in certain genera of monkeys; whilst in\nother genera, as in Cercopithecus, most of the species can be determined\nwith certainty.  In the American genus Cebus, the various forms are ranked\nby some naturalists as species, by others as mere geographical races.  Now\nif numerous specimens of Cebus were collected from all parts of South\nAmerica, and those forms which at present appear to be specifically\ndistinct, were found to graduate into each other by close steps, they would\nusually be ranked as mere varieties or races; and this course has been\nfollowed by most naturalists with respect to the races of man.\nNevertheless, it must be confessed that there are forms, at least in the\nvegetable kingdom (19.  Prof. Nageli has carefully described several\nstriking cases in his 'Botanische Mittheilungen,' B. ii. 1866, ss. 294-369.\nProf. Asa Gray has made analogous remarks on some intermediate forms in the\nCompositae of N. America.), which we cannot avoid naming as species, but\nwhich are connected together by numberless gradations, independently of\nintercrossing.\n\nSome naturalists have lately employed the term \"sub-species\" to designate\nforms which possess many of the characteristics of true species, but which\nhardly deserve so high a rank.  Now if we reflect on the weighty arguments\nabove given, for raising the races of man to the dignity of species, and\nthe insuperable difficulties on the other side in defining them, it seems\nthat the term \"sub-species\" might here be used with propriety.  But from\nlong habit the term \"race\" will perhaps always be employed.  The choice of\nterms is only so far important in that it is desirable to use, as far as\npossible, the same terms for the same degrees of difference.  Unfortunately\nthis can rarely be done:  for the larger genera generally include closely-\nallied forms, which can be distinguished only with much difficulty, whilst\nthe smaller genera within the same family include forms that are perfectly\ndistinct; yet all must be ranked equally as species.  So again, species\nwithin the same large genus by no means resemble each other to the same\ndegree:  on the contrary, some of them can generally be arranged in little\ngroups round other species, like satellites round planets.  (20.  'Origin\nof Species,' 5th edit. p. 68.)\n\nThe question whether mankind consists of one or several species has of late\nyears been much discussed by anthropologists, who are divided into the two\nschools of monogenists and polygenists.  Those who do not admit the\nprinciple of evolution, must look at species as separate creations, or in\nsome manner as distinct entities; and they must decide what forms of man\nthey will consider as species by the analogy of the method commonly pursued\nin ranking other organic beings as species.  But it is a hopeless endeavour\nto decide this point, until some definition of the term \"species\" is\ngenerally accepted; and the definition must not include an indeterminate\nelement such as an act of creation.  We might as well attempt without any\ndefinition to decide whether a certain number of houses should be called a\nvillage, town, or city.  We have a practical illustration of the difficulty\nin the never-ending doubts whether many closely-allied mammals, birds,\ninsects, and plants, which represent each other respectively in North\nAmerica and Europe, should be ranked as species or geographical races; and\nthe like holds true of the productions of many islands situated at some\nlittle distance from the nearest continent.\n\nThose naturalists, on the other hand, who admit the principle of evolution,\nand this is now admitted by the majority of rising men, will feel no doubt\nthat all the races of man are descended from a single primitive stock;\nwhether or not they may think fit to designate the races as distinct\nspecies, for the sake of expressing their amount of difference.  (21.  See\nProf. Huxley to this effect in the 'Fortnightly Review,' 1865, p. 275.)\nWith our domestic animals the question whether the various races have\narisen from one or more species is somewhat different.  Although it may be\nadmitted that all the races, as well as all the natural species within the\nsame genus, have sprung from the same primitive stock, yet it is a fit\nsubject for discussion, whether all the domestic races of the dog, for\ninstance, have acquired their present amount of difference since some one\nspecies was first domesticated by man; or whether they owe some of their\ncharacters to inheritance from distinct species, which had already been\ndifferentiated in a state of nature.  With man no such question can arise,\nfor he cannot be said to have been domesticated at any particular period.\n\nDuring an early stage in the divergence of the races of man from a common\nstock, the differences between the races and their number must have been\nsmall; consequently as far as their distinguishing characters are\nconcerned, they then had less claim to rank as distinct species than the\nexisting so-called races.  Nevertheless, so arbitrary is the term of\nspecies, that such early races would perhaps have been ranked by some\nnaturalists as distinct species, if their differences, although extremely\nslight, had been more constant than they are at present, and had not\ngraduated into each other.\n\nIt is however possible, though far from probable, that the early\nprogenitors of man might formerly have diverged much in character, until\nthey became more unlike each other than any now existing races; but that\nsubsequently, as suggested by Vogt (22.  'Lectures on Man,' Eng. translat.,\n1864, p. 468.), they converged in character.  When man selects the\noffspring of two distinct species for the same object, he sometimes induces\na considerable amount of convergence, as far as general appearance is\nconcerned.  This is the case, as shewn by von Nathusius (23.  'Die Rassen\ndes Schweines,' 1860, s. 46.  'Vorstudien fuer Geschichte,' etc.,\nSchweinesschaedel, 1864, s. 104.  With respect to cattle, see M. de\nQuatrefages, 'Unite de l'Espece Humaine,' 1861, p. 119.), with the improved\nbreeds of the pig, which are descended from two distinct species; and in a\nless marked manner with the improved breeds of cattle.  A great anatomist,\nGratiolet, maintains that the anthropomorphous apes do not form a natural\nsub-group; but that the orang is a highly developed gibbon or\nsemnopithecus, the chimpanzee a highly developed macacus, and the gorilla a\nhighly developed mandrill.  If this conclusion, which rests almost\nexclusively on brain-characters, be admitted, we should have a case of\nconvergence at least in external characters, for the anthropomorphous apes\nare certainly more like each other in many points, than they are to other\napes.  All analogical resemblances, as of a whale to a fish, may indeed be\nsaid to be cases of convergence; but this term has never been applied to\nsuperficial and adaptive resemblances.  It would, however, be extremely\nrash to attribute to convergence close similarity of character in many\npoints of structure amongst the modified descendants of widely distinct\nbeings.  The form of a crystal is determined solely by the molecular\nforces, and it is not surprising that dissimilar substances should\nsometimes assume the same form; but with organic beings we should bear in\nmind that the form of each depends on an infinity of complex relations,\nnamely on variations, due to causes far too intricate to be followed,--on\nthe nature of the variations preserved, these depending on the physical\nconditions, and still more on the surrounding organisms which compete with\neach,--and lastly, on inheritance (in itself a fluctuating element) from\ninnumerable progenitors, all of which have had their forms determined\nthrough equally complex relations.  It appears incredible that the modified\ndescendants of two organisms, if these differed from each other in a marked\nmanner, should ever afterwards converge so closely as to lead to a near\napproach to identity throughout their whole organisation.  In the case of\nthe convergent races of pigs above referred to, evidence of their descent\nfrom two primitive stocks is, according to von Nathusius, still plainly\nretained, in certain bones of their skulls.  If the races of man had\ndescended, as is supposed by some naturalists, from two or more species,\nwhich differed from each other as much, or nearly as much, as does the\norang from the gorilla, it can hardly be doubted that marked differences in\nthe structure of certain bones would still be discoverable in man as he now\nexists.\n\nAlthough the existing races of man differ in many respects, as in colour,\nhair, shape of skull, proportions of the body, etc., yet if their whole\nstructure be taken into consideration they are found to resemble each other\nclosely in a multitude of points.  Many of these are of so unimportant or\nof so singular a nature, that it is extremely improbable that they should\nhave been independently acquired by aboriginally distinct species or races.\nThe same remark holds good with equal or greater force with respect to the\nnumerous points of mental similarity between the most distinct races of\nman.  The American aborigines, Negroes and Europeans are as different from\neach other in mind as any three races that can be named; yet I was\nincessantly struck, whilst living with the Fuegians on board the \"Beagle,\"\nwith the many little traits of character, shewing how similar their minds\nwere to ours; and so it was with a full-blooded negro with whom I happened\nonce to be intimate.\n\nHe who will read Mr. Tylor's and Sir J. Lubbock's interesting works (24.\nTylor's 'Early History of Mankind,' 1865:  with respect to gesture-\nlanguage, see p. 54.  Lubbock's 'Prehistoric Times,' 2nd edit. 1869.) can\nhardly fail to be deeply impressed with the close similarity between the\nmen of all races in tastes, dispositions and habits.  This is shewn by the\npleasure which they all take in dancing, rude music, acting, painting,\ntattooing, and otherwise decorating themselves; in their mutual\ncomprehension of gesture-language, by the same expression in their\nfeatures, and by the same inarticulate cries, when excited by the same\nemotions.  This similarity, or rather identity, is striking, when\ncontrasted with the different expressions and cries made by distinct\nspecies of monkeys.  There is good evidence that the art of shooting with\nbows and arrows has not been handed down from any common progenitor of\nmankind, yet as Westropp and Nilsson have remarked (25.  'On Analogous\nForms of Implements,' in 'Memoirs of Anthropological Society' by H.M.\nWestropp.  'The Primitive Inhabitants of Scandinavia,' Eng. translat.,\nedited by Sir J. Lubbock, 1868, p. 104.), the stone arrow-heads, brought\nfrom the most distant parts of the world, and manufactured at the most\nremote periods, are almost identical; and this fact can only be accounted\nfor by the various races having similar inventive or mental powers.  The\nsame observation has been made by archaeologists (26.  Westropp 'On\nCromlechs,' etc., 'Journal of Ethnological Soc.' as given in 'Scientific\nOpinion,' June 2nd, 1869, p. 3.) with respect to certain widely-prevalent\nornaments, such as zig-zags, etc.; and with respect to various simple\nbeliefs and customs, such as the burying of the dead under megalithic\nstructures.  I remember observing in South America (27.  'Journal of\nResearches:  Voyage of the \"Beagle,\"' p. 46.), that there, as in so many\nother parts of the world, men have generally chosen the summits of lofty\nhills, to throw up piles of stones, either as a record of some remarkable\nevent, or for burying their dead.\n\nNow when naturalists observe a close agreement in numerous small details of\nhabits, tastes, and dispositions between two or more domestic races, or\nbetween nearly-allied natural forms, they use this fact as an argument that\nthey are descended from a common progenitor who was thus endowed; and\nconsequently that all should be classed under the same species.  The same\nargument may be applied with much force to the races of man.\n\nAs it is improbable that the numerous and unimportant points of resemblance\nbetween the several races of man in bodily structure and mental faculties\n(I do not here refer to similar customs) should all have been independently\nacquired, they must have been inherited from progenitors who had these same\ncharacters.  We thus gain some insight into the early state of man, before\nhe had spread step by step over the face of the earth.  The spreading of\nman to regions widely separated by the sea, no doubt, preceded any great\namount of divergence of character in the several races; for otherwise we\nshould sometimes meet with the same race in distinct continents; and this\nis never the case.  Sir J. Lubbock, after comparing the arts now practised\nby savages in all parts of the world, specifies those which man could not\nhave known, when he first wandered from his original birthplace; for if\nonce learnt they would never have been forgotten.  (28.  'Prehistoric\nTimes,' 1869, p. 574.)  He thus shews that \"the spear, which is but a\ndevelopment of the knife-point, and the club, which is but a long hammer,\nare the only things left.\"  He admits, however, that the art of making fire\nprobably had been already discovered, for it is common to all the races now\nexisting, and was known to the ancient cave-inhabitants of Europe.  Perhaps\nthe art of making rude canoes or rafts was likewise known; but as man\nexisted at a remote epoch, when the land in many places stood at a very\ndifferent level to what it does now, he would have been able, without the\naid of canoes, to have spread widely.  Sir J. Lubbock further remarks how\nimprobable it is that our earliest ancestors could have \"counted as high as\nten, considering that so many races now in existence cannot get beyond\nfour.\"  Nevertheless, at this early period, the intellectual and social\nfaculties of man could hardly have been inferior in any extreme degree to\nthose possessed at present by the lowest savages; otherwise primeval man\ncould not have been so eminently successful in the struggle for life, as\nproved by his early and wide diffusion.\n\nFrom the fundamental differences between certain languages, some\nphilologists have inferred that when man first became widely diffused, he\nwas not a speaking animal; but it may be suspected that languages, far less\nperfect than any now spoken, aided by gestures, might have been used, and\nyet have left no traces on subsequent and more highly-developed tongues.\nWithout the use of some language, however imperfect, it appears doubtful\nwhether man's intellect could have risen to the standard implied by his\ndominant position at an early period.\n\nWhether primeval man, when he possessed but few arts, and those of the\nrudest kind, and when his power of language was extremely imperfect, would\nhave deserved to be called man, must depend on the definition which we\nemploy.  In a series of forms graduating insensibly from some ape-like\ncreature to man as he now exists, it would be impossible to fix on any\ndefinite point where the term \"man\" ought to be used.  But this is a matter\nof very little importance.  So again, it is almost a matter of indifference\nwhether the so-called races of man are thus designated, or are ranked as\nspecies or sub-species; but the latter term appears the more appropriate.\nFinally, we may conclude that when the principle of evolution is generally\naccepted, as it surely will be before long, the dispute between the\nmonogenists and the polygenists will die a silent and unobserved death.\n\nOne other question ought not to be passed over without notice, namely,\nwhether, as is sometimes assumed, each sub-species or race of man has\nsprung from a single pair of progenitors.  With our domestic animals a new\nrace can readily be formed by carefully matching the varying offspring from\na single pair, or even from a single individual possessing some new\ncharacter; but most of our races have been formed, not intentionally from a\nselected pair, but unconsciously by the preservation of many individuals\nwhich have varied, however slightly, in some useful or desired manner.  If\nin one country stronger and heavier horses, and in another country lighter\nand fleeter ones, were habitually preferred, we may feel sure that two\ndistinct sub-breeds would be produced in the course of time, without any\none pair having been separated and bred from, in either country.  Many\nraces have been thus formed, and their manner of formation is closely\nanalogous to that of natural species.  We know, also, that the horses taken\nto the Falkland Islands have, during successive generations, become smaller\nand weaker, whilst those which have run wild on the Pampas have acquired\nlarger and coarser heads; and such changes are manifestly due, not to any\none pair, but to all the individuals having been subjected to the same\nconditions, aided, perhaps, by the principle of reversion.  The new sub-\nbreeds in such cases are not descended from any single pair, but from many\nindividuals which have varied in different degrees, but in the same general\nmanner; and we may conclude that the races of man have been similarly\nproduced, the modifications being either the direct result of exposure to\ndifferent conditions, or the indirect result of some form of selection.\nBut to this latter subject we shall presently return.\n\nON THE EXTINCTION OF THE RACES OF MAN.\n\nThe partial or complete extinction of many races and sub-races of man is\nhistorically known.  Humboldt saw in South America a parrot which was the\nsole living creature that could speak a word of the language of a lost\ntribe.  Ancient monuments and stone implements found in all parts of the\nworld, about which no tradition has been preserved by the present\ninhabitants, indicate much extinction.  Some small and broken tribes,\nremnants of former races, still survive in isolated and generally\nmountainous districts.  In Europe the ancient races were all, according to\nShaaffhausen (29.  Translation in 'Anthropological Review,' Oct. 1868, p.\n431.), \"lower in the scale than the rudest living savages\"; they must\ntherefore have differed, to a certain extent, from any existing race.  The\nremains described by Professor Broca from Les Eyzies, though they\nunfortunately appear to have belonged to a single family, indicate a race\nwith a most singular combination of low or simious, and of high\ncharacteristics.  This race is \"entirely different from any other, ancient\nor modern, that we have heard of.\"  (30.  'Transactions, International\nCongress of Prehistoric Archaeology' 1868, pp. 172-175.  See also Broca\n(tr.) in 'Anthropological Review,' Oct. 1868, p. 410.)  It differed,\ntherefore, from the quaternary race of the caverns of Belgium.\n\nMan can long resist conditions which appear extremely unfavourable for his\nexistence.  (31.  Dr. Gerland, 'Ueber das Aussterben der Naturvoelker,'\n1868, s. 82.)  He has long lived in the extreme regions of the North, with\nno wood for his canoes or implements, and with only blubber as fuel, and\nmelted snow as drink.  In the southern extremity of America the Fuegians\nsurvive without the protection of clothes, or of any building worthy to be\ncalled a hovel.  In South Africa the aborigines wander over arid plains,\nwhere dangerous beasts abound.  Man can withstand the deadly influence of\nthe Terai at the foot of the Himalaya, and the pestilential shores of\ntropical Africa.\n\nExtinction follows chiefly from the competition of tribe with tribe, and\nrace with race.  Various checks are always in action, serving to keep down\nthe numbers of each savage tribe,--such as periodical famines, nomadic\nhabits and the consequent deaths of infants, prolonged suckling, wars,\naccidents, sickness, licentiousness, the stealing of women, infanticide,\nand especially lessened fertility.  If any one of these checks increases in\npower, even slightly, the tribe thus affected tends to decrease; and when\nof two adjoining tribes one becomes less numerous and less powerful than\nthe other, the contest is soon settled by war, slaughter, cannibalism,\nslavery, and absorption.  Even when a weaker tribe is not thus abruptly\nswept away, if it once begins to decrease, it generally goes on decreasing\nuntil it becomes extinct.  (32.  Gerland (ibid. s. 12) gives facts in\nsupport of this statement.)\n\nWhen civilised nations come into contact with barbarians the struggle is\nshort, except where a deadly climate gives its aid to the native race.  Of\nthe causes which lead to the victory of civilised nations, some are plain\nand simple, others complex and obscure.  We can see that the cultivation of\nthe land will be fatal in many ways to savages, for they cannot, or will\nnot, change their habits.  New diseases and vices have in some cases proved\nhighly destructive; and it appears that a new disease often causes much\ndeath, until those who are most susceptible to its destructive influence\nare gradually weeded out (33.  See remarks to this effect in Sir H.\nHolland's 'Medical Notes and Reflections,' 1839, p. 390.); and so it may be\nwith the evil effects from spirituous liquors, as well as with the\nunconquerably strong taste for them shewn by so many savages.  It further\nappears, mysterious as is the fact, that the first meeting of distinct and\nseparated people generates disease.  (34.  I have collected ('Journal of\nResearches:  Voyage of the \"Beagle,\"' p. 435) a good many cases bearing on\nthis subject; see also Gerland, ibid. s. 8.  Poeppig speaks of the \"breath\nof civilisation as poisonous to savages.\")  Mr. Sproat, who in Vancouver\nIsland closely attended to the subject of extinction, believed that changed\nhabits of life, consequent on the advent of Europeans, induces much ill\nhealth.  He lays, also, great stress on the apparently trifling cause that\nthe natives become \"bewildered and dull by the new life around them; they\nlose the motives for exertion, and get no new ones in their place.\"  (35.\nSproat, 'Scenes and Studies of Savage Life,' 1868, p. 284.)\n\nThe grade of their civilisation seems to be a most important element in the\nsuccess of competing nations.  A few centuries ago Europe feared the\ninroads of Eastern barbarians; now any such fear would be ridiculous.  It\nis a more curious fact, as Mr. Bagehot has remarked, that savages did not\nformerly waste away before the classical nations, as they now do before\nmodern civilised nations; had they done so, the old moralists would have\nmused over the event; but there is no lament in any writer of that period\nover the perishing barbarians.  (36.  Bagehot, 'Physics and Politics,'\n'Fortnightly Review,' April 1, 1868, p. 455.)  The most potent of all the\ncauses of extinction, appears in many cases to be lessened fertility and\nill-health, especially amongst the children, arising from changed\nconditions of life, notwithstanding that the new conditions may not be\ninjurious in themselves.  I am much indebted to Mr. H.H. Howorth for having\ncalled my attention to this subject, and for having given me information\nrespecting it.  I have collected the following cases.\n\nWhen Tasmania was first colonised the natives were roughly estimated by\nsome at 7000 and by others at 20,000.  Their number was soon greatly\nreduced, chiefly by fighting with the English and with each other.  After\nthe famous hunt by all the colonists, when the remaining natives delivered\nthemselves up to the government, they consisted only of 120 individuals\n(37.  All the statements here given are taken from 'The Last of the\nTasmanians,' by J. Bonwick, 1870.), who were in 1832 transported to\nFlinders Island.  This island, situated between Tasmania and Australia, is\nforty miles long, and from twelve to eighteen miles broad:  it seems\nhealthy, and the natives were well treated.  Nevertheless, they suffered\ngreatly in health.  In 1834 they consisted (Bonwick, p. 250) of forty-seven\nadult males, forty-eight adult females, and sixteen children, or in all of\n111 souls.  In 1835 only one hundred were left.  As they continued rapidly\nto decrease, and as they themselves thought that they should not perish so\nquickly elsewhere, they were removed in 1847 to Oyster Cove in the southern\npart of Tasmania.  They then consisted (Dec. 20th, 1847) of fourteen men,\ntwenty-two women and ten children.  (38.  This is the statement of the\nGovernor of Tasmania, Sir W. Denison, 'Varieties of Vice-Regal Life,' 1870,\nvol. i. p. 67.)  But the change of site did no good.  Disease and death\nstill pursued them, and in 1864 one man (who died in 1869), and three\nelderly women alone survived.  The infertility of the women is even a more\nremarkable fact than the liability of all to ill-health and death.  At the\ntime when only nine women were left at Oyster Cove, they told Mr. Bonwick\n(p. 386), that only two had ever borne children:  and these two had\ntogether produced only three children!\n\nWith respect to the cause of this extraordinary state of things, Dr. Story\nremarks that death followed the attempts to civilise the natives.  \"If left\nto themselves to roam as they were wont and undisturbed, they would have\nreared more children, and there would have been less mortality.\"  Another\ncareful observer of the natives, Mr. Davis, remarks, \"The births have been\nfew and the deaths numerous.  This may have been in a great measure owing\nto their change of living and food; but more so to their banishment from\nthe mainland of Van Diemen's Land, and consequent depression of spirits\"\n(Bonwick, pp. 388, 390).\n\nSimilar facts have been observed in two widely different parts of\nAustralia.  The celebrated explorer, Mr. Gregory, told Mr. Bonwick, that in\nQueensland \"the want of reproduction was being already felt with the\nblacks, even in the most recently settled parts, and that decay would set\nin.\"  Of thirteen aborigines from Shark's Bay who visited Murchison River,\ntwelve died of consumption within three months.  (39.  For these cases, see\nBonwick's 'Daily Life of the Tasmanians,' 1870, p. 90:  and the 'Last of\nthe Tasmanians,' 1870, p. 386.)\n\nThe decrease of the Maories of New Zealand has been carefully investigated\nby Mr. Fenton, in an admirable Report, from which all the following\nstatements, with one exception, are taken.  (40.  'Observations on the\nAboriginal Inhabitants of New Zealand,' published by the Government, 1859.)\nThe decrease in number since 1830 is admitted by every one, including the\nnatives themselves, and is still steadily progressing.  Although it has\nhitherto been found impossible to take an actual census of the natives,\ntheir numbers were carefully estimated by residents in many districts.  The\nresult seems trustworthy, and shows that during the fourteen years,\nprevious to 1858, the decrease was 19.42 per cent.  Some of the tribes,\nthus carefully examined, lived above a hundred miles apart, some on the\ncoast, some inland; and their means of subsistence and habits differed to a\ncertain extent (p. 28).  The total number in 1858 was believed to be\n53,700, and in 1872, after a second interval of fourteen years, another\ncensus was taken, and the number is given as only 36,359, shewing a\ndecrease of 32.29 per cent!  (41.  'New Zealand,' by Alex. Kennedy, 1873,\np. 47.)  Mr. Fenton, after shewing in detail the insufficiency of the\nvarious causes, usually assigned in explanation of this extraordinary\ndecrease, such as new diseases, the profligacy of the women, drunkenness,\nwars, etc., concludes on weighty grounds that it depends chiefly on the\nunproductiveness of the women, and on the extraordinary mortality of the\nyoung children (pp. 31, 34).  In proof of this he shews (p. 33) that in\n1844 there was one non-adult for every 2.57 adults; whereas in 1858 there\nwas only one non-adult for every 3.27 adults.  The mortality of the adults\nis also great.  He adduces as a further cause of the decrease the\ninequality of the sexes; for fewer females are born than males.  To this\nlatter point, depending perhaps on a widely distinct cause, I shall return\nin a future chapter.  Mr. Fenton contrasts with astonishment the decrease\nin New Zealand with the increase in Ireland; countries not very dissimilar\nin climate, and where the inhabitants now follow nearly similar habits.\nThe Maories themselves (p. 35) \"attribute their decadence, in some measure,\nto the introduction of new food and clothing, and the attendant change of\nhabits\"; and it will be seen, when we consider the influence of changed\nconditions on fertility, that they are probably right.  The diminution\nbegan between the years 1830 and 1840; and Mr. Fenton shews (p. 40) that\nabout 1830, the art of manufacturing putrid corn (maize), by long steeping\nin water, was discovered and largely practised; and this proves that a\nchange of habits was beginning amongst the natives, even when New Zealand\nwas only thinly inhabited by Europeans.  When I visited the Bay of Islands\nin 1835, the dress and food of the inhabitants had already been much\nmodified:  they raised potatoes, maize, and other agricultural produce, and\nexchanged them for English manufactured goods and tobacco.\n\nIt is evident from many statements in the life of Bishop Patteson (42.\n'Life of J.C. Patteson,' by C.M. Younge, 1874; see more especially vol. i.\np. 530.), that the Melanesians of the New Hebrides and neighbouring\narchipelagoes, suffered to an extraordinary degree in health, and perished\nin large numbers, when they were removed to New Zealand, Norfolk Island,\nand other salubrious places, in order to be educated as missionaries.\n\nThe decrease of the native population of the Sandwich Islands is as\nnotorious as that of New Zealand.  It has been roughly estimated by those\nbest capable of judging, that when Cook discovered the Islands in 1779, the\npopulation amounted to about 300,000.  According to a loose census in 1823,\nthe numbers then were 142,050.  In 1832, and at several subsequent periods,\nan accurate census was officially taken, but I have been able to obtain\nonly the following returns:\n                Native Population          Annual rate of decrease\n                                           per cent., assuming it to\n              (Except during 1832 and      have been uniform between\n              1836, when the few           the successive censuses;\n              foreigners in the islands    these censuses being taken\n  Year        were included.)              at irregular intervals.\n\n  1832              130,313\n                                                   4.46\n  1836              108,579\n                                                   2.47\n  1853               71,019\n                                                   0.81\n  1860               67,084\n                                                   2.18\n  1866               58,765\n                                                   2.17\n  1872               51,531\n\nWe here see that in the interval of forty years, between 1832 and 1872, the\npopulation has decreased no less than sixty-eight per cent.!  This has been\nattributed by most writers to the profligacy of the women, to former bloody\nwars, and to the severe labour imposed on conquered tribes and to newly\nintroduced diseases, which have been on several occasions extremely\ndestructive.  No doubt these and other such causes have been highly\nefficient, and may account for the extraordinary rate of decrease between\nthe years 1832 and 1836; but the most potent of all the causes seems to be\nlessened fertility.  According to Dr. Ruschenberger of the U.S. Navy, who\nvisited these islands between 1835 and 1837, in one district of Hawaii,\nonly twenty-five men out of 1134, and in another district only ten out of\n637, had a family with as many as three children.  Of eighty married women,\nonly thirty-nine had ever borne children; and \"the official report gives an\naverage of half a child to each married couple in the whole island.\"  This\nis almost exactly the same average as with the Tasmanians at Oyster Cove.\nJarves, who published his History in 1843, says that \"families who have\nthree children are freed from all taxes; those having more, are rewarded by\ngifts of land and other encouragements.\"  This unparalleled enactment by\nthe government well shews how infertile the race had become.  The Rev. A.\nBishop stated in the Hawaiian 'Spectator' in 1839, that a large proportion\nof the children die at early ages, and Bishop Staley informs me that this\nis still the case, just as in New Zealand.  This has been attributed to the\nneglect of the children by the women, but it is probably in large part due\nto innate weakness of constitution in the children, in relation to the\nlessened fertility of their parents.  There is, moreover, a further\nresemblance to the case of New Zealand, in the fact that there is a large\nexcess of male over female births:  the census of 1872 gives 31,650 males\nto 25,247 females of all ages, that is 125.36 males for every 100 females;\nwhereas in all civilised countries the females exceed the males.  No doubt\nthe profligacy of the women may in part account for their small fertility;\nbut their changed habits of life is a much more probable cause, and which\nwill at the same time account for the increased mortality, especially of\nthe children.  The islands were visited by Cook in 1779, Vancouver in 1794,\nand often subsequently by whalers.  In 1819 missionaries arrived, and found\nthat idolatry had been already abolished, and other changes effected by the\nking.  After this period there was a rapid change in almost all the habits\nof life of the natives, and they soon became \"the most civilised of the\nPacific Islanders.\"  One of my informants, Mr. Coan, who was born on the\nislands, remarks that the natives have undergone a greater change in their\nhabits of life in the course of fifty years than Englishmen during a\nthousand years.  From information received from Bishop Staley, it does not\nappear that the poorer classes have ever much changed their diet, although\nmany new kinds of fruit have been introduced, and the sugar-cane is in\nuniversal use.  Owing, however, to their passion for imitating Europeans,\nthey altered their manner of dressing at an early period, and the use of\nalcoholic drinks became very general.  Although these changes appear\ninconsiderable, I can well believe, from what is known with respect to\nanimals, that they might suffice to lessen the fertility of the natives.\n(43.  The foregoing statements are taken chiefly from the following works:\nJarves' 'History of the Hawaiian Islands,' 1843, pp. 400-407.  Cheever,\n'Life in the Sandwich Islands,' 1851, p. 277.  Ruschenberger is quoted by\nBonwick, 'Last of the Tasmanians,' 1870, p. 378.  Bishop is quoted by Sir\nE. Belcher, 'Voyage Round the World,' 1843, vol. i. p. 272.  I owe the\ncensus of the several years to the kindness of Mr. Coan, at the request of\nDr. Youmans of New York; and in most cases I have compared the Youmans\nfigures with those given in several of the above-named works.  I have\nomitted the census for 1850, as I have seen two widely different numbers\ngiven.)\n\nLastly, Mr. Macnamara states (44.  'The Indian Medical Gazette,' Nov. 1,\n1871, p. 240.) that the low and degraded inhabitants of the Andaman\nIslands, on the eastern side of the Gulf of Bengal, are \"eminently\nsusceptible to any change of climate:  in fact, take them away from their\nisland homes, and they are almost certain to die, and that independently of\ndiet or extraneous influences.\"  He further states that the inhabitants of\nthe Valley of Nepal, which is extremely hot in summer, and also the various\nhill-tribes of India, suffer from dysentery and fever when on the plains;\nand they die if they attempt to pass the whole year there.\n\nWe thus see that many of the wilder races of man are apt to suffer much in\nhealth when subjected to changed conditions or habits of life, and not\nexclusively from being transported to a new climate.  Mere alterations in\nhabits, which do not appear injurious in themselves, seem to have this same\neffect; and in several cases the children are particularly liable to\nsuffer.  It has often been said, as Mr. Macnamara remarks, that man can\nresist with impunity the greatest diversities of climate and other changes;\nbut this is true only of the civilised races.  Man in his wild condition\nseems to be in this respect almost as susceptible as his nearest allies,\nthe anthropoid apes, which have never yet survived long, when removed from\ntheir native country.\n\nLessened fertility from changed conditions, as in the case of the\nTasmanians, Maories, Sandwich Islanders, and apparently the Australians, is\nstill more interesting than their liability to ill-health and death; for\neven a slight degree of infertility, combined with those other causes which\ntend to check the increase of every population, would sooner or later lead\nto extinction.  The diminution of fertility may be explained in some cases\nby the profligacy of the women (as until lately with the Tahitians), but\nMr. Fenton has shewn that this explanation by no means suffices with the\nNew Zealanders, nor does it with the Tasmanians.\n\nIn the paper above quoted, Mr. Macnamara gives reasons for believing that\nthe inhabitants of districts subject to malaria are apt to be sterile; but\nthis cannot apply in several of the above cases.  Some writers have\nsuggested that the aborigines of islands have suffered in fertility and\nhealth from long continued inter-breeding; but in the above cases\ninfertility has coincided too closely with the arrival of Europeans for us\nto admit this explanation.  Nor have we at present any reason to believe\nthat man is highly sensitive to the evil effects of inter-breeding,\nespecially in areas so large as New Zealand, and the Sandwich archipelago\nwith its diversified stations.  On the contrary, it is known that the\npresent inhabitants of Norfolk Island are nearly all cousins or near\nrelations, as are the Todas in India, and the inhabitants of some of the\nWestern Islands of Scotland; and yet they seem not to have suffered in\nfertility.  (45.  On the close relationship of the Norfolk Islanders, Sir\nW. Denison, 'Varieties of Vice-Regal Life,' vol. i. 1870, p. 410.  For the\nTodas, see Col. Marshall's work 1873, p. 110.  For the Western Islands of\nScotland, Dr. Mitchell, 'Edinburgh Medical Journal,' March to June, 1865.)\n\nA much more probable view is suggested by the analogy of the lower animals.\nThe reproductive system can be shewn to be susceptible to an extraordinary\ndegree (though why we know not) to changed conditions of life; and this\nsusceptibility leads both to beneficial and to evil results.  A large\ncollection of facts on this subject is given in chap. xviii. of vol. ii. of\nmy 'Variation of Animals and Plants under Domestication.' I can here give\nonly the briefest abstract; and every one interested in the subject may\nconsult the above work.  Very slight changes increase the health, vigour,\nand fertility of most or all organic beings, whilst other changes are known\nto render a large number of animals sterile.  One of the most familiar\ncases, is that of tamed elephants not breeding in India; though they often\nbreed in Ava, where the females are allowed to roam about the forests to\nsome extent, and are thus placed under more natural conditions.  The case\nof various American monkeys, both sexes of which have been kept for many\nyears together in their own countries, and yet have very rarely or never\nbred, is a more apposite instance, because of their relationship to man.\nIt is remarkable how slight a change in the conditions often induces\nsterility in a wild animal when captured; and this is the more strange as\nall our domesticated animals have become more fertile than they were in a\nstate of nature; and some of them can resist the most unnatural conditions\nwith undiminished fertility.  (46.  For the evidence on this head, see\n'Variation of Animals,' etc., vol. ii. p. 111.)  Certain groups of animals\nare much more liable than others to be affected by captivity; and generally\nall the species of the same group are affected in the same manner.  But\nsometimes a single species in a group is rendered sterile, whilst the\nothers are not so; on the other hand, a single species may retain its\nfertility whilst most of the others fail to breed.  The males and females\nof some species when confined, or when allowed to live almost, but not\nquite free, in their native country, never unite; others thus circumstanced\nfrequently unite but never produce offspring; others again produce some\noffspring, but fewer than in a state of nature; and as bearing on the above\ncases of man, it is important to remark that the young are apt to be weak\nand sickly, or malformed, and to perish at an early age.\n\nSeeing how general is this law of the susceptibility of the reproductive\nsystem to changed conditions of life, and that it holds good with our\nnearest allies, the Quadrumana, I can hardly doubt that it applies to man\nin his primeval state.  Hence if savages of any race are induced suddenly\nto change their habits of life, they become more or less sterile, and their\nyoung offspring suffer in health, in the same manner and from the same\ncause, as do the elephant and hunting-leopard in India, many monkeys in\nAmerica, and a host of animals of all kinds, on removal from their natural\nconditions.\n\nWe can see why it is that aborigines, who have long inhabited islands, and\nwho must have been long exposed to nearly uniform conditions, should be\nspecially affected by any change in their habits, as seems to be the case.\nCivilised races can certainly resist changes of all kinds far better than\nsavages; and in this respect they resemble domesticated animals, for though\nthe latter sometimes suffer in health (for instance European dogs in\nIndia), yet they are rarely rendered sterile, though a few such instances\nhave been recorded.  (47.  'Variation of Animals,' etc., vol. ii. p. 16.)\nThe immunity of civilised races and domesticated animals is probably due to\ntheir having been subjected to a greater extent, and therefore having grown\nsomewhat more accustomed, to diversified or varying conditions, than the\nmajority of wild animals; and to their having formerly immigrated or been\ncarried from country to country, and to different families or sub-races\nhaving inter-crossed.  It appears that a cross with civilised races at once\ngives to an aboriginal race an immunity from the evil consequences of\nchanged conditions.  Thus the crossed offspring from the Tahitians and\nEnglish, when settled in Pitcairn Island, increased so rapidly that the\nisland was soon overstocked; and in June 1856 they were removed to Norfolk\nIsland.  They then consisted of 60 married persons and 134 children, making\na total of 194.  Here they likewise increased so rapidly, that although\nsixteen of them returned to Pitcairn Island in 1859, they numbered in\nJanuary 1868, 300 souls; the males and females being in exactly equal\nnumbers.  What a contrast does this case present with that of the\nTasmanians; the Norfolk Islanders INCREASED in only twelve and a half years\nfrom 194 to 300; whereas the Tasmanians DECREASED during fifteen years from\n120 to 46, of which latter number only ten were children.  (48.  These\ndetails are taken from 'The Mutineers of the \"Bounty,\"' by Lady Belcher,\n1870; and from 'Pitcairn Island,' ordered to be printed by the House of\nCommons, May 29, 1863.  The following statements about the Sandwich\nIslanders are from the 'Honolulu Gazette,' and from Mr. Coan.)\n\nSo again in the interval between the census of 1866 and 1872 the natives of\nfull blood in the Sandwich Islands decreased by 8081, whilst the half-\ncastes, who are believed to be healthier, increased by 847; but I do not\nknow whether the latter number includes the offspring from the half-castes,\nor only the half-castes of the first generation.\n\nThe cases which I have here given all relate to aborigines, who have been\nsubjected to new conditions as the result of the immigration of civilised\nmen.  But sterility and ill-health would probably follow, if savages were\ncompelled by any cause, such as the inroad of a conquering tribe, to desert\ntheir homes and to change their habits.  It is an interesting circumstance\nthat the chief check to wild animals becoming domesticated, which implies\nthe power of their breeding freely when first captured, and one chief check\nto wild men, when brought into contact with civilisation, surviving to form\na civilised race, is the same, namely, sterility from changed conditions of\nlife.\n\nFinally, although the gradual decrease and ultimate extinction of the races\nof man is a highly complex problem, depending on many causes which differ\nin different places and at different times; it is the same problem as that\npresented by the extinction of one of the higher animals--of the fossil\nhorse, for instance, which disappeared from South America, soon afterwards\nto be replaced, within the same districts, by countless troups of the\nSpanish horse.  The New Zealander seems conscious of this parallelism, for\nhe compares his future fate with that of the native rat now almost\nexterminated by the European rat.  Though the difficulty is great to our\nimagination, and really great, if we wish to ascertain the precise causes\nand their manner of action, it ought not to be so to our reason, as long as\nwe keep steadily in mind that the increase of each species and each race is\nconstantly checked in various ways; so that if any new check, even a slight\none, be superadded, the race will surely decrease in number; and decreasing\nnumbers will sooner or later lead to extinction; the end, in most cases,\nbeing promptly determined by the inroads of conquering tribes.\n\nON THE FORMATION OF THE RACES OF MAN.\n\nIn some cases the crossing of distinct races has led to the formation of a\nnew race.  The singular fact that the Europeans and Hindoos, who belong to\nthe same Aryan stock, and speak a language fundamentally the same, differ\nwidely in appearance, whilst Europeans differ but little from Jews, who\nbelong to the Semitic stock, and speak quite another language, has been\naccounted for by Broca (49.  'On Anthropology,' translation,\n'Anthropological Review,' Jan. 1868, p. 38.), through certain Aryan\nbranches having been largely crossed by indigenous tribes during their wide\ndiffusion.  When two races in close contact cross, the first result is a\nheterogeneous mixture:  thus Mr. Hunter, in describing the Santali or hill-\ntribes of India, says that hundreds of imperceptible gradations may be\ntraced \"from the black, squat tribes of the mountains to the tall olive-\ncoloured Brahman, with his intellectual brow, calm eyes, and high but\nnarrow head\"; so that it is necessary in courts of justice to ask the\nwitnesses whether they are Santalis or Hindoos.  (50.  'The Annals of Rural\nBengal,' 1868, p. 134.)  Whether a heterogeneous people, such as the\ninhabitants of some of the Polynesian islands, formed by the crossing of\ntwo distinct races, with few or no pure members left, would ever become\nhomogeneous, is not known from direct evidence.  But as with our\ndomesticated animals, a cross-breed can certainly be fixed and made uniform\nby careful selection (51.  'The Variation of Animals and Plants under\nDomestication,' vol. ii. p. 95.) in the course of a few generations, we may\ninfer that the free intercrossing of a heterogeneous mixture during a long\ndescent would supply the place of selection, and overcome any tendency to\nreversion; so that the crossed race would ultimately become homogeneous,\nthough it might not partake in an equal degree of the characters of the two\nparent-races.\n\nOf all the differences between the races of man, the colour of the skin is\nthe most conspicuous and one of the best marked.  It was formerly thought\nthat differences of this kind could be accounted for by long exposure to\ndifferent climates; but Pallas first shewed that this is not tenable, and\nhe has since been followed by almost all anthropologists.  (52.  Pallas,\n'Act. Acad. St. Petersburg,' 1780, part ii. p. 69.  He was followed by\nRudolphi, in his 'Beytrage zur Anthropologie,' 1812.  An excellent summary\nof the evidence is given by Godron, 'De l'Espece,' 1859, vol. ii. p. 246,\netc.)  This view has been rejected chiefly because the distribution of the\nvariously coloured races, most of whom must have long inhabited their\npresent homes, does not coincide with corresponding differences of climate.\nSome little weight may be given to such cases as that of the Dutch\nfamilies, who, as we hear on excellent authority (53.  Sir Andrew Smith, as\nquoted by Knox, 'Races of Man,' 1850, p. 473.), have not undergone the\nleast change of colour after residing for three centuries in South Africa.\nAn argument on the same side may likewise be drawn from the uniform\nappearance in various parts of the world of gipsies and Jews, though the\nuniformity of the latter has been somewhat exaggerated.  (54.  See De\nQuatrefages on this head, 'Revue des Cours Scientifiques,' Oct. 17, 1868,\np. 731.)  A very damp or a very dry atmosphere has been supposed to be more\ninfluential in modifying the colour of the skin than mere heat; but as\nD'Orbigny in South America, and Livingstone in Africa, arrived at\ndiametrically opposite conclusions with respect to dampness and dryness,\nany conclusion on this head must be considered as very doubtful.  (55.\nLivingstone's 'Travels and Researches in S. Africa,' 1857, pp. 338, 339.\nD'Orbigny, as quoted by Godron, 'De l'Espece,' vol. ii. p. 266.)\n\nVarious facts, which I have given elsewhere, prove that the colour of the\nskin and hair is sometimes correlated in a surprising manner with a\ncomplete immunity from the action of certain vegetable poisons, and from\nthe attacks of certain parasites.  Hence it occurred to me, that negroes\nand other dark races might have acquired their dark tints by the darker\nindividuals escaping from the deadly influence of the miasma of their\nnative countries, during a long series of generations.\n\nI afterwards found that this same idea had long ago occurred to Dr. Wells.\n(56.  See a paper read before the Royal Soc. in 1813, and published in his\nEssays in 1818.  I have given an account of Dr. Wells' views in the\nHistorical Sketch (p. xvi.) to my 'Origin of Species.'  Various cases of\ncolour correlated with constitutional peculiarities are given in my\n'Variation of Animals and Plants under Domestication,' vol. ii. pp. 227,\n335.)  It has long been known that negroes, and even mulattoes, are almost\ncompletely exempt from the yellow-fever, so destructive in tropical\nAmerica.  (57.  See, for instance, Nott and Gliddon, 'Types of Mankind,' p.\n68.)  They likewise escape to a large extent the fatal intermittent fevers,\nthat prevail along at least 2600 miles of the shores of Africa, and which\nannually cause one-fifth of the white settlers to die, and another fifth to\nreturn home invalided.  (58.  Major Tulloch, in a paper read before the\nStatistical Society, April 20, 1840, and given in the 'Athenaeum,' 1840, p.\n353.)  This immunity in the negro seems to be partly inherent, depending on\nsome unknown peculiarity of constitution, and partly the result of\nacclimatisation.  Pouchet (59.  'The Plurality of the Human Race'\n(translat.), 1864, p. 60.) states that the negro regiments recruited near\nthe Soudan, and borrowed from the Viceroy of Egypt for the Mexican war,\nescaped the yellow-fever almost equally with the negroes originally brought\nfrom various parts of Africa and accustomed to the climate of the West\nIndies.  That acclimatisation plays a part, is shewn by the many cases in\nwhich negroes have become somewhat liable to tropical fevers, after having\nresided for some time in a colder climate.  (60.  Quatrefages, 'Unite de\nl'Espece Humaine,' 1861, p. 205.  Waitz, 'Introduction to Anthropology,'\ntranslat., vol. i. 1863, p. 124.  Livingstone gives analogous cases in his\n'Travels.')  The nature of the climate under which the white races have\nlong resided, likewise has some influence on them; for during the fearful\nepidemic of yellow fever in Demerara during 1837, Dr. Blair found that the\ndeath-rate of the immigrants was proportional to the latitude of the\ncountry whence they had come.  With the negro the immunity, as far as it is\nthe result of acclimatisation, implies exposure during a prodigious length\nof time; for the aborigines of tropical America who have resided there from\ntime immemorial, are not exempt from yellow fever; and the Rev. H.B.\nTristram states, that there are districts in Northern Africa which the\nnative inhabitants are compelled annually to leave, though the negroes can\nremain with safety.\n\nThat the immunity of the negro is in any degree correlated with the colour\nof his skin is a mere conjecture:  it may be correlated with some\ndifference in his blood, nervous system, or other tissues.  Nevertheless,\nfrom the facts above alluded to, and from some connection apparently\nexisting between complexion and a tendency to consumption, the conjecture\nseemed to me not improbable.  Consequently I endeavoured, with but little\nsuccess (61.  In the spring of 1862 I obtained permission from the\nDirector-General of the Medical department of the Army, to transmit to the\nsurgeons of the various regiments on foreign service a blank table, with\nthe following appended remarks, but I have received no returns.  \"As\nseveral well-marked cases have been recorded with our domestic animals of a\nrelation between the colour of the dermal appendages and the constitution;\nand it being notorious that there is some limited degree of relation\nbetween the colour of the races of man and the climate inhabited by them;\nthe following investigation seems worth consideration.  Namely, whether\nthere is any relation in Europeans between the colour of their hair, and\ntheir liability to the diseases of tropical countries.  If the surgeons of\nthe several regiments, when stationed in unhealthy tropical districts,\nwould be so good as first to count, as a standard of comparison, how many\nmen, in the force whence the sick are drawn, have dark and light-coloured\nhair, and hair of intermediate or doubtful tints; and if a similar account\nwere kept by the same medical gentlemen, of all the men who suffered from\nmalarious and yellow fevers, or from dysentery, it would soon be apparent,\nafter some thousand cases had been tabulated, whether there exists any\nrelation between the colour of the hair and constitutional liability to\ntropical diseases.  Perhaps no such relation would be discovered, but the\ninvestigation is well worth making.  In case any positive result were\nobtained, it might be of some practical use in selecting men for any\nparticular service.  Theoretically the result would be of high interest, as\nindicating one means by which a race of men inhabiting from a remote period\nan unhealthy tropical climate, might have become dark-coloured by the\nbetter preservation of dark-haired or dark-complexioned individuals during\na long succession of generations.\"), to ascertain how far it holds good.\nThe late Dr. Daniell, who had long lived on the West Coast of Africa, told\nme that he did not believe in any such relation.  He was himself unusually\nfair, and had withstood the climate in a wonderful manner.  When he first\narrived as a boy on the coast, an old and experienced negro chief predicted\nfrom his appearance that this would prove the case.  Dr. Nicholson, of\nAntigua, after having attended to this subject, writes to me that dark-\ncoloured Europeans escape the yellow fever more than those that are light-\ncoloured.  Mr. J.M. Harris altogether denies that Europeans with dark hair\nwithstand a hot climate better than other men:  on the contrary, experience\nhas taught him in making a selection of men for service on the coast of\nAfrica, to choose those with red hair.  (62.  'Anthropological Review,'\nJan. 1866, p. xxi.  Dr. Sharpe also says, with respect to India ('Man a\nSpecial Creation,' 1873, p. 118), \"that it has been noticed by some medical\nofficers that Europeans with light hair and florid complexions suffer less\nfrom diseases of tropical countries than persons with dark hair and sallow\ncomplexions; and, so far as I know, there appear to be good grounds for\nthis remark.\"  On the other hand, Mr. Heddle, of Sierra Leone, \"who has had\nmore clerks killed under him than any other man,\" by the climate of the\nWest African Coast (W. Reade, 'African Sketch Book,' vol. ii. p. 522),\nholds a directly opposite view, as does Capt. Burton.)  As far, therefore,\nas these slight indications go, there seems no foundation for the\nhypothesis, that blackness has resulted from the darker and darker\nindividuals having survived better during long exposure to fever-generating\nmiasma.\n\nDr. Sharpe remarks (63.  'Man a Special Creation,' 1873, p. 119.), that a\ntropical sun, which burns and blisters a white skin, does not injure a\nblack one at all; and, as he adds, this is not due to habit in the\nindividual, for children only six or eight months old are often carried\nabout naked, and are not affected.  I have been assured by a medical man,\nthat some years ago during each summer, but not during the winter, his\nhands became marked with light brown patches, like, although larger than\nfreckles, and that these patches were never affected by sun-burning, whilst\nthe white parts of his skin have on several occasions been much inflamed\nand blistered.  With the lower animals there is, also, a constitutional\ndifference in liability to the action of the sun between those parts of the\nskin clothed with white hair and other parts.  (64.  'Variation of Animals\nand Plants under Domestication,' vol. ii. pp. 336, 337.)  Whether the\nsaving of the skin from being thus burnt is of sufficient importance to\naccount for a dark tint having been gradually acquired by man through\nnatural selection, I am unable to judge.  If it be so, we should have to\nassume that the natives of tropical America have lived there for a much\nshorter time than the Negroes in Africa, or the Papuans in the southern\nparts of the Malay archipelago, just as the lighter-coloured Hindoos have\nresided in India for a shorter time than the darker aborigines of the\ncentral and southern parts of the peninsula.\n\nAlthough with our present knowledge we cannot account for the differences\nof colour in the races of man, through any advantage thus gained, or from\nthe direct action of climate; yet we must not quite ignore the latter\nagency, for there is good reason to believe that some inherited effect is\nthus produced.  (65.  See, for instance, Quatrefages ('Revue des Cours\nScientifiques,' Oct. 10, 1868, p. 724) on the effects of residence in\nAbyssinia and Arabia, and other analogous cases.  Dr. Rolle ('Der Mensch,\nseine Abstammung,' etc., 1865, s. 99) states, on the authority of Khanikof,\nthat the greater number of German families settled in Georgia, have\nacquired in the course of two generations dark hair and eyes.  Mr. D.\nForbes informs me that the Quichuas in the Andes vary greatly in colour,\naccording to the position of the valleys inhabited by them.)\n\nWe have seen in the second chapter that the conditions of life affect the\ndevelopment of the bodily frame in a direct manner, and that the effects\nare transmitted.  Thus, as is generally admitted, the European settlers in\nthe United States undergo a slight but extraordinary rapid change of\nappearance.  Their bodies and limbs become elongated; and I hear from Col.\nBernys that during the late war in the United States, good evidence was\nafforded of this fact by the ridiculous appearance presented by the German\nregiments, when dressed in ready-made clothes manufactured for the American\nmarket, and which were much too long for the men in every way.  There is,\nalso, a considerable body of evidence shewing that in the Southern States\nthe house-slaves of the third generation present a markedly different\nappearance from the field-slaves.  (66.  Harlan, 'Medical Researches,' p.\n532.  Quatrefages ('Unite de l'Espece Humaine,' 1861, p. 128) has collected\nmuch evidence on this head.)\n\nIf, however, we look to the races of man as distributed over the world, we\nmust infer that their characteristic differences cannot be accounted for by\nthe direct action of different conditions of life, even after exposure to\nthem for an enormous period of time.  The Esquimaux live exclusively on\nanimal food; they are clothed in thick fur, and are exposed to intense cold\nand to prolonged darkness; yet they do not differ in any extreme degree\nfrom the inhabitants of Southern China, who live entirely on vegetable\nfood, and are exposed almost naked to a hot, glaring climate.  The\nunclothed Fuegians live on the marine productions of their inhospitable\nshores; the Botocudos of Brazil wander about the hot forests of the\ninterior and live chiefly on vegetable productions; yet these tribes\nresemble each other so closely that the Fuegians on board the \"Beagle\" were\nmistaken by some Brazilians for Botocudos.  The Botocudos again, as well as\nthe other inhabitants of tropical America, are wholly different from the\nNegroes who inhabit the opposite shores of the Atlantic, are exposed to a\nnearly similar climate, and follow nearly the same habits of life.\n\nNor can the differences between the races of man be accounted for by the\ninherited effects of the increased or decreased use of parts, except to a\nquite insignificant degree.  Men who habitually live in canoes, may have\ntheir legs somewhat stunted; those who inhabit lofty regions may have their\nchests enlarged; and those who constantly use certain sense-organs may have\nthe cavities in which they are lodged somewhat increased in size, and their\nfeatures consequently a little modified.  With civilised nations, the\nreduced size of the jaws from lessened use--the habitual play of different\nmuscles serving to express different emotions--and the increased size of\nthe brain from greater intellectual activity, have together produced a\nconsiderable effect on their general appearance when compared with savages.\n(67.  See Prof. Schaaffhausen, translat., in 'Anthropological Review,' Oct.\n1868, p. 429.)  Increased bodily stature, without any corresponding\nincrease in the size of the brain, may (judging from the previously adduced\ncase of rabbits), have given to some races an elongated skull of the\ndolichocephalic type.\n\nLastly, the little-understood principle of correlated development has\nsometimes come into action, as in the case of great muscular development\nand strongly projecting supra-orbital ridges.  The colour of the skin and\nhair are plainly correlated, as is the texture of the hair with its colour\nin the Mandans of North America.  (68.  Mr. Catlin states ('N. American\nIndians,' 3rd ed., 1842, vol. i. p. 49) that in the whole tribe of the\nMandans, about one in ten or twelve of the members, of all ages and both\nsexes, have bright silvery grey hair, which is hereditary.  Now this hair\nis as coarse and harsh as that of a horse's mane, whilst the hair of other\ncolours is fine and soft.)  The colour also of the skin, and the odour\nemitted by it, are likewise in some manner connected.  With the breeds of\nsheep the number of hairs within a given space and the number of excretory\npores are related.  (69.  On the odour of the skin, Godron, 'Sur l'Espece,'\ntom. ii. p. 217.  On the pores in the skin, Dr. Wilckens, 'Die Aufgaben der\nLandwirth. Zootechnik,' 1869, s. 7.)  If we may judge from the analogy of\nour domesticated animals, many modifications of structure in man probably\ncome under this principle of correlated development.\n\nWe have now seen that the external characteristic differences between the\nraces of man cannot be accounted for in a satisfactory manner by the direct\naction of the conditions of life, nor by the effects of the continued use\nof parts, nor through the principle of correlation.  We are therefore led\nto enquire whether slight individual differences, to which man is eminently\nliable, may not have been preserved and augmented during a long series of\ngenerations through natural selection.  But here we are at once met by the\nobjection that beneficial variations alone can be thus preserved; and as\nfar as we are enabled to judge, although always liable to err on this head,\nnone of the differences between the races of man are of any direct or\nspecial service to him.  The intellectual and moral or social faculties\nmust of course be excepted from this remark.  The great variability of all\nthe external differences between the races of man, likewise indicates that\nthey cannot be of much importance; for if important, they would long ago\nhave been either fixed and preserved, or eliminated.  In this respect man\nresembles those forms, called by naturalists protean or polymorphic, which\nhave remained extremely variable, owing, as it seems, to such variations\nbeing of an indifferent nature, and to their having thus escaped the action\nof natural selection.\n\nWe have thus far been baffled in all our attempts to account for the\ndifferences between the races of man; but there remains one important\nagency, namely Sexual Selection, which appears to have acted powerfully on\nman, as on many other animals.  I do not intend to assert that sexual\nselection will account for all the differences between the races.  An\nunexplained residuum is left, about which we can only say, in our\nignorance, that as individuals are continually born with, for instance,\nheads a little rounder or narrower, and with noses a little longer or\nshorter, such slight differences might become fixed and uniform, if the\nunknown agencies which induced them were to act in a more constant manner,\naided by long-continued intercrossing.  Such variations come under the\nprovisional class, alluded to in our second chapter, which for want of a\nbetter term are often called spontaneous.  Nor do I pretend that the\neffects of sexual selection can be indicated with scientific precision; but\nit can be shewn that it would be an inexplicable fact if man had not been\nmodified by this agency, which appears to have acted powerfully on\ninnumerable animals.  It can further be shewn that the differences between\nthe races of man, as in colour, hairiness, form of features, etc., are of a\nkind which might have been expected to come under the influence of sexual\nselection.  But in order to treat this subject properly, I have found it\nnecessary to pass the whole animal kingdom in review.  I have therefore\ndevoted to it the Second Part of this work.  At the close I shall return to\nman, and, after attempting to shew how far he has been modified through\nsexual selection, will give a brief summary of the chapters in this First\nPart.\n\n\nNOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE\nDEVELOPMENT OF THE BRAIN IN MAN AND APES BY PROFESSOR HUXLEY, F.R.S.\n\nThe controversy respecting the nature and the extent of the differences in\nthe structure of the brain in man and the apes, which arose some fifteen\nyears ago, has not yet come to an end, though the subject matter of the\ndispute is, at present, totally different from what it was formerly.  It\nwas originally asserted and re-asserted, with singular pertinacity, that\nthe brain of all the apes, even the highest, differs from that of man, in\nthe absence of such conspicuous structures as the posterior lobes of the\ncerebral hemispheres, with the posterior cornu of the lateral ventricle and\nthe hippocampus minor, contained in those lobes, which are so obvious in\nman.\n\nBut the truth that the three structures in question are as well developed\nin apes' as in human brains, or even better; and that it is characteristic\nof all the Primates (if we exclude the Lemurs) to have these parts well\ndeveloped, stands at present on as secure a basis as any proposition in\ncomparative anatomy.  Moreover, it is admitted by every one of the long\nseries of anatomists who, of late years, have paid special attention to the\narrangement of the complicated sulci and gyri which appear upon the surface\nof the cerebral hemispheres in man and the higher apes, that they are\ndisposed after the very same pattern in him, as in them.  Every principal\ngyrus and sulcus of a chimpanzee's brain is clearly represented in that of\na man, so that the terminology which applies to the one answers for the\nother.  On this point there is no difference of opinion.  Some years since,\nProfessor Bischoff published a memoir (70.  'Die Grosshirn-Windungen des\nMenschen;' 'Abhandlungen der K. Bayerischen Akademie,' B. x. 1868.) on the\ncerebral convolutions of man and apes; and as the purpose of my learned\ncolleague was certainly not to diminish the value of the differences\nbetween apes and men in this respect, I am glad to make a citation from\nhim.\n\n\"That the apes, and especially the orang, chimpanzee and gorilla, come very\nclose to man in their organisation, much nearer than to any other animal,\nis a well known fact, disputed by nobody.  Looking at the matter from the\npoint of view of organisation alone, no one probably would ever have\ndisputed the view of Linnaeus, that man should be placed, merely as a\npeculiar species, at the head of the mammalia and of those apes.  Both\nshew, in all their organs, so close an affinity, that the most exact\nanatomical investigation is needed in order to demonstrate those\ndifferences which really exist.  So it is with the brains.  The brains of\nman, the orang, the chimpanzee, the gorilla, in spite of all the important\ndifferences which they present, come very close to one another\" (loc. cit.\np. 101).\n\nThere remains, then, no dispute as to the resemblance in fundamental\ncharacters, between the ape's brain and man's:  nor any as to the\nwonderfully close similarity between the chimpanzee, orang and man, in even\nthe details of the arrangement of the gyri and sulci of the cerebral\nhemispheres.  Nor, turning to the differences between the brains of the\nhighest apes and that of man, is there any serious question as to the\nnature and extent of these differences.  It is admitted that the man's\ncerebral hemispheres are absolutely and relatively larger than those of the\norang and chimpanzee; that his frontal lobes are less excavated by the\nupward protrusion of the roof of the orbits; that his gyri and sulci are,\nas a rule, less symmetrically disposed, and present a greater number of\nsecondary plications.  And it is admitted that, as a rule, in man, the\ntemporo-occipital or \"external perpendicular\" fissure, which is usually so\nstrongly marked a feature of the ape's brain is but faintly marked.  But it\nis also clear, that none of these differences constitutes a sharp\ndemarcation between the man's and the ape's brain.  In respect to the\nexternal perpendicular fissure of Gratiolet, in the human brain for\ninstance, Professor Turner remarks:  (71.  'Convolutions of the Human\nCerebrum Topographically Considered,' 1866, p. 12.)\n\n\"In some brains it appears simply as an indentation of the margin of the\nhemisphere, but, in others, it extends for some distance more or less\ntransversely outwards.  I saw it in the right hemisphere of a female brain\npass more than two inches outwards; and on another specimen, also the right\nhemisphere, it proceeded for four-tenths of an inch outwards, and then\nextended downwards, as far as the lower margin of the outer surface of the\nhemisphere.  The imperfect definition of this fissure in the majority of\nhuman brains, as compared with its remarkable distinctness in the brain of\nmost Quadrumana, is owing to the presence, in the former, of certain\nsuperficial, well marked, secondary convolutions which bridge it over and\nconnect the parietal with the occipital lobe.  The closer the first of\nthese bridging gyri lies to the longitudinal fissure, the shorter is the\nexternal parieto-occipital fissure\" (loc. cit. p. 12).\n\nThe obliteration of the external perpendicular fissure of Gratiolet,\ntherefore, is not a constant character of the human brain.  On the other\nhand, its full development is not a constant character of the higher ape's\nbrain.  For, in the chimpanzee, the more or less extensive obliteration of\nthe external perpendicular sulcus by \"bridging convolutions,\" on one side\nor the other, has been noted over and over again by Prof. Rolleston, Mr.\nMarshall, M. Broca and Professor Turner.  At the conclusion of a special\npaper on this subject the latter writes:  (72.  Notes more especially on\nthe bridging convolutions in the Brain of the Chimpanzee, 'Proceedings of\nthe Royal Society of Edinburgh,' 1865-6.)\n\n\"The three specimens of the brain of a chimpanzee, just described, prove,\nthat the generalisation which Gratiolet has attempted to draw of the\ncomplete absence of the first connecting convolution and the concealment of\nthe second, as essentially characteristic features in the brain of this\nanimal, is by no means universally applicable.  In only one specimen did\nthe brain, in these particulars, follow the law which Gratiolet has\nexpressed.  As regards the presence of the superior bridging convolution, I\nam inclined to think that it has existed in one hemisphere, at least, in a\nmajority of the brains of this animal which have, up to this time, been\nfigured or described.  The superficial position of the second bridging\nconvolution is evidently less frequent, and has as yet, I believe, only\nbeen seen in the brain (A) recorded in this communication.  The\nasymmetrical arrangement in the convolutions of the two hemispheres, which\nprevious observers have referred to in their descriptions, is also well\nillustrated in these specimens\" (pp. 8, 9).\n\nEven were the presence of the temporo-occipital, or external perpendicular,\nsulcus, a mark of distinction between the higher apes and man, the value of\nsuch a distinctive character would be rendered very doubtful by the\nstructure of the brain in the Platyrrhine apes.  In fact, while the\ntemporo-occipital is one of the most constant of sulci in the Catarrhine,\nor Old World, apes, it is never very strongly developed in the New World\napes; it is absent in the smaller Platyrrhini; rudimentary in Pithecia (73.\nFlower, 'On the Anatomy of Pithecia Monachus,' 'Proceedings of the\nZoological Society,' 1862.); and more or less obliterated by bridging\nconvolutions in Ateles.\n\nA character which is thus variable within the limits of a single group can\nhave no great taxonomic value.\n\nIt is further established, that the degree of asymmetry of the convolution\nof the two sides in the human brain is subject to much individual\nvariation; and that, in those individuals of the Bushman race who have been\nexamined, the gyri and sulci of the two hemispheres are considerably less\ncomplicated and more symmetrical than in the European brain, while, in some\nindividuals of the chimpanzee, their complexity and asymmetry become\nnotable.  This is particularly the case in the brain of a young male\nchimpanzee figured by M. Broca.  ('L'ordre des Primates,' p. 165, fig. 11.)\n\nAgain, as respects the question of absolute size, it is established that\nthe difference between the largest and the smallest healthy human brain is\ngreater than the difference between the smallest healthy human brain and\nthe largest chimpanzee's or orang's brain.\n\nMoreover, there is one circumstance in which the orang's and chimpanzee's\nbrains resemble man's, but in which they differ from the lower apes, and\nthat is the presence of two corpora candicantia--the Cynomorpha having but\none.\n\nIn view of these facts I do not hesitate in this year 1874, to repeat and\ninsist upon the proposition which I enunciated in 1863:  (74.  'Man's Place\nin Nature,' p. 102.)\n\n\"So far as cerebral structure goes, therefore, it is clear that man differs\nless from the chimpanzee or the orang, than these do even from the monkeys,\nand that the difference between the brain of the chimpanzee and of man is\nalmost insignificant when compared with that between the chimpanzee brain\nand that of a Lemur.\"\n\nIn the paper to which I have referred, Professor Bischoff does not deny the\nsecond part of this statement, but he first makes the irrelevant remark\nthat it is not wonderful if the brains of an orang and a Lemur are very\ndifferent; and secondly, goes on to assert that, \"If we successively\ncompare the brain of a man with that of an orang; the brain of this with\nthat of a chimpanzee; of this with that of a gorilla, and so on of a\nHylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus,\nCallithrix, Lemur, Stenops, Hapale, we shall not meet with a greater, or\neven as great a, break in the degree of development of the convolutions, as\nwe find between the brain of a man and that of an orang or chimpanzee.\"\n\nTo which I reply, firstly, that whether this assertion be true or false, it\nhas nothing whatever to do with the proposition enunciated in 'Man's Place\nin Nature,' which refers not to the development of the convolutions alone,\nbut to the structure of the whole brain.  If Professor Bischoff had taken\nthe trouble to refer to p. 96 of the work he criticises, in fact, he would\nhave found the following passage:  \"And it is a remarkable circumstance\nthat though, so far as our present knowledge extends, there IS one true\nstructural break in the series of forms of Simian brains, this hiatus does\nnot lie between man and the manlike apes, but between the lower and the\nlowest Simians, or in other words, between the Old and New World apes and\nmonkeys and the Lemurs.  Every Lemur which has yet been examined, in fact,\nhas its cerebellum partially visible from above; and its posterior lobe,\nwith the contained posterior cornu and hippocampus minor, more or less\nrudimentary.  Every marmoset, American monkey, Old World monkey, baboon or\nmanlike ape, on the contrary, has its cerebellum entirely hidden,\nposteriorly, by the cerebral lobes, and possesses a large posterior cornu\nwith a well-developed hippocampus minor.\"\n\nThis statement was a strictly accurate account of what was known when it\nwas made; and it does not appear to me to be more than apparently weakened\nby the subsequent discovery of the relatively small development of the\nposterior lobes in the Siamang and in the Howling monkey.  Notwithstanding\nthe exceptional brevity of the posterior lobes in these two species, no one\nwill pretend that their brains, in the slightest degree, approach those of\nthe Lemurs.  And if, instead of putting Hapale out of its natural place, as\nProfessor Bischoff most unaccountably does, we write the series of animals\nhe has chosen to mention as follows:  Homo, Pithecus, Troglodytes,\nHylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus,\nCallithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great\nbreak in this series lies between Hapale and Lemur, and that this break is\nconsiderably greater than that between any other two terms of that series.\nProfessor Bischoff ignores the fact that long before he wrote, Gratiolet\nhad suggested the separation of the Lemurs from the other Primates on the\nvery ground of the difference in their cerebral characters; and that\nProfessor Flower had made the following observations in the course of his\ndescription of the brain of the Javan Loris:  (75.  'Transactions of the\nZoological Society,' vol. v. 1862.)\n\n\"And it is especially remarkable that, in the development of the posterior\nlobes, there is no approximation to the Lemurine, short hemisphered brain,\nin those monkeys which are commonly supposed to approach this family in\nother respects, viz. the lower members of the Platyrrhine group.\"\n\nSo far as the structure of the adult brain is concerned, then, the very\nconsiderable additions to our knowledge, which have been made by the\nresearches of so many investigators, during the past ten years, fully\njustify the statement which I made in 1863.  But it has been said, that,\nadmitting the similarity between the adult brains of man and apes, they are\nnevertheless, in reality, widely different, because they exhibit\nfundamental differences in the mode of their development.  No one would be\nmore ready than I to admit the force of this argument, if such fundamental\ndifferences of development really exist.  But I deny that they do exist.\nOn the contrary, there is a fundamental agreement in the development of the\nbrain in men and apes.\n\nGratiolet originated the statement that there is a fundamental difference\nin the development of the brains of apes and that of man--consisting in\nthis; that, in the apes, the sulci which first make their appearance are\nsituated on the posterior region of the cerebral hemispheres, while, in the\nhuman foetus, the sulci first become visible on the frontal lobes.  (76.\nChez tous les singes, les plis posterieurs se developpent les premiers;\nles plis anterieurs se developpent plus tard, aussi la vertebre occipitale\net la parietale sont-elles relativement tres-grandes chez le foetus.\nL'Homme presente une exception remarquable quant a l'epoque de l'apparition\ndes plis frontaux, qui sont les premiers indiques; mais le developpement\ngeneral du lobe frontal, envisage seulement par rapport a son volume, suit\nles memes lois que dans les singes:  Gratiolet, 'Memoire sur les plis\ncerebres de l'Homme et des Primateaux,' p. 39, Tab. iv, fig. 3.)\n\nThis general statement is based upon two observations, the one of a Gibbon\nalmost ready to be born, in which the posterior gyri were \"well developed,\"\nwhile those of the frontal lobes were \"hardly indicated\" (77.  Gratiolet's\nwords are (loc. cit. p. 39):  \"Dans le foetus dont il s'agit les plis\ncerebraux posterieurs sont bien developpes, tandis que les plis du lobe\nfrontal sont a peine indiques.\"  The figure, however (Pl. iv, fig. 3),\nshews the fissure of Rolando, and one of the frontal sulci plainly enough.\nNevertheless, M. Alix, in his 'Notice sur les travaux anthropologiques de\nGratiolet' ('Mem. de la Societe d'Anthropologie de Paris,' 1868, page 32),\nwrites thus:  \"Gratiolet a eu entre les mains le cerveau d'un foetus de\nGibbon, singe eminemment superieur, et tellement rapproche de l'orang, que\ndes naturalistes tres-competents l'ont range parmi les anthropoides.  M.\nHuxley, par exemple, n'hesite pas sur ce point.  Eh bien, c'est sur le\ncerveau d'un foetus de Gibbon que Gratiolet a vu LES CIRCONVOLUTIONS DU\nLOBE TEMPORO-SPHENOIDAL DEJA DEVELOPPEES LORSQU'IL N'EXISTENT PAS ENCORE DE\nPLIS SUR LE LOBE FRONTAL.  Il etait donc bien autorise a dire que, chez\nl'homme les circonvolutions apparaissent d'a en w, tandis que chez les\nsinges elles se developpent d'w en a.\"), and the other of a human foetus at\nthe 22nd or 23rd week of uterogestation, in which Gratiolet notes that the\ninsula was uncovered, but that nevertheless \"des incisures sement de lobe\nanterieur, une scissure peu profonde indique la separation du lobe\noccipital, tres-reduit, d'ailleurs des cette epoque.  Le reste de la\nsurface cerebrale est encore absolument lisse.\"\n\nThree views of this brain are given in Plate II, figs. 1, 2, 3, of the work\ncited, shewing the upper, lateral and inferior views of the hemispheres,\nbut not the inner view.  It is worthy of note that the figure by no means\nbears out Gratiolet's description, inasmuch as the fissure (antero-\ntemporal) on the posterior half of the face of the hemisphere is more\nmarked than any of those vaguely indicated in the anterior half.  If the\nfigure is correct, it in no way justifies Gratiolet's conclusion:  \"Il y a\ndonc entre ces cerveaux [those of a Callithrix and of a Gibbon] et celui du\nfoetus humain une difference fondamental.  Chez celui-ci, longtemps avant\nque les plis temporaux apparaissent, les plis frontaux, ESSAYENT\nd'exister.\"\n\nSince Gratiolet's time, however, the development of the gyri and sulci of\nthe brain has been made the subject of renewed investigation by Schmidt,\nBischoff, Pansch (78.  'Ueber die typische Anordnung der Furchen und\nWindungen auf den Grosshirn-Hemisphaeren des Menschen und der Affen,'\n'Archiv fuer Anthropologie,' iii. 1868.), and more particularly by Ecker\n(79.  'Zur Entwicklungs Geschichte der Furchen und Windungen der Grosshirn-\nHemisphaeren im Foetus des Menschen,'  'Archiv fuer Anthropologie,' iii.\n1868.), whose work is not only the latest, but by far the most complete,\nmemoir on the subject.\n\nThe final results of their inquiries may be summed up as follows:--\n\n1.  In the human foetus, the sylvian fissure is formed in the course of the\nthird month of uterogestation.  In this, and in the fourth month, the\ncerebral hemispheres are smooth and rounded (with the exception of the\nsylvian depression), and they project backwards far beyond the cerebellum.\n\n2.  The sulci, properly so called, begin to appear in the interval between\nthe end of the fourth and the beginning of the sixth month of foetal life,\nbut Ecker is careful to point out that, not only the time, but the order,\nof their appearance is subject to considerable individual variation.  In no\ncase, however, are either the frontal or the temporal sulci the earliest.\n\nThe first which appears, in fact, lies on the inner face of the hemisphere\n(whence doubtless Gratiolet, who does not seem to have examined that face\nin his foetus, overlooked it), and is either the internal perpendicular\n(occipito-parietal), or the calcarine sulcus, these two being close\ntogether and eventually running into one another.  As a rule the occipito-\nparietal is the earlier of the two.\n\n3.  At the latter part of this period, another sulcus, the \"posterio-\nparietal,\" or \"Fissure of Rolando\" is developed, and it is followed, in the\ncourse of the sixth month, by the other principal sulci of the frontal,\nparietal, temporal and occipital lobes.  There is, however, no clear\nevidence that one of these constantly appears before the other; and it is\nremarkable that, in the brain at the period described and figured by Ecker\n(loc. cit. pp. 212-213, Taf. II, figs. 1, 2, 3, 4), the antero-temporal\nsulcus (scissure parallele) so characteristic of the ape's brain, is as\nwell, if not better developed than the fissure of Rolando, and is much more\nmarked than the proper frontal sulci.\n\nTaking the facts as they now stand, it appears to me that the order of the\nappearance of the sulci and gyri in the foetal human brain is in perfect\nharmony with the general doctrine of evolution, and with the view that man\nhas been evolved from some ape-like form; though there can be no doubt that\nform was, in many respects, different from any member of the Primates now\nliving.\n\nVon Baer taught us, half a century ago, that, in the course of their\ndevelopment, allied animals put on at first, the characters of the greater\ngroups to which they belong, and, by degrees, assume those which restrict\nthem within the limits of their family, genus, and species; and he proved,\nat the same time, that no developmental stage of a higher animal is\nprecisely similar to the adult condition of any lower animal.  It is quite\ncorrect to say that a frog passes through the condition of a fish, inasmuch\nas at one period of its life the tadpole has all the characters of a fish,\nand if it went no further, would have to be grouped among fishes.  But it\nis equally true that a tadpole is very different from any known fish.\n\nIn like manner, the brain of a human foetus, at the fifth month, may\ncorrectly be said to be, not only the brain of an ape, but that of an\nArctopithecine or marmoset-like ape; for its hemispheres, with their great\nposterior lobster, and with no sulci but the sylvian and the calcarine,\npresent the characteristics found only in the group of the Arctopithecine\nPrimates.  But it is equally true, as Gratiolet remarks, that, in its\nwidely open sylvian fissure, it differs from the brain of any actual\nmarmoset.  No doubt it would be much more similar to the brain of an\nadvanced foetus of a marmoset.  But we know nothing whatever of the\ndevelopment of the brain in the marmosets.  In the Platyrrhini proper, the\nonly observation with which I am acquainted is due to Pansch, who found in\nthe brain of a foetal Cebus Apella, in addition to the sylvian fissure and\nthe deep calcarine fissure, only a very shallow antero-temporal fissure\n(scissure parallele of Gratiolet).\n\nNow this fact, taken together with the circumstance that the antero-\ntemporal sulcus is present in such Platyrrhini as the Saimiri, which\npresent mere traces of sulci on the anterior half of the exterior of the\ncerebral hemispheres, or none at all, undoubtedly, so far as it goes,\naffords fair evidence in favour of Gratiolet's hypothesis, that the\nposterior sulci appear before the anterior, in the brains of the\nPlatyrrhini.  But, it by no means follows, that the rule which may hold\ngood for the Platyrrhini extends to the Catarrhini.  We have no information\nwhatever respecting the development of the brain in the Cynomorpha; and, as\nregards the Anthropomorpha, nothing but the account of the brain of the\nGibbon, near birth, already referred to.  At the present moment there is\nnot a shadow of evidence to shew that the sulci of a chimpanzee's, or\norang's, brain do not appear in the same order as a man's.\n\nGratiolet opens his preface with the aphorism:  \"Il est dangereux dans les\nsciences de conclure trop vite.\"  I fear he must have forgotten this sound\nmaxim by the time he had reached the discussion of the differences between\nmen and apes, in the body of his work.  No doubt, the excellent author of\none of the most remarkable contributions to the just understanding of the\nmammalian brain which has ever been made, would have been the first to\nadmit the insufficiency of his data had he lived to profit by the advance\nof inquiry.  The misfortune is that his conclusions have been employed by\npersons incompetent to appreciate their foundation, as arguments in favour\nof obscurantism.  (80.  For example, M. l'Abbe Lecomte in his terrible\npamphlet, 'Le Darwinisme et l'origine de l'Homme,' 1873.)\n\nBut it is important to remark that, whether Gratiolet was right or wrong in\nhis hypothesis respecting the relative order of appearance of the temporal\nand frontal sulci, the fact remains; that before either temporal or frontal\nsulci, appear, the foetal brain of man presents characters which are found\nonly in the lowest group of the Primates (leaving out the Lemurs); and that\nthis is exactly what we should expect to be the case, if man has resulted\nfrom the gradual modification of the same form as that from which the other\nPrimates have sprung.\n\n\n\nPART II.  SEXUAL SELECTION.\n\n\nCHAPTER VIII.\n\nPRINCIPLES OF SEXUAL SELECTION.\n\nSecondary sexual characters--Sexual selection--Manner of action--Excess of\nmales--Polygamy--The male alone generally modified through sexual\nselection--Eagerness of the male--Variability of the male--Choice exerted\nby the female--Sexual compared with natural selection--Inheritance, at\ncorresponding periods of life, at corresponding seasons of the year, and as\nlimited by sex--Relations between the several forms of inheritance--Causes\nwhy one sex and the young are not modified through sexual selection--\nSupplement on the proportional numbers of the two sexes throughout the\nanimal kingdom--The proportion of the sexes in relation to natural\nselection.\n\nWith animals which have their sexes separated, the males necessarily differ\nfrom the females in their organs of reproduction; and these are the primary\nsexual characters.  But the sexes often differ in what Hunter has called\nsecondary sexual characters, which are not directly connected with the act\nof reproduction; for instance, the male possesses certain organs of sense\nor locomotion, of which the female is quite destitute, or has them more\nhighly-developed, in order that he may readily find or reach her; or again\nthe male has special organs of prehension for holding her securely.  These\nlatter organs, of infinitely diversified kinds, graduate into those which\nare commonly ranked as primary, and in some cases can hardly be\ndistinguished from them; we see instances of this in the complex appendages\nat the apex of the abdomen in male insects.  Unless indeed we confine the\nterm \"primary\" to the reproductive glands, it is scarcely possible to\ndecide which ought to be called primary and which secondary.\n\nThe female often differs from the male in having organs for the nourishment\nor protection of her young, such as the mammary glands of mammals, and the\nabdominal sacks of the marsupials.  In some few cases also the male\npossesses similar organs, which are wanting in the female, such as the\nreceptacles for the ova in certain male fishes, and those temporarily\ndeveloped in certain male frogs.  The females of most bees are provided\nwith a special apparatus for collecting and carrying pollen, and their\novipositor is modified into a sting for the defence of the larvae and the\ncommunity.  Many similar cases could be given, but they do not here concern\nus.  There are, however, other sexual differences quite unconnected with\nthe primary reproductive organs, and it is with these that we are more\nespecially concerned--such as the greater size, strength, and pugnacity of\nthe male, his weapons of offence or means of defence against rivals, his\ngaudy colouring and various ornaments, his power of song, and other such\ncharacters.\n\nBesides the primary and secondary sexual differences, such as the\nforegoing, the males and females of some animals differ in structures\nrelated to different habits of life, and not at all, or only indirectly, to\nthe reproductive functions.  Thus the females of certain flies (Culicidae\nand Tabanidae) are blood-suckers, whilst the males, living on flowers, have\nmouths destitute of mandibles.  (1.  Westwood, 'Modern Classification of\nInsects,' vol. ii. 1840, p. 541.  For the statement about Tanais, mentioned\nbelow, I am indebted to Fritz Muller.)  The males of certain moths and of\nsome crustaceans (e.g. Tanais) have imperfect, closed mouths, and cannot\nfeed.  The complemental males of certain Cirripedes live like epiphytic\nplants either on the female or the hermaphrodite form, and are destitute of\na mouth and of prehensile limbs.  In these cases it is the male which has\nbeen modified, and has lost certain important organs, which the females\npossess.  In other cases it is the female which has lost such parts; for\ninstance, the female glow-worm is destitute of wings, as also are many\nfemale moths, some of which never leave their cocoons.  Many female\nparasitic crustaceans have lost their natatory legs.  In some weevil-\nbeetles (Curculionidae) there is a great difference between the male and\nfemale in the length of the rostrum or snout (2.  Kirby and Spence,\n'Introduction to Entomology,' vol. iii. 1826, p. 309.); but the meaning of\nthis and of many analogous differences, is not at all understood.\nDifferences of structure between the two sexes in relation to different\nhabits of life are generally confined to the lower animals; but with some\nfew birds the beak of the male differs from that of the female.  In the\nHuia of New Zealand the difference is wonderfully great, and we hear from\nDr. Buller (3.  'Birds of New Zealand,' 1872, p. 66.) that the male uses\nhis strong beak in chiselling the larvae of insects out of decayed wood,\nwhilst the female probes the softer parts with her far longer, much curved\nand pliant beak:  and thus they mutually aid each other.  In most cases,\ndifferences of structure between the sexes are more or less directly\nconnected with the propagation of the species:  thus a female, which has to\nnourish a multitude of ova, requires more food than the male, and\nconsequently requires special means for procuring it.  A male animal, which\nlives for a very short time, might lose its organs for procuring food\nthrough disuse, without detriment; but he would retain his locomotive\norgans in a perfect state, so that he might reach the female.  The female,\non the other hand, might safely lose her organs for flying, swimming, or\nwalking, if she gradually acquired habits which rendered such powers\nuseless.\n\nWe are, however, here concerned only with sexual selection.  This depends\non the advantage which certain individuals have over others of the same sex\nand species solely in respect of reproduction.  When, as in the cases above\nmentioned, the two sexes differ in structure in relation to different\nhabits of life, they have no doubt been modified through natural selection,\nand by inheritance limited to one and the same sex.  So again the primary\nsexual organs, and those for nourishing or protecting the young, come under\nthe same influence; for those individuals which generated or nourished\ntheir offspring best, would leave, ceteris paribus, the greatest number to\ninherit their superiority; whilst those which generated or nourished their\noffspring badly, would leave but few to inherit their weaker powers.  As\nthe male has to find the female, he requires organs of sense and\nlocomotion, but if these organs are necessary for the other purposes of\nlife, as is generally the case, they will have been developed through\nnatural selection.  When the male has found the female, he sometimes\nabsolutely requires prehensile organs to hold her; thus Dr. Wallace informs\nme that the males of certain moths cannot unite with the females if their\ntarsi or feet are broken.  The males of many oceanic crustaceans, when\nadult, have their legs and antennae modified in an extraordinary manner for\nthe prehension of the female; hence we may suspect that it is because these\nanimals are washed about by the waves of the open sea, that they require\nthese organs in order to propagate their kind, and if so, their development\nhas been the result of ordinary or natural selection.  Some animals\nextremely low in the scale have been modified for this same purpose; thus\nthe males of certain parasitic worms, when fully grown, have the lower\nsurface of the terminal part of their bodies roughened like a rasp, and\nwith this they coil round and permanently hold the females.  (4.  M.\nPerrier advances this case ('Revue Scientifique,' Feb. 1, 1873, p. 865) as\none fatal to the belief in sexual election, inasmuch as he supposes that I\nattribute all the differences between the sexes to sexual selection.  This\ndistinguished naturalist, therefore, like so many other Frenchmen, has not\ntaken the trouble to understand even the first principles of sexual\nselection.  An English naturalist insists that the claspers of certain male\nanimals could not have been developed through the choice of the female!\nHad I not met with this remark, I should not have thought it possible for\nany one to have read this chapter and to have imagined that I maintain that\nthe choice of the female had anything to do with the development of the\nprehensile organs in the male.)\n\nWhen the two sexes follow exactly the same habits of life, and the male has\nthe sensory or locomotive organs more highly developed than those of the\nfemale, it may be that the perfection of these is indispensable to the male\nfor finding the female; but in the vast majority of cases, they serve only\nto give one male an advantage over another, for with sufficient time, the\nless well-endowed males would succeed in pairing with the females; and\njudging from the structure of the female, they would be in all other\nrespects equally well adapted for their ordinary habits of life.  Since in\nsuch cases the males have acquired their present structure, not from being\nbetter fitted to survive in the struggle for existence, but from having\ngained an advantage over other males, and from having transmitted this\nadvantage to their male offspring alone, sexual selection must here have\ncome into action.  It was the importance of this distinction which led me\nto designate this form of selection as Sexual Selection.  So again, if the\nchief service rendered to the male by his prehensile organs is to prevent\nthe escape of the female before the arrival of other males, or when\nassaulted by them, these organs will have been perfected through sexual\nselection, that is by the advantage acquired by certain individuals over\ntheir rivals.  But in most cases of this kind it is impossible to\ndistinguish between the effects of natural and sexual selection.  Whole\nchapters could be filled with details on the differences between the sexes\nin their sensory, locomotive, and prehensile organs.  As, however, these\nstructures are not more interesting than others adapted for the ordinary\npurposes of life I shall pass them over almost entirely, giving only a few\ninstances under each class.\n\nThere are many other structures and instincts which must have been\ndeveloped through sexual selection--such as the weapons of offence and the\nmeans of defence of the males for fighting with and driving away their\nrivals--their courage and pugnacity--their various ornaments--their\ncontrivances for producing vocal or instrumental music--and their glands\nfor emitting odours, most of these latter structures serving only to allure\nor excite the female.  It is clear that these characters are the result of\nsexual and not of ordinary selection, since unarmed, unornamented, or\nunattractive males would succeed equally well in the battle for life and in\nleaving a numerous progeny, but for the presence of better endowed males.\nWe may infer that this would be the case, because the females, which are\nunarmed and unornamented, are able to survive and procreate their kind.\nSecondary sexual characters of the kind just referred to, will be fully\ndiscussed in the following chapters, as being in many respects interesting,\nbut especially as depending on the will, choice, and rivalry of the\nindividuals of either sex.  When we behold two males fighting for the\npossession of the female, or several male birds displaying their gorgeous\nplumage, and performing strange antics before an assembled body of females,\nwe cannot doubt that, though led by instinct, they know what they are\nabout, and consciously exert their mental and bodily powers.\n\nJust as man can improve the breeds of his game-cocks by the selection of\nthose birds which are victorious in the cockpit, so it appears that the\nstrongest and most vigorous males, or those provided with the best weapons,\nhave prevailed under nature, and have led to the improvement of the natural\nbreed or species.  A slight degree of variability leading to some\nadvantage, however slight, in reiterated deadly contests would suffice for\nthe work of sexual selection; and it is certain that secondary sexual\ncharacters are eminently variable.  Just as man can give beauty, according\nto his standard of taste, to his male poultry, or more strictly can modify\nthe beauty originally acquired by the parent species, can give to the\nSebright bantam a new and elegant plumage, an erect and peculiar carriage--\nso it appears that female birds in a state of nature, have by a long\nselection of the more attractive males, added to their beauty or other\nattractive qualities.  No doubt this implies powers of discrimination and\ntaste on the part of the female which will at first appear extremely\nimprobable; but by the facts to be adduced hereafter, I hope to be able to\nshew that the females actually have these powers.  When, however, it is\nsaid that the lower animals have a sense of beauty, it must not be supposed\nthat such sense is comparable with that of a cultivated man, with his\nmultiform and complex associated ideas.  A more just comparison would be\nbetween the taste for the beautiful in animals, and that in the lowest\nsavages, who admire and deck themselves with any brilliant, glittering, or\ncurious object.\n\nFrom our ignorance on several points, the precise manner in which sexual\nselection acts is somewhat uncertain.  Nevertheless if those naturalists\nwho already believe in the mutability of species, will read the following\nchapters, they will, I think, agree with me, that sexual selection has\nplayed an important part in the history of the organic world.  It is\ncertain that amongst almost all animals there is a struggle between the\nmales for the possession of the female.  This fact is so notorious that it\nwould be superfluous to give instances.  Hence the females have the\nopportunity of selecting one out of several males, on the supposition that\ntheir mental capacity suffices for the exertion of a choice.  In many cases\nspecial circumstances tend to make the struggle between the males\nparticularly severe.  Thus the males of our migratory birds generally\narrive at their places of breeding before the females, so that many males\nare ready to contend for each female.  I am informed by Mr. Jenner Weir,\nthat the bird-catchers assert that this is invariably the case with the\nnightingale and blackcap, and with respect to the latter he can himself\nconfirm the statement.\n\nMr. Swaysland of Brighton has been in the habit, during the last forty\nyears, of catching our migratory birds on their first arrival, and he has\nnever known the females of any species to arrive before their males.\nDuring one spring he shot thirty-nine males of Ray's wagtail (Budytes Raii)\nbefore he saw a single female.  Mr. Gould has ascertained by the dissection\nof those snipes which arrive the first in this country, that the males come\nbefore the females.  And the like holds good with most of the migratory\nbirds of the United States.  (5.  J.A. Allen, on the 'Mammals and Winter\nBirds of Florida,' Bulletin of Comparative Zoology, Harvard College, p.\n268.)  The majority of the male salmon in our rivers, on coming up from the\nsea, are ready to breed before the females.  So it appears to be with frogs\nand toads.  Throughout the great class of insects the males almost always\nare the first to emerge from the pupal state, so that they generally abound\nfor a time before any females can be seen.  (6.  Even with those plants in\nwhich the sexes are separate, the male flowers are generally mature before\nthe female.  As first shewn by C.K. Sprengel, many hermaphrodite plants are\ndichogamous; that is, their male and female organs are not ready at the\nsame time, so that they cannot be self-fertilised.  Now in such flowers,\nthe pollen is in general matured before the stigma, though there are\nexceptional cases in which the female organs are beforehand.)  The cause of\nthis difference between the males and females in their periods of arrival\nand maturity is sufficiently obvious.  Those males which annually first\nmigrated into any country, or which in the spring were first ready to\nbreed, or were the most eager, would leave the largest number of offspring;\nand these would tend to inherit similar instincts and constitutions.  It\nmust be borne in mind that it would have been impossible to change very\nmaterially the time of sexual maturity in the females, without at the same\ntime interfering with the period of the production of the young--a period\nwhich must be determined by the seasons of the year.  On the whole there\ncan be no doubt that with almost all animals, in which the sexes are\nseparate, there is a constantly recurrent struggle between the males for\nthe possession of the females.\n\nOur difficulty in regard to sexual selection lies in understanding how it\nis that the males which conquer other males, or those which prove the most\nattractive to the females, leave a greater number of offspring to inherit\ntheir superiority than their beaten and less attractive rivals.  Unless\nthis result does follow, the characters which give to certain males an\nadvantage over others, could not be perfected and augmented through sexual\nselection.  When the sexes exist in exactly equal numbers, the worst-\nendowed males will (except where polygamy prevails), ultimately find\nfemales, and leave as many offspring, as well fitted for their general\nhabits of life, as the best-endowed males.  From various facts and\nconsiderations, I formerly inferred that with most animals, in which\nsecondary sexual characters are well developed, the males considerably\nexceeded the females in number; but this is not by any means always true.\nIf the males were to the females as two to one, or as three to two, or even\nin a somewhat lower ratio, the whole affair would be simple; for the\nbetter-armed or more attractive males would leave the largest number of\noffspring.  But after investigating, as far as possible, the numerical\nproportion of the sexes, I do not believe that any great inequality in\nnumber commonly exists.  In most cases sexual selection appears to have\nbeen effective in the following manner.\n\nLet us take any species, a bird for instance, and divide the females\ninhabiting a district into two equal bodies, the one consisting of the more\nvigorous and better-nourished individuals, and the other of the less\nvigorous and healthy.  The former, there can be little doubt, would be\nready to breed in the spring before the others; and this is the opinion of\nMr. Jenner Weir, who has carefully attended to the habits of birds during\nmany years.  There can also be no doubt that the most vigorous, best-\nnourished and earliest breeders would on an average succeed in rearing the\nlargest number of fine offspring.  (7.  Here is excellent evidence on the\ncharacter of the offspring from an experienced ornithologist.  Mr. J.A.\nAllen, in speaking ('Mammals and Winter Birds of E. Florida,' p. 229) of\nthe later broods, after the accidental destruction of the first, says, that\nthese \"are found to be smaller and paler-coloured than those hatched\nearlier in the season.  In cases where several broods are reared each year,\nas a general rule the birds of the earlier broods seem in all respects the\nmost perfect and vigorous.\")  The males, as we have seen, are generally\nready to breed before the females; the strongest, and with some species the\nbest armed of the males, drive away the weaker; and the former would then\nunite with the more vigorous and better-nourished females, because they are\nthe first to breed.  (8.  Hermann Mueller has come to this same conclusion\nwith respect to those female bees which are the first to emerge from the\npupa each year.  See his remarkable essay, 'Anwendung der Darwin'schen\nLehre auf Bienen,' 'Verh. d. V. Jahrg.' xxix. p. 45.)  Such vigorous pairs\nwould surely rear a larger number of offspring than the retarded females,\nwhich would be compelled to unite with the conquered and less powerful\nmales, supposing the sexes to be numerically equal; and this is all that is\nwanted to add, in the course of successive generations, to the size,\nstrength and courage of the males, or to improve their weapons.\n\nBut in very many cases the males which conquer their rivals, do not obtain\npossession of the females, independently of the choice of the latter.  The\ncourtship of animals is by no means so simple and short an affair as might\nbe thought.  The females are most excited by, or prefer pairing with, the\nmore ornamented males, or those which are the best songsters, or play the\nbest antics; but it is obviously probable that they would at the same time\nprefer the more vigorous and lively males, and this has in some cases been\nconfirmed by actual observation.  (9.  With respect to poultry, I have\nreceived information, hereafter to be given, to this effect.  Even with birds,\nsuch as pigeons, which pair for life, the female, as I hear from Mr. Jenner\nWeir, will desert her mate if he is injured or grows weak.)  Thus the more\nvigorous females, which are the first to breed, will have the choice of\nmany males; and though they may not always select the strongest or best\narmed, they will select those which are vigorous and well armed, and in\nother respects the most attractive.  Both sexes, therefore, of such early\npairs would as above explained, have an advantage over others in rearing\noffspring; and this apparently has sufficed during a long course of\ngenerations to add not only to the strength and fighting powers of the\nmales, but likewise to their various ornaments or other attractions.\n\nIn the converse and much rarer case of the males selecting particular\nfemales, it is plain that those which were the most vigorous and had\nconquered others, would have the freest choice; and it is almost certain\nthat they would select vigorous as well as attractive females.  Such pairs\nwould have an advantage in rearing offspring, more especially if the male\nhad the power to defend the female during the pairing-season as occurs with\nsome of the higher animals, or aided her in providing for the young.  The\nsame principles would apply if each sex preferred and selected certain\nindividuals of the opposite sex; supposing that they selected not only the\nmore attractive, but likewise the more vigorous individuals.\n\nNUMERICAL PROPORTION OF THE TWO SEXES.\n\nI have remarked that sexual selection would be a simple affair if the males\nwere considerably more numerous than the females.  Hence I was led to\ninvestigate, as far as I could, the proportions between the two sexes of as\nmany animals as possible; but the materials are scanty.  I will here give\nonly a brief abstract of the results, retaining the details for a\nsupplementary discussion, so as not to interfere with the course of my\nargument.  Domesticated animals alone afford the means of ascertaining the\nproportional numbers at birth; but no records have been specially kept for\nthis purpose.  By indirect means, however, I have collected a considerable\nbody of statistics, from which it appears that with most of our domestic\nanimals the sexes are nearly equal at birth.  Thus 25,560 births of race-\nhorses have been recorded during twenty-one years, and the male births were\nto the female births as 99.7 to 100.  In greyhounds the inequality is\ngreater than with any other animal, for out of 6878 births during twelve\nyears, the male births were to the female as 110.1 to 100.  It is, however,\nin some degree doubtful whether it is safe to infer that the proportion\nwould be the same under natural conditions as under domestication; for\nslight and unknown differences in the conditions affect the proportion of\nthe sexes.  Thus with mankind, the male births in England are as 104.5, in\nRussia as 108.9, and with the Jews of Livonia as 120, to 100 female births.\nBut I shall recur to this curious point of the excess of male births in the\nsupplement to this chapter.  At the Cape of Good Hope, however, male\nchildren of European extraction have been born during several years in the\nproportion of between 90 and 99 to 100 female children.\n\nFor our present purpose we are concerned with the proportions of the sexes,\nnot only at birth, but also at maturity, and this adds another element of\ndoubt; for it is a well-ascertained fact that with man the number of males\ndying before or during birth, and during the first two years of infancy, is\nconsiderably larger than that of females.  So it almost certainly is with\nmale lambs, and probably with some other animals.  The males of some\nspecies kill one another by fighting; or they drive one another about until\nthey become greatly emaciated.  They must also be often exposed to various\ndangers, whilst wandering about in eager search for the females.  In many\nkinds of fish the males are much smaller than the females, and they are\nbelieved often to be devoured by the latter, or by other fishes.  The\nfemales of some birds appear to die earlier than the males; they are also\nliable to be destroyed on their nests, or whilst in charge of their young.\nWith insects the female larvae are often larger than those of the males,\nand would consequently be more likely to be devoured.  In some cases the\nmature females are less active and less rapid in their movements than the\nmales, and could not escape so well from danger.  Hence, with animals in a\nstate of nature, we must rely on mere estimation, in order to judge of the\nproportions of the sexes at maturity; and this is but little trustworthy,\nexcept when the inequality is strongly marked.  Nevertheless, as far as a\njudgment can be formed, we may conclude from the facts given in the\nsupplement, that the males of some few mammals, of many birds, of some fish\nand insects, are considerably more numerous than the females.\n\nThe proportion between the sexes fluctuates slightly during successive\nyears:  thus with race-horses, for every 100 mares born the stallions\nvaried from 107.1 in one year to 92.6 in another year, and with greyhounds\nfrom 116.3 to 95.3.  But had larger numbers been tabulated throughout an\narea more extensive than England, these fluctuations would probably have\ndisappeared; and such as they are, would hardly suffice to lead to\neffective sexual selection in a state of nature.  Nevertheless, in the\ncases of some few wild animals, as shewn in the supplement, the proportions\nseem to fluctuate either during different seasons or in different\nlocalities in a sufficient degree to lead to such selection.  For it should\nbe observed that any advantage, gained during certain years or in certain\nlocalities by those males which were able to conquer their rivals, or were\nthe most attractive to the females, would probably be transmitted to the\noffspring, and would not subsequently be eliminated.  During the succeeding\nseasons, when, from the equality of the sexes, every male was able to\nprocure a female, the stronger or more attractive males previously produced\nwould still have at least as good a chance of leaving offspring as the\nweaker or less attractive.\n\nPOLYGAMY.\n\nThe practice of polygamy leads to the same results as would follow from an\nactual inequality in the number of the sexes; for if each male secures two\nor more females, many males cannot pair; and the latter assuredly will be\nthe weaker or less attractive individuals.  Many mammals and some few birds\nare polygamous, but with animals belonging to the lower classes I have\nfound no evidence of this habit.  The intellectual powers of such animals\nare, perhaps, not sufficient to lead them to collect and guard a harem of\nfemales.  That some relation exists between polygamy and the development of\nsecondary sexual characters, appears nearly certain; and this supports the\nview that a numerical preponderance of males would be eminently favourable\nto the action of sexual selection.  Nevertheless many animals, which are\nstrictly monogamous, especially birds, display strongly-marked secondary\nsexual characters; whilst some few animals, which are polygamous, do not\nhave such characters.\n\nWe will first briefly run through the mammals, and then turn to birds.  The\ngorilla seems to be polygamous, and the male differs considerably from the\nfemale; so it is with some baboons, which live in herds containing twice as\nmany adult females as males.  In South America the Mycetes caraya presents\nwell-marked sexual differences, in colour, beard, and vocal organs; and the\nmale generally lives with two or three wives:  the male of the Cebus\ncapucinus differs somewhat from the female, and appears to be polygamous.\n(10.  On the Gorilla, Savage and Wyman, 'Boston Journal of Natural\nHistory,' vol. v. 1845-47, p. 423.  On Cynocephalus, Brehm, 'Thierleben,'\nB. i. 1864, s. 77.  On Mycetes, Rengger, 'Naturgeschichte der Saeugethiere\nvon Paraguay,' 1830, ss. 14, 20.  On Cebus, Brehm, ibid. s. 108.)  Little\nis known on this head with respect to most other monkeys, but some species\nare strictly monogamous.  The ruminants are eminently polygamous, and they\npresent sexual differences more frequently than almost any other group of\nmammals; this holds good, especially in their weapons, but also in other\ncharacters.  Most deer, cattle, and sheep are polygamous; as are most\nantelopes, though some are monogamous.  Sir Andrew Smith, in speaking of\nthe antelopes of South Africa, says that in herds of about a dozen there\nwas rarely more than one mature male.  The Asiatic Antilope saiga appears\nto be the most inordinate polygamist in the world; for Pallas (11.  Pallas,\n'Spicilegia Zoolog., Fasc.' xii. 1777, p. 29.  Sir Andrew Smith,\n'Illustrations of the Zoology of S. Africa,' 1849, pl. 29, on the Kobus.\nOwen, in his 'Anatomy of Vertebrates' (vol. iii. 1868, p. 633) gives a\ntable shewing incidentally which species of antelopes are gregarious.)\nstates that the male drives away all rivals, and collects a herd of about a\nhundred females and kids together; the female is hornless and has softer\nhair, but does not otherwise differ much from the male.  The wild horse of\nthe Falkland Islands and of the Western States of N. America is polygamous,\nbut, except in his greater size and in the proportions of his body, differs\nbut little from the mare.  The wild boar presents well-marked sexual\ncharacters, in his great tusks and some other points.  In Europe and in\nIndia he leads a solitary life, except during the breeding-season; but as\nis believed by Sir W. Elliot, who has had many opportunities in India of\nobserving this animal, he consorts at this season with several females.\nWhether this holds good in Europe is doubtful, but it is supported by some\nevidence.  The adult male Indian elephant, like the boar, passes much of\nhis time in solitude; but as Dr. Campbell states, when with others, \"It is\nrare to find more than one male with a whole herd of females\"; the larger\nmales expelling or killing the smaller and weaker ones.  The male differs\nfrom the female in his immense tusks, greater size, strength, and\nendurance; so great is the difference in these respects that the males when\ncaught are valued at one-fifth more than the females.  (12.  Dr. Campbell,\nin 'Proc. Zoolog. Soc.' 1869, p. 138.  See also an interesting paper by\nLieut. Johnstone, in 'Proceedings, Asiatic Society of Bengal,' May 1868.)\nThe sexes of other pachydermatous animals differ very little or not at all,\nand, as far as known, they are not polygamists.  Nor have I heard of any\nspecies in the Orders of Cheiroptera, Edentata, Insectivora and Rodents\nbeing polygamous, excepting that amongst the Rodents, the common rat,\naccording to some rat-catchers, lives with several females.  Nevertheless\nthe two sexes of some sloths (Edentata) differ in the character and colour\nof certain patches of hair on their shoulders.  (13.  Dr. Gray, in 'Annals\nand Magazine of Natural History,' 1871, p. 302.)  And many kinds of bats\n(Cheiroptera) present well-marked sexual differences, chiefly in the males\npossessing odoriferous glands and pouches, and by their being of a lighter\ncolour.  (14.  See Dr. Dobson's excellent paper in 'Proceedings of the\nZoological Society,' 1873, p. 241.)  In the great order of Rodents, as far\nas I can learn, the sexes rarely differ, and when they do so, it is but\nslightly in the tint of the fur.\n\nAs I hear from Sir Andrew Smith, the lion in South Africa sometimes lives\nwith a single female, but generally with more, and, in one case, was found\nwith as many as five females; so that he is polygamous.  As far as I can\ndiscover, he is the only polygamist amongst all the terrestrial Carnivora,\nand he alone presents well-marked sexual characters.  If, however, we turn\nto the marine Carnivora, as we shall hereafter see, the case is widely\ndifferent; for many species of seals offer extraordinary sexual\ndifferences, and they are eminently polygamous.  Thus, according to Peron,\nthe male sea-elephant of the Southern Ocean always possesses several\nfemales, and the sea-lion of Forster is said to be surrounded by from\ntwenty to thirty females.  In the North, the male sea-bear of Steller is\naccompanied by even a greater number of females.  It is an interesting\nfact, as Dr. Gill remarks (15.  'The Eared Seals,' American Naturalist,\nvol. iv. Jan. 1871.), that in the monogamous species, \"or those living in\nsmall communities, there is little difference in size between the males and\nfemales; in the social species, or rather those of which the males have\nharems, the males are vastly larger than the females.\"\n\nAmongst birds, many species, the sexes of which differ greatly from each\nother, are certainly monogamous.  In Great Britain we see well-marked\nsexual differences, for instance, in the wild-duck which pairs with a\nsingle female, the common blackbird, and the bullfinch which is said to\npair for life.  I am informed by Mr. Wallace that the like is true of the\nChatterers or Cotingidae of South America, and of many other birds.  In\nseveral groups I have not been able to discover whether the species are\npolygamous or monogamous.  Lesson says that birds of paradise, so\nremarkable for their sexual differences, are polygamous, but Mr. Wallace\ndoubts whether he had sufficient evidence.  Mr. Salvin tells me he has been\nled to believe that humming-birds are polygamous.  The male widow-bird,\nremarkable for his caudal plumes, certainly seems to be a polygamist.  (16.\n'The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird.  See also on\nthe Vidua axillaris, ibid. vol. ii. 1860, p. 211.  On the polygamy of the\nCapercailzie and Great Bustard, see L. Lloyd, 'Game Birds of Sweden,' 1867,\npp. 19, and 182.  Montagu and Selby speak of the Black Grouse as polygamous\nand of the Red Grouse as monogamous.)  I have been assured by Mr. Jenner\nWeir and by others, that it is somewhat common for three starlings to\nfrequent the same nest; but whether this is a case of polygamy or polyandry\nhas not been ascertained.\n\nThe Gallinaceae exhibit almost as strongly marked sexual differences as\nbirds of paradise or humming-birds, and many of the species are, as is well\nknown, polygamous; others being strictly monogamous.  What a contrast is\npresented between the sexes of the polygamous peacock or pheasant, and the\nmonogamous guinea-fowl or partridge!  Many similar cases could be given, as\nin the grouse tribe, in which the males of the polygamous capercailzie and\nblack-cock differ greatly from the females; whilst the sexes of the\nmonogamous red grouse and ptarmigan differ very little.  In the Cursores,\nexcept amongst the bustards, few species offer strongly-marked sexual\ndifferences, and the great bustard (Otis tarda) is said to be polygamous.\nWith the Grallatores, extremely few species differ sexually, but the ruff\n(Machetes pugnax) affords a marked exception, and this species is believed\nby Montagu to be a polygamist.  Hence it appears that amongst birds there\noften exists a close relation between polygamy and the development of\nstrongly-marked sexual differences.  I asked Mr. Bartlett, of the\nZoological Gardens, who has had very large experience with birds, whether\nthe male tragopan (one of the Gallinaceae) was polygamous, and I was struck\nby his answering, \"I do not know, but should think so from his splendid\ncolours.\"\n\nIt deserves notice that the instinct of pairing with a single female is\neasily lost under domestication.  The wild-duck is strictly monogamous, the\ndomestic-duck highly polygamous.  The Rev. W.D. Fox informs me that out of\nsome half-tamed wild-ducks, on a large pond in his neighbourhood, so many\nmallards were shot by the gamekeeper that only one was left for every seven\nor eight females; yet unusually large broods were reared.  The guinea-fowl\nis strictly monogamous; but Mr. Fox finds that his birds succeed best when\nhe keeps one cock to two or three hens.  Canary-birds pair in a state of\nnature, but the breeders in England successfully put one male to four or\nfive females.  I have noticed these cases, as rendering it probable that\nwild monogamous species might readily become either temporarily or\npermanently polygamous.\n\nToo little is known of the habits of reptiles and fishes to enable us to\nspeak of their marriage arrangements.  The stickle-back (Gasterosteus),\nhowever, is said to be a polygamist (17.  Noel Humphreys, 'River Gardens,'\n1857.); and the male during the breeding-season differs conspicuously from\nthe female.\n\nTo sum up on the means through which, as far as we can judge, sexual\nselection has led to the development of secondary sexual characters.  It\nhas been shewn that the largest number of vigorous offspring will be reared\nfrom the pairing of the strongest and best-armed males, victorious in\ncontests over other males, with the most vigorous and best-nourished\nfemales, which are the first to breed in the spring.  If such females\nselect the more attractive, and at the same time vigorous males, they will\nrear a larger number of offspring than the retarded females, which must\npair with the less vigorous and less attractive males.  So it will be if\nthe more vigorous males select the more attractive and at the same time\nhealthy and vigorous females; and this will especially hold good if the\nmale defends the female, and aids in providing food for the young.  The\nadvantage thus gained by the more vigorous pairs in rearing a larger number\nof offspring has apparently sufficed to render sexual selection efficient.\nBut a large numerical preponderance of males over females will be still\nmore efficient; whether the preponderance is only occasional and local, or\npermanent; whether it occurs at birth, or afterwards from the greater\ndestruction of the females; or whether it indirectly follows from the\npractice of polygamy.\n\nTHE MALE GENERALLY MORE MODIFIED THAN THE FEMALE.\n\nThroughout the animal kingdom, when the sexes differ in external\nappearance, it is, with rare exceptions, the male which has been the more\nmodified; for, generally, the female retains a closer resemblance to the\nyoung of her own species, and to other adult members of the same group.\nThe cause of this seems to lie in the males of almost all animals having\nstronger passions than the females.  Hence it is the males that fight\ntogether and sedulously display their charms before the females; and the\nvictors transmit their superiority to their male offspring.  Why both sexes\ndo not thus acquire the characters of their fathers, will be considered\nhereafter.  That the males of all mammals eagerly pursue the females is\nnotorious to every one.  So it is with birds; but many cock birds do not so\nmuch pursue the hen, as display their plumage, perform strange antics, and\npour forth their song in her presence.  The male in the few fish observed\nseems much more eager than the female; and the same is true of alligators,\nand apparently of Batrachians.  Throughout the enormous class of insects,\nas Kirby remarks, \"the law is that the male shall seek the female.\"  (18.\nKirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 342.)\nTwo good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that\nthe males of spiders and crustaceans are more active and more erratic in\ntheir habits than the females.  When the organs of sense or locomotion are\npresent in the one sex of insects and crustaceans and absent in the other,\nor when, as is frequently the case, they are more highly developed in the\none than in the other, it is, as far as I can discover, almost invariably\nthe male which retains such organs, or has them most developed; and this\nshews that the male is the more active member in the courtship of the\nsexes.  (19.  One parasitic Hymenopterous insect (Westwood, 'Modern Class.\nof Insects,' vol. ii. p. 160) forms an exception to the rule, as the male\nhas rudimentary wings, and never quits the cell in which it is born, whilst\nthe female has well-developed wings.  Audouin believes that the females of\nthis species are impregnated by the males which are born in the same cells\nwith them; but it is much more probable that the females visit other cells,\nso that close inter-breeding is thus avoided.  We shall hereafter meet in\nvarious classes, with a few exceptional cases, in which the female, instead\nof the male, is the seeker and wooer.)\n\nThe female, on the other hand, with the rarest exceptions, is less eager\nthan the male.  As the illustrious Hunter (20.  'Essays and Observations,'\nedited by Owen, vol. i. 1861, p. 194.) long ago observed, she generally\n\"requires to be courted;\" she is coy, and may often be seen endeavouring\nfor a long time to escape from the male.  Every observer of the habits of\nanimals will be able to call to mind instances of this kind.  It is shewn\nby various facts, given hereafter, and by the results fairly attributable\nto sexual selection, that the female, though comparatively passive,\ngenerally exerts some choice and accepts one male in preference to others.\nOr she may accept, as appearances would sometimes lead us to believe, not\nthe male which is the most attractive to her, but the one which is the\nleast distasteful.  The exertion of some choice on the part of the female\nseems a law almost as general as the eagerness of the male.\n\nWe are naturally led to enquire why the male, in so many and such distinct\nclasses, has become more eager than the female, so that he searches for\nher, and plays the more active part in courtship.  It would be no advantage\nand some loss of power if each sex searched for the other; but why should\nthe male almost always be the seeker?  The ovules of plants after\nfertilisation have to be nourished for a time; hence the pollen is\nnecessarily brought to the female organs--being placed on the stigma, by\nmeans of insects or the wind, or by the spontaneous movements of the\nstamens; and in the Algae, etc., by the locomotive power of the\nantherozooids.  With lowly-organised aquatic animals, permanently affixed\nto the same spot and having their sexes separate, the male element is\ninvariably brought to the female; and of this we can see the reason, for\neven if the ova were detached before fertilisation, and did not require\nsubsequent nourishment or protection, there would yet be greater difficulty\nin transporting them than the male element, because, being larger than the\nlatter, they are produced in far smaller numbers.  So that many of the\nlower animals are, in this respect, analogous with plants.  (21.  Prof.\nSachs ('Lehrbuch der Botanik,' 1870, S. 633) in speaking of the male and\nfemale reproductive cells, remarks, \"verhaelt sich die eine bei der\nVereinigung activ,...die andere erscheint bei der Vereinigung passiv.\")\nThe males of affixed and aquatic animals having been led to emit their\nfertilising element in this way, it is natural that any of their\ndescendants, which rose in the scale and became locomotive, should retain\nthe same habit; and they would approach the female as closely as possible,\nin order not to risk the loss of the fertilising element in a long passage\nof it through the water.  With some few of the lower animals, the females\nalone are fixed, and the males of these must be the seekers.  But it is\ndifficult to understand why the males of species, of which the progenitors\nwere primordially free, should invariably have acquired the habit of\napproaching the females, instead of being approached by them.  But in all\ncases, in order that the males should seek efficiently, it would be\nnecessary that they should be endowed with strong passions; and the\nacquirement of such passions would naturally follow from the more eager\nleaving a larger number of offspring than the less eager.\n\nThe great eagerness of the males has thus indirectly led to their much more\nfrequently developing secondary sexual characters than the females.  But\nthe development of such characters would be much aided, if the males were\nmore liable to vary than the females--as I concluded they were--after a\nlong study of domesticated animals.  Von Nathusius, who has had very wide\nexperience, is strongly of the same opinion.  (22.  'Vortraege uber\nViehzucht,' 1872, p. 63.)  Good evidence also in favour of this conclusion\ncan be produced by a comparison of the two sexes in mankind.  During the\nNovara Expedition (23.  'Reise der Novara:  Anthropolog. Theil,' 1867, ss.\n216-269.  The results were calculated by Dr. Weisbach from measurements\nmade by Drs. K. Scherzer and Schwarz.  On the greater variability of the\nmales of domesticated animals, see my 'Variation of Animals and Plants\nunder Domestication,' vol. ii. 1868, p. 75.) a vast number of measurements\nwas made of various parts of the body in different races, and the men were\nfound in almost every case to present a greater range of variation than the\nwomen; but I shall have to recur to this subject in a future chapter.  Mr.\nJ. Wood (24.  'Proceedings of the Royal Society,' vol. xvi. July 1868, pp.\n519 and 524.), who has carefully attended to the variation of the muscles\nin man, puts in italics the conclusion that \"the greatest number of\nabnormalities in each subject is found in the males.\"  He had previously\nremarked that \"altogether in 102 subjects, the varieties of redundancy were\nfound to be half as many again as in females, contrasting widely with the\ngreater frequency of deficiency in females before described.\"  Professor\nMacalister likewise remarks (25.  'Proc. Royal Irish Academy,' vol. x.\n1868, p. 123.) that variations in the muscles \"are probably more common in\nmales than females.\"  Certain muscles which are not normally present in\nmankind are also more frequently developed in the male than in the female\nsex, although exceptions to this rule are said to occur.  Dr. Burt Wilder\n(26.  'Massachusetts Medical Society,' vol. ii. No. 3, 1868, p. 9.) has\ntabulated the cases of 152 individuals with supernumerary digits, of which\n86 were males, and 39, or less than half, females, the remaining 27 being\nof unknown sex.  It should not, however, be overlooked that women would\nmore frequently endeavour to conceal a deformity of this kind than men.\nAgain, Dr. L. Meyer asserts that the ears of man are more variable in form\nthan those of a woman.  (27.  'Archiv fur Path. Anat. und Phys.' 1871, p.\n488.)  Lastly the temperature is more variable in man than in woman.  (28.\nThe conclusions recently arrived at by Dr. J. Stockton Hough, on the\ntemperature of man, are given in the 'Pop. Sci. Review,' Jan. 1st, 1874, p.\n97.)\n\nThe cause of the greater general variability in the male sex, than in the\nfemale is unknown, except in so far as secondary sexual characters are\nextraordinarily variable, and are usually confined to the males; and, as we\nshall presently see, this fact is, to a certain extent, intelligible.\nThrough the action of sexual and natural selection male animals have been\nrendered in very many instances widely different from their females; but\nindependently of selection the two sexes, from differing constitutionally,\ntend to vary in a somewhat different manner.  The female has to expend much\norganic matter in the formation of her ova, whereas the male expends much\nforce in fierce contests with his rivals, in wandering about in search of\nthe female, in exerting his voice, pouring out odoriferous secretions,\netc.:  and this expenditure is generally concentrated within a short\nperiod.  The great vigour of the male during the season of love seems often\nto intensify his colours, independently of any marked difference from the\nfemale.  (29.  Prof. Mantegazza is inclined to believe ('Lettera a Carlo\nDarwin,' 'Archivio per l'Anthropologia,' 1871, p. 306) that the bright\ncolours, common in so many male animals, are due to the presence and\nretention by them of the spermatic fluid; but this can hardly be the case;\nfor many male birds, for instance young pheasants, become brightly coloured\nin the autumn of their first year.)  In mankind, and even as low down in\nthe organic scale as in the Lepidoptera, the temperature of the body is\nhigher in the male than in the female, accompanied in the case of man by a\nslower pulse.  (30.  For mankind, see Dr. J. Stockton Hough, whose\nconclusions are given in the 'Popular Science Review,' 1874, p. 97.  See\nGirard's observations on the Lepidoptera, as given in the 'Zoological\nRecord,' 1869, p. 347.)  On the whole the expenditure of matter and force\nby the two sexes is probably nearly equal, though effected in very\ndifferent ways and at different rates.\n\nFrom the causes just specified the two sexes can hardly fail to differ\nsomewhat in constitution, at least during the breeding-season; and,\nalthough they may be subjected to exactly the same conditions, they will\ntend to vary in a different manner.  If such variations are of no service\nto either sex, they will not be accumulated and increased by sexual or\nnatural selection.  Nevertheless, they may become permanent if the exciting\ncause acts permanently; and in accordance with a frequent form of\ninheritance they may be transmitted to that sex alone in which they first\nappeared.  In this case the two sexes will come to present permanent, yet\nunimportant, differences of character.  For instance, Mr. Allen shews that\nwith a large number of birds inhabiting the northern and southern United\nStates, the specimens from the south are darker-coloured than those from\nthe north; and this seems to be the direct result of the difference in\ntemperature, light, etc., between the two regions.  Now, in some few cases,\nthe two sexes of the same species appear to have been differently affected;\nin the Agelaeus phoeniceus the males have had their colours greatly\nintensified in the south; whereas with Cardinalis virginianus it is the\nfemales which have been thus affected; with Quiscalus major the females\nhave been rendered extremely variable in tint, whilst the males remain\nnearly uniform.  (31.  'Mammals and Birds of E. Florida,' pp. 234, 280,\n295.)\n\nA few exceptional cases occur in various classes of animals, in which the\nfemales instead of the males have acquired well pronounced secondary sexual\ncharacters, such as brighter colours, greater size, strength, or pugnacity.\nWith birds there has sometimes been a complete transposition of the\nordinary characters proper to each sex; the females having become the more\neager in courtship, the males remaining comparatively passive, but\napparently selecting the more attractive females, as we may infer from the\nresults.  Certain hen birds have thus been rendered more highly coloured or\notherwise ornamented, as well as more powerful and pugnacious than the\ncocks; these characters being transmitted to the female offspring alone.\n\nIt may be suggested that in some cases a double process of selection has\nbeen carried on; that the males have selected the more attractive females,\nand the latter the more attractive males.  This process, however, though it\nmight lead to the modification of both sexes, would not make the one sex\ndifferent from the other, unless indeed their tastes for the beautiful\ndiffered; but this is a supposition too improbable to be worth considering\nin the case of any animal, excepting man.  There are, however, many animals\nin which the sexes resemble each other, both being furnished with the same\nornaments, which analogy would lead us to attribute to the agency of sexual\nselection.  In such cases it may be suggested with more plausibility, that\nthere has been a double or mutual process of sexual selection; the more\nvigorous and precocious females selecting the more attractive and vigorous\nmales, the latter rejecting all except the more attractive females.  But\nfrom what we know of the habits of animals, this view is hardly probable,\nfor the male is generally eager to pair with any female.  It is more\nprobable that the ornaments common to both sexes were acquired by one sex,\ngenerally the male, and then transmitted to the offspring of both sexes.\nIf, indeed, during a lengthened period the males of any species were\ngreatly to exceed the females in number, and then during another lengthened\nperiod, but under different conditions, the reverse were to occur, a\ndouble, but not simultaneous, process of sexual selection might easily be\ncarried on, by which the two sexes might be rendered widely different.\n\nWe shall hereafter see that many animals exist, of which neither sex is\nbrilliantly coloured or provided with special ornaments, and yet the\nmembers of both sexes or of one alone have probably acquired simple\ncolours, such as white or black, through sexual selection.  The absence of\nbright tints or other ornaments may be the result of variations of the\nright kind never having occurred, or of the animals themselves having\npreferred plain black or white.  Obscure tints have often been developed\nthrough natural selection for the sake of protection, and the acquirement\nthrough sexual selection of conspicuous colours, appears to have been\nsometimes checked from the danger thus incurred.  But in other cases the\nmales during long ages may have struggled together for the possession of\nthe females, and yet no effect will have been produced, unless a larger\nnumber of offspring were left by the more successful males to inherit their\nsuperiority, than by the less successful:  and this, as previously shewn,\ndepends on many complex contingencies.\n\nSexual selection acts in a less rigorous manner than natural selection.\nThe latter produces its effects by the life or death at all ages of the\nmore or less successful individuals.  Death, indeed, not rarely ensues from\nthe conflicts of rival males.  But generally the less successful male\nmerely fails to obtain a female, or obtains a retarded and less vigorous\nfemale later in the season, or, if polygamous, obtains fewer females; so\nthat they leave fewer, less vigorous, or no offspring.  In regard to\nstructures acquired through ordinary or natural selection, there is in most\ncases, as long as the conditions of life remain the same, a limit to the\namount of advantageous modification in relation to certain special\npurposes; but in regard to structures adapted to make one male victorious\nover another, either in fighting or in charming the female, there is no\ndefinite limit to the amount of advantageous modification; so that as long\nas the proper variations arise the work of sexual selection will go on.\nThis circumstance may partly account for the frequent and extraordinary\namount of variability presented by secondary sexual characters.\nNevertheless, natural selection will determine that such characters shall\nnot be acquired by the victorious males, if they would be highly injurious,\neither by expending too much of their vital powers, or by exposing them to\nany great danger.  The development, however, of certain structures--of the\nhorns, for instance, in certain stags--has been carried to a wonderful\nextreme; and in some cases to an extreme which, as far as the general\nconditions of life are concerned, must be slightly injurious to the male.\nFrom this fact we learn that the advantages which favoured males derive\nfrom conquering other males in battle or courtship, and thus leaving a\nnumerous progeny, are in the long run greater than those derived from\nrather more perfect adaptation to their conditions of life.  We shall\nfurther see, and it could never have been anticipated, that the power to\ncharm the female has sometimes been more important than the power to\nconquer other males in battle.\n\nLAWS OF INHERITANCE.\n\nIn order to understand how sexual selection has acted on many animals of\nmany classes, and in the course of ages has produced a conspicuous result,\nit is necessary to bear in mind the laws of inheritance, as far as they are\nknown.  Two distinct elements are included under the term \"inheritance\"--\nthe transmission, and the development of characters; but as these generally\ngo together, the distinction is often overlooked.  We see this distinction\nin those characters which are transmitted through the early years of life,\nbut are developed only at maturity or during old age.  We see the same\ndistinction more clearly with secondary sexual characters, for these are\ntransmitted through both sexes, though developed in one alone.  That they\nare present in both sexes, is manifest when two species, having strongly-\nmarked sexual characters, are crossed, for each transmits the characters\nproper to its own male and female sex to the hybrid offspring of either\nsex.  The same fact is likewise manifest, when characters proper to the\nmale are occasionally developed in the female when she grows old or becomes\ndiseased, as, for instance, when the common hen assumes the flowing tail-\nfeathers, hackles, comb, spurs, voice, and even pugnacity of the cock.\nConversely, the same thing is evident, more or less plainly, with castrated\nmales.  Again, independently of old age or disease, characters are\noccasionally transferred from the male to the female, as when, in certain\nbreeds of the fowl, spurs regularly appear in the young and healthy\nfemales.  But in truth they are simply developed in the female; for in\nevery breed each detail in the structure of the spur is transmitted through\nthe female to her male offspring.  Many cases will hereafter be given,\nwhere the female exhibits, more or less perfectly, characters proper to the\nmale, in whom they must have been first developed, and then transferred to\nthe female.  The converse case of the first development of characters in\nthe female and of transference to the male, is less frequent; it will\ntherefore be well to give one striking instance.  With bees the pollen-\ncollecting apparatus is used by the female alone for gathering pollen for\nthe larvae, yet in most of the species it is partially developed in the\nmales to whom it is quite useless, and it is perfectly developed in the\nmales of Bombus or the humble-bee.  (32.  H. Muller, 'Anwendung der\nDarwin'schen Lehre,' etc., Verh. d. n. V. Jahrg., xxix. p. 42.)  As not a\nsingle other Hymenopterous insect, not even the wasp, which is closely\nallied to the bee, is provided with a pollen-collecting apparatus, we have\nno grounds for supposing that male bees primordially collected pollen as\nwell as the females; although we have some reason to suspect that male\nmammals primordially suckled their young as well as the females.  Lastly,\nin all cases of reversion, characters are transmitted through two, three,\nor many more generations, and are then developed under certain unknown\nfavourable conditions.  This important distinction between transmission and\ndevelopment will be best kept in mind by the aid of the hypothesis of\npangenesis.  According to this hypothesis, every unit or cell of the body\nthrows off gemmules or undeveloped atoms, which are transmitted to the\noffspring of both sexes, and are multiplied by self-division.  They may\nremain undeveloped during the early years of life or during successive\ngenerations; and their development into units or cells, like those from\nwhich they were derived, depends on their affinity for, and union with\nother units or cells previously developed in the due order of growth.\n\nINHERITANCE AT CORRESPONDING PERIODS OF LIFE.\n\nThis tendency is well established.  A new character, appearing in a young\nanimal, whether it lasts throughout life or is only transient, will, in\ngeneral, reappear in the offspring at the same age and last for the same\ntime.  If, on the other hand, a new character appears at maturity, or even\nduring old age, it tends to reappear in the offspring at the same advanced\nage.  When deviations from this rule occur, the transmitted characters much\noftener appear before, than after the corresponding age.  As I have dwelt\non this subject sufficiently in another work (33.  The 'Variation of\nAnimals and Plants under Domestication,' vol. ii. 1868, p. 75.  In the last\nchapter but one, the provisional hypothesis of pangenesis, above alluded\nto, is fully explained.), I will here merely give two or three instances,\nfor the sake of recalling the subject to the reader's mind.  In several\nbreeds of the Fowl, the down-covered chickens, the young birds in their\nfirst true plumage, and the adults differ greatly from one another, as well\nas from their common parent-form, the Gallus bankiva; and these characters\nare faithfully transmitted by each breed to their offspring at the\ncorresponding periods of life.  For instance, the chickens of spangled\nHamburgs, whilst covered with down, have a few dark spots on the head and\nrump, but are not striped longitudinally, as in many other breeds; in their\nfirst true plumage, \"they are beautifully pencilled,\" that is each feather\nis transversely marked by numerous dark bars; but in their second plumage\nthe feathers all become spangled or tipped with a dark round spot.  (34.\nThese facts are given on the high authority of a great breeder, Mr. Teebay;\nsee Tegetmeier's 'Poultry Book,' 1868, p. 158.  On the characters of\nchickens of different breeds, and on the breeds of the pigeon, alluded to\nin the following paragraph, see 'Variation of Animals,' etc., vol. i. pp.\n160, 249; vol. ii. p. 77.)  Hence in this breed variations have occurred\nat, and been transmitted to, three distinct periods of life.  The Pigeon\noffers a more remarkable case, because the aboriginal parent species does\nnot undergo any change of plumage with advancing age, excepting that at\nmaturity the breast becomes more iridescent; yet there are breeds which do\nnot acquire their characteristic colours until they have moulted two,\nthree, or four times; and these modifications of plumage are regularly\ntransmitted.\n\nINHERITANCE AT CORRESPONDING SEASONS OF THE YEAR.\n\nWith animals in a state of nature, innumerable instances occur of\ncharacters appearing periodically at different seasons.  We see this in the\nhorns of the stag, and in the fur of Arctic animals which becomes thick and\nwhite during the winter.  Many birds acquire bright colours and other\ndecorations during the breeding-season alone.  Pallas states (35.  'Novae\nspecies Quadrupedum e Glirium ordine,' 1778, p. 7.  On the transmission of\ncolour by the horse, see 'Variation of Animals and Plants under\nDomestication,' vol. i. p. 51.  Also vol. ii. p. 71, for a general\ndiscussion on 'Inheritance as limited by Sex.'), that in Siberia domestic\ncattle and horses become lighter-coloured during the winter; and I have\nmyself observed, and heard of similar strongly marked changes of colour,\nthat is, from brownish cream-colour or reddish-brown to a perfect white, in\nseveral ponies in England.  Although I do not know that this tendency to\nchange the colour of the coat during different seasons is transmitted, yet\nit probably is so, as all shades of colour are strongly inherited by the\nhorse.  Nor is this form of inheritance, as limited by the seasons, more\nremarkable than its limitation by age or sex.\n\nINHERITANCE AS LIMITED BY SEX.\n\nThe equal transmission of characters to both sexes is the commonest form of\ninheritance, at least with those animals which do not present strongly-\nmarked sexual differences, and indeed with many of these.  But characters\nare somewhat commonly transferred exclusively to that sex, in which they\nfirst appear.  Ample evidence on this head has been advanced in my work on\n'Variation under Domestication,' but a few instances may here be given.\nThere are breeds of the sheep and goat, in which the horns of the male\ndiffer greatly in shape from those of the female; and these differences,\nacquired under domestication, are regularly transmitted to the same sex.\nAs a rule, it is the females alone in cats which are tortoise-shell, the\ncorresponding colour in the males being rusty-red.  With most breeds of the\nfowl, the characters proper to each sex are transmitted to the same sex\nalone.  So general is this form of transmission that it is an anomaly when\nvariations in certain breeds are transmitted equally to both sexes.  There\nare also certain sub-breeds of the fowl in which the males can hardly be\ndistinguished from one another, whilst the females differ considerably in\ncolour.  The sexes of the pigeon in the parent-species do not differ in any\nexternal character; nevertheless, in certain domesticated breeds the male\nis coloured differently from the female.  (36.  Dr. Chapuis, 'Le Pigeon\nVoyageur Belge,' 1865, p. 87.  Boitard et Corbie, 'Les Pigeons de Voliere,'\netc., 1824, p. 173.  See, also, on similar differences in certain breeds at\nModena, 'Le variazioni dei Colombi domestici,' del Paolo Bonizzi, 1873.)\nThe wattle in the English Carrier pigeon, and the crop in the Pouter, are\nmore highly developed in the male than in the female; and although these\ncharacters have been gained through long-continued selection by man, the\nslight differences between the sexes are wholly due to the form of\ninheritance which has prevailed; for they have arisen, not from, but rather\nin opposition to, the wish of the breeder.\n\n\nMost of our domestic races have been formed by the accumulation of many\nslight variations; and as some of the successive steps have been\ntransmitted to one sex alone, and some to both sexes, we find in the\ndifferent breeds of the same species all gradations between great sexual\ndissimilarity and complete similarity.  Instances have already been given\nwith the breeds of the fowl and pigeon, and under nature analogous cases\nare common.  With animals under domestication, but whether in nature I will\nnot venture to say, one sex may lose characters proper to it, and may thus\ncome somewhat to resemble the opposite sex; for instance, the males of some\nbreeds of the fowl have lost their masculine tail-plumes and hackles.  On\nthe other hand, the differences between the sexes may be increased under\ndomestication, as with merino sheep, in which the ewes have lost their\nhorns.  Again, characters proper to one sex may suddenly appear in the\nother sex; as in those sub-breeds of the fowl in which the hens acquire\nspurs whilst young; or, as in certain Polish sub-breeds, in which the\nfemales, as there is reason to believe, originally acquired a crest, and\nsubsequently transferred it to the males.  All these cases are intelligible\non the hypothesis of pangenesis; for they depend on the gemmules of certain\nparts, although present in both sexes, becoming, through the influence of\ndomestication, either dormant or developed in either sex.\n\nThere is one difficult question which it will be convenient to defer to a\nfuture chapter; namely, whether a character at first developed in both\nsexes, could through selection be limited in its development to one sex\nalone.  If, for instance, a breeder observed that some of his pigeons (of\nwhich the characters are usually transferred in an equal degree to both\nsexes) varied into pale blue, could he by long-continued selection make a\nbreed, in which the males alone should be of this tint, whilst the females\nremained unchanged?  I will here only say, that this, though perhaps not\nimpossible, would be extremely difficult; for the natural result of\nbreeding from the pale-blue males would be to change the whole stock of\nboth sexes to this tint.  If, however, variations of the desired tint\nappeared, which were from the first limited in their development to the\nmale sex, there would not be the least difficulty in making a breed with\nthe two sexes of a different colour, as indeed has been effected with a\nBelgian breed, in which the males alone are streaked with black.  In a\nsimilar manner, if any variation appeared in a female pigeon, which was\nfrom the first sexually limited in its development to the females, it would\nbe easy to make a breed with the females alone thus characterised; but if\nthe variation was not thus originally limited, the process would be\nextremely difficult, perhaps impossible.  (37.  Since the publication of\nthe first edition of this work, it has been highly satisfactory to me to\nfind the following remarks (the 'Field,' Sept. 1872) from so experienced a\nbreeder as Mr. Tegetmeier.  After describing some curious cases in pigeons,\nof the transmission of colour by one sex alone, and the formation of a sub-\nbreed with this character, he says:  \"It is a singular circumstance that\nMr. Darwin should have suggested the possibility of modifying the sexual\ncolours of birds by a course of artificial selection.  When he did so, he\nwas in ignorance of these facts that I have related; but it is remarkable\nhow very closely he suggested the right method of procedure.\")\n\nON THE RELATION BETWEEN THE PERIOD OF DEVELOPMENT OF A CHARACTER AND ITS\nTRANSMISSION TO ONE SEX OR TO BOTH SEXES.\n\nWhy certain characters should be inherited by both sexes, and other\ncharacters by one sex alone, namely by that sex in which the character\nfirst appeared, is in most cases quite unknown.  We cannot even conjecture\nwhy with certain sub-breeds of the pigeon, black striae, though transmitted\nthrough the female, should be developed in the male alone, whilst every\nother character is equally transferred to both sexes.  Why, again, with\ncats, the tortoise-shell colour should, with rare exceptions, be developed\nin the female alone.  The very same character, such as deficient or\nsupernumerary digits, colour-blindness, etc., may with mankind be inherited\nby the males alone of one family, and in another family by the females\nalone, though in both cases transmitted through the opposite as well as\nthrough the same sex.  (38.  References are given in my 'Variation of\nAnimals and Plants under Domestication,' vol. ii. p. 72.)  Although we are\nthus ignorant, the two following rules seem often to hold good--that\nvariations which first appear in either sex at a late period of life, tend\nto be developed in the same sex alone; whilst variations which first appear\nearly in life in either sex tend to be developed in both sexes.  I am,\nhowever, far from supposing that this is the sole determining cause.  As I\nhave not elsewhere discussed this subject, and it has an important bearing\non sexual selection, I must here enter into lengthy and somewhat intricate\ndetails.\n\nIt is in itself probable that any character appearing at an early age would\ntend to be inherited equally by both sexes, for the sexes do not differ\nmuch in constitution before the power of reproduction is gained.  On the\nother hand, after this power has been gained and the sexes have come to\ndiffer in constitution, the gemmules (if I may again use the language of\npangenesis) which are cast off from each varying part in the one sex would\nbe much more likely to possess the proper affinities for uniting with the\ntissues of the same sex, and thus becoming developed, than with those of\nthe opposite sex.\n\nI was first led to infer that a relation of this kind exists, from the fact\nthat whenever and in whatever manner the adult male differs from the adult\nfemale, he differs in the same manner from the young of both sexes.  The\ngenerality of this fact is quite remarkable:  it holds good with almost all\nmammals, birds, amphibians, and fishes; also with many crustaceans,\nspiders, and some few insects, such as certain orthoptera and libellulae.\nIn all these cases the variations, through the accumulation of which the\nmale acquired his proper masculine characters, must have occurred at a\nsomewhat late period of life; otherwise the young males would have been\nsimilarly characterised; and conformably with our rule, the variations are\ntransmitted to and developed in the adult males alone.  When, on the other\nhand, the adult male closely resembles the young of both sexes (these, with\nrare exceptions, being alike), he generally resembles the adult female; and\nin most of these cases the variations through which the young and old\nacquired their present characters, probably occurred, according to our\nrule, during youth.  But there is here room for doubt, for characters are\nsometimes transferred to the offspring at an earlier age than that at which\nthey first appeared in the parents, so that the parents may have varied\nwhen adult, and have transferred their characters to their offspring whilst\nyoung.  There are, moreover, many animals, in which the two sexes closely\nresemble each other, and yet both differ from their young:  and here the\ncharacters of the adults must have been acquired late in life;\nnevertheless, these characters, in apparent contradiction to our rule, are\ntransferred to both sexes.  We must not however, overlook the possibility\nor even probability of successive variations of the same nature occurring,\nunder exposure to similar conditions, simultaneously in both sexes at a\nrather late period of life; and in this case the variations would be\ntransferred to the offspring of both sexes at a corresponding late age; and\nthere would then be no real contradiction to the rule that variations\noccurring late in life are transferred exclusively to the sex in which they\nfirst appeared.  This latter rule seems to hold true more generally than\nthe second one, namely, that variations which occur in either sex early in\nlife tend to be transferred to both sexes.  As it was obviously impossible\neven to estimate in how large a number of cases throughout the animal\nkingdom these two propositions held good, it occurred to me to investigate\nsome striking or crucial instances, and to rely on the result.\n\nAn excellent case for investigation is afforded by the Deer family.  In all\nthe species, but one, the horns are developed only in the males, though\ncertainly transmitted through the females, and capable of abnormal\ndevelopment in them.  In the reindeer, on the other hand, the female is\nprovided with horns; so that in this species, the horns ought, according to\nour rule, to appear early in life, long before the two sexes are mature and\nhave come to differ much in constitution.  In all the other species the\nhorns ought to appear later in life, which would lead to their development\nin that sex alone, in which they first appeared in the progenitor of the\nwhole Family.  Now in seven species, belonging to distinct sections of the\nfamily and inhabiting different regions, in which the stags alone bear\nhorns, I find that the horns first appear at periods, varying from nine\nmonths after birth in the roebuck, to ten, twelve or even more months in\nthe stags of the six other and larger species.  (39.  I am much obliged to\nMr. Cupples for having made enquiries for me in regard to the Roebuck and\nRed Deer of Scotland from Mr. Robertson, the experienced head-forester to\nthe Marquis of Breadalbane.  In regard to Fallow-deer, I have to thank Mr.\nEyton and others for information.  For the Cervus alces of N. America, see\n'Land and Water,' 1868, pp. 221 and 254; and for the C. Virginianus and\nstrongyloceros of the same continent, see J.D. Caton, in 'Ottawa Acad. of\nNat. Sc.' 1868, p. 13.  For Cervus Eldi of Pegu, see Lieut. Beaven,\n'Proccedings of the Zoological Society,' 1867, p. 762.)  But with the\nreindeer the case is widely different; for, as I hear from Prof. Nilsson,\nwho kindly made special enquiries for me in Lapland, the horns appear in\nthe young animals within four or five weeks after birth, and at the same\ntime in both sexes.  So that here we have a structure, developed at a most\nunusually early age in one species of the family, and likewise common to\nboth sexes in this one species alone.\n\nIn several kinds of antelopes, only the males are provided with horns,\nwhilst in the greater number both sexes bear horns.  With respect to the\nperiod of development, Mr. Blyth informs me that there was at one time in\nthe Zoological Gardens a young koodoo (Ant. strepsiceros), of which the\nmales alone are horned, and also the young of a closely-allied species, the\neland (Ant. oreas), in which both sexes are horned.  Now it is in strict\nconformity with our rule, that in the young male koodoo, although ten\nmonths old, the horns were remarkably small, considering the size\nultimately attained by them; whilst in the young male eland, although only\nthree months old, the horns were already very much larger than in the\nkoodoo.  It is also a noticeable fact that in the prong-horned antelope\n(40.  Antilocapra Americana.  I have to thank Dr. Canfield for information\nwith respect to the horns of the female:  see also his paper in\n'Proceedings of the Zoological Society,' 1866, p. 109.  Also Owen, 'Anatomy\nof Vertebrates,' vol. iii. p. 627), only a few of the females, about one in\nfive, have horns, and these are in a rudimentary state, though sometimes\nabove four inches long:  so that as far as concerns the possession of horns\nby the males alone, this species is in an intermediate condition, and the\nhorns do not appear until about five or six months after birth.  Therefore\nin comparison with what little we know of the development of the horns in\nother antelopes, and from what we do know with respect to the horns of\ndeer, cattle, etc., those of the prong-horned antelope appear at an\nintermediate period of life,--that is, not very early, as in cattle and\nsheep, nor very late, as in the larger deer and antelopes.  The horns of\nsheep, goats, and cattle, which are well developed in both sexes, though\nnot quite equal in size, can be felt, or even seen, at birth or soon\nafterwards.  (41.  I have been assured that the horns of the sheep in North\nWales can always be felt, and are sometimes even an inch in length, at\nbirth.  Youatt says ('Cattle,' 1834, p. 277), that the prominence of the\nfrontal bone in cattle penetrates the cutis at birth, and that the horny\nmatter is soon formed over it.)  Our rule, however, seems to fail in some\nbreeds of sheep, for instance merinos, in which the rams alone are horned;\nfor I cannot find on enquiry (42.  I am greatly indebted to Prof. Victor\nCarus for having made enquiries for me, from the highest authorities, with\nrespect to the merino sheep of Saxony.  On the Guinea coast of Africa there\nis, however, a breed of sheep in which, as with merinos, the rams alone\nbear horns; and Mr. Winwood Reade informs me that in one case observed by\nhim, a young ram, born on Feb. 10th, first shewed horns on March 6th, so\nthat in this instance, in conformity with rule, the development of the\nhorns occurred at a later period of life than in Welsh sheep, in which both\nsexes are horned.), that the horns are developed later in life in this\nbreed than in ordinary sheep in which both sexes are horned.  But with\ndomesticated sheep the presence or absence of horns is not a firmly fixed\ncharacter; for a certain proportion of the merino ewes bear small horns,\nand some of the rams are hornless; and in most breeds hornless ewes are\noccasionally produced.\n\nDr. W. Marshall has lately made a special study of the protuberances so\ncommon on the heads of birds (43.  'Ueber die knochernen Schaedelhoecker der\nVoegel,' in the 'Niederland. Archiv fur Zoologie,' B.i. Heft 2, 1872.), and\nhe comes to the following conclusion:--that with those species in which\nthey are confined to the males, they are developed late in life; whereas\nwith those species in which they are common to the two sexes, they are\ndeveloped at a very early period.  This is certainly a striking\nconfirmation of my two laws of inheritance.\n\nIn most of the species of the splendid family of the Pheasants, the males\ndiffer conspicuously from the females, and they acquire their ornaments at\na rather late period of life.  The eared pheasant (Crossoptilon auritum),\nhowever, offers a remarkable exception, for both sexes possess the fine\ncaudal plumes, the large ear-tufts and the crimson velvet about the head; I\nfind that all these characters appear very early in life in accordance with\nrule.  The adult male can, however, be distinguished from the adult female\nby the presence of spurs; and conformably with our rule, these do not begin\nto be developed before the age of six months, as I am assured by Mr.\nBartlett, and even at this age, the two sexes can hardly be distinguished.\n(44.  In the common peacock (Pavo cristatus) the male alone possesses\nspurs, whilst both sexes of the Java Peacock (P. muticus) offer the unusual\ncase of being furnished with spurs.  Hence I fully expected that in the\nlatter species they would have been developed earlier in life than in the\ncommon peacock; but M. Hegt of Amsterdam informs me, that with young birds\nof the previous year, of both species, compared on April 23rd, 1869, there\nwas no difference in the development of the spurs.  The spurs, however,\nwere as yet represented merely by slight knobs or elevations.  I presume\nthat I should have been informed if any difference in the rate of\ndevelopment had been observed subsequently.)  The male and female Peacock\ndiffer conspicuously from each other in almost every part of their plumage,\nexcept in the elegant head-crest, which is common to both sexes; and this\nis developed very early in life, long before the other ornaments, which are\nconfined to the male.  The wild-duck offers an analogous case, for the\nbeautiful green speculum on the wings is common to both sexes, though\nduller and somewhat smaller in the female, and it is developed early in\nlife, whilst the curled tail-feathers and other ornaments of the male are\ndeveloped later.  (45.  In some other species of the Duck family the\nspeculum differs in a greater degree in the two sexes; but I have not been\nable to discover whether its full development occurs later in life in the\nmales of such species, than in the male of the common duck, as ought to be\nthe case according to our rule.  With the allied Mergus cucullatus we have,\nhowever, a case of this kind:  the two sexes differ conspicuously in\ngeneral plumage, and to a considerable degree in the speculum, which is\npure white in the male and greyish-white in the female.  Now the young\nmales at first entirely resemble the females, and have a greyish-white\nspeculum, which becomes pure white at an earlier age than that at which the\nadult male acquires his other and more strongly-marked sexual differences:\nsee Audubon, 'Ornithological Biography,' vol. iii. 1835, pp. 249-250.)\nBetween such extreme cases of close sexual resemblance and wide\ndissimilarity, as those of the Crossoptilon and peacock, many intermediate\nones could be given, in which the characters follow our two rules in their\norder of development.\n\nAs most insects emerge from the pupal state in a mature condition, it is\ndoubtful whether the period of development can determine the transference\nof their characters to one or to both sexes.  But we do not know that the\ncoloured scales, for instance, in two species of butterflies, in one of\nwhich the sexes differ in colour, whilst in the other they are alike, are\ndeveloped at the same relative age in the cocoon.  Nor do we know whether\nall the scales are simultaneously developed on the wings of the same\nspecies of butterfly, in which certain coloured marks are confined to one\nsex, whilst others are common to both sexes.  A difference of this kind in\nthe period of development is not so improbable as it may at first appear;\nfor with the Orthoptera, which assume their adult state, not by a single\nmetamorphosis, but by a succession of moults, the young males of some\nspecies at first resemble the females, and acquire their distinctive\nmasculine characters only at a later moult.  Strictly analogous cases occur\nat the successive moults of certain male crustaceans.\n\nWe have as yet considered the transference of characters, relatively to\ntheir period of development, only in species in a natural state; we will\nnow turn to domesticated animals, and first touch on monstrosities and\ndiseases.  The presence of supernumerary digits, and the absence of certain\nphalanges, must be determined at an early embryonic period--the tendency to\nprofuse bleeding is at least congenital, as is probably colour-blindness--\nyet these peculiarities, and other similar ones, are often limited in their\ntransmission to one sex; so that the rule that characters, developed at an\nearly period, tend to be transmitted to both sexes, here wholly fails.  But\nthis rule, as before remarked, does not appear to be nearly so general as\nthe converse one, namely, that characters which appear late in life in one\nsex are transmitted exclusively to the same sex.  From the fact of the\nabove abnormal peculiarities becoming attached to one sex, long before the\nsexual functions are active, we may infer that there must be some\ndifference between the sexes at an extremely early age.  With respect to\nsexually-limited diseases, we know too little of the period at which they\noriginate, to draw any safe conclusion.  Gout, however, seems to fall under\nour rule, for it is generally caused by intemperance during manhood, and is\ntransmitted from the father to his sons in a much more marked manner than\nto his daughters.\n\nIn the various domestic breeds of sheep, goats, and cattle, the males\ndiffer from their respective females in the shape or development of their\nhorns, forehead, mane, dewlap, tail, and hump on the shoulders; and these\npeculiarities, in accordance with our rule, are not fully developed until a\nrather late period of life.  The sexes of dogs do not differ, except that\nin certain breeds, especially in the Scotch deer-hound, the male is much\nlarger and heavier than the female; and, as we shall see in a future\nchapter, the male goes on increasing in size to an unusually late period of\nlife, which, according to rule, will account for his increased size being\ntransmitted to his male offspring alone.  On the other hand, the tortoise-\nshell colour, which is confined to female cats, is quite distinct at birth,\nand this case violates the rule.  There is a breed of pigeons in which the\nmales alone are streaked with black, and the streaks can be detected even\nin the nestlings; but they become more conspicuous at each successive\nmoult, so that this case partly opposes and partly supports the rule.  With\nthe English Carrier and Pouter pigeons, the full development of the wattle\nand the crop occurs rather late in life, and conformably with the rule,\nthese characters are transmitted in full perfection to the males alone.\nThe following cases perhaps come within the class previously alluded to, in\nwhich both sexes have varied in the same manner at a rather late period of\nlife, and have consequently transferred their new characters to both sexes\nat a corresponding late period; and if so, these cases are not opposed to\nour rule:--there exist sub-breeds of the pigeon, described by Neumeister\n(46.  'Das Ganze der Taubenzucht,' 1837, ss. 21, 24.  For the case of the\nstreaked pigeons, see Dr. Chapuis, 'Le pigeon voyageur Belge,' 1865, p.\n87.), in which both sexes change their colour during two or three moults\n(as is likewise the case with the Almond Tumbler); nevertheless, these\nchanges, though occurring rather late in life, are common to both sexes.\nOne variety of the Canary-bird, namely the London Prize, offers a nearly\nanalogous case.\n\nWith the breeds of the Fowl the inheritance of various characters by one or\nboth sexes, seems generally determined by the period at which such\ncharacters are developed.  Thus in all the many breeds in which the adult\nmale differs greatly in colour from the female, as well as from the wild\nparent-species, he differs also from the young male, so that the newly-\nacquired characters must have appeared at a rather late period of life.  On\nthe other hand, in most of the breeds in which the two sexes resemble each\nother, the young are coloured in nearly the same manner as their parents,\nand this renders it probable that their colours first appeared early in\nlife.  We have instances of this fact in all black and white breeds, in\nwhich the young and old of both sexes are alike; nor can it be maintained\nthat there is something peculiar in a black or white plumage, which leads\nto its transference to both sexes; for the males alone of many natural\nspecies are either black or white, the females being differently coloured.\nWith the so-called Cuckoo sub-breeds of the fowl, in which the feathers are\ntransversely pencilled with dark stripes, both sexes and the chickens are\ncoloured in nearly the same manner.  The laced plumage of the Sebright\nbantam is the same in both sexes, and in the young chickens the wing-\nfeathers are distinctly, though imperfectly laced.  Spangled Hamburgs,\nhowever, offer a partial exception; for the two sexes, though not quite\nalike, resemble each other more closely than do the sexes of the aboriginal\nparent-species; yet they acquire their characteristic plumage late in life,\nfor the chickens are distinctly pencilled.  With respect to other\ncharacters besides colour, in the wild-parent species and in most of the\ndomestic breeds, the males alone possess a well-developed comb; but in the\nyoung of the Spanish fowl it is largely developed at a very early age, and,\nin accordance with this early development in the male, it is of unusual\nsize in the adult female.  In the Game breeds pugnacity is developed at a\nwonderfully early age, of which curious proofs could be given; and this\ncharacter is transmitted to both sexes, so that the hens, from their\nextreme pugnacity, are now generally exhibited in separate pens.  With the\nPolish breeds the bony protuberance of the skull which supports the crest\nis partially developed even before the chickens are hatched, and the crest\nitself soon begins to grow, though at first feebly (47.  For full\nparticulars and references on all these points respecting the several\nbreeds of the Fowl, see 'Variation of Animals and Plants under\nDomestication,' vol. i. pp. 250, 256.  In regard to the higher animals, the\nsexual differences which have arisen under domestication are described in\nthe same work under the head of each species.); and in this breed the\nadults of both sexes are characterised by a great bony protuberance and an\nimmense crest.\n\nFinally, from what we have now seen of the relation which exists in many\nnatural species and domesticated races, between the period of the\ndevelopment of their characters and the manner of their transmission--for\nexample, the striking fact of the early growth of the horns in the\nreindeer, in which both sexes bear horns, in comparison with their much\nlater growth in the other species in which the male alone bears horns--we\nmay conclude that one, though not the sole cause of characters being\nexclusively inherited by one sex, is their development at a late age.  And\nsecondly, that one, though apparently a less efficient cause of characters\nbeing inherited by both sexes, is their development at an early age, whilst\nthe sexes differ but little in constitution.  It appears, however, that\nsome difference must exist between the sexes even during a very early\nembryonic period, for characters developed at this age not rarely become\nattached to one sex.\n\nSUMMARY AND CONCLUDING REMARKS.\n\nFrom the foregoing discussion on the various laws of inheritance, we learn\nthat the characters of the parents often, or even generally, tend to become\ndeveloped in the offspring of the same sex, at the same age, and\nperiodically at the same season of the year, in which they first appeared\nin the parents.  But these rules, owing to unknown causes, are far from\nbeing fixed.  Hence during the modification of a species, the successive\nchanges may readily be transmitted in different ways; some to one sex, and\nsome to both; some to the offspring at one age, and some to the offspring\nat all ages.  Not only are the laws of inheritance extremely complex, but\nso are the causes which induce and govern variability.  The variations thus\ninduced are preserved and accumulated by sexual selection, which is in\nitself an extremely complex affair, depending, as it does, on the ardour in\nlove, the courage, and the rivalry of the males, as well as on the powers\nof perception, the taste, and will of the female.  Sexual selection will\nalso be largely dominated by natural selection tending towards the general\nwelfare of the species.  Hence the manner in which the individuals of\neither or both sexes have been affected through sexual selection cannot\nfail to be complex in the highest degree.\n\nWhen variations occur late in life in one sex, and are transmitted to the\nsame sex at the same age, the other sex and the young are left unmodified.\nWhen they occur late in life, but are transmitted to both sexes at the same\nage, the young alone are left unmodified.  Variations, however, may occur\nat any period of life in one sex or in both, and be transmitted to both\nsexes at all ages, and then all the individuals of the species are\nsimilarly modified.  In the following chapters it will be seen that all\nthese cases frequently occur in nature.\n\nSexual selection can never act on any animal before the age for\nreproduction arrives.  From the great eagerness of the male it has\ngenerally acted on this sex and not on the females.  The males have thus\nbecome provided with weapons for fighting with their rivals, with organs\nfor discovering and securely holding the female, and for exciting or\ncharming her.  When the sexes differ in these respects, it is also, as we\nhave seen, an extremely general law that the adult male differs more or\nless from the young male; and we may conclude from this fact that the\nsuccessive variations, by which the adult male became modified, did not\ngenerally occur much before the age for reproduction.  Whenever some or\nmany of the variations occurred early in life, the young males would\npartake more or less of the characters of the adult males; and differences\nof this kind between the old and young males may be observed in many\nspecies of animals.\n\nIt is probable that young male animals have often tended to vary in a\nmanner which would not only have been of no use to them at an early age,\nbut would have been actually injurious--as by acquiring bright colours,\nwhich would render them conspicuous to their enemies, or by acquiring\nstructures, such as great horns, which would expend much vital force in\ntheir development.  Variations of this kind occurring in the young males\nwould almost certainly be eliminated through natural selection.  With the\nadult and experienced males, on the other hand, the advantages derived from\nthe acquisition of such characters, would more than counterbalance some\nexposure to danger, and some loss of vital force.\n\nAs variations which give to the male a better chance of conquering other\nmales, or of finding, securing, or charming the opposite sex, would, if\nthey happened to arise in the female, be of no service to her, they would\nnot be preserved in her through sexual selection.  We have also good\nevidence with domesticated animals, that variations of all kinds are, if\nnot carefully selected, soon lost through intercrossing and accidental\ndeaths.  Consequently in a state of nature, if variations of the above kind\nchanced to arise in the female line, and to be transmitted exclusively in\nthis line, they would be extremely liable to be lost.  If, however, the\nfemales varied and transmitted their newly acquired characters to their\noffspring of both sexes, the characters which were advantageous to the\nmales would be preserved by them through sexual selection, and the two\nsexes would in consequence be modified in the same manner, although such\ncharacters were of no use to the females:  but I shall hereafter have to\nrecur to these more intricate contingencies.  Lastly, the females may\nacquire, and apparently have often acquired by transference, characters\nfrom the male sex.\n\nAs variations occurring later in life, and transmitted to one sex alone,\nhave incessantly been taken advantage of and accumulated through sexual\nselection in relation to the reproduction of the species; therefore it\nappears, at first sight, an unaccountable fact that similar variations have\nnot frequently been accumulated through natural selection, in relation to\nthe ordinary habits of life.  If this had occurred, the two sexes would\noften have been differently modified, for the sake, for instance, of\ncapturing prey or of escaping from danger.  Differences of this kind\nbetween the two sexes do occasionally occur, especially in the lower\nclasses.  But this implies that the two sexes follow different habits in\ntheir struggles for existence, which is a rare circumstance with the higher\nanimals.  The case, however, is widely different with the reproductive\nfunctions, in which respect the sexes necessarily differ.  For variations\nin structure which are related to these functions, have often proved of\nvalue to one sex, and from having arisen at a late period of life, have\nbeen transmitted to one sex alone; and such variations, thus preserved and\ntransmitted, have given rise to secondary sexual characters.\n\nIn the following chapters, I shall treat of the secondary sexual characters\nin animals of all classes, and shall endeavour in each case to apply the\nprinciples explained in the present chapter.  The lowest classes will\ndetain us for a very short time, but the higher animals, especially birds,\nmust be treated at considerable length.  It should be borne in mind that\nfor reasons already assigned, I intend to give only a few illustrative\ninstances of the innumerable structures by the aid of which the male finds\nthe female, or, when found, holds her.  On the other hand, all structures\nand instincts by the aid of which the male conquers other males, and by\nwhich he allures or excites the female, will be fully discussed, as these\nare in many ways the most interesting.\n\nSUPPLEMENT ON THE PROPORTIONAL NUMBERS OF THE TWO SEXES IN ANIMALS\nBELONGING TO VARIOUS CLASSES.\n\nAs no one, as far as I can discover, has paid attention to the relative\nnumbers of the two sexes throughout the animal kingdom, I will here give\nsuch materials as I have been able to collect, although they are extremely\nimperfect.  They consist in only a few instances of actual enumeration, and\nthe numbers are not very large.  As the proportions are known with\ncertainty only in mankind, I will first give them as a standard of\ncomparison.\n\nMAN.\n\nIn England during ten years (from 1857 to 1866) the average number of\nchildren born alive yearly was 707,120, in the proportion of 104.5 males to\n100 females.  But in 1857 the male births throughout England were as 105.2,\nand in 1865 as 104.0 to 100.  Looking to separate districts, in\nBuckinghamshire (where about 5000 children are annually born) the MEAN\nproportion of male to female births, during the whole period of the above\nten years, was as 102.8 to 100; whilst in N. Wales (where the average\nannual births are 12,873) it was as high as 106.2 to 100.  Taking a still\nsmaller district, viz., Rutlandshire (where the annual births average only\n739), in 1864 the male births were as 114.6, and in 1862 as only 97.0 to\n100; but even in this small district the average of the 7385 births during\nthe whole ten years, was as 104.5 to 100:  that is in the same ratio as\nthroughout England.  (48.  'Twenty-ninth Annual Report of the Registrar-\nGeneral for 1866.'  In this report (p. xii.) a special decennial table is\ngiven.)  The proportions are sometimes slightly disturbed by unknown\ncauses; thus Prof. Faye states \"that in some districts of Norway there has\nbeen during a decennial period a steady deficiency of boys, whilst in\nothers the opposite condition has existed.\"  In France during forty-four\nyears the male to the female births have been as 106.2 to 100; but during\nthis period it has occurred five times in one department, and six times in\nanother, that the female births have exceeded the males.  In Russia the\naverage proportion is as high as 108.9, and in Philadelphia in the United\nStates as 110.5 to 100.  (49.  For Norway and Russia, see abstract of Prof.\nFaye's researches, in 'British and Foreign Medico-Chirurg. Review,' April\n1867, pp. 343, 345.  For France, the 'Annuaire pour l'An 1867,' p. 213.\nFor Philadelphia, Dr. Stockton Hough, 'Social Science Assoc.' 1874.  For\nthe Cape of Good Hope, Quetelet as quoted by Dr. H.H. Zouteveen, in the\nDutch Translation of this work (vol. i. p. 417), where much information is\ngiven on the proportion of the sexes.)  The average for Europe, deduced by\nBickes from about seventy million births, is 106 males to 100 females.  On\nthe other hand, with white children born at the Cape of Good Hope, the\nproportion of males is so low as to fluctuate during successive years\nbetween 90 and 99 males for every 100 females.  It is a singular fact that\nwith Jews the proportion of male births is decidedly larger than with\nChristians:  thus in Prussia the proportion is as 113, in Breslau as 114,\nand in Livonia as 120 to 100; the Christian births in these countries being\nthe same as usual, for instance, in Livonia as 104 to 100.  (50.  In regard\nto the Jews, see M. Thury, 'La Loi de Production des Sexes,' 1863, p. 25.)\n\nProf. Faye remarks that \"a still greater preponderance of males would be\nmet with, if death struck both sexes in equal proportion in the womb and\nduring birth.  But the fact is, that for every 100 still-born females, we\nhave in several countries from 134.6 to 144.9 still-born males.  During the\nfirst four or five years of life, also, more male children die than\nfemales, for example in England, during the first year, 126 boys die for\nevery 100 girls--a proportion which in France is still more unfavourable.\"\n(51.  'British and Foreign Medico-Chirurg. Review,' April 1867, p. 343.\nDr. Stark also remarks ('Tenth Annual Report of Births, Deaths, etc., in\nScotland,' 1867, p. xxviii.) that \"These examples may suffice to show that,\nat almost every stage of life, the males in Scotland have a greater\nliability to death and a higher death-rate than the females.  The fact,\nhowever, of this peculiarity being most strongly developed at that\ninfantile period of life when the dress, food, and general treatment of\nboth sexes are alike, seems to prove that the higher male death-rate is an\nimpressed, natural, and constitutional peculiarity due to sex alone.\")  Dr.\nStockton Hough accounts for these facts in part by the more frequent\ndefective development of males than of females.  We have before seen that\nthe male sex is more variable in structure than the female; and variations\nin important organs would generally be injurious.  But the size of the\nbody, and especially of the head, being greater in male than female infants\nis another cause:  for the males are thus more liable to be injured during\nparturition.  Consequently the still-born males are more numerous; and, as\na highly competent judge, Dr. Crichton Browne (52.  'West Riding Lunatic\nAsylum Reports,' vol. i. 1871, p. 8.  Sir J. Simpson has proved that the\nhead of the male infant exceeds that of the female by 3/8ths of an inch in\ncircumference, and by 1/8th in transverse diameter.  Quetelet has shewn\nthat woman is born smaller than man; see Dr. Duncan, 'Fecundity, Fertility,\nand Sterility,' 1871, p. 382.), believes, male infants often suffer in\nhealth for some years after birth.  Owing to this excess in the death-rate\nof male children, both at birth and for some time subsequently, and owing\nto the exposure of grown men to various dangers, and to their tendency to\nemigrate, the females in all old-settled countries, where statistical\nrecords have been kept, are found to preponderate considerably over the\nmales.  (53.  With the savage Guaranys of Paraguay, according to the\naccurate Azara ('Voyages dans l'Amerique merid.' tom. ii. 1809, pp. 60,\n179), the women are to the men in the proportion of 14 to 13.)\n\nIt seems at first sight a mysterious fact that in different nations, under\ndifferent conditions and climates, in Naples, Prussia, Westphalia, Holland,\nFrance, England and the United States, the excess of male over female\nbirths is less when they are illegitimate than when legitimate.  (54.\nBabbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90,\non still-born children.  On illegitimate children in England, see 'Report\nof Registrar-General for 1866,' p. xv.)  This has been explained by\ndifferent writers in many different ways, as from the mothers being\ngenerally young, from the large proportion of first pregnancies, etc.  But\nwe have seen that male infants, from the large size of their heads, suffer\nmore than female infants during parturition; and as the mothers of\nillegitimate children must be more liable than other women to undergo bad\nlabours, from various causes, such as attempts at concealment by tight\nlacing, hard work, distress of mind, etc., their male infants would\nproportionably suffer.  And this probably is the most efficient of all the\ncauses of the proportion of males to females born alive being less amongst\nillegitimate children than amongst the legitimate.  With most animals the\ngreater size of the adult male than of the female, is due to the stronger\nmales having conquered the weaker in their struggles for the possession of\nthe females, and no doubt it is owing to this fact that the two sexes of at\nleast some animals differ in size at birth.  Thus we have the curious fact\nthat we may attribute the more frequent deaths of male than female infants,\nespecially amongst the illegitimate, at least in part to sexual selection.\n\nIt has often been supposed that the relative age of the two parents\ndetermine the sex of the offspring; and Prof. Leuckart (55.  Leuckart, in\nWagner 'Handwoerterbuch der Phys.' B. iv. 1853, s. 774.) has advanced what\nhe considers sufficient evidence, with respect to man and certain\ndomesticated animals, that this is one important though not the sole factor\nin the result.  So again the period of impregnation relatively to the state\nof the female has been thought by some to be the efficient cause; but\nrecent observations discountenance this belief.  According to Dr. Stockton\nHough (56.  'Social Science Association of Philadelphia,' 1874.), the\nseason of the year, the poverty or wealth of the parents, residence in the\ncountry or in cities, the crossing of foreign immigrants, etc., all\ninfluence the proportion of the sexes.  With mankind, polygamy has also\nbeen supposed to lead to the birth of a greater proportion of female\ninfants; but Dr. J. Campbell (57.  'Anthropological Review,' April 1870, p.\ncviii.) carefully attended to this subject in the harems of Siam, and\nconcludes that the proportion of male to female births is the same as from\nmonogamous unions.  Hardly any animal has been rendered so highly\npolygamous as the English race-horse, and we shall immediately see that his\nmale and female offspring are almost exactly equal in number.  I will now\ngive the facts which I have collected with respect to the proportional\nnumbers of the sexes of various animals; and will then briefly discuss how\nfar selection has come into play in determining the result.\n\nHORSES.\n\nMr. Tegetmeier has been so kind as to tabulate for me from the 'Racing\nCalendar' the births of race-horses during a period of twenty-one years,\nviz., from 1846 to 1867; 1849 being omitted, as no returns were that year\npublished.  The total births were 25,560 (58.  During eleven years a record\nwas kept of the number of mares which proved barren or prematurely slipped\ntheir foals; and it deserves notice, as shewing how infertile these highly-\nnurtured and rather closely-interbred animals have become, that not far\nfrom one-third of the mares failed to produce living foals.  Thus during\n1866, 809 male colts and 816 female colts were born, and 743 mares failed\nto produce offspring.  During 1867, 836 males and 902 females were born,\nand 794 mares failed.), consisting of 12,763 males and 12,797 females, or\nin the proportion of 99.7 males to 100 females.  As these numbers are\ntolerably large, and as they are drawn from all parts of England, during\nseveral years, we may with much confidence conclude that with the domestic\nhorse, or at least with the race-horse, the two sexes are produced in\nalmost equal numbers.  The fluctuations in the proportions during\nsuccessive years are closely like those which occur with mankind, when a\nsmall and thinly-populated area is considered; thus in 1856 the male horses\nwere as 107.1, and in 1867 as only 92.6 to 100 females.  In the tabulated\nreturns the proportions vary in cycles, for the males exceeded the females\nduring six successive years; and the females exceeded the males during two\nperiods each of four years; this, however, may be accidental; at least I\ncan detect nothing of the kind with man in the decennial table in the\nRegistrar's Report for 1866.\n\nDOGS.\n\nDuring a period of twelve years, from 1857 to 1868, the births of a large\nnumber of greyhounds, throughout England, were sent to the 'Field'\nnewspaper; and I am again indebted to Mr. Tegetmeier for carefully\ntabulating the results.  The recorded births were 6878, consisting of 3605\nmales and 3273 females, that is, in the proportion of 110.1 males to 100\nfemales.  The greatest fluctuations occurred in 1864, when the proportion\nwas as 95.3 males, and in 1867, as 116.3 males to 100 females.  The above\naverage proportion of 110.1 to 100 is probably nearly correct in the case\nof the greyhound, but whether it would hold with other domesticated breeds\nis in some degree doubtful.  Mr. Cupples has enquired from several great\nbreeders of dogs, and finds that all without exception believe that females\nare produced in excess; but he suggests that this belief may have arisen\nfrom females being less valued, and from the consequent disappointment\nproducing a stronger impression on the mind.\n\nSHEEP.\n\nThe sexes of sheep are not ascertained by agriculturists until several\nmonths after birth, at the period when the males are castrated; so that the\nfollowing returns do not give the proportions at birth.  Moreover, I find\nthat several great breeders in Scotland, who annually raise some thousand\nsheep, are firmly convinced that a larger proportion of males than of\nfemales die during the first year or two.  Therefore the proportion of\nmales would be somewhat larger at birth than at the age of castration.\nThis is a remarkable coincidence with what, as we have seen, occurs with\nmankind, and both cases probably depend on the same cause.  I have received\nreturns from four gentlemen in England who have bred Lowland sheep, chiefly\nLeicesters, during the last ten to sixteen years; they amount altogether to\n8965 births, consisting of 4407 males and 4558 females; that is in the\nproportion of 96.7 males to 100 females.  With respect to Cheviot and\nblack-faced sheep bred in Scotland, I have received returns from six\nbreeders, two of them on a large scale, chiefly for the years 1867-1869,\nbut some of the returns extend back to 1862.  The total number recorded\namounts to 50,685, consisting of 25,071 males and 25,614 females or in the\nproportion of 97.9 males to 100 females.  If we take the English and Scotch\nreturns together, the total number amounts to 59,650, consisting of 29,478\nmales and 30,172 females, or as 97.7 to 100.  So that with sheep at the age\nof castration the females are certainly in excess of the males, but\nprobably this would not hold good at birth.  (59.  I am much indebted to\nMr. Cupples for having procured for me the above returns from Scotland, as\nwell as some of the following returns on cattle.  Mr. R. Elliot, of\nLaighwood, first called my attention to the premature deaths of the males,\n--a statement subsequently confirmed by Mr. Aitchison and others.  To this\nlatter gentleman, and to Mr. Payan, I owe my thanks for large returns as to\nsheep.)\n\nOf CATTLE I have received returns from nine gentlemen of 982 births, too\nfew to be trusted; these consisted of 477 bull-calves and 505 cow-calves;\ni.e., in the proportion of 94.4 males to 100 females.  The Rev. W.D. Fox\ninforms me that in 1867 out of 34 calves born on a farm in Derbyshire only\none was a bull.  Mr. Harrison Weir has enquired from several breeders of\nPIGS, and most of them estimate the male to the female births as about 7 to\n6.  This same gentleman has bred RABBITS for many years, and has noticed\nthat a far greater number of bucks are produced than does.  But estimations\nare of little value.\n\nOf mammalia in a state of nature I have been able to learn very little.  In\nregard to the common rat, I have received conflicting statements.  Mr. R.\nElliot, of Laighwood, informs me that a rat-catcher assured him that he had\nalways found the males in great excess, even with the young in the nest.\nIn consequence of this, Mr. Elliot himself subsequently examined some\nhundred old ones, and found the statement true.  Mr. F. Buckland has bred a\nlarge number of white rats, and he also believes that the males greatly\nexceed the females.  In regard to Moles, it is said that \"the males are\nmuch more numerous than the females\" (60.  Bell, 'History of British\nQuadrupeds,' p. 100.):  and as the catching of these animals is a special\noccupation, the statement may perhaps be trusted.  Sir A. Smith, in\ndescribing an antelope of S. Africa (61.  'Illustrations of the Zoology of\nS. Africa,' 1849, pl. 29.) (Kobus ellipsiprymnus), remarks, that in the\nherds of this and other species, the males are few in number compared with\nthe females:  the natives believe that they are born in this proportion;\nothers believe that the younger males are expelled from the herds, and Sir\nA. Smith says, that though he has himself never seen herds consisting of\nyoung males alone, others affirm that this does occur.  It appears probable\nthat the young when expelled from the herd, would often fall a prey to the\nmany beasts of prey of the country.\n\nBIRDS.\n\nWith respect to the FOWL, I have received only one account, namely, that\nout of 1001 chickens of a highly-bred stock of Cochins, reared during eight\nyears by Mr. Stretch, 487 proved males and 514 females; i.e., as 94.7 to\n100.  In regard to domestic pigeons there is good evidence either that the\nmales are produced in excess, or that they live longer; for these birds\ninvariably pair, and single males, as Mr. Tegetmeier informs me, can always\nbe purchased cheaper than females.  Usually the two birds reared from the\ntwo eggs laid in the same nest are a male and a female; but Mr. Harrison\nWeir, who has been so large a breeder, says that he has often bred two\ncocks from the same nest, and seldom two hens; moreover, the hen is\ngenerally the weaker of the two, and more liable to perish.\n\nWith respect to birds in a state of nature, Mr. Gould and others (62.\nBrehm ('Thierleben,' B. iv. s. 990) comes to the same conclusion.) are\nconvinced that the males are generally the more numerous; and as the young\nmales of many species resemble the females, the latter would naturally\nappear to be the more numerous.  Large numbers of pheasants are reared by\nMr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr.\nJenner Weir that four or five males to one female are generally produced.\nAn experienced observer remarks (63.  On the authority of L. Lloyd, 'Game\nBirds of Sweden,' 1867, pp. 12, 132.), that in Scandinavia the broods of\nthe capercailzie and black-cock contain more males than females; and that\nwith the Dal-ripa (a kind of ptarmigan) more males than females attend the\nleks or places of courtship; but this latter circumstance is accounted for\nby some observers by a greater number of hen birds being killed by vermin.\nFrom various facts given by White of Selborne (64.  'Nat. Hist. of\nSelborne,' letter xxix. edit. of 1825, vol. i. p. 139.), it seems clear\nthat the males of the partridge must be in considerable excess in the south\nof England; and I have been assured that this is the case in Scotland.  Mr.\nWeir on enquiring from the dealers, who receive at certain seasons large\nnumbers of ruffs (Machetes pugnax), was told that the males are much the\nmore numerous.  This same naturalist has also enquired for me from the\nbirdcatchers, who annually catch an astonishing number of various small\nspecies alive for the London market, and he was unhesitatingly answered by\nan old and trustworthy man, that with the chaffinch the males are in large\nexcess:  he thought as high as 2 males to 1 female, or at least as high as\n5 to 3.  (65.  Mr. Jenner Weir received similar information, on making\nenquiries during the following year.  To shew the number of living\nchaffinches caught, I may mention that in 1869 there was a match between\ntwo experts, and one man caught in a day 62, and another 40, male\nchaffinches.  The greatest number ever caught by one man in a single day\nwas 70.)  The males of the blackbird, he likewise maintained, were by far\nthe more numerous, whether caught by traps or by netting at night.  These\nstatements may apparently be trusted, because this same man said that the\nsexes are about equal with the lark, the twite (Linaria montana), and\ngoldfinch.  On the other hand, he is certain that with the common linnet,\nthe females preponderate greatly, but unequally during different years;\nduring some years he has found the females to the males as four to one.  It\nshould, however, be borne in mind, that the chief season for catching birds\ndoes not begin till September, so that with some species partial migrations\nmay have begun, and the flocks at this period often consist of hens alone.\nMr. Salvin paid particular attention to the sexes of the humming-birds in\nCentral America, and is convinced that with most of the species the males\nare in excess; thus one year he procured 204 specimens belonging to ten\nspecies, and these consisted of 166 males and of only 38 females.  With two\nother species the females were in excess:  but the proportions apparently\nvary either during different seasons or in different localities; for on one\noccasion the males of Campylopterus hemileucurus were to the females as 5\nto 2, and on another occasion (66.  'Ibis,' vol. ii. p. 260, as quoted in\nGould's 'Trochilidae,' 1861, p. 52.  For the foregoing proportions, I am\nindebted to Mr. Salvin for a table of his results.) in exactly the reversed\nratio.  As bearing on this latter point, I may add, that Mr. Powys found in\nCorfu and Epirus the sexes of the chaffinch keeping apart, and \"the females\nby far the most numerous\"; whilst in Palestine Mr. Tristram found \"the male\nflocks appearing greatly to exceed the female in number.\"  (67.  'Ibis,'\n1860, p. 137; and 1867, p. 369.)  So again with the Quiscalus major, Mr. G.\nTaylor says, that in Florida there were \"very few females in proportion to\nthe males,\" (68.  'Ibis,' 1862, p. 187.) whilst in Honduras the proportion\nwas the other way, the species there having the character of a polygamist.\n\nFISH.\n\nWith fish the proportional numbers of the sexes can be ascertained only by\ncatching them in the adult or nearly adult state; and there are many\ndifficulties in arriving at any just conclusion.  (69.  Leuckart quotes\nBloch (Wagner, 'Handwoerterbuch der Phys.' B. iv. 1853, s. 775), that with\nfish there are twice as many males as females.)  Infertile females might\nreadily be mistaken for males, as Dr. Gunther has remarked to me in regard\nto trout.  With some species the males are believed to die soon after\nfertilising the ova.  With many species the males are of much smaller size\nthan the females, so that a large number of males would escape from the\nsame net by which the females were caught.  M. Carbonnier (70.  Quoted in\nthe 'Farmer,' March 18, 1869, p. 369.), who has especially attended to the\nnatural history of the pike (Esox lucius), states that many males, owing to\ntheir small size, are devoured by the larger females; and he believes that\nthe males of almost all fish are exposed from this same cause to greater\ndanger than the females.  Nevertheless, in the few cases in which the\nproportional numbers have been actually observed, the males appear to be\nlargely in excess.  Thus Mr. R. Buist, the superintendent of the\nStormontfield experiments, says that in 1865, out of 70 salmon first landed\nfor the purpose of obtaining the ova, upwards of 60 were males.  In 1867 he\nagain \"calls attention to the vast disproportion of the males to the\nfemales.  We had at the outset at least ten males to one female.\"\nAfterwards females sufficient for obtaining ova were procured.  He adds,\n\"from the great proportion of the males, they are constantly fighting and\ntearing each other on the spawning-beds.\"  (71.  'The Stormontfield\nPiscicultural Experiments,' 1866, p. 23.  The 'Field' newspaper, June 29,\n1867.)  This disproportion, no doubt, can be accounted for in part, but\nwhether wholly is doubtful, by the males ascending the rivers before the\nfemales.  Mr. F. Buckland remarks in regard to trout, that \"it is a curious\nfact that the males preponderate very largely in number over the females.\nIt INVARIABLY happens that when the first rush of fish is made to the net,\nthere will be at least seven or eight males to one female found captive.  I\ncannot quite account for this; either the males are more numerous than the\nfemales, or the latter seek safety by concealment rather than flight.\"  He\nthen adds, that by carefully searching the banks sufficient females for\nobtaining ova can be found.  (72.  'Land and Water,' 1868, p. 41.)  Mr. H.\nLee informs me that out of 212 trout, taken for this purpose in Lord\nPortsmouth's park, 150 were males and 62 females.\n\nThe males of the Cyprinidae likewise seem to be in excess; but several\nmembers of this Family, viz., the carp, tench, bream and minnow, appear\nregularly to follow the practice, rare in the animal kingdom, of polyandry;\nfor the female whilst spawning is always attended by two males, one on each\nside, and in the case of the bream by three or four males.  This fact is so\nwell known, that it is always recommended to stock a pond with two male\ntenches to one female, or at least with three males to two females.  With\nthe minnow, an excellent observer states, that on the spawning-beds the\nmales are ten times as numerous as the females; when a female comes amongst\nthe males, \"she is immediately pressed closely by a male on each side; and\nwhen they have been in that situation for a time, are superseded by other\ntwo males.\"  (73.  Yarrell, 'Hist. British Fishes,' vol. i. 1826, p. 307;\non the Cyprinus carpio, p. 331; on the Tinca vulgaris, p. 331; on the\nAbramis brama, p. 336.  See, for the minnow (Leuciscus phoxinus), 'Loudon's\nMagazine of Natural History,' vol. v. 1832, p. 682.)\n\nINSECTS.\n\nIn this great Class, the Lepidoptera almost alone afford means for judging\nof the proportional numbers of the sexes; for they have been collected with\nspecial care by many good observers, and have been largely bred from the\negg or caterpillar state.  I had hoped that some breeders of silk-moths\nmight have kept an exact record, but after writing to France and Italy, and\nconsulting various treatises, I cannot find that this has ever been done.\nThe general opinion appears to be that the sexes are nearly equal, but in\nItaly, as I hear from Professor Canestrini, many breeders are convinced\nthat the females are produced in excess.  This same naturalist, however,\ninforms me, that in the two yearly broods of the Ailanthus silk-moth\n(Bombyx cynthia), the males greatly preponderate in the first, whilst in\nthe second the two sexes are nearly equal, or the females rather in excess.\n\nIn regard to Butterflies in a state of nature, several observers have been\nmuch struck by the apparently enormous preponderance of the males.  (74.\nLeuckart quotes Meinecke (Wagner, 'Handwoerterbuch der Phys.' B. iv. 1853,\ns. 775) that the males of Butterflies are three or four times as numerous\nas the females.)  Thus Mr. Bates (75.  'The Naturalist on the Amazons,'\nvol. ii. 1863, pp. 228, 347.), in speaking of several species, about a\nhundred in number, which inhabit the upper Amazons, says that the males are\nmuch more numerous than the females, even in the proportion of a hundred to\none.  In North America, Edwards, who had great experience, estimates in the\ngenus Papilio the males to the females as four to one; and Mr. Walsh, who\ninformed me of this statement, says that with P. turnus this is certainly\nthe case.  In South Africa, Mr. R. Trimen found the males in excess in 19\nspecies (76.  Four of these cases are given by Mr. Trimen in his\n'Rhopalocera Africae Australis.'); and in one of these, which swarms in\nopen places, he estimated the number of males as fifty to one female.  With\nanother species, in which the males are numerous in certain localities, he\ncollected only five females during seven years.  In the island of Bourbon,\nM. Maillard states that the males of one species of Papilio are twenty\ntimes as numerous as the females.  (77.  Quoted by Trimen, 'Transactions of\nthe Ent. Society,' vol. v. part iv. 1866, p. 330.)  Mr. Trimen informs me\nthat as far as he has himself seen, or heard from others, it is rare for\nthe females of any butterfly to exceed the males in number; but three South\nAfrican species perhaps offer an exception.  Mr. Wallace (78.\n'Transactions, Linnean Society,' vol. xxv. p. 37.) states that the females\nof Ornithoptera croesus, in the Malay archipelago, are more common and more\neasily caught than the males; but this is a rare butterfly.  I may here\nadd, that in Hyperythra, a genus of moths, Guenee says, that from four to\nfive females are sent in collections from India for one male.\n\nWhen this subject of the proportional numbers of the sexes of insects was\nbrought before the Entomological Society (79.  'Proceedings, Entomological\nSociety,' Feb. 17, 1868.), it was generally admitted that the males of most\nLepidoptera, in the adult or imago state, are caught in greater numbers\nthan the females:  but this fact was attributed by various observers to the\nmore retiring habits of the females, and to the males emerging earlier from\nthe cocoon.  This latter circumstance is well known to occur with most\nLepidoptera, as well as with other insects.  So that, as M. Personnat\nremarks, the males of the domesticated Bombyx Yamamai, are useless at the\nbeginning of the season, and the females at the end, from the want of\nmates.  (80.  Quoted by Dr. Wallace in 'Proceedings, Entomological\nSociety,' 3rd series, vol. v. 1867, p. 487.)  I cannot, however, persuade\nmyself that these causes suffice to explain the great excess of males, in\nthe above cases of certain butterflies which are extremely common in their\nnative countries.  Mr. Stainton, who has paid very close attention during\nmany years to the smaller moths, informs me that when he collected them in\nthe imago state, he thought that the males were ten times as numerous as\nthe females, but that since he has reared them on a large scale from the\ncaterpillar state, he is convinced that the females are the more numerous.\nSeveral entomologists concur in this view.  Mr. Doubleday, however, and\nsome others, take an opposite view, and are convinced that they have reared\nfrom the eggs and caterpillars a larger proportion of males than of\nfemales.\n\nBesides the more active habits of the males, their earlier emergence from\nthe cocoon, and in some cases their frequenting more open stations, other\ncauses may be assigned for an apparent or real difference in the\nproportional numbers of the sexes of Lepidoptera, when captured in the\nimago state, and when reared from the egg or caterpillar state.  I hear\nfrom Professor Canestrini, that it is believed by many breeders in Italy,\nthat the female caterpillar of the silk-moth suffers more from the recent\ndisease than the male; and Dr. Staudinger informs me that in rearing\nLepidoptera more females die in the cocoon than males.  With many species\nthe female caterpillar is larger than the male, and a collector would\nnaturally choose the finest specimens, and thus unintentionally collect a\nlarger number of females.  Three collectors have told me that this was\ntheir practice; but Dr. Wallace is sure that most collectors take all the\nspecimens which they can find of the rarer kinds, which alone are worth the\ntrouble of rearing.  Birds when surrounded by caterpillars would probably\ndevour the largest; and Professor Canestrini informs me that in Italy some\nbreeders believe, though on insufficient evidence, that in the first broods\nof the Ailanthus silk-moth, the wasps destroy a larger number of the female\nthan of the male caterpillars.  Dr. Wallace further remarks that female\ncaterpillars, from being larger than the males, require more time for their\ndevelopment, and consume more food and moisture:  and thus they would be\nexposed during a longer time to danger from ichneumons, birds, etc., and in\ntimes of scarcity would perish in greater numbers.  Hence it appears quite\npossible that in a state of nature, fewer female Lepidoptera may reach\nmaturity than males; and for our special object we are concerned with their\nrelative numbers at maturity, when the sexes are ready to propagate their\nkind.\n\nThe manner in which the males of certain moths congregate in extraordinary\nnumbers round a single female, apparently indicates a great excess of\nmales, though this fact may perhaps be accounted for by the earlier\nemergence of the males from their cocoons.  Mr. Stainton informs me that\nfrom twelve to twenty males, may often be seen congregated round a female\nElachista rufocinerea.  It is well known that if a virgin Lasiocampa\nquercus or Saturnia carpini be exposed in a cage, vast numbers of males\ncollect round her, and if confined in a room will even come down the\nchimney to her.  Mr. Doubleday believes that he has seen from fifty to a\nhundred males of both these species attracted in the course of a single day\nby a female in confinement.  In the Isle of Wight Mr. Trimen exposed a box\nin which a female of the Lasiocampa had been confined on the previous day,\nand five males soon endeavoured to gain admittance.  In Australia, Mr.\nVerreaux, having placed the female of a small Bombyx in a box in his\npocket, was followed by a crowd of males, so that about 200 entered the\nhouse with him.  (81.  Blanchard, 'Metamorphoses, Moeurs des Insectes,'\n1868, pp. 225-226.)\n\nMr. Doubleday has called my attention to M. Staudinger's (82.\n'Lepidopteren-Doubletten Liste,' Berlin, No. x. 1866.) list of Lepidoptera,\nwhich gives the prices of the males and females of 300 species or well-\nmarked varieties of butterflies (Rhopalocera).  The prices for both sexes\nof the very common species are of course the same; but in 114 of the rarer\nspecies they differ; the males being in all cases, excepting one, the\ncheaper.  On an average of the prices of the 113 species, the price of the\nmale to that of the female is as 100 to 149; and this apparently indicates\nthat inversely the males exceed the females in the same proportion.  About\n2000 species or varieties of moths (Heterocera) are catalogued, those with\nwingless females being here excluded on account of the difference in habits\nbetween the two sexes:  of these 2000 species, 141 differ in price\naccording to sex, the males of 130 being cheaper, and those of only 11\nbeing dearer than the females.  The average price of the males of the 130\nspecies, to that of the females, is as 100 to 143.  With respect to the\nbutterflies in this priced list, Mr. Doubleday thinks (and no man in\nEngland has had more experience), that there is nothing in the habits of\nthe species which can account for the difference in the prices of the two\nsexes, and that it can be accounted for only by an excess in the number of\nthe males.  But I am bound to add that Dr. Staudinger informs me, that he\nis himself of a different opinion.  He thinks that the less active habits\nof the females and the earlier emergence of the males will account for his\ncollectors securing a larger number of males than of females, and\nconsequently for the lower prices of the former.  With respect to specimens\nreared from the caterpillar-state, Dr. Staudinger believes, as previously\nstated, that a greater number of females than of males die whilst confined\nto the cocoons.  He adds that with certain species one sex seems to\npreponderate over the other during certain years.\n\nOf direct observations on the sexes of Lepidoptera, reared either from eggs\nor caterpillars, I have received only the few following cases:  (See\nfollowing table.)\n\nSo that in these eight lots of cocoons and eggs, males were produced in\nexcess.  Taken together the proportion of males is as 122.7 to 100 females.\nBut the numbers are hardly large enough to be trustworthy.\n\nOn the whole, from these various sources of evidence, all pointing in the\nsame direction, I infer that with most species of Lepidoptera, the mature\nmales generally exceed the females in number, whatever the proportions may\nbe at their first emergence from the egg.\n\n                                                    Males   Females\n  The Rev. J. Hellins* of Exeter reared, during\n    1868, imagos of 73 species, which\n    consisted of                                     153       137\n\n  Mr. Albert Jones of Eltham reared, during\n    1868, imagos of 9 species, which\n    consisted of                                     159       126\n\n  During 1869 he reared imagos from 4 species\n    consisting of                                    114       112\n\n  Mr. Buckler of Emsworth, Hants, during 1869,\n    reared imagos from 74 species,\n    consisting of                                    180       169\n\n  Dr. Wallace of Colchester reared from one\n    brood of Bombyx cynthia                           52        48\n\n  Dr. Wallace raised, from cocoons of Bombyx\n    Pernyi sent from China, during 1869              224       123\n\n  Dr. Wallace raised, during 1868 and 1869, from\n    two lots of cocoons of Bombyx yamamai             52        46\n\n                                           Total     934       761\n\n(*83.  This naturalist has been so kind as to send me some results from\nformer years, in which the females seemed to preponderate; but so many of\nthe figures were estimates, that I found it impossible to tabulate them.)\n\nWith reference to the other Orders of insects, I have been able to collect\nvery little reliable information.  With the stag-beetle (Lucanus cervus)\n\"the males appear to be much more numerous than the females\"; but when, as\nCornelius remarked during 1867, an unusual number of these beetles appeared\nin one part of Germany, the females appeared to exceed the males as six to\none.  With one of the Elateridae, the males are said to be much more\nnumerous than the females, and \"two or three are often found united with\none female (84.  Gunther's 'Record of Zoological Literature,' 1867, p. 260.\nOn the excess of female Lucanus, ibid, p. 250.  On the males of Lucanus in\nEngland, Westwood,' 'Modern Classification of Insects,' vol. i. p. 187.  On\nthe Siagonium, ibid. p. 172.); so that here polyandry seems to prevail.\"\nWith Siagonium (Staphylinidae), in which the males are furnished with\nhorns, \"the females are far more numerous than the opposite sex.\"  Mr.\nJanson stated at the Entomological Society that the females of the bark\nfeeding Tomicus villosus are so common as to be a plague, whilst the males\nare so rare as to be hardly known.\n\nIt is hardly worth while saying anything about the proportion of the sexes\nin certain species and even groups of insects, for the males are unknown or\nvery rare, and the females are parthenogenetic, that is, fertile without\nsexual union; examples of this are afforded by several of the Cynipidae.\n(85.  Walsh in 'The American Entomologist,' vol. i. 1869, p. 103.  F.\nSmith, 'Record of Zoological Lit.' 1867, p. 328.)  In all the gall-making\nCynipidae known to Mr. Walsh, the females are four or five times as\nnumerous as the males; and so it is, as he informs me, with the gall-making\nCecidomyiidae (Diptera).  With some common species of Saw-flies\n(Tenthredinae) Mr. F. Smith has reared hundreds of specimens from larvae of\nall sizes, but has never reared a single male; on the other hand, Curtis\nsays (86.  'Farm Insects,' pp. 45-46.), that with certain species\n(Athalia), bred by him, the males were to the females as six to one; whilst\nexactly the reverse occurred with the mature insects of the same species\ncaught in the fields.  In the family of bees, Hermann Mueller (87.\n'Anwendung der Darwin'schen Lehre,' Verh. d. n. Jahrg., xxiv.), collected a\nlarge number of specimens of many species, and reared others from the\ncocoons, and counted the sexes.  He found that the males of some species\ngreatly exceeded the females in number; in others the reverse occurred; and\nin others the two sexes were nearly equal.  But as in most cases the males\nemerge from the cocoons before the females, they are at the commencement of\nthe breeding-season practically in excess.  Mueller also observed that the\nrelative number of the two sexes in some species differed much in different\nlocalities.  But as H. Mueller has himself remarked to me, these remarks\nmust be received with some caution, as one sex might more easily escape\nobservation than the other.  Thus his brother Fritz Mueller has noticed in\nBrazil that the two sexes of the same species of bee sometimes frequent\ndifferent kinds of flowers.  With respect to the Orthoptera, I know hardly\nanything about the relative number of the sexes:  Korte (88.  'Die Strich,\nZug oder Wanderheuschrecke,' 1828, p. 20.), however, says that out of 500\nlocusts which he examined, the males were to the females as five to six.\nWith the Neuroptera, Mr. Walsh states that in many, but by no means in all\nthe species of the Odonatous group, there is a great overplus of males:  in\nthe genus Hetaerina, also, the males are generally at least four times as\nnumerous as the females.  In certain species in the genus Gomphus the males\nare equally in excess, whilst in two other species, the females are twice\nor thrice as numerous as the males.  In some European species of Psocus\nthousands of females may be collected without a single male, whilst with\nother species of the same genus both sexes are common.  (89.  'Observations\non N. American Neuroptera,' by H. Hagen and B.D. Walsh, 'Proceedings, Ent.\nSoc. Philadelphia,' Oct. 1863, pp. 168, 223, 239.)  In England, Mr.\nMacLachlan has captured hundreds of the female Apatania muliebris, but has\nnever seen the male; and of Boreus hyemalis only four or five males have\nbeen seen here.  (90.  'Proceedings, Ent. Soc. London,' Feb. 17, 1868.)\nWith most of these species (excepting the Tenthredinae) there is at present\nno evidence that the females are subject to parthenogenesis; and thus we\nsee how ignorant we are of the causes of the apparent discrepancy in the\nproportion of the two sexes.\n\nIn the other classes of the Articulata I have been able to collect still\nless information.  With spiders, Mr. Blackwall, who has carefully attended\nto this class during many years, writes to me that the males from their\nmore erratic habits are more commonly seen, and therefore appear more\nnumerous.  This is actually the case with a few species; but he mentions\nseveral species in six genera, in which the females appear to be much more\nnumerous than the males.  (91.  Another great authority with respect to\nthis class, Prof. Thorell of Upsala ('On European Spiders,' 1869-70, part\ni. p. 205), speaks as if female spiders were generally commoner than the\nmales.)  The small size of the males in comparison with the females (a\npeculiarity which is sometimes carried to an extreme degree), and their\nwidely different appearance, may account in some instances for their rarity\nin collections.  (92.  See, on this subject, Mr. O.P. Cambridge, as quoted\nin 'Quarterly Journal of Science,' 1868, page 429.)\n\nSome of the lower Crustaceans are able to propagate their kind sexually,\nand this will account for the extreme rarity of the males; thus von Siebold\n(93.  'Beitraege zur Parthenogenesis,' p. 174.) carefully examined no less\nthan 13,000 specimens of Apus from twenty-one localities, and amongst these\nhe found only 319 males.  With some other forms (as Tanais and Cypris), as\nFritz Mueller informs me, there is reason to believe that the males are much\nshorter-lived than the females; and this would explain their scarcity,\nsupposing the two sexes to be at first equal in number.  On the other hand,\nMueller has invariably taken far more males than females of the Diastylidae\nand of Cypridina on the shores of Brazil:  thus with a species in the\nlatter genus, 63 specimens caught the same day included 57 males; but he\nsuggests that this preponderance may be due to some unknown difference in\nthe habits of the two sexes.  With one of the higher Brazilian crabs,\nnamely a Gelasimus, Fritz Mueller found the males to be more numerous than\nthe females.  According to the large experience of Mr. C. Spence Bate, the\nreverse seems to be the case with six common British crabs, the names of\nwhich he has given me.\n\nTHE PROPORTION OF THE SEXES IN RELATION TO NATURAL SELECTION.\n\nThere is reason to suspect that in some cases man has by selection\nindirectly influenced his own sex-producing powers.  Certain women tend to\nproduce during their whole lives more children of one sex than of the\nother:  and the same holds good of many animals, for instance, cows and\nhorses; thus Mr. Wright of Yeldersley House informs me that one of his Arab\nmares, though put seven times to different horses, produced seven fillies.\nThough I have very little evidence on this head, analogy would lead to the\nbelief, that the tendency to produce either sex would be inherited like\nalmost every other peculiarity, for instance, that of producing twins; and\nconcerning the above tendency a good authority, Mr. J. Downing, has\ncommunicated to me facts which seem to prove that this does occur in\ncertain families of short-horn cattle.  Col. Marshall (94.  'The Todas,'\n1873, pp. 100, 111, 194, 196.) has recently found on careful examination\nthat the Todas, a hill-tribe of India, consist of 112 males and 84 females\nof all ages--that is in a ratio of 133.3 males to 100 females.  The Todas,\nwho are polyandrous in their marriages, during former times invariably\npractised female infanticide; but this practice has now been discontinued\nfor a considerable period.  Of the children born within late years, the\nmales are more numerous than the females, in the proportion of 124 to 100.\nColonel Marshall accounts for this fact in the following ingenious manner.\n\"Let us for the purpose of illustration take three families as representing\nan average of the entire tribe; say that one mother gives birth to six\ndaughters and no sons; a second mother has six sons only, whilst the third\nmother has three sons and three daughters.  The first mother, following the\ntribal custom, destroys four daughters and preserves two.  The second\nretains her six sons.  The third kills two daughters and keeps one, as also\nher three sons.  We have then from the three families, nine sons and three\ndaughters, with which to continue the breed.  But whilst the males belong\nto families in which the tendency to produce sons is great, the females are\nof those of a converse inclination.  Thus the bias strengthens with each\ngeneration, until, as we find, families grow to have habitually more sons\nthan daughters.\"\n\nThat this result would follow from the above form of infanticide seems\nalmost certain; that is if we assume that a sex-producing tendency is\ninherited.  But as the above numbers are so extremely scanty, I have\nsearched for additional evidence, but cannot decide whether what I have\nfound is trustworthy; nevertheless the facts are, perhaps, worth giving.\nThe Maories of New Zealand have long practised infanticide; and Mr. Fenton\n(95.  'Aboriginal Inhabitants of New Zealand:  Government Report,' 1859, p.\n36.) states that he \"has met with instances of women who have destroyed\nfour, six, and even seven children, mostly females.  However, the universal\ntestimony of those best qualified to judge, is conclusive that this custom\nhas for many years been almost extinct.  Probably the year 1835 may be\nnamed as the period of its ceasing to exist.\"  Now amongst the New\nZealanders, as with the Todas, male births are considerably in excess.  Mr.\nFenton remarks (p. 30), \"One fact is certain, although the exact period of\nthe commencement of this singular condition of the disproportion of the\nsexes cannot be demonstratively fixed, it is quite clear that this course\nof decrease was in full operation during the years 1830 to 1844, when the\nnon-adult population of 1844 was being produced, and has continued with\ngreat energy up to the present time.\"  The following statements are taken\nfrom Mr. Fenton (p. 26), but as the numbers are not large, and as the\ncensus was not accurate, uniform results cannot be expected.  It should be\nborne in mind in this and the following cases, that the normal state of\nevery population is an excess of women, at least in all civilised\ncountries, chiefly owing to the greater mortality of the male sex during\nyouth, and partly to accidents of all kinds later in life.  In 1858, the\nnative population of New Zealand was estimated as consisting of 31,667\nmales and 24,303 females of all ages, that is in the ratio of 130.3 males\nto 100 females.  But during this same year, and in certain limited\ndistricts, the numbers were ascertained with much care, and the males of\nall ages were here 753 and the females 616; that is in the ratio of 122.2\nmales to 100 females.  It is more important for us that during this same\nyear of 1858, the NON-ADULT males within the same district were found to be\n178, and the NON-ADULT females 142, that is in the ratio of 125.3 to 100.\nIt may be added that in 1844, at which period female infanticide had only\nlately ceased, the NON-ADULT males in one district were 281, and the NON-\nADULT females only 194, that is in the ratio of 144.8 males to 100 females.\n\nIn the Sandwich Islands, the males exceed the females in number.\nInfanticide was formerly practised there to a frightful extent, but was by\nno means confined to female infants, as is shewn by Mr. Ellis (96.\n'Narrative of a Tour through Hawaii,' 1826, p. 298.), and as I have been\ninformed by Bishop Staley and the Rev. Mr. Coan.  Nevertheless, another\napparently trustworthy writer, Mr. Jarves (97.  'History of the Sandwich\nIslands,' 1843, p. 93.), whose observations apply to the whole archipelago,\nremarks:--\"Numbers of women are to be found, who confess to the murder of\nfrom three to six or eight children,\" and he adds, \"females from being\nconsidered less useful than males were more often destroyed.\"  From what is\nknown to occur in other parts of the world, this statement is probable; but\nmust be received with much caution.  The practice of infanticide ceased\nabout the year 1819, when idolatry was abolished and missionaries settled\nin the Islands.  A careful census in 1839 of the adult and taxable men and\nwomen in the island of Kauai and in one district of Oahu (Jarves, p. 404),\ngives 4723 males and 3776 females; that is in the ratio of 125.08 to 100.\nAt the same time the number of males under fourteen years in Kauai and\nunder eighteen in Oahu was 1797, and of females of the same ages 1429; and\nhere we have the ratio of 125.75 males to 100 females.\n\nIn a census of all the islands in 1850 (98.  This is given in the Rev. H.T.\nCheever's 'Life in the Sandwich Islands,' 1851, p. 277.), the males of all\nages amount to 36,272, and the females to 33,128, or as 109.49 to 100.  The\nmales under seventeen years amounted to 10,773, and the females under the\nsame age to 9593, or as 112.3 to 100.  From the census of 1872, the\nproportion of males of all ages (including half-castes) to females, is as\n125.36 to 100.  It must be borne in mind that all these returns for the\nSandwich Islands give the proportion of living males to living females, and\nnot of the births; and judging from all civilised countries the proportion\nof males would have been considerably higher if the numbers had referred to\nbirths.  (99.  Dr. Coulter, in describing ('Journal R. Geograph. Soc.' vol.\nv. 1835, p. 67) the state of California about the year 1830, says that the\nnatives, reclaimed by the Spanish missionaries, have nearly all perished,\nor are perishing, although well treated, not driven from their native land,\nand kept from the use of spirits.  He attributes this, in great part, to\nthe undoubted fact that the men greatly exceed the women in number; but he\ndoes not know whether this is due to a failure of female offspring, or to\nmore females dying during early youth.  The latter alternative, according\nto all analogy, is very improbable.  He adds that \"infanticide, properly so\ncalled, is not common, though very frequent recourse is had to abortion.\"\nIf Dr. Coulter is correct about infanticide, this case cannot be advanced\nin support of Colonel Marshall's view.  From the rapid decrease of the\nreclaimed natives, we may suspect that, as in the cases lately given, their\nfertility has been diminished from changed habits of life.\n\nI had hoped to gain some light on this subject from the breeding of dogs;\ninasmuch as in most breeds, with the exception, perhaps, of greyhounds,\nmany more female puppies are destroyed than males, just as with the Toda\ninfants.  Mr. Cupples assures me that this is usual with Scotch deer-\nhounds.  Unfortunately, I know nothing of the proportion of the sexes in\nany breed, excepting greyhounds, and there the male births are to the\nfemales as 110.1 to 100.  Now from enquiries made from many breeders, it\nseems that the females are in some respects more esteemed, though otherwise\ntroublesome; and it does not appear that the female puppies of the best-\nbred dogs are systematically destroyed more than the males, though this\ndoes sometimes take place to a limited extent.  Therefore I am unable to\ndecide whether we can, on the above principles, account for the\npreponderance of male births in greyhounds.  On the other hand, we have\nseen that with horses, cattle, and sheep, which are too valuable for the\nyoung of either sex to be destroyed, if there is any difference, the\nfemales are slightly in excess.)\n\nFrom the several foregoing cases we have some reason to believe that\ninfanticide practised in the manner above explained, tends to make a male-\nproducing race; but I am far from supposing that this practice in the case\nof man, or some analogous process with other species, has been the sole\ndetermining cause of an excess of males.  There may be some unknown law\nleading to this result in decreasing races, which have already become\nsomewhat infertile.  Besides the several causes previously alluded to, the\ngreater facility of parturition amongst savages, and the less consequent\ninjury to their male infants, would tend to increase the proportion of\nlive-born males to females.  There does not, however, seem to be any\nnecessary connection between savage life and a marked excess of males; that\nis if we may judge by the character of the scanty offspring of the lately\nexisting Tasmanians and of the crossed offspring of the Tahitians now\ninhabiting Norfolk Island.\n\nAs the males and females of many animals differ somewhat in habits and are\nexposed in different degrees to danger, it is probable that in many cases,\nmore of one sex than of the other are habitually destroyed.  But as far as\nI can trace out the complication of causes, an indiscriminate though large\ndestruction of either sex would not tend to modify the sex-producing power\nof the species.  With strictly social animals, such as bees or ants, which\nproduce a vast number of sterile and fertile females in comparison with the\nmales, and to whom this preponderance is of paramount importance, we can\nsee that those communities would flourish best which contained females\nhaving a strong inherited tendency to produce more and more females; and in\nsuch cases an unequal sex-producing tendency would be ultimately gained\nthrough natural selection.  With animals living in herds or troops, in\nwhich the males come to the front and defend the herd, as with the bisons\nof North America and certain baboons, it is conceivable that a male-\nproducing tendency might be gained by natural selection; for the\nindividuals of the better defended herds would leave more numerous\ndescendants.  In the case of mankind the advantage arising from having a\npreponderance of men in the tribe is supposed to be one chief cause of the\npractice of female infanticide.\n\nIn no case, as far as we can see, would an inherited tendency to produce\nboth sexes in equal numbers or to produce one sex in excess, be a direct\nadvantage or disadvantage to certain individuals more than to others; for\ninstance, an individual with a tendency to produce more males than females\nwould not succeed better in the battle for life than an individual with an\nopposite tendency; and therefore a tendency of this kind could not be\ngained through natural selection.  Nevertheless, there are certain animals\n(for instance, fishes and cirripedes) in which two or more males appear to\nbe necessary for the fertilisation of the female; and the males accordingly\nlargely preponderate, but it is by no means obvious how this male-producing\ntendency could have been acquired.  I formerly thought that when a tendency\nto produce the two sexes in equal numbers was advantageous to the species,\nit would follow from natural selection, but I now see that the whole\nproblem is so intricate that it is safer to leave its solution for the\nfuture.\n\n\nCHAPTER IX.\n\nSECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM.\n\nThese characters absent in the lowest classes--Brilliant colours--Mollusca\n--Annelids--Crustacea, secondary sexual characters strongly developed;\ndimorphism; colour; characters not acquired before maturity--Spiders,\nsexual colours of; stridulation by the males--Myriapoda.\n\nWith animals belonging to the lower classes, the two sexes are not rarely\nunited in the same individual, and therefore secondary sexual characters\ncannot be developed.  In many cases where the sexes are separate, both are\npermanently attached to some support, and the one cannot search or struggle\nfor the other.  Moreover it is almost certain that these animals have too\nimperfect senses and much too low mental powers to appreciate each other's\nbeauty or other attractions, or to feel rivalry.\n\nHence in these classes or sub-kingdoms, such as the Protozoa, Coelenterata,\nEchinodermata, Scolecida, secondary sexual characters, of the kind which we\nhave to consider, do not occur:  and this fact agrees with the belief that\nsuch characters in the higher classes have been acquired through sexual\nselection, which depends on the will, desire, and choice of either sex.\nNevertheless some few apparent exceptions occur; thus, as I hear from Dr.\nBaird, the males of certain Entozoa, or internal parasitic worms, differ\nslightly in colour from the females; but we have no reason to suppose that\nsuch differences have been augmented through sexual selection.\nContrivances by which the male holds the female, and which are\nindispensable for the propagation of the species, are independent of sexual\nselection, and have been acquired through ordinary selection.\n\nMany of the lower animals, whether hermaphrodites or with separate sexes,\nare ornamented with the most brilliant tints, or are shaded and striped in\nan elegant manner; for instance, many corals and sea-anemones (Actiniae),\nsome jelly-fish (Medusae, Porpita, etc.), some Planariae, many star-fishes,\nEchini, Ascidians, etc.; but we may conclude from the reasons already\nindicated, namely, the union of the two sexes in some of these animals, the\npermanently affixed condition of others, and the low mental powers of all,\nthat such colours do not serve as a sexual attraction, and have not been\nacquired through sexual selection.  It should be borne in mind that in no\ncase have we sufficient evidence that colours have been thus acquired,\nexcept where one sex is much more brilliantly or conspicuously coloured\nthan the other, and where there is no difference in habits between the\nsexes sufficient to account for their different colours.  But the evidence\nis rendered as complete as it can ever be, only when the more ornamented\nindividuals, almost always the males, voluntarily display their attractions\nbefore the other sex; for we cannot believe that such display is useless,\nand if it be advantageous, sexual selection will almost inevitably follow.\nWe may, however, extend this conclusion to both sexes, when coloured alike,\nif their colours are plainly analogous to those of one sex alone in certain\nother species of the same group.\n\nHow, then, are we to account for the beautiful or even gorgeous colours of\nmany animals in the lowest classes?  It appears doubtful whether such\ncolours often serve as a protection; but that we may easily err on this\nhead, will be admitted by every one who reads Mr. Wallace's excellent essay\non this subject.  It would not, for instance, at first occur to any one\nthat the transparency of the Medusae, or jelly-fish, is of the highest\nservice to them as a protection; but when we are reminded by Haeckel that\nnot only the Medusae, but many floating Mollusca, crustaceans, and even\nsmall oceanic fishes partake of this same glass-like appearance, often\naccompanied by prismatic colours, we can hardly doubt that they thus escape\nthe notice of pelagic birds and other enemies.  M. Giard is also convinced\n(1.  'Archives de Zoolog. Exper.' Oct. 1872, p. 563.) that the bright tints\nof certain sponges and ascidians serve as a protection.  Conspicuous\ncolours are likewise beneficial to many animals as a warning to their\nwould-be devourers that they are distasteful, or that they possess some\nspecial means of defence; but this subject will be discussed more\nconveniently hereafter.\n\nWe can, in our ignorance of most of the lowest animals, only say that their\nbright tints result either from the chemical nature or the minute structure\nof their tissues, independently of any benefit thus derived.  Hardly any\ncolour is finer than that of arterial blood; but there is no reason to\nsuppose that the colour of the blood is in itself any advantage; and though\nit adds to the beauty of the maiden's cheek, no one will pretend that it\nhas been acquired for this purpose.  So again with many animals, especially\nthe lower ones, the bile is richly coloured; thus, as I am informed by Mr.\nHancock, the extreme beauty of the Eolidae (naked sea-slugs) is chiefly due\nto the biliary glands being seen through the translucent integuments--this\nbeauty being probably of no service to these animals.  The tints of the\ndecaying leaves in an American forest are described by every one as\ngorgeous; yet no one supposes that these tints are of the least advantage\nto the trees.  Bearing in mind how many substances closely analogous to\nnatural organic compounds have been recently formed by chemists, and which\nexhibit the most splendid colours, it would have been a strange fact if\nsubstances similarly coloured had not often originated, independently of\nany useful end thus gained, in the complex laboratory of living organisms.\n\nTHE SUB-KINGDOM OF THE MOLLUSCA.\n\nThroughout this great division of the animal kingdom, as far as I can\ndiscover, secondary sexual characters, such as we are here considering,\nnever occur.  Nor could they be expected in the three lowest classes,\nnamely, in the Ascidians, Polyzoa, and Brachiopods (constituting the\nMolluscoida of some authors), for most of these animals are permanently\naffixed to a support or have their sexes united in the same individual.  In\nthe Lamellibranchiata, or bivalve shells, hermaphroditism is not rare.  In\nthe next higher class of the Gasteropoda, or univalve shells, the sexes are\neither united or separate.  But in the latter case the males never possess\nspecial organs for finding, securing, or charming the females, or for\nfighting with other males.  As I am informed by Mr. Gwyn Jeffreys, the sole\nexternal difference between the sexes consists in the shell sometimes\ndiffering a little in form; for instance, the shell of the male periwinkle\n(Littorina littorea) is narrower and has a more elongated spire than that\nof the female.  But differences of this nature, it may be presumed, are\ndirectly connected with the act of reproduction, or with the development of\nthe ova.\n\nThe Gasteropoda, though capable of locomotion and furnished with imperfect\neyes, do not appear to be endowed with sufficient mental powers for the\nmembers of the same sex to struggle together in rivalry, and thus to\nacquire secondary sexual characters.  Nevertheless with the pulmoniferous\ngasteropods, or land-snails, the pairing is preceded by courtship; for\nthese animals, though hermaphrodites, are compelled by their structure to\npair together.  Agassiz remarks, \"Quiconque a eu l'occasion d'observer les\namours des limacons, ne saurait mettre en doute la seduction deployee dans\nles mouvements et les allures qui preparent et accomplissent le double\nembrassement de ces hermaphrodites.\"  (2.  'De l'Espece et de la Class.'\netc., 1869, p. 106.)  These animals appear also susceptible of some degree\nof permanent attachment:  an accurate observer, Mr. Lonsdale, informs me\nthat he placed a pair of land-snails, (Helix pomatia), one of which was\nweakly, into a small and ill-provided garden.  After a short time the\nstrong and healthy individual disappeared, and was traced by its track of\nslime over a wall into an adjoining well-stocked garden.  Mr. Lonsdale\nconcluded that it had deserted its sickly mate; but after an absence of\ntwenty-four hours it returned, and apparently communicated the result of\nits successful exploration, for both then started along the same track and\ndisappeared over the wall.\n\nEven in the highest class of the Mollusca, the Cephalopoda or cuttle-\nfishes, in which the sexes are separate, secondary sexual characters of the\npresent kind do not, as far as I can discover, occur.  This is a surprising\ncircumstance, as these animals possess highly-developed sense-organs and\nhave considerable mental powers, as will be admitted by every one who has\nwatched their artful endeavours to escape from an enemy.  (3.  See, for\ninstance, the account which I have given in my 'Journal of Researches,'\n1845, p. 7.)  Certain Cephalopoda, however, are characterised by one\nextraordinary sexual character, namely that the male element collects\nwithin one of the arms or tentacles, which is then cast off, and clinging\nby its sucking-discs to the female, lives for a time an independent life.\nSo completely does the cast-off arm resemble a separate animal, that it was\ndescribed by Cuvier as a parasitic worm under the name of Hectocotyle.  But\nthis marvellous structure may be classed as a primary rather than as a\nsecondary sexual character.\n\nAlthough with the Mollusca sexual selection does not seem to have come into\nplay; yet many univalve and bivalve shells, such as volutes, cones,\nscallops, etc., are beautifully coloured and shaped.  The colours do not\nappear in most cases to be of any use as a protection; they are probably\nthe direct result, as in the lowest classes, of the nature of the tissues;\nthe patterns and the sculpture of the shell depending on its manner of\ngrowth.  The amount of light seems to be influential to a certain extent;\nfor although, as repeatedly stated by Mr. Gwyn Jeffreys, the shells of some\nspecies living at a profound depth are brightly coloured, yet we generally\nsee the lower surfaces, as well as the parts covered by the mantle, less\nhighly-coloured than the upper and exposed surfaces.  (4.  I have given\n('Geological Observations on Volcanic Islands,' 1844, p. 53) a curious\ninstance of the influence of light on the colours of a frondescent\nincrustation, deposited by the surf on the coast-rocks of Ascension and\nformed by the solution of triturated sea-shells.) In some cases, as with\nshells living amongst corals or brightly-tinted seaweeds, the bright\ncolours may serve as a protection.  (5.  Dr. Morse has lately discussed\nthis subject in his paper on the 'Adaptive Coloration of Mollusca,' 'Proc.\nBoston Soc. of Nat. Hist.' vol. xiv. April 1871.)  But that many of the\nnudibranch Mollusca, or sea-slugs, are as beautifully coloured as any\nshells, may be seen in Messrs.  Alder and Hancock's magnificent work; and\nfrom information kindly given me by Mr. Hancock, it seems extremely\ndoubtful whether these colours usually serve as a protection.  With some\nspecies this may be the case, as with one kind which lives on the green\nleaves of algae, and is itself bright-green.  But many brightly-coloured,\nwhite, or otherwise conspicuous species, do not seek concealment; whilst\nagain some equally conspicuous species, as well as other dull-coloured\nkinds live under stones and in dark recesses.  So that with these\nnudibranch molluscs, colour apparently does not stand in any close relation\nto the nature of the places which they inhabit.\n\nThese naked sea-slugs are hermaphrodites, yet they pair together, as do\nland-snails, many of which have extremely pretty shells.  It is conceivable\nthat two hermaphrodites, attracted by each other's greater beauty, might\nunite and leave offspring which would inherit their parents' greater\nbeauty.  But with such lowly-organised creatures this is extremely\nimprobable.  Nor is it at all obvious how the offspring from the more\nbeautiful pairs of hermaphrodites would have any advantage over the\noffspring of the less beautiful, so as to increase in number, unless indeed\nvigour and beauty generally coincided.  We have not here the case of a\nnumber of males becoming mature before the females, with the more beautiful\nmales selected by the more vigorous females.  If, indeed, brilliant colours\nwere beneficial to a hermaphrodite animal in relation to its general habits\nof life, the more brightly-tinted individuals would succeed best and would\nincrease in number; but this would be a case of natural and not of sexual\nselection.\n\nSUB-KINGDOM OF THE VERMES:  CLASS, ANNELIDA (OR SEA-WORMS).\n\nIn this class, although the sexes, when separate, sometimes differ from\neach other in characters of such importance that they have been placed\nunder distinct genera or even families, yet the differences do not seem of\nthe kind which can be safely attributed to sexual selection.  These animals\nare often beautifully coloured, but as the sexes do not differ in this\nrespect, we are but little concerned with them.  Even the Nemertians,\nthough so lowly organised, \"vie in beauty and variety of colouring with any\nother group in the invertebrate series\"; yet Dr. McIntosh (6.  See his\nbeautiful monograph on 'British Annelids,' part i. 1873, p. 3.) cannot\ndiscover that these colours are of any service.  The sedentary annelids\nbecome duller-coloured, according to M. Quatrefages (7.  See M. Perrier:\n'L'Origine de l'Homme d'apres Darwin,' 'Revue Scientifique', Feb. 1873, p.\n866.), after the period of reproduction; and this I presume may be\nattributed to their less vigorous condition at that time.  All these worm-\nlike animals apparently stand too low in the scale for the individuals of\neither sex to exert any choice in selecting a partner, or for the\nindividuals of the same sex to struggle together in rivalry.\n\nSUB-KINGDOM OF THE ARTHROPODA:  CLASS, CRUSTACEA.\n\nIn this great class we first meet with undoubted secondary sexual\ncharacters, often developed in a remarkable manner.  Unfortunately the\nhabits of crustaceans are very imperfectly known, and we cannot explain the\nuses of many structures peculiar to one sex.  With the lower parasitic\nspecies the males are of small size, and they alone are furnished with\nperfect swimming-legs, antennae and sense-organs; the females being\ndestitute of these organs, with their bodies often consisting of a mere\ndistorted mass.  But these extraordinary differences between the two sexes\nare no doubt related to their widely different habits of life, and\nconsequently do not concern us.  In various crustaceans, belonging to\ndistinct families, the anterior antennae are furnished with peculiar\nthread-like bodies, which are believed to act as smelling-organs, and these\nare much more numerous in the males than in the females.  As the males,\nwithout any unusual development of their olfactory organs, would almost\ncertainly be able sooner or later to find the females, the increased number\nof the smelling-threads has probably been acquired through sexual\nselection, by the better provided males having been the more successful in\nfinding partners and in producing offspring.  Fritz Mueller has described a\nremarkable dimorphic species of Tanais, in which the male is represented by\ntwo distinct forms, which never graduate into each other.  In the one form\nthe male is furnished with more numerous smelling-threads, and in the other\nform with more powerful and more elongated chelae or pincers, which serve\nto hold the female.  Fritz Mueller suggests that these differences between\nthe two male forms of the same species may have originated in certain\nindividuals having varied in the number of the smelling-threads, whilst\nother individuals varied in the shape and size of their chelae; so that of\nthe former, those which were best able to find the female, and of the\nlatter, those which were best able to hold her, have left the greatest\nnumber of progeny to inherit their respective advantages.  (8.  'Facts and\nArguments for Darwin,' English translat., 1869, p. 20.  See the previous\ndiscussion on the olfactory threads.  Sars has described a somewhat\nanalogous case (as quoted in 'Nature,' 1870, p. 455) in a Norwegian\ncrustacean, the Pontoporeia affinis.)\n\n[Fig.4.  Labidocera Darwinii (from Lubbock).  Labelled are:\na.  Part of right anterior antenna of male, forming a prehensile organ.\nb.  Posterior pair of thoracic legs of male.\nc.  Ditto of female.]\n\nIn some of the lower crustaceans, the right anterior antenna of the male\ndiffers greatly in structure from the left, the latter resembling in its\nsimple tapering joints the antennae of the female.  In the male the\nmodified antenna is either swollen in the middle or angularly bent, or\nconverted (Fig. 4) into an elegant, and sometimes wonderfully complex,\nprehensile organ.  (9.  See Sir J. Lubbock in 'Annals and Mag. of Nat.\nHist.' vol. xi. 1853, pl. i. and x.; and vol. xii. (1853), pl. vii.  See\nalso Lubbock in 'Transactions, Entomological Society,' vol. iv. new series,\n1856-1858, p. 8.  With respect to the zigzagged antennae mentioned below,\nsee Fritz Mueller, 'Facts and Arguments for Darwin,' 1869, p. 40, foot-\nnote.)  It serves, as I hear from Sir J. Lubbock, to hold the female, and\nfor this same purpose one of the two posterior legs (b) on the same side of\nthe body is converted into a forceps.  In another family the inferior or\nposterior antennae are \"curiously zigzagged\" in the males alone.\n\n[Fig. 5.  Anterior part of body of Callianassa (from Milne-Edwards),\nshowing the unequal and differently-constructed right and left-hand chelae\nof the male.  N.B.--The artist by mistake has reversed the drawing, and\nmade the left-hand chela the largest.\n\nFig. 6.  Second leg of male Orchestia Tucuratinga (from Fritz Mueller).\n\nFig. 7.  Ditto of female.]\n\nIn the higher crustaceans the anterior legs are developed into chelae or\npincers; and these are generally larger in the male than in the female,--so\nmuch so that the market value of the male edible crab (Cancer pagurus),\naccording to Mr. C. Spence Bate, is five times as great as that of the\nfemale.  In many species the chelae are of unequal size on the opposite\nside of the body, the right-hand one being, as I am informed by Mr. Bate,\ngenerally, though not invariably, the largest.  This inequality is also\noften much greater in the male than in the female.  The two chelae of the\nmale often differ in structure (Figs. 5, 6, and 7), the smaller one\nresembling that of the female.  What advantage is gained by their\ninequality in size on the opposite sides of the body, and by the inequality\nbeing much greater in the male than in the female; and why, when they are\nof equal size, both are often much larger in the male than in the female,\nis not known.  As I hear from Mr. Bate, the chelae are sometimes of such\nlength and size that they cannot possibly be used for carrying food to the\nmouth.  In the males of certain fresh-water prawns (Palaemon) the right leg\nis actually longer than the whole body.  (10.  See a paper by Mr. C. Spence\nBate, with figures, in 'Proceedings, Zoological Society,' 1868, p. 363; and\non the nomenclature of the genus, ibid. p. 585.  I am greatly indebted to\nMr. Spence Bate for nearly all the above statements with respect to the\nchelae of the higher crustaceans.)  The great size of the one leg with its\nchelae may aid the male in fighting with his rivals; but this will not\naccount for their inequality in the female on the opposite sides of the\nbody.  In Gelasimus, according to a statement quoted by Milne Edwards (11.\n'Hist. Nat. des Crust.' tom. ii. 1837, p. 50.), the male and the female\nlive in the same burrow, and this shews that they pair; the male closes the\nmouth of the burrow with one of its chelae, which is enormously developed;\nso that here it indirectly serves as a means of defence.  Their main use,\nhowever, is probably to seize and to secure the female, and this in some\ninstances, as with Gammarus, is known to be the case.  The male of the\nhermit or soldier crab (Pagurus) for weeks together, carries about the\nshell inhabited by the female.  (12.  Mr. C. Spence Bate, 'British\nAssociation, Fourth Report on the Fauna of S. Devon.')  The sexes, however,\nof the common shore-crab (Carcinus maenas), as Mr. Bate informs me, unite\ndirectly after the female has moulted her hard shell, when she is so soft\nthat she would be injured if seized by the strong pincers of the male; but\nas she is caught and carried about by the male before moulting, she could\nthen be seized with impunity.\n\n[Fig.8.  Orchestia Darwinii (from Fritz Mueller), showing the differently-\nconstructed chelae of the two male forms.]\n\nFritz Mueller states that certain species of Melita are distinguished from\nall other amphipods by the females having \"the coxal lamellae of the\npenultimate pair of feet produced into hook-like processes, of which the\nmales lay hold with the hands of the first pair.\"  The development of these\nhook-like processes has probably followed from those females which were the\nmost securely held during the act of reproduction, having left the largest\nnumber of offspring.  Another Brazilian amphipod (see Orchestia darwinii,\nFig. 8) presents a case of dimorphism, like that of Tanais; for there are\ntwo male forms, which differ in the structure of their chelae.  (13.  Fritz\nMueller, 'Facts and Arguments for Darwin,' 1869, pp. 25-28.)  As either\nchela would certainly suffice to hold the female,--for both are now used\nfor this purpose,--the two male forms probably originated by some having\nvaried in one manner and some in another; both forms having derived certain\nspecial, but nearly equal advantages, from their differently shaped organs.\n\nIt is not known that male crustaceans fight together for the possession of\nthe females, but it is probably the case; for with most animals when the\nmale is larger than the female, he seems to owe his greater size to his\nancestors having fought with other males during many generations.  In most\nof the orders, especially in the highest or the Brachyura, the male is\nlarger than the female; the parasitic genera, however, in which the sexes\nfollow different habits of life, and most of the Entomostraca must be\nexcepted.  The chelae of many crustaceans are weapons well adapted for\nfighting.  Thus when a Devil-crab (Portunus puber) was seen by a son of Mr.\nBate fighting with a Carcinus maenas, the latter was soon thrown on its\nback, and had every limb torn from its body.  When several males of a\nBrazilian Gelasimus, a species furnished with immense pincers, were placed\ntogether in a glass vessel by Fritz Mueller, they mutilated and killed one\nanother.  Mr. Bate put a large male Carcinus maenas into a pan of water,\ninhabited by a female which was paired with a smaller male; but the latter\nwas soon dispossessed.  Mr. Bate adds, \"if they fought, the victory was a\nbloodless one, for I saw no wounds.\"  This same naturalist separated a male\nsand-skipper (so common on our sea-shores), Gammarus marinus, from its\nfemale, both of whom were imprisoned in the same vessel with many\nindividuals of the same species.  The female, when thus divorced, soon\njoined the others.  After a time the male was put again into the same\nvessel; and he then, after swimming about for a time, dashed into the\ncrowd, and without any fighting at once took away his wife.  This fact\nshews that in the Amphipoda, an order low in the scale, the males and\nfemales recognise each other, and are mutually attached.\n\nThe mental powers of the Crustacea are probably higher than at first sight\nappears probable.  Any one who tries to catch one of the shore-crabs, so\ncommon on tropical coasts, will perceive how wary and alert they are.\nThere is a large crab (Birgus latro), found on coral islands, which makes a\nthick bed of the picked fibres of the cocoa-nut, at the bottom of a deep\nburrow.  It feeds on the fallen fruit of this tree by tearing off the husk,\nfibre by fibre; and it always begins at that end where the three eye-like\ndepressions are situated.  It then breaks through one of these eyes by\nhammering with its heavy front pincers, and turning round, extracts the\nalbuminous core with its narrow posterior pincers.  But these actions are\nprobably instinctive, so that they would be performed as well by a young\nanimal as by an old one.  The following case, however, can hardly be so\nconsidered:  a trustworthy naturalist, Mr. Gardner (14.  'Travels in the\nInterior of Brazil,' 1846, p. 111.  I have given, in my 'Journal of\nResearches,' p. 463, an account of the habits of the Birgus.), whilst\nwatching a shore-crab (Gelasimus) making its burrow, threw some shells\ntowards the hole.  One rolled in, and three other shells remained within a\nfew inches of the mouth.  In about five minutes the crab brought out the\nshell which had fallen in, and carried it away to a distance of a foot; it\nthen saw the three other shells lying near, and evidently thinking that\nthey might likewise roll in, carried them to the spot where it had laid the\nfirst.  It would, I think, be difficult to distinguish this act from one\nperformed by man by the aid of reason.\n\nMr. Bate does not know of any well-marked case of difference of colour in\nthe two sexes of our British crustaceans, in which respect the sexes of the\nhigher animals so often differ.  In some cases, however, the males and\nfemales differ slightly in tint, but Mr. Bate thinks not more than may be\naccounted for by their different habits of life, such as by the male\nwandering more about, and being thus more exposed to the light.  Dr. Power\ntried to distinguish by colour the sexes of the several species which\ninhabit the Mauritius, but failed, except with one species of Squilla,\nprobably S. stylifera, the male of which is described as being \"of a\nbeautiful bluish-green,\" with some of the appendages cherry-red, whilst the\nfemale is clouded with brown and grey, \"with the red about her much less\nvivid than in the male.\"  (15.  Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.'\n1869, p. 3.  I am indebted to Mr. Bate for Dr. Power's statement.)  In this\ncase, we may suspect the agency of sexual selection.  From M. Bert's\nobservations on Daphnia, when placed in a vessel illuminated by a prism, we\nhave reason to believe that even the lowest crustaceans can distinguish\ncolours.  With Saphirina (an oceanic genus of Entomostraca), the males are\nfurnished with minute shields or cell-like bodies, which exhibit beautiful\nchanging colours; these are absent in the females, and in both sexes of one\nspecies.  (16.  Claus, 'Die freilebenden Copepoden,' 1863, s. 35.)  It\nwould, however, be extremely rash to conclude that these curious organs\nserve to attract the females.  I am informed by Fritz Mueller, that in the\nfemale of a Brazilian species of Gelasimus, the whole body is of a nearly\nuniform greyish-brown.  In the male the posterior part of the cephalo-\nthorax is pure white, with the anterior part of a rich green, shading into\ndark brown; and it is remarkable that these colours are liable to change in\nthe course of a few minutes--the white becoming dirty grey or even black,\nthe green \"losing much of its brilliancy.\"  It deserves especial notice\nthat the males do not acquire their bright colours until they become\nmature.  They appear to be much more numerous than the females; they differ\nalso in the larger size of their chelae.  In some species of the genus,\nprobably in all, the sexes pair and inhabit the same burrow.  They are\nalso, as we have seen, highly intelligent animals.  From these various\nconsiderations it seems probable that the male in this species has become\ngaily ornamented in order to attract or excite the female.\n\nIt has just been stated that the male Gelasimus does not acquire his\nconspicuous colours until mature and nearly ready to breed.  This seems a\ngeneral rule in the whole class in respect to the many remarkable\nstructural differences between the sexes.  We shall hereafter find the same\nlaw prevailing throughout the great sub-kingdom of the Vertebrata; and in\nall cases it is eminently distinctive of characters which have been\nacquired through sexual selection.  Fritz Mueller (17.  'Facts and\nArguments,' etc., p. 79.) gives some striking instances of this law; thus\nthe male sand-hopper (Orchestia) does not, until nearly full grown, acquire\nhis large claspers, which are very differently constructed from those of\nthe female; whilst young, his claspers resemble those of the female.\n\nCLASS, ARACHNIDA (SPIDERS).\n\nThe sexes do not generally differ much in colour, but the males are often\ndarker than the females, as may be seen in Mr. Blackwall's magnificent\nwork.  (18.  'A History of the Spiders of Great Britain,' 1861-64.  For the\nfollowing facts, see pp. 77, 88, 102.)  In some species, however, the\ndifference is conspicuous:  thus the female of Sparassus smaragdulus is\ndullish green, whilst the adult male has the abdomen of a fine yellow, with\nthree longitudinal stripes of rich red.  In certain species of Thomisus the\nsexes closely resemble each other, in others they differ much; and\nanalogous cases occur in many other genera.  It is often difficult to say\nwhich of the two sexes departs most from the ordinary coloration of the\ngenus to which the species belong; but Mr. Blackwall thinks that, as a\ngeneral rule, it is the male; and Canestrini (19.  This author has recently\npublished a valuable essay on the 'Caratteri sessuali secondarii degli\nArachnidi,' in the 'Atti della Soc. Veneto-Trentina di Sc. Nat. Padova,'\nvol. i. Fasc. 3, 1873.) remarks that in certain genera the males can be\nspecifically distinguished with ease, but the females with great\ndifficulty.  I am informed by Mr. Blackwall that the sexes whilst young\nusually resemble each other; and both often undergo great changes in colour\nduring their successive moults, before arriving at maturity.  In other\ncases the male alone appears to change colour.  Thus the male of the above\nbright-coloured Sparassus at first resembles the female, and acquires his\npeculiar tints only when nearly adult.  Spiders are possessed of acute\nsenses, and exhibit much intelligence; as is well known, the females often\nshew the strongest affection for their eggs, which they carry about\nenveloped in a silken web.  The males search eagerly for the females, and\nhave been seen by Canestrini and others to fight for possession of them.\nThis same author says that the union of the two sexes has been observed in\nabout twenty species; and he asserts positively that the female rejects\nsome of the males who court her, threatens them with open mandibles, and at\nlast after long hesitation accepts the chosen one.  From these several\nconsiderations, we may admit with some confidence that the well-marked\ndifferences in colour between the sexes of certain species are the results\nof sexual selection; though we have not here the best kind of evidence,--\nthe display by the male of his ornaments.  From the extreme variability of\ncolour in the male of some species, for instance of Theridion lineatum, it\nwould appear that these sexual characters of the males have not as yet\nbecome well fixed.  Canestrini draws the same conclusion from the fact that\nthe males of certain species present two forms, differing from each other\nin the size and length of their jaws; and this reminds us of the above\ncases of dimorphic crustaceans.\n\nThe male is generally much smaller than the female, sometimes to an\nextraordinary degree (20.  Aug. Vinson ('Araneides des Iles de la Reunion,'\npl. vi. figs. 1 and 2) gives a good instance of the small size of the male,\nin Epeira nigra.  In this species, as I may add, the male is testaceous and\nthe female black with legs banded with red.  Other even more striking cases\nof inequality in size between the sexes have been recorded ('Quarterly\nJournal of Science,' July 1868, p. 429); but I have not seen the original\naccounts.), and he is forced to be extremely cautious in making his\nadvances, as the female often carries her coyness to a dangerous pitch.  De\nGeer saw a male that \"in the midst of his preparatory caresses was seized\nby the object of his attentions, enveloped by her in a web and then\ndevoured, a sight which, as he adds, filled him with horror and\nindignation.\"  (21.  Kirby and Spence, 'Introduction to Entomology,' vol.\ni. 1818, p. 280.)  The Rev. O.P. Cambridge (22.  'Proceedings, Zoological\nSociety,' 1871, p. 621.) accounts in the following manner for the extreme\nsmallness of the male in the genus Nephila.  \"M. Vinson gives a graphic\naccount of the agile way in which the diminutive male escapes from the\nferocity of the female, by gliding about and playing hide and seek over her\nbody and along her gigantic limbs:  in such a pursuit it is evident that\nthe chances of escape would be in favour of the smallest males, while the\nlarger ones would fall early victims; thus gradually a diminutive race of\nmales would be selected, until at last they would dwindle to the smallest\npossible size compatible with the exercise of their generative functions,--\nin fact, probably to the size we now see them, i.e., so small as to be a\nsort of parasite upon the female, and either beneath her notice, or too\nagile and too small for her to catch without great difficulty.\"\n\nWestring has made the interesting discovery that the males of several\nspecies of Theridion (23.  Theridion (Asagena, Sund.) serratipes, 4-\npunctatum et guttatum; see Westring, in Kroyer, 'Naturhist. Tidskrift,'\nvol. iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342.  See, also, for\nother species, 'Araneae Suecicae,' p. 184.) have the power of making a\nstridulating sound, whilst the females are mute.  The apparatus consists of\na serrated ridge at the base of the abdomen, against which the hard hinder\npart of the thorax is rubbed; and of this structure not a trace can be\ndetected in the females.  It deserves notice that several writers,\nincluding the well-known arachnologist Walckenaer, have declared that\nspiders are attracted by music.  (24.  Dr. H.H. van Zouteveen, in his Dutch\ntranslation of this work (vol. i. p. 444), has collected several cases.)\nFrom the analogy of the Orthoptera and Homoptera, to be described in the\nnext chapter, we may feel almost sure that the stridulation serves, as\nWestring also believes, to call or to excite the female; and this is the\nfirst case known to me in the ascending scale of the animal kingdom of\nsounds emitted for this purpose.  (25.  Hilgendorf, however, has lately\ncalled attention to an analogous structure in some of the higher\ncrustaceans, which seems adapted to produce sound; see 'Zoological Record,'\n1869, p. 603.)\n\nCLASS, MYRIAPODA.\n\nIn neither of the two orders in this class, the millipedes and centipedes,\ncan I find any well-marked instances of such sexual differences as more\nparticularly concern us.  In Glomeris limbata, however, and perhaps in some\nfew other species, the males differ slightly in colour from the females;\nbut this Glomeris is a highly variable species.  In the males of the\nDiplopoda, the legs belonging either to one of the anterior or of the\nposterior segments of the body are modified into prehensile hooks which\nserve to secure the female.  In some species of Iulus the tarsi of the male\nare furnished with membranous suckers for the same purpose.  As we shall\nsee when we treat of Insects, it is a much more unusual circumstance, that\nit is the female in Lithobius, which is furnished with prehensile\nappendages at the extremity of her body for holding the male.  (26.\nWalckenaer et P. Gervais, 'Hist. Nat. des Insectes:  Apteres,' tom. iv.\n1847, pp. 17, 19, 68.)\n\n\nCHAPTER X.\n\nSECONDARY SEXUAL CHARACTERS OF INSECTS.\n\nDiversified structures possessed by the males for seizing the females--\nDifferences between the sexes, of which the meaning is not understood--\nDifference in size between the sexes--Thysanura--Diptera--Hemiptera--\nHomoptera, musical powers possessed by the males alone--Orthoptera, musical\ninstruments of the males, much diversified in structure; pugnacity;\ncolours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity\nand odours--Coleoptera, colours; furnished with great horns, apparently as\nan ornament; battles, stridulating organs generally common to both sexes.\n\nIn the immense class of insects the sexes sometimes differ in their\nlocomotive-organs, and often in their sense-organs, as in the pectinated\nand beautifully plumose antennae of the males of many species.  In Chloeon,\none of the Ephemerae, the male has great pillared eyes, of which the female\nis entirely destitute.  (1.  Sir J. Lubbock, 'Transact. Linnean Soc.' vol.\nxxv, 1866, p. 484.  With respect to the Mutillidae see Westwood, 'Modern\nClass. of Insects,' vol. ii. p. 213.)  The ocelli are absent in the females\nof certain insects, as in the Mutillidae; and here the females are likewise\nwingless.  But we are chiefly concerned with structures by which one male\nis enabled to conquer another, either in battle or courtship, through his\nstrength, pugnacity, ornaments, or music.  The innumerable contrivances,\ntherefore, by which the male is able to seize the female, may be briefly\npassed over.  Besides the complex structures at the apex of the abdomen,\nwhich ought perhaps to be ranked as primary organs (2.  These organs in the\nmale often differ in closely-allied species, and afford excellent specific\ncharacters.  But their importance, from a functional point of view, as Mr.\nR. MacLachlan has remarked to me, has probably been overrated.  It has been\nsuggested, that slight differences in these organs would suffice to prevent\nthe intercrossing of well-marked varieties or incipient species, and would\nthus aid in their development.  That this can hardly be the case, we may\ninfer from the many recorded cases (see, for instance, Bronn, 'Geschichte\nder Natur,' B. ii. 1843, s. 164; and Westwood, 'Transact. Ent. Soc.' vol.\niii. 1842, p. 195) of distinct species having been observed in union.  Mr.\nMacLachlan informs me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when\nseveral species of Phryganidae, which present strongly-pronounced\ndifferences of this kind, were confined together by Dr. Aug. Meyer, THEY\nCOUPLED, and one pair produced fertile ova.), \"it is astonishing,\" as Mr.\nB.D. Walsh (3.  'The Practical Entomologist,' Philadelphia, vol. ii. May\n1867, p. 88.) has remarked, \"how many different organs are worked in by\nnature for the seemingly insignificant object of enabling the male to grasp\nthe female firmly.\"  The mandibles or jaws are sometimes used for this\npurpose; thus the male Corydalis cornutus (a neuropterous insect in some\ndegree allied to the Dragon flies, etc.) has immense curved jaws, many\ntimes longer than those of the female; and they are smooth instead of being\ntoothed, so that he is thus enabled to seize her without injury.  (4.  Mr.\nWalsh, ibid. p. 107.)  One of the stag-beetles of North America (Lucanus\nelaphus) uses his jaws, which are much larger than those of the female, for\nthe same purpose, but probably likewise for fighting.  In one of the sand-\nwasps (Ammophila) the jaws in the two sexes are closely alike, but are used\nfor widely different purposes:  the males, as Professor Westwood observes,\n\"are exceedingly ardent, seizing their partners round the neck with their\nsickle-shaped jaws\" (5.  'Modern Classification of Insects,' vol. ii. 1840,\npp. 205, 206.  Mr. Walsh, who called my attention to the double use of the\njaws, says that he has repeatedly observed this fact.); whilst the females\nuse these organs for burrowing in sand-banks and making their nests.\n\n[Fig. 9. Crabro cribrarius.  Upper figure, male; lower figure, female.]\n\nThe tarsi of the front-legs are dilated in many male beetles, or are\nfurnished with broad cushions of hairs; and in many genera of water-beetles\nthey are armed with a round flat sucker, so that the male may adhere to the\nslippery body of the female.  It is a much more unusual circumstance that\nthe females of some water-beetles (Dytiscus) have their elytra deeply\ngrooved, and in Acilius sulcatus thickly set with hairs, as an aid to the\nmale.  The females of some other water-beetles (Hydroporus) have their\nelytra punctured for the same purpose.  (6.  We have here a curious and\ninexplicable case of dimorphism, for some of the females of four European\nspecies of Dytiscus, and of certain species of Hydroporus, have their\nelytra smooth; and no intermediate gradations between the sulcated or\npunctured, and the quite smooth elytra have been observed.  See Dr. H.\nSchaum, as quoted in the 'Zoologist,' vols. v.-vi. 1847-48, p. 1896.  Also\nKirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 305.)\nIn the male of Crabro cribrarius (Fig. 9), it is the tibia which is dilated\ninto a broad horny plate, with minute membraneous dots, giving to it a\nsingular appearance like that of a riddle.  (7.  Westwood, 'Modern Class.'\nvol. ii. p. 193.  The following statement about Penthe, and others in\ninverted commas, are taken from Mr. Walsh, 'Practical Entomologist,'\nPhiladelphia, vol. iii. p. 88.)  In the male of Penthe (a genus of beetles)\na few of the middle joints of the antennae are dilated and furnished on the\ninferior surface with cushions of hair, exactly like those on the tarsi of\nthe Carabidae, \"and obviously for the same end.\"  In male dragon-flies,\n\"the appendages at the tip of the tail are modified in an almost infinite\nvariety of curious patterns to enable them to embrace the neck of the\nfemale.\"  Lastly, in the males of many insects, the legs are furnished with\npeculiar spines, knobs or spurs; or the whole leg is bowed or thickened,\nbut this is by no means invariably a sexual character; or one pair, or all\nthree pairs are elongated, sometimes to an extravagant length. (8.  Kirby\nand Spence, 'Introduct.' etc., vol. iii. pp. 332-336.)\n\n[Fig. 10.  Taphroderes distortus (much enlarged).  Upper figure, male;\nlower figure, female.]\n\nThe sexes of many species in all the orders present differences, of which\nthe meaning is not understood.  One curious case is that of a beetle (Fig.\n10), the male of which has left mandible much enlarged; so that the mouth\nis greatly distorted.  In another Carabidous beetle, Eurygnathus (9.\n'Insecta Maderensia,' 1854, page 20.), we have the case, unique as far as\nknown to Mr. Wollaston, of the head of the female being much broader and\nlarger, though in a variable degree, than that of the male.  Any number of\nsuch cases could be given.  They abound in the Lepidoptera:  one of the\nmost extraordinary is that certain male butterflies have their fore-legs\nmore or less atrophied, with the tibiae and tarsi reduced to mere\nrudimentary knobs.  The wings, also, in the two sexes often differ in\nneuration (10.  E. Doubleday, 'Annals and Mag. of Nat. Hist.' vol. i. 1848,\np. 379.  I may add that the wings in certain Hymenoptera (see Shuckard,\n'Fossorial Hymenoptera,' 1837, pp. 39-43) differ in neuration according to\nsex.), and sometimes considerably in outline, as in the Aricoris epitus,\nwhich was shewn to me in the British Museum by Mr. A. Butler.  The males of\ncertain South American butterflies have tufts of hair on the margins of the\nwings, and horny excrescences on the discs of the posterior pair.  (11.\nH.W. Bates, in 'Journal of Proc. Linn. Soc.' vol. vi. 1862, p. 74.  Mr.\nWonfor's observations are quoted in 'Popular Science Review,' 1868, p.\n343.)  In several British butterflies, as shewn by Mr. Wonfor, the males\nalone are in parts clothed with peculiar scales.\n\nThe use of the bright light of the female glow-worm has been subject to\nmuch discussion.  The male is feebly luminous, as are the larvae and even\nthe eggs.  It has been supposed by some authors that the light serves to\nfrighten away enemies, and by others to guide the male to the female.  At\nlast, Mr. Belt (12.  'The Naturalist in Nicaragua,' 1874, pp. 316-320.  On\nthe phosphorescence of the eggs, see 'Annals and Magazine of Natural\nHistory,' Nov. 1871, p. 372.) appears to have solved the difficulty:  he\nfinds that all the Lampyridae which he has tried are highly distasteful to\ninsectivorous mammals and birds.  Hence it is in accordance with Mr. Bates'\nview, hereafter to be explained, that many insects mimic the Lampyridae\nclosely, in order to be mistaken for them, and thus to escape destruction.\nHe further believes that the luminous species profit by being at once\nrecognised as unpalatable.  It is probable that the same explanation may be\nextended to the Elaters, both sexes of which are highly luminous.  It is\nnot known why the wings of the female glow-worm have not been developed;\nbut in her present state she closely resembles a larva, and as larvae are\nso largely preyed on by many animals, we can understand why she has been\nrendered so much more luminous and conspicuous than the male; and why the\nlarvae themselves are likewise luminous.\n\nDIFFERENCE IN SIZE BETWEEN THE SEXES.\n\nWith insects of all kinds the males are commonly smaller than the females;\nand this difference can often be detected even in the larval state.  So\nconsiderable is the difference between the male and female cocoons of the\nsilk-moth (Bombyx mori), that in France they are separated by a particular\nmode of weighing.  (13.  Robinet, 'Vers a Soie,' 1848, p. 207.)  In the\nlower classes of the animal kingdom, the greater size of the females seems\ngenerally to depend on their developing an enormous number of ova; and this\nmay to a certain extent hold good with insects.  But Dr. Wallace has\nsuggested a much more probable explanation.  He finds, after carefully\nattending to the development of the caterpillars of Bombyx cynthia and\nyamamai, and especially to that of some dwarfed caterpillars reared from a\nsecond brood on unnatural food, \"that in proportion as the individual moth\nis finer, so is the time required for its metamorphosis longer; and for\nthis reason the female, which is the larger and heavier insect, from having\nto carry her numerous eggs, will be preceded by the male, which is smaller\nand has less to mature.\"  (14.  'Transact. Ent. Soc.' 3rd series, vol. v.\np. 486.)  Now as most insects are short-lived, and as they are exposed to\nmany dangers, it would manifestly be advantageous to the female to be\nimpregnated as soon as possible.  This end would be gained by the males\nbeing first matured in large numbers ready for the advent of the females;\nand this again would naturally follow, as Mr. A.R. Wallace has remarked\n(15.  'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. lxxi.), through natural\nselection; for the smaller males would be first matured, and thus would\nprocreate a large number of offspring which would inherit the reduced size\nof their male parents, whilst the larger males from being matured later\nwould leave fewer offspring.\n\nThere are, however, exceptions to the rule of male insects being smaller\nthan the females:  and some of these exceptions are intelligible.  Size and\nstrength would be an advantage to the males, which fight for the possession\nof the females; and in these cases, as with the stag-beetle (Lucanus), the\nmales are larger than the females.  There are, however, other beetles which\nare not known to fight together, of which the males exceed the females in\nsize; and the meaning of this fact is not known; but in some of these\ncases, as with the huge Dynastes and Megasoma, we can at least see that\nthere would be no necessity for the males to be smaller than the females,\nin order to be matured before them, for these beetles are not short-lived,\nand there would be ample time for the pairing of the sexes.  So again, male\ndragon-flies (Libellulidae) are sometimes sensibly larger, and never\nsmaller, than the females (16.  For this and other statements on the size\nof the sexes, see Kirby and Spence, ibid. vol. iii. p. 300; on the duration\nof life in insects, see p. 344.); and as Mr. MacLachlan believes, they do\nnot generally pair with the females until a week or fortnight has elapsed,\nand until they have assumed their proper masculine colours.  But the most\ncurious case, shewing on what complex and easily-overlooked relations, so\ntrifling a character as difference in size between the sexes may depend, is\nthat of the aculeate Hymenoptera; for Mr. F. Smith informs me that\nthroughout nearly the whole of this large group, the males, in accordance\nwith the general rule, are smaller than the females, and emerge about a\nweek before them; but amongst the Bees, the males of Apis mellifica,\nAnthidium manicatum, and Anthophora acervorum, and amongst the Fossores,\nthe males of the Methoca ichneumonides, are larger than the females.  The\nexplanation of this anomaly is that a marriage flight is absolutely\nnecessary with these species, and the male requires great strength and size\nin order to carry the female through the air.  Increased size has here been\nacquired in opposition to the usual relation between size and the period of\ndevelopment, for the males, though larger, emerge before the smaller\nfemales.\n\nWe will now review the several Orders, selecting such facts as more\nparticularly concern us.  The Lepidoptera (Butterflies and Moths) will be\nretained for a separate chapter.\n\nORDER, THYSANURA.\n\nThe members of this lowly organised order are wingless, dull-coloured,\nminute insects, with ugly, almost misshapen heads and bodies.  Their sexes\ndo not differ, but they are interesting as shewing us that the males pay\nsedulous court to the females even low down in the animal scale.  Sir J.\nLubbock (17.  'Transact. Linnean Soc.' vol. xxvi. 1868, p. 296.) says:  \"it\nis very amusing to see these little creatures (Smynthurus luteus)\ncoquetting together.  The male, which is much smaller than the female, runs\nround her, and they butt one another, standing face to face and moving\nbackward and forward like two playful lambs.  Then the female pretends to\nrun away and the male runs after her with a queer appearance of anger, gets\nin front and stands facing her again; then she turns coyly round, but he,\nquicker and more active, scuttles round too, and seems to whip her with his\nantennae; then for a bit they stand face to face, play with their antennae,\nand seem to be all in all to one another.\"\n\nORDER, DIPTERA (FLIES).\n\nThe sexes differ little in colour.  The greatest difference, known to Mr.\nF. Walker, is in the genus Bibio, in which the males are blackish or quite\nblack, and the females obscure brownish-orange.  The genus Elaphomyia,\ndiscovered by Mr. Wallace (18.  'The Malay Archipelago,' vol. ii. 1869, p.\n313.) in New Guinea, is highly remarkable, as the males are furnished with\nhorns, of which the females are quite destitute.  The horns spring from\nbeneath the eyes, and curiously resemble those of a stag, being either\nbranched or palmated.  In one of the species, they equal the whole body in\nlength.  They might be thought to be adapted for fighting, but as in one\nspecies they are of a beautiful pink colour, edged with black, with a pale\ncentral stripe, and as these insects have altogether a very elegant\nappearance, it is perhaps more probable that they serve as ornaments.  That\nthe males of some Diptera fight together is certain; Prof. Westwood (19.\n'Modern Classification of Insects,' vol. ii. 1840, p. 526.) has several\ntimes seen this with the Tipulae.  The males of other Diptera apparently\ntry to win the females by their music:  H. Mueller (20.  'Anwendung,' etc.,\n'Verh. d. n. V. Jahrg.' xxix. p. 80.  Mayer, in 'American Naturalist,'\n1874, p. 236.) watched for some time two males of an Eristalis courting a\nfemale; they hovered above her, and flew from side to side, making a high\nhumming noise at the same time.  Gnats and mosquitoes (Culicidae) also seem\nto attract each other by humming; and Prof. Mayer has recently ascertained\nthat the hairs on the antennae of the male vibrate in unison with the notes\nof a tuning-fork, within the range of the sounds emitted by the female.\nThe longer hairs vibrate sympathetically with the graver notes, and the\nshorter hairs with the higher ones.  Landois also asserts that he has\nrepeatedly drawn down a whole swarm of gnats by uttering a particular note.\nIt may be added that the mental faculties of the Diptera are probably\nhigher than in most other insects, in accordance with their highly-\ndeveloped nervous system.  (21.  See Mr. B.T. Lowne's interesting work, 'On\nthe Anatomy of the Blow-fly, Musca vomitoria,' 1870, p. 14.  He remarks (p.\n33) that, \"the captured flies utter a peculiar plaintive note, and that\nthis sound causes other flies to disappear.\")\n\nORDER, HEMIPTERA (FIELD-BUGS).\n\nMr. J.W. Douglas, who has particularly attended to the British species, has\nkindly given me an account of their sexual differences.  The males of some\nspecies are furnished with wings, whilst the females are wingless; the\nsexes differ in the form of their bodies, elytra, antennae and tarsi; but\nas the signification of these differences are unknown, they may be here\npassed over.  The females are generally larger and more robust than the\nmales.  With British, and, as far as Mr. Douglas knows, with exotic\nspecies, the sexes do not commonly differ much in colour; but in about six\nBritish species the male is considerably darker than the female, and in\nabout four other species the female is darker than the male.  Both sexes of\nsome species are beautifully coloured; and as these insects emit an\nextremely nauseous odour, their conspicuous colours may serve as a signal\nthat they are unpalatable to insectivorous animals.  In some few cases\ntheir colours appear to be directly protective:  thus Prof. Hoffmann\ninforms me that he could hardly distinguish a small pink and green species\nfrom the buds on the trunks of lime-trees, which this insect frequents.\n\nSome species of Reduvidae make a stridulating noise; and, in the case of\nPirates stridulus, this is said (22.  Westwood, 'Modern Classification of\nInsects,' vol. ii. p. 473.) to be effected by the movement of the neck\nwithin the pro-thoracic cavity.  According to Westring, Reduvius personatus\nalso stridulates.  But I have no reason to suppose that this is a sexual\ncharacter, excepting that with non-social insects there seems to be no use\nfor sound-producing organs, unless it be as a sexual call.\n\nORDER:  HOMOPTERA.\n\nEvery one who has wandered in a tropical forest must have been astonished\nat the din made by the male Cicadae.  The females are mute; as the Grecian\npoet Xenarchus says, \"Happy the Cicadas live, since they all have voiceless\nwives.\"  The noise thus made could be plainly heard on board the \"Beagle,\"\nwhen anchored at a quarter of a mile from the shore of Brazil; and Captain\nHancock says it can be heard at the distance of a mile.  The Greeks\nformerly kept, and the Chinese now keep these insects in cages for the sake\nof their song, so that it must be pleasing to the ears of some men.  (23.\nThese particulars are taken from Westwood's 'Modern Classification of\nInsects,' vol. ii. 1840, p. 422.  See, also, on the Fulgoridae, Kirby and\nSpence, 'Introduct.' vol. ii. p. 401.)  The Cicadidae usually sing during\nthe day, whilst the Fulgoridae appear to be night-songsters.  The sound,\naccording to Landois (24.  'Zeitschrift fuer wissenschaft. Zoolog.' B. xvii.\n1867, ss. 152-158.), is produced by the vibration of the lips of the\nspiracles, which are set into motion by a current of air emitted from the\ntracheae; but this view has lately been disputed.  Dr. Powell appears to\nhave proved (25.  'Transactions of the New Zealand Institute,' vol. v.\n1873, p. 286.) that it is produced by the vibration of a membrane, set into\naction by a special muscle.  In the living insect, whilst stridulating,\nthis membrane can be seen to vibrate; and in the dead insect the proper\nsound is heard, if the muscle, when a little dried and hardened, is pulled\nwith the point of a pin.  In the female the whole complex musical apparatus\nis present, but is much less developed than in the male, and is never used\nfor producing sound.\n\nWith respect to the object of the music,  Dr. Hartman, in speaking of the\nCicada septemdecim of the United States, says (26.  I am indebted to Mr.\nWalsh for having sent me this extract from 'A Journal of the Doings of\nCicada septemdecim,' by Dr. Hartman.), \"the drums are now (June 6th and\n7th, 1851) heard in all directions.  This I believe to be the marital\nsummons from the males.  Standing in thick chestnut sprouts about as high\nas my head, where hundreds were around me, I observed the females coming\naround the drumming males.\"  He adds, \"this season (Aug. 1868) a dwarf\npear-tree in my garden produced about fifty larvae of Cic. pruinosa; and I\nseveral times noticed the females to alight near a male while he was\nuttering his clanging notes.\"  Fritz Mueller writes to me from S. Brazil\nthat he has often listened to a musical contest between two or three males\nof a species with a particularly loud voice, seated at a considerable\ndistance from each other:  as soon as one had finished his song, another\nimmediately began, and then another.  As there is so much rivalry between\nthe males, it is probable that the females not only find them by their\nsounds, but that, like female birds, they are excited or allured by the\nmale with the most attractive voice.\n\nI have not heard of any well-marked cases of ornamental differences between\nthe sexes of the Homoptera.  Mr. Douglas informs me that there are three\nBritish species, in which the male is black or marked with black bands,\nwhilst the females are pale-coloured or obscure.\n\nORDER, ORTHOPTERA (CRICKETS AND GRASSHOPPERS).\n\nThe males in the three saltatorial families in this Order are remarkable\nfor their musical powers, namely the Achetidae or crickets, the Locustidae\nfor which there is no equivalent English name, and the Acridiidae or\ngrasshoppers.  The stridulation produced by some of the Locustidae is so\nloud that it can be heard during the night at the distance of a mile (27.\nL. Guilding, 'Transactions of the Linnean Society,' vol. xv. p. 154.); and\nthat made by certain species is not unmusical even to the human ear, so\nthat the Indians on the Amazons keep them in wicker cages.  All observers\nagree that the sounds serve either to call or excite the mute females.\nWith respect to the migratory locusts of Russia, Korte has given (28.  I\nstate this on the authority of Koppen, 'Ueber die Heuschrecken in\nSuedrussland,' 1866, p. 32, for I have in vain endeavoured to procure\nKorte's work.) an interesting case of selection by the female of a male.\nThe males of this species (Pachytylus migratorius) whilst coupled with the\nfemale stridulate from anger or jealousy, if approached by other males.\nThe house-cricket when surprised at night uses its voice to warn its\nfellows.  (29.  Gilbert White, 'Natural History of Selborne,' vol. ii.\n1825, p. 262.)  In North America the Katy-did (Platyphyllum concavum, one\nof the Locustidae) is described (30.  Harris, 'Insects of New England,'\n1842, p. 128.) as mounting on the upper branches of a tree, and in the\nevening beginning \"his noisy babble, while rival notes issue from the\nneighbouring trees, and the groves resound with the call of Katy-did-she-\ndid the live-long night.\"  Mr. Bates, in speaking of the European field-\ncricket (one of the Achetidae), says \"the male has been observed to place\nhimself in the evening at the entrance of his burrow, and stridulate until\na female approaches, when the louder notes are succeeded by a more subdued\ntone, whilst the successful musician caresses with his antennae the mate he\nhas won.\" (31.  'The Naturalist on the Amazons,' vol. i. 1863, p. 252.  Mr.\nBates gives a very interesting discussion on the gradations in the musical\napparatus of the three families.  See also Westwood, 'Modern Classification\nof Insects,' vol. ii. pp. 445 and 453.)  Dr. Scudder was able to excite one\nof these insects to answer him, by rubbing on a file with a quill.  (32.\n'Proceedings of the Boston Society of Natural History,' vol. xi. April\n1868.)  In both sexes a remarkable auditory apparatus has been discovered\nby Von Siebold, situated in the front legs.  (33.  'Nouveau Manuel d'Anat.\nComp.'  (French translat.), tom. 1, 1850, p. 567.)\n\n[Fig.11.  Gryllus campestris (from Landois).\nRight-hand figure, under side of part of a wing-nervure, much magnified,\nshowing the teeth, st.\nLeft-hand figure, upper surface of wing-cover, with the projecting, smooth\nnervure, r, across which the teeth (st) are scraped.\n\nFig.12.  Teeth of Nervure of Gryllus domesticus (from Landois).]\n\nIn the three Families the sounds are differently produced.  In the males of\nthe Achetidae both wing-covers have the same apparatus; and this in the\nfield-cricket (see Gryllus campestris, Fig. 11) consists, as described by\nLandois (34.  'Zeitschrift fuer wissenschaft. Zoolog.' B. xvii. 1867, s.\n117.), of from 131 to 138 sharp, transverse ridges or teeth (st) on the\nunder side of one of the nervures of the wing-cover.  This toothed nervure\nis rapidly scraped across a projecting, smooth, hard nervure (r) on the\nupper surface of the opposite wing.  First one wing is rubbed over the\nother, and then the movement is reversed.  Both wings are raised a little\nat the same time, so as to increase the resonance.  In some species the\nwing-covers of the males are furnished at the base with a talc-like plate.\n(35.  Westwood, 'Modern Classification of Insects,' vol. i. p. 440.)  I\nhere give a drawing (Fig. 12) of the teeth on the under side of the nervure\nof another species of Gryllus, viz., G. domesticus.  With respect to the\nformation of these teeth, Dr. Gruber has shewn (36.  'Ueber der Tonapparat\nder Locustiden, ein Beitrag zum Darwinismus,' 'Zeitschrift fuer\nwissenschaft. Zoolog.' B. xxii. 1872, p. 100.) that they have been\ndeveloped by the aid of selection, from the minute scales and hairs with\nwhich the wings and body are covered, and I came to the same conclusion\nwith respect to those of the Coleoptera.  But Dr. Gruber further shews that\ntheir development is in part directly due to the stimulus from the friction\nof one wing over the other.\n\n[Fig.13.  Chlorocoelus Tanana (from Bates).\na,b.  Lobes of opposite wing-covers.]\n\nIn the Locustidae the opposite wing-covers differ from each other in\nstructure (Fig. 13), and the action cannot, as in the last family, be\nreversed.  The left wing, which acts as the bow, lies over the right wing\nwhich serves as the fiddle.  One of the nervures (a) on the under surface\nof the former is finely serrated, and is scraped across the prominent\nnervures on the upper surface of the opposite or right wing.  In our\nBritish Phasgonura viridissima it appeared to me that the serrated nervure\nis rubbed against the rounded hind-corner of the opposite wing, the edge of\nwhich is thickened, coloured brown, and very sharp.  In the right wing, but\nnot in the left, there is a little plate, as transparent as talc,\nsurrounded by nervures, and called the speculum.  In Ephippiger vitium, a\nmember of this same family, we have a curious subordinate modification; for\nthe wing-covers are greatly reduced in size, but \"the posterior part of the\npro-thorax is elevated into a kind of dome over the wing-covers, and which\nhas probably the effect of increasing the sound.\"  (37.  Westwood 'Modern\nClassification of Insects,' vol. i. p. 453.)\n\nWe thus see that the musical apparatus is more differentiated or\nspecialised in the Locustidae (which include, I believe, the most powerful\nperformers in the Order), than in the Achetidae, in which both wing-covers\nhave the same structure and the same function.  (38.  Landois, 'Zeitschrift\nfuer wissenschaft. Zoolog.' B. xvii. 1867, ss. 121, 122.)  Landois, however,\ndetected in one of the Locustidae, namely in Decticus, a short and narrow\nrow of small teeth, mere rudiments, on the inferior surface of the right\nwing-cover, which underlies the other and is never used as the bow.  I\nobserved the same rudimentary structure on the under side of the right\nwing-cover in Phasgonura viridissima.  Hence we may infer with confidence\nthat the Locustidae are descended from a form, in which, as in the existing\nAchetidae, both wing-covers had serrated nervures on the under surface, and\ncould be indifferently used as the bow; but that in the Locustidae the two\nwing-covers gradually became differentiated and perfected, on the principle\nof the division of labour, the one to act exclusively as the bow, and the\nother as the fiddle.  Dr. Gruber takes the same view, and has shewn that\nrudimentary teeth are commonly found on the inferior surface of the right\nwing.  By what steps the more simple apparatus in the Achetidae originated,\nwe do not know, but it is probable that the basal portions of the wing-\ncovers originally overlapped each other as they do at present; and that the\nfriction of the nervures produced a grating sound, as is now the case with\nthe wing-covers of the females.  (39.  Mr. Walsh also informs me that he\nhas noticed that the female of the Platyphyllum concavum, \"when captured\nmakes a feeble grating noise by shuffling her wing-covers together.\")  A\ngrating sound thus occasionally and accidentally made by the males, if it\nserved them ever so little as a love-call to the females, might readily\nhave been intensified through sexual selection, by variations in the\nroughness of the nervures having been continually preserved.\n\n[Fig.14.  Hind-leg of Stenobothrus pratorum:\nr, the stridulating ridge;\nlower figure, the teeth forming the ridge, much magnified (from Landois).\n\nFig.15.  Pneumora (from specimens in the British Museum).\nUpper figure, male;\nlower figure, female.]\n\nIn the last and third family, namely the Acridiidae or grasshoppers, the\nstridulation is produced in a very different manner, and according to Dr.\nScudder, is not so shrill as in the preceding Families.  The inner surface\nof the femur (Fig. 14, r) is furnished with a longitudinal row of minute,\nelegant, lancet-shaped, elastic teeth, from 85 to 93 in number (40.\nLandois, ibid. s. 113.); and these are scraped across the sharp, projecting\nnervures on the wing-covers, which are thus made to vibrate and resound.\nHarris (41.  'Insects of New England,' 1842, p. 133.) says that when one of\nthe males begins to play, he first \"bends the shank of the hind-leg beneath\nthe thigh, where it is lodged in a furrow designed to receive it, and then\ndraws the leg briskly up and down.  He does not play both fiddles together,\nbut alternately, first upon one and then on the other.\"  In many species,\nthe base of the abdomen is hollowed out into a great cavity which is\nbelieved to act as a resounding board.  In Pneumora (Fig. 15), a S. African\ngenus belonging to the same family, we meet with a new and remarkable\nmodification; in the males a small notched ridge projects obliquely from\neach side of the abdomen, against which the hind femora are rubbed.  (42.\nWestwood, 'Modern Classification,' vol i. p. 462.)  As the male is\nfurnished with wings (the female being wingless), it is remarkable that the\nthighs are not rubbed in the usual manner against the wing-covers; but this\nmay perhaps be accounted for by the unusually small size of the hind-legs.\nI have not been able to examine the inner surface of the thighs, which,\njudging from analogy, would be finely serrated.  The species of Pneumora\nhave been more profoundly modified for the sake of stridulation than any\nother orthopterous insect; for in the male the whole body has been\nconverted into a musical instrument, being distended with air, like a great\npellucid bladder, so as to increase the resonance.  Mr. Trimen informs me\nthat at the Cape of Good Hope these insects make a wonderful noise during\nthe night.\n\nIn the three foregoing families, the females are almost always destitute of\nan efficient musical apparatus.  But there are a few exceptions to this\nrule, for Dr. Gruber has shewn that both sexes of Ephippiger vitium are\nthus provided; though the organs differ in the male and female to a certain\nextent.  Hence we cannot suppose that they have been transferred from the\nmale to the female, as appears to have been the case with the secondary\nsexual characters of many other animals.  They must have been independently\ndeveloped in the two sexes, which no doubt mutually call to each other\nduring the season of love.  In most other Locustidae (but not according to\nLandois in Decticus) the females have rudiments of the stridulatory organs\nproper to the male; from whom it is probable that these have been\ntransferred.  Landois also found such rudiments on the under surface of the\nwing-covers of the female Achetidae, and on the femora of the female\nAcridiidae.  In the Homoptera, also, the females have the proper musical\napparatus in a functionless state; and we shall hereafter meet in other\ndivisions of the animal kingdom with many instances of structures proper to\nthe male being present in a rudimentary condition in the female.\n\nLandois has observed another important fact, namely, that in the females of\nthe Acridiidae, the stridulating teeth on the femora remain throughout life\nin the same condition in which they first appear during the larval state in\nboth sexes.  In the males, on the other hand, they become further\ndeveloped, and acquire their perfect structure at the last moult, when the\ninsect is mature and ready to breed.\n\nFrom the facts now given, we see that the means by which the males of the\nOrthoptera produce their sounds are extremely diversified, and are\naltogether different from those employed by the Homoptera.  (43.  Landois\nhas recently found in certain Orthoptera rudimentary structures closely\nsimilar to the sound-producing organs in the Homoptera; and this is a\nsurprising fact.  See 'Zeitschrift fuer wissenschaft, Zoolog.' B. xxii. Heft\n3, 1871, p. 348.)  But throughout the animal kingdom we often find the same\nobject gained by the most diversified means; this seems due to the whole\norganisation having undergone multifarious changes in the course of ages,\nand as part after part varied different variations were taken advantage of\nfor the same general purpose.  The diversity of means for producing sound\nin the three families of the Orthoptera and in the Homoptera, impresses the\nmind with the high importance of these structures to the males, for the\nsake of calling or alluring the females.  We need feel no surprise at the\namount of modification which the Orthoptera have undergone in this respect,\nas we now know, from Dr. Scudder's remarkable discovery (44.\n'Transactions, Entomological Society,' 3rd series, vol. ii. ('Journal of\nProceedings,' p. 117).), that there has been more than ample time.  This\nnaturalist has lately found a fossil insect in the Devonian formation of\nNew Brunswick, which is furnished with \"the well-known tympanum or\nstridulating apparatus of the male Locustidae.\"  The insect, though in most\nrespects related to the Neuroptera, appears, as is so often the case with\nvery ancient forms, to connect the two related Orders of the Neuroptera and\nOrthoptera.\n\nI have but little more to say on the Orthoptera.  Some of the species are\nvery pugnacious:  when two male field-crickets (Gryllus campestris) are\nconfined together, they fight till one kills the other; and the species of\nMantis are described as manoeuvring with their sword-like front-limbs, like\nhussars with their sabres.  The Chinese keep these insects in little bamboo\ncages, and match them like game-cocks.  (45.  Westwood, 'Modern\nClassification of Insects,' vol. i. p. 427; for crickets, p. 445.)  With\nrespect to colour, some exotic locusts are beautifully ornamented; the\nposterior wings being marked with red, blue, and black; but as throughout\nthe Order the sexes rarely differ much in colour, it is not probable that\nthey owe their bright tints to sexual selection.  Conspicuous colours may\nbe of use to these insects, by giving notice that they are unpalatable.\nThus it has been observed (46.  Mr. Ch. Horne, in 'Proceedings of the\nEntomological Society,' May 3, 1869, p. xii.) that a bright-coloured Indian\nlocust was invariably rejected when offered to birds and lizards.  Some\ncases, however, are known of sexual differences in colour in this Order.\nThe male of an American cricket (47.  The Oecanthus nivalis, Harris,\n'Insects of New England,' 1842, p. 124.  The two sexes of OE. pellucidus of\nEurope differ, as I hear from Victor Carus, in nearly the same manner.) is\ndescribed as being as white as ivory, whilst the female varies from almost\nwhite to greenish-yellow or dusky.  Mr. Walsh informs me that the adult\nmale of Spectrum femoratum (one of the Phasmidae) \"is of a shining\nbrownish-yellow colour; the adult female being of a dull, opaque, cinereous\nbrown; the young of both sexes being green.\"  Lastly, I may mention that\nthe male of one curious kind of cricket (48.  Platyblemnus:  Westwood,\n'Modern Classification,' vol. i. p. 447.) is furnished with \"a long\nmembranous appendage, which falls over the face like a veil;\" but what its\nuse may be, is not known.\n\nORDER, NEUROPTERA.\n\nLittle need here be said, except as to colour.  In the Ephemeridae the\nsexes often differ slightly in their obscure tints (49.  B.D. Walsh, the\n'Pseudo-neuroptera of Illinois,' in 'Proceedings of the Entomological\nSociety of Philadelphia,' 1862, p. 361.); but it is not probable that the\nmales are thus rendered attractive to the females.  The Libellulidae, or\ndragon-flies, are ornamented with splendid green, blue, yellow, and\nvermilion metallic tints; and the sexes often differ.  Thus, as Prof.\nWestwood remarks (50.  'Modern Classification,' vol. ii. p. 37.), the males\nof some of the Agrionidae, \"are of a rich blue with black wings, whilst the\nfemales are fine green with colourless wings.\"  But in Agrion Ramburii\nthese colours are exactly reversed in the two sexes.  (51.  Walsh, ibid. p.\n381.  I am indebted to this naturalist for the following facts on\nHetaerina, Anax, and Gomphus.)  In the extensive N. American genus of\nHetaerina, the males alone have a beautiful carmine spot at the base of\neach wing.  In Anax junius the basal part of the abdomen in the male is a\nvivid ultramarine blue, and in the female grass-green.  In the allied genus\nGomphus, on the other hand, and in some other genera, the sexes differ but\nlittle in colour.  In closely-allied forms throughout the animal kingdom,\nsimilar cases of the sexes differing greatly, or very little, or not at\nall, are of frequent occurrence.  Although there is so wide a difference in\ncolour between the sexes of many Libellulidae, it is often difficult to say\nwhich is the more brilliant; and the ordinary coloration of the two sexes\nis reversed, as we have just seen, in one species of Agrion.  It is not\nprobable that their colours in any case have been gained as a protection.\nMr. MacLachlan, who has closely attended to this family, writes to me that\ndragon-flies--the tyrants of the insect-world--are the least liable of any\ninsect to be attacked by birds or other enemies, and he believes that their\nbright colours serve as a sexual attraction.  Certain dragon-flies\napparently are attracted by particular colours:  Mr. Patterson observed\n(52.  'Transactions, Ent. Soc.' vol. i. 1836, p. lxxxi.) that the\nAgrionidae, of which the males are blue, settled in numbers on the blue\nfloat of a fishing line; whilst two other species were attracted by shining\nwhite colours.\n\nIt is an interesting fact, first noticed by Schelver, that, in several\ngenera belonging to two sub-families, the males on first emergence from the\npupal state, are coloured exactly like the females; but that their bodies\nin a short time assume a conspicuous milky-blue tint, owing to the\nexudation of a kind of oil, soluble in ether and alcohol.  Mr. MacLachlan\nbelieves that in the male of Libellula depressa this change of colour does\nnot occur until nearly a fortnight after the metamorphosis, when the sexes\nare ready to pair.\n\nCertain species of Neurothemis present, according to Brauer (53.  See\nabstract in the 'Zoological Record' for 1867, p. 450.), a curious case of\ndimorphism, some of the females having ordinary wings, whilst others have\nthem \"very richly netted, as in the males of the same species.\"  Brauer\n\"explains the phenomenon on Darwinian principles by the supposition that\nthe close netting of the veins is a secondary sexual character in the\nmales, which has been abruptly transferred to some of the females, instead\nof, as generally occurs, to all of them.\"  Mr. MacLachlan informs me of\nanother instance of dimorphism in several species of Agrion, in which some\nindividuals are of an orange colour, and these are invariably females.\nThis is probably a case of reversion; for in the true Libellulae, when the\nsexes differ in colour, the females are orange or yellow; so that supposing\nAgrion to be descended from some primordial form which resembled the\ntypical Libellulae in its sexual characters, it would not be surprising\nthat a tendency to vary in this manner should occur in the females alone.\n\nAlthough many dragon-flies are large, powerful, and fierce insects, the\nmales have not been observed by Mr. MacLachlan to fight together,\nexcepting, as he believes, in some of the smaller species of Agrion.  In\nanother group in this Order, namely, the Termites or white ants, both sexes\nat the time of swarming may be seen running about, \"the male after the\nfemale, sometimes two chasing one female, and contending with great\neagerness who shall win the prize.\"  (54.  Kirby and Spence, 'Introduction\nto Entomology,' vol. ii. 1818, p. 35.)  The Atropos pulsatorius is said to\nmake a noise with its jaws, which is answered by other individuals.  (55.\nHouzeau, 'Les Facultes Mentales,' etc. Tom. i. p. 104.)\n\nORDER, HYMENOPTERA.\n\nThat inimitable observer, M. Fabre (56.  See an interesting article, 'The\nWritings of Fabre,' in 'Nat. Hist. Review,' April 1862, p. 122.), in\ndescribing the habits of Cerceris, a wasp-like insect, remarks that \"fights\nfrequently ensue between the males for the possession of some particular\nfemale, who sits an apparently unconcerned beholder of the struggle for\nsupremacy, and when the victory is decided, quietly flies away in company\nwith the conqueror.\"  Westwood (57.  'Journal of Proceedings of\nEntomological Society,' Sept. 7, 1863, p. 169.) says that the males of one\nof the saw-flies (Tenthredinae) \"have been found fighting together, with\ntheir mandibles locked.\"  As M. Fabre speaks of the males of Cerceris\nstriving to obtain a particular female, it may be well to bear in mind that\ninsects belonging to this Order have the power of recognising each other\nafter long intervals of time, and are deeply attached.  For instance,\nPierre Huber, whose accuracy no one doubts, separated some ants, and when,\nafter an interval of four months, they met others which had formerly\nbelonged to the same community, they recognised and caressed one another\nwith their antennae.  Had they been strangers they would have fought\ntogether.  Again, when two communities engage in a battle, the ants on the\nsame side sometimes attack each other in the general confusion, but they\nsoon perceive their mistake, and the one ant soothes the other.  (58.  P.\nHuber, 'Recherches sur les Moeurs des Fourmis,' 1810, pp. 150, 165.)\n\nIn this Order slight differences in colour, according to sex, are common,\nbut conspicuous differences are rare except in the family of Bees; yet both\nsexes of certain groups are so brilliantly coloured--for instance in\nChrysis, in which vermilion and metallic greens prevail--that we are\ntempted to attribute the result to sexual selection.  In the Ichneumonidae,\naccording to Mr. Walsh (59.  'Proceedings of the Entomological Society of\nPhiladelphia,' 1866, pp. 238, 239.), the males are almost universally\nlighter-coloured than the females.  On the other hand, in the\nTenthredinidae the males are generally darker than the females.  In the\nSiricidae the sexes frequently differ; thus the male of Sirex juvencus is\nbanded with orange, whilst the female is dark purple; but it is difficult\nto say which sex is the more ornamented.  In Tremex columbae the female is\nmuch brighter coloured than the male.  I am informed by Mr. F. Smith, that\nthe male ants of several species are black, the females being testaceous.\n\nIn the family of Bees, especially in the solitary species, as I hear from\nthe same entomologist, the sexes often differ in colour.  The males are\ngenerally the brighter, and in Bombus as well as in Apathus, much more\nvariable in colour than the females.  In Anthophora retusa the male is of a\nrich fulvous-brown, whilst the female is quite black:  so are the females\nof several species of Xylocopa, the males being bright yellow.  On the\nother hand the females of some species, as of Andraena fulva, are much\nbrighter coloured than the males.  Such differences in colour can hardly be\naccounted for by the males being defenceless and thus requiring protection,\nwhilst the females are well defended by their stings.  H. Mueller (60.\n'Anwendung der Darwinschen Lehre auf Bienen,' Verh. d. n. V. Jahrg. xxix.),\nwho has particularly attended to the habits of bees, attributes these\ndifferences in colour in chief part to sexual selection.  That bees have a\nkeen perception of colour is certain.  He says that the males search\neagerly and fight for the possession of the females; and he accounts\nthrough such contests for the mandibles of the males being in certain\nspecies larger than those of the females.  In some cases the males are far\nmore numerous than the females, either early in the season, or at all times\nand places, or locally; whereas the females in other cases are apparently\nin excess.  In some species the more beautiful males appear to have been\nselected by the females; and in others the more beautiful females by the\nmales.  Consequently in certain genera (Mueller, p. 42), the males of the\nseveral species differ much in appearance, whilst the females are almost\nindistinguishable; in other genera the reverse occurs.  H. Mueller believes\n(p. 82) that the colours gained by one sex through sexual selection have\noften been transferred in a variable degree to the other sex, just as the\npollen-collecting apparatus of the female has often been transferred to the\nmale, to whom it is absolutely useless.  (61.  M. Perrier in his article\n'la Selection sexuelle d'apres Darwin' ('Revue Scientifique,' Feb. 1873, p.\n868), without apparently having reflected much on the subject, objects that\nas the males of social bees are known to be produced from unfertilised ova,\nthey could not transmit new characters to their male offspring.  This is an\nextraordinary objection.  A female bee fertilised by a male, which\npresented some character facilitating the union of the sexes, or rendering\nhim more attractive to the female, would lay eggs which would produce only\nfemales; but these young females would next year produce males; and will it\nbe pretended that such males would not inherit the characters of their male\ngrandfathers?  To take a case with ordinary animals as nearly parallel as\npossible:  if a female of any white quadruped or bird were crossed by a\nmale of a black breed, and the male and female offspring were paired\ntogether, will it be pretended that the grandchildren would not inherit a\ntendency to blackness from their male grandfather?  The acquirement of new\ncharacters by the sterile worker-bees is a much more difficult case, but I\nhave endeavoured to shew in my 'Origin of Species,' how these sterile\nbeings are subjected to the power of natural selection.)\n\nMutilla Europaea makes a stridulating noise; and according to Goureau (62.\nQuoted by Westwood, 'Modern Classification of Insects,' vol. ii. p. 214.)\nboth sexes have this power.  He attributes the sound to the friction of the\nthird and preceding abdominal segments, and I find that these surfaces are\nmarked with very fine concentric ridges; but so is the projecting thoracic\ncollar into which the head articulates, and this collar, when scratched\nwith the point of a needle, emits the proper sound.  It is rather\nsurprising that both sexes should have the power of stridulating, as the\nmale is winged and the female wingless.  It is notorious that Bees express\ncertain emotions, as of anger, by the tone of their humming; and according\nto H. Mueller (p. 80), the males of some species make a peculiar singing\nnoise whilst pursuing the females.\n\nORDER, COLEOPTERA (BEETLES).\n\nMany beetles are coloured so as to resemble the surfaces which they\nhabitually frequent, and they thus escape detection by their enemies.\nOther species, for instance diamond-beetles, are ornamented with splendid\ncolours, which are often arranged in stripes, spots, crosses, and other\nelegant patterns.  Such colours can hardly serve directly as a protection,\nexcept in the case of certain flower-feeding species; but they may serve as\na warning or means of recognition, on the same principle as the\nphosphorescence of the glow-worm.  As with beetles the colours of the two\nsexes are generally alike, we have no evidence that they have been gained\nthrough sexual selection; but this is at least possible, for they have been\ndeveloped in one sex and then transferred to the other; and this view is\neven in some degree probable in those groups which possess other well-\nmarked secondary sexual characters.  Blind beetles, which cannot of course\nbehold each other's beauty, never, as I hear from Mr. Waterhouse, jun.,\nexhibit bright colours, though they often have polished coats; but the\nexplanation of their obscurity may be that they generally inhabit caves and\nother obscure stations.\n\nSome Longicorns, especially certain Prionidae, offer an exception to the\nrule that the sexes of beetles do not differ in colour.  Most of these\ninsects are large and splendidly coloured.  The males in the genus Pyrodes\n(63.  Pyrodes pulcherrimus, in which the sexes differ conspicuously, has\nbeen described by Mr. Bates in 'Transact. Ent. Soc.' 1869, p. 50.  I will\nspecify the few other cases in which I have heard of a difference in colour\nbetween the sexes of beetles.  Kirby and Spence ('Introduct. to\nEntomology,' vol. iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the\nLeptura testacea; the male of the latter being testaceous, with a black\nthorax, and the female of a dull red all over.  These two latter beetles\nbelong to the family of Longicorns.  Messrs. R. Trimen and Waterhouse,\njun., inform me of two Lamellicorns, viz., a Peritrichia and Trichius, the\nmale of the latter being more obscurely coloured than the female.  In\nTillus elongatus the male is black, and the female always, as it is\nbelieved, of a dark blue colour, with a red thorax.  The male, also, of\nOrsodacna atra, as I hear from Mr. Walsh, is black, the female (the so-\ncalled O. ruficollis) having a rufous thorax.), which I saw in Mr. Bates's\ncollection, are generally redder but rather duller than the females, the\nlatter being coloured of a more or less splendid golden-green.  On the\nother hand, in one species the male is golden-green, the female being\nrichly tinted with red and purple.  In the genus Esmeralda the sexes differ\nso greatly in colour that they have been ranked as distinct species; in one\nspecies both are of a beautiful shining green, but the male has a red\nthorax.  On the whole, as far as I could judge, the females of those\nPrionidae, in which the sexes differ, are coloured more richly than the\nmales, and this does not accord with the common rule in regard to colour,\nwhen acquired through sexual selection.\n\n[Fig.16.  Chalcosoma atlas.\nUpper figure, male (reduced);\nlower figure, female (nat. size).\n\nFig. 17.  Copris isidis.\n\nFig. 18.  Phanaeus faunus.\n\nFig. 19.  Dipelicus cantori.\n\nFig. 20.  Onthophagus rangifer, enlarged.\n(In Figs. 17 to 20 the left-hand figures are males.)]\n\nA most remarkable distinction between the sexes of many beetles is\npresented by the great horns which rise from the head, thorax, and clypeus\nof the males; and in some few cases from the under surface of the body.\nThese horns, in the great family of the Lamellicorns, resemble those of\nvarious quadrupeds, such as stags, rhinoceroses, etc., and are wonderful\nboth from their size and diversified shapes.  Instead of describing them, I\nhave given figures of the males and females of some of the more remarkable\nforms.  (Figs. 16 to 20.)  The females generally exhibit rudiments of the\nhorns in the form of small knobs or ridges; but some are destitute of even\nthe slightest rudiment.  On the other hand, the horns are nearly as well\ndeveloped in the female as in the male Phanaeus lancifer; and only a little\nless well developed in the females of some other species of this genus and\nof Copris.  I am informed by Mr. Bates that the horns do not differ in any\nmanner corresponding with the more important characteristic differences\nbetween the several subdivisions of the family:  thus within the same\nsection of the genus Onthophagus, there are species which have a single\nhorn, and others which have two.\n\nIn almost all cases, the horns are remarkable from their excessive\nvariability; so that a graduated series can be formed, from the most highly\ndeveloped males to others so degenerate that they can barely be\ndistinguished from the females.  Mr. Walsh (64.  'Proceedings of the\nEntomological Society of Philadephia,' 1864, p. 228.) found that in\nPhanaeus carnifex the horns were thrice as long in some males as in others.\nMr. Bates, after examining above a hundred males of Onthophagus rangifer\n(Fig. 20), thought that he had at last discovered a species in which the\nhorns did not vary; but further research proved the contrary.\n\nThe extraordinary size of the horns, and their widely different structure\nin closely-allied forms, indicate that they have been formed for some\npurpose; but their excessive variability in the males of the same species\nleads to the inference that this purpose cannot be of a definite nature.\nThe horns do not shew marks of friction, as if used for any ordinary work.\nSome authors suppose (65.  Kirby and Spence, 'Introduction to Entomology,'\nvol. iii. p. 300.) that as the males wander about much more than the\nfemales, they require horns as a defence against their enemies; but as the\nhorns are often blunt, they do not seem well adapted for defence.  The most\nobvious conjecture is that they are used by the males for fighting\ntogether; but the males have never been observed to fight; nor could Mr.\nBates, after a careful examination of numerous species, find any sufficient\nevidence, in their mutilated or broken condition, of their having been thus\nused.  If the males had been habitual fighters, the size of their bodies\nwould probably have been increased through sexual selection, so as to have\nexceeded that of the females; but Mr. Bates, after comparing the two sexes\nin above a hundred species of the Copridae, did not find any marked\ndifference in this respect amongst well-developed individuals.  In Lethrus,\nmoreover, a beetle belonging to the same great division of the\nLamellicorns, the males are known to fight, but are not provided with\nhorns, though their mandibles are much larger than those of the female.\n\nThe conclusion that the horns have been acquired as ornaments is that which\nbest agrees with the fact of their having been so immensely, yet not\nfixedly, developed,--as shewn by their extreme variability in the same\nspecies, and by their extreme diversity in closely-allied species.  This\nview will at first appear extremely improbable; but we shall hereafter find\nwith many animals standing much higher in the scale, namely fishes,\namphibians, reptiles and birds, that various kinds of crests, knobs, horns\nand combs have been developed apparently for this sole purpose.\n\n[Fig.21.  Onitis furcifer, male viewed from beneath.\n\nFig.22.  Onitis furcifer.\nLeft-hand figure, male, viewed laterally.\nRight-hand figure, female.\na. Rudiment of cephalic horn.\nb. Trace of thoracic horn or crest.]\n\nThe males of Onitis furcifer (Fig. 21), and of some other species of the\ngenus, are furnished with singular projections on their anterior femora,\nand with a great fork or pair of horns on the lower surface of the thorax.\nJudging from other insects, these may aid the male in clinging to the\nfemale.  Although the males have not even a trace of a horn on the upper\nsurface of the body, yet the females plainly exhibit a rudiment of a single\nhorn on the head (Fig. 22, a), and of a crest (b) on the thorax.  That the\nslight thoracic crest in the female is a rudiment of a projection proper to\nthe male, though entirely absent in the male of this particular species, is\nclear:  for the female of Bubas bison (a genus which comes next to Onitis)\nhas a similar slight crest on the thorax, and the male bears a great\nprojection in the same situation.  So, again, there can hardly be a doubt\nthat the little point (a) on the head of the female Onitis furcifer, as\nwell as on the head of the females of two or three allied species, is a\nrudimentary representative of the cephalic horn, which is common to the\nmales of so many Lamellicorn beetles, as in Phanaeus (Fig. 18).\n\nThe old belief that rudiments have been created to complete the scheme of\nnature is here so far from holding good, that we have a complete inversion\nof the ordinary state of things in the family.  We may reasonably suspect\nthat the males originally bore horns and transferred them to the females in\na rudimentary condition, as in so many other Lamellicorns.  Why the males\nsubsequently lost their horns, we know not; but this may have been caused\nthrough the principle of compensation, owing to the development of the\nlarge horns and projections on the lower surface; and as these are confined\nto the males, the rudiments of the upper horns on the females would not\nhave been thus obliterated.\n\n[Fig. 23.  Bledius taurus, magnified.\nLeft-hand figure, male;\nright-hand figure, female.]\n\nThe cases hitherto given refer to the Lamellicorns, but the males of some\nfew other beetles, belonging to two widely distinct groups, namely, the\nCurculionidae and Staphylinidae, are furnished with horns--in the former on\nthe lower surface of the body (66.  Kirby and Spence, 'Introduction to\nEntomology,' vol. iii. p. 329.), in the latter on the upper surface of the\nhead and thorax.  In the Staphylinidae, the horns of the males are\nextraordinarily variable in the same species, just as we have seen with the\nLamellicorns.  In Siagonium we have a case of dimorphism, for the males can\nbe divided into two sets, differing greatly in the size of their bodies and\nin the development of their horns, without intermediate gradations.  In a\nspecies of Bledius (Fig. 23), also belonging to the Staphylinidae,\nProfessor Westwood states that, \"male specimens can be found in the same\nlocality in which the central horn of the thorax is very large, but the\nhorns of the head quite rudimental; and others, in which the thoracic horn\nis much shorter, whilst the protuberances on the head are long.\"  (67.\n'Modern Classification of Insects,' vol. i. p. 172:  Siagonium, p. 172.  In\nthe British Museum I noticed one male specimen of Siagonium in an\nintermediate condition, so that the dimorphism is not strict.)  Here we\napparently have a case of compensation, which throws light on that just\ngiven, of the supposed loss of the upper horns by the males of Onitis.\n\nLAW OF BATTLE.\n\nSome male beetles, which seem ill-fitted for fighting, nevertheless engage\nin conflicts for the possession of the females.  Mr. Wallace (68.  'The\nMalay Archipelago,' vol. ii. 1869, p. 276.  Riley, Sixth 'Report on Insects\nof Missouri,' 1874, p. 115.) saw two males of Leptorhynchus angustatus, a\nlinear beetle with a much elongated rostrum, \"fighting for a female, who\nstood close by busy at her boring.  They pushed at each other with their\nrostra, and clawed and thumped, apparently in the greatest rage.\"  The\nsmaller male, however, \"soon ran away, acknowledging himself vanquished.\"\nIn some few cases male beetles are well adapted for fighting, by possessing\ngreat toothed mandibles, much larger than those of the females.  This is\nthe case with the common stag-beetle (Lucanus cervus), the males of which\nemerge from the pupal state about a week before the other sex, so that\nseveral may often be seen pursuing the same female.  At this season they\nengage in fierce conflicts.  When Mr. A.H. Davis (69.  'Entomological\nMagazine,' vol. i. 1833, p. 82.  See also on the conflicts of this species,\nKirby and Spence, ibid. vol. iii. p. 314; and Westwood, ibid. vol. i. p.\n187.) enclosed two males with one female in a box, the larger male severely\npinched the smaller one, until he resigned his pretensions.  A friend\ninforms me that when a boy he often put the males together to see them\nfight, and he noticed that they were much bolder and fiercer than the\nfemales, as with the higher animals.  The males would seize hold of his\nfinger, if held in front of them, but not so the females, although they\nhave stronger jaws.  The males of many of the Lucanidae, as well as of the\nabove-mentioned Leptorhynchus, are larger and more powerful insects than\nthe females.  The two sexes of Lethrus cephalotes (one of the Lamellicorns)\ninhabit the same burrow; and the male has larger mandibles than the female.\nIf, during the breeding-season, a strange male attempts to enter the\nburrow, he is attacked; the female does not remain passive, but closes the\nmouth of the burrow, and encourages her mate by continually pushing him on\nfrom behind; and the battle lasts until the aggressor is killed or runs\naway.  (70.  Quoted from Fischer, in 'Dict. Class. d'Hist. Nat.' tom. x. p.\n324.)  The two sexes of another Lamellicorn beetle, the Ateuchus\ncicatricosus, live in pairs, and seem much attached to each other; the male\nexcites the females to roll the balls of dung in which the ova are\ndeposited; and if she is removed, he becomes much agitated.  If the male is\nremoved the female ceases all work, and as M. Brulerie believes, would\nremain on the same spot until she died.  (71.  'Ann. Soc. Entomolog.\nFrance,' 1866, as quoted in 'Journal of Travel,' by A. Murray, 1868, p.\n135.)\n\n[Fig. 24.  Chiasognathus Grantii, reduced.\nUpper figure, male;\nlower figure, female.]\n\nThe great mandibles of the male Lucanidae are extremely variable both in\nsize and structure, and in this respect resemble the horns on the head and\nthorax of many male Lamellicorns and Staphylinidae.  A perfect series can\nbe formed from the best-provided to the worst-provided or degenerate males.\nAlthough the mandibles of the common stag-beetle, and probably of many\nother species, are used as efficient weapons for fighting, it is doubtful\nwhether their great size can thus be accounted for.  We have seen that they\nare used by the Lucanus elaphus of N. America for seizing the female.  As\nthey are so conspicuous and so elegantly branched, and as owing to their\ngreat length they are not well adapted for pinching, the suspicion has\ncrossed my mind that they may in addition serve as an ornament, like the\nhorns on the head and thorax of the various species above described.  The\nmale Chiasognathus grantii of S. Chile--a splendid beetle belonging to the\nsame family--has enormously developed mandibles (Fig. 24); he is bold and\npugnacious; when threatened he faces round, opens his great jaws, and at\nthe same time stridulates loudly.  But the mandibles were not strong enough\nto pinch my finger so as to cause actual pain.\n\nSexual selection, which implies the possession of considerable perceptive\npowers and of strong passions, seems to have been more effective with the\nLamellicorns than with any other family of beetles.  With some species the\nmales are provided with weapons for fighting; some live in pairs and shew\nmutual affection; many have the power of stridulating when excited; many\nare furnished with the most extraordinary horns, apparently for the sake of\nornament; and some, which are diurnal in their habits, are gorgeously\ncoloured.  Lastly, several of the largest beetles in the world belong to\nthis family, which was placed by Linnaeus and Fabricius as the head of the\nOrder.  (72.  Westwood, 'Modern Classification,' vol. i. p. 184.)\n\nSTRIDULATING ORGANS.\n\nBeetles belonging to many and widely distinct families possess these\norgans.  The sound thus produced can sometimes be heard at the distance of\nseveral feet or even yards (73.  Wollaston, 'On Certain Musical\nCurculionidae,' 'Annals and Mag. of Nat. Hist.' vol. vi. 1860, p. 14.), but\nit is not comparable with that made by the Orthoptera.  The rasp generally\nconsists of a narrow, slightly-raised surface, crossed by very fine,\nparallel ribs, sometimes so fine as to cause iridescent colours, and having\na very elegant appearance under the microscope.  In some cases, as with\nTyphoeus, minute, bristly or scale-like prominences, with which the whole\nsurrounding surface is covered in approximately parallel lines, could be\ntraced passing into the ribs of the rasp.  The transition takes place by\ntheir becoming confluent and straight, and at the same time more prominent\nand smooth.  A hard ridge on an adjoining part of the body serves as the\nscraper for the rasp, but this scraper in some cases has been specially\nmodified for the purpose.  It is rapidly moved across the rasp, or\nconversely the rasp across the scraper.\n\n[Fig.25.  Necrophorus (from Landois).\nr. The two rasps.\nLeft-hand figure, part of the rasp highly magnified.]\n\nThese organs are situated in widely different positions.  In the carrion-\nbeetles (Necrophorus) two parallel rasps (r, Fig. 25) stand on the dorsal\nsurface of the fifth abdominal segment, each rasp (74.  Landois,\n'Zeitschrift fur wissenschaft Zoolog.' B. xvii. 1867, s. 127.) consisting\nof 126 to 140 fine ribs.  These ribs are scraped against the posterior\nmargins of the elytra, a small portion of which projects beyond the general\noutline.  In many Crioceridae, and in Clythra 4-punctata (one of the\nChrysomelidae), and in some Tenebrionidae, etc. (75.  I am greatly indebted\nto Mr. G.R. Crotch for having sent me many prepared specimens of various\nbeetles belonging to these three families and to others, as well as for\nvaluable information.  He believes that the power of stridulation in the\nClythra has not been previously observed.  I am also much indebted to Mr.\nE.W. Janson, for information and specimens.  I may add that my son, Mr. F.\nDarwin, finds that Dermestes murinus stridulates, but he searched in vain\nfor the apparatus.  Scolytus has lately been described by Dr. Chapman as a\nstridulator, in the 'Entomologist's Monthly Magazine,' vol. vi. p. 130.),\nthe rasp is seated on the dorsal apex of the abdomen, on the pygidium or\npro-pygidium, and is scraped in the same manner by the elytra.  In\nHeterocerus, which belongs to another family, the rasps are placed on the\nsides of the first abdominal segment, and are scraped by ridges on the\nfemora.  (76.  Schiodte, translated, in 'Annals and Magazine of Natural\nHistory,' vol. xx. 1867, p. 37.)  In certain Curculionidae and Carabidae\n(77.  Westring has described (Kroyer, 'Naturhist. Tidskrift,' B. ii. 1848-\n49, p. 334) the stridulating organs in these two, as well as in other\nfamilies.  In the Carabidae I have examined Elaphrus uliginosus and\nBlethisa multipunctata, sent to me by Mr. Crotch.  In Blethisa the\ntransverse ridges on the furrowed border of the abdominal segment do not,\nas far as I could judge, come into play in scraping the rasps on the\nelytra.), the parts are completely reversed in position, for the rasps are\nseated on the inferior surface of the elytra, near their apices, or along\ntheir outer margins, and the edges of the abdominal segments serve as the\nscrapers.  In Pelobius Hermanni (one of Dytiscidae or water-beetles) a\nstrong ridge runs parallel and near to the sutural margin of the elytra,\nand is crossed by ribs, coarse in the middle part, but becoming gradually\nfiner at both ends, especially at the upper end; when this insect is held\nunder water or in the air, a stridulating noise is produced by the extreme\nhorny margin of the abdomen being scraped against the rasps.  In a great\nnumber of long-horned beetles (Longicornia) the organs are situated quite\notherwise, the rasp being on the meso-thorax, which is rubbed against the\npro-thorax; Landois counted 238 very fine ribs on the rasp of Cerambyx\nheros.\n\n[Fig.26.  Hind-leg of Geotrupes stercorarius (from Landois).\nr.  Rasp.  c. Coxa.  f. Femur.  t. Tibia.  tr. Tarsi.]\n\nMany Lamellicorns have the power of stridulating, and the organs differ\ngreatly in position.  Some species stridulate very loudly, so that when Mr.\nF. Smith caught a Trox sabulosus, a gamekeeper, who stood by, thought he\nhad caught a mouse; but I failed to discover the proper organs in this\nbeetle.  In Geotrupes and Typhoeus, a narrow ridge runs obliquely across\n(r, Fig. 26) the coxa of each hind-leg (having in G. stercorarius 84 ribs),\nwhich is scraped by a specially projecting part of one of the abdominal\nsegments.  In the nearly allied Copris lunaris, an excessively narrow fine\nrasp runs along the sutural margin of the elytra, with another short rasp\nnear the basal outer margin; but in some other Coprini the rasp is seated,\naccording to Leconte (78.  I am indebted to Mr. Walsh, of Illinois, for\nhaving sent me extracts from Leconte's 'Introduction to Entomology,' pp.\n101, 143.), on the dorsal surface of the abdomen.  In Oryctes it is seated\non the pro-pygidium; and, according to the same entomologist, in some other\nDynastini, on the under surface of the elytra.  Lastly, Westring states\nthat in Omaloplia brunnea the rasp is placed on the pro-sternum, and the\nscraper on the meta-sternum, the parts thus occupying the under surface of\nthe body, instead of the upper surface as in the Longicorns.\n\nWe thus see that in the different coleopterous families the stridulating\norgans are wonderfully diversified in position, but not much in structure.\nWithin the same family some species are provided with these organs, and\nothers are destitute of them.  This diversity is intelligible, if we\nsuppose that originally various beetles made a shuffling or hissing noise\nby the rubbing together of any hard and rough parts of their bodies, which\nhappened to be in contact; and that from the noise thus produced being in\nsome way useful, the rough surfaces were gradually developed into regular\nstridulating organs.  Some beetles as they move, now produce, either\nintentionally or unintentionally, a shuffling noise, without possessing any\nproper organs for the purpose.  Mr. Wallace informs me that the Euchirus\nlongimanus (a Lamellicorn, with the anterior legs wonderfully elongated in\nthe male) \"makes, whilst moving, a low hissing sound by the protrusion and\ncontraction of the abdomen; and when seized it produces a grating sound by\nrubbing its hind-legs against the edges of the elytra.\"  The hissing sound\nis clearly due to a narrow rasp running along the sutural margin of each\nelytron; and I could likewise make the grating sound by rubbing the\nshagreened surface of the femur against the granulated margin of the\ncorresponding elytron; but I could not here detect any proper rasp; nor is\nit likely that I could have overlooked it in so large an insect.  After\nexamining Cychrus, and reading what Westring has written about this beetle,\nit seems very doubtful whether it possesses any true rasp, though it has\nthe power of emitting a sound.\n\nFrom the analogy of the Orthoptera and Homoptera, I expected to find the\nstridulating organs in the Coleoptera differing according to sex; but\nLandois, who has carefully examined several species, observed no such\ndifference; nor did Westring; nor did Mr. G.R. Crotch in preparing the many\nspecimens which he had the kindness to send me.  Any difference in these\norgans, if slight, would, however, be difficult to detect, on account of\ntheir great variability.  Thus, in the first pair of specimens of\nNecrophorus humator and of Pelobius which I examined, the rasp was\nconsiderably larger in the male than in the female; but not so with\nsucceeding specimens.  In Geotrupes stercorarius the rasp appeared to me\nthicker, opaquer, and more prominent in three males than in the same number\nof females; in order, therefore, to discover whether the sexes differed in\ntheir power of stridulating, my son, Mr. F. Darwin, collected fifty-seven\nliving specimens, which he separated into two lots, according as they made\na greater or lesser noise, when held in the same manner.  He then examined\nall these specimens, and found that the males were very nearly in the same\nproportion to the females in both the lots.  Mr. F. Smith has kept alive\nnumerous specimens of Monoynchus pseudacori (Curculionidae), and is\nconvinced that both sexes stridulate, and apparently in an equal degree.\n\nNevertheless, the power of stridulating is certainly a sexual character in\nsome few Coleoptera.  Mr. Crotch discovered that the males alone of two\nspecies of Heliopathes (Tenebrionidae) possess stridulating organs.  I\nexamined five males of H. gibbus, and in all these there was a well-\ndeveloped rasp, partially divided into two, on the dorsal surface of the\nterminal abdominal segment; whilst in the same number of females there was\nnot even a rudiment of the rasp, the membrane of this segment being\ntransparent, and much thinner than in the male.  In H. cribratostriatus the\nmale has a similar rasp, excepting that it is not partially divided into\ntwo portions, and the female is completely destitute of this organ; the\nmale in addition has on the apical margins of the elytra, on each side of\nthe suture, three or four short longitudinal ridges, which are crossed by\nextremely fine ribs, parallel to and resembling those on the abdominal\nrasp; whether these ridges serve as an independent rasp, or as a scraper\nfor the abdominal rasp, I could not decide:  the female exhibits no trace\n\nof this latter structure.\n\nAgain, in three species of the Lamellicorn genus Oryctes, we have a nearly\nparallel case.  In the females of O. gryphus and nasicornis the ribs on the\nrasp of the pro-pygidium are less continuous and less distinct than in the\nmales; but the chief difference is that the whole upper surface of this\nsegment, when held in the proper light, is seen to be clothed with hairs,\nwhich are absent or are represented by excessively fine down in the males.\nIt should be noticed that in all Coleoptera the effective part of the rasp\nis destitute of hairs.  In O. senegalensis the difference between the sexes\nis more strongly marked, and this is best seen when the proper abdominal\nsegment is cleaned and viewed as a transparent object.  In the female the\nwhole surface is covered with little separate crests, bearing spines;\nwhilst in the male these crests in proceeding towards the apex, become more\nand more confluent, regular, and naked; so that three-fourths of the\nsegment is covered with extremely fine parallel ribs, which are quite\nabsent in the female.  In the females, however, of all three species of\nOryctes, a slight grating or stridulating sound is produced, when the\nabdomen of a softened specimen is pushed backwards and forwards.\n\nIn the case of the Heliopathes and Oryctes there can hardly be a doubt that\nthe males stridulate in order to call or to excite the females; but with\nmost beetles the stridulation apparently serves both sexes as a mutual\ncall.  Beetles stridulate under various emotions, in the same manner as\nbirds use their voices for many purposes besides singing to their mates.\nThe great Chiasognathus stridulates in anger or defiance; many species do\nthe same from distress or fear, if held so that they cannot escape; by\nstriking the hollow stems of trees in the Canary Islands, Messrs. Wollaston\nand Crotch were able to discover the presence of beetles belonging to the\ngenus Acalles by their stridulation.  Lastly, the male Ateuchus stridulates\nto encourage the female in her work, and from distress when she is removed.\n(79.  M. P. de la Brulerie, as quoted in 'Journal of Travel,' A. Murray,\nvol. i. 1868, p. 135.)  Some naturalists believe that beetles make this\nnoise to frighten away their enemies; but I cannot think that a quadruped\nor bird, able to devour a large beetle, would be frightened by so slight a\nsound.  The belief that the stridulation serves as a sexual call is\nsupported by the fact that death-ticks (Anobium tessellatum) are well known\nto answer each other's ticking, and, as I have myself observed, a tapping\nnoise artificially made.  Mr. Doubleday also informs me that he has\nsometimes observed a female ticking (80.  According to Mr. Doubleday, \"the\nnoise is produced by the insect raising itself on its legs as high as it\ncan, and then striking its thorax five or six times, in rapid succession,\nagainst the substance upon which it is sitting.\"  For references on this\nsubject see Landois, 'Zeitschrift fuer wissen. Zoolog.' B. xvii. s. 131.\nOlivier says (as quoted by Kirby and Spence, 'Introduction to Entomology,'\nvol. ii. p. 395) that the female of Pimelia striata produces a rather loud\nsound by striking her abdomen against any hard substance, \"and that the\nmale, obedient to this call, soon attends her, and they pair.\"), and in an\nhour or two afterwards has found her united with a male, and on one\noccasion surrounded by several males.  Finally, it is probable that the two\nsexes of many kinds of beetles were at first enabled to find each other by\nthe slight shuffling noise produced by the rubbing together of the\nadjoining hard parts of their bodies; and that as those males or females\nwhich made the greatest noise succeeded best in finding partners,\nrugosities on various parts of their bodies were gradually developed by\nmeans of sexual selection into true stridulating organs.\n\n\nCHAPTER XI.\n\nINSECTS, continued.\n\nORDER LEPIDOPTERA.  (BUTTERFLIES AND MOTHS.)\n\nCourtship of butterflies--Battles--Ticking noise--Colours common to both\n\nsexes, or more brilliant in the males--Examples--Not due to the direct\naction of the conditions of life--Colours adapted for protection--Colours\nof moths--Display--Perceptive powers of the Lepidoptera--Variability--\nCauses of the difference in colour between the males and females--Mimicry,\nfemale butterflies more brilliantly coloured than the males--Bright colours\nof caterpillars--Summary and concluding remarks on the secondary sexual\ncharacters of insects--Birds and insects compared.\n\nIn this great Order the most interesting points for us are the differences\nin colour between the sexes of the same species, and between the distinct\nspecies of the same genus.  Nearly the whole of the following chapter will\nbe devoted to this subject; but I will first make a few remarks on one or\ntwo other points.  Several males may often be seen pursuing and crowding\nround the same female.  Their courtship appears to be a prolonged affair,\nfor I have frequently watched one or more males pirouetting round a female\nuntil I was tired, without seeing the end of the courtship.  Mr. A.G.\nButler also informs me that he has several times watched a male courting a\nfemale for a full quarter of an hour; but she pertinaciously refused him,\nand at last settled on the ground and closed her wings, so as to escape\nfrom his addresses.\n\nAlthough butterflies are weak and fragile creatures, they are pugnacious,\nand an emperor butterfly (1.  Apatura Iris:  'The Entomologist's Weekly\nIntelligence,' 1859, p. 139.  For the Bornean Butterflies, see C.\nCollingwood, 'Rambles of a Naturalist,' 1868, p. 183.) has been captured\nwith the tips of its wings broken from a conflict with another male.  Mr.\nCollingwood, in speaking of the frequent battles between the butterflies of\nBorneo, says, \"They whirl round each other with the greatest rapidity, and\nappear to be incited by the greatest ferocity.\"\n\nThe Ageronia feronia makes a noise like that produced by a toothed wheel\npassing under a spring catch, and which can be heard at the distance of\nseveral yards:  I noticed this sound at Rio de Janeiro, only when two of\nthese butterflies were chasing each other in an irregular course, so that\nit is probably made during the courtship of the sexes.  (2.  See my\n'Journal of Researches,' 1845, p. 33.  Mr. Doubleday has detected ('Proc.\nEnt. Soc.' March 3, 1845, p. 123) a peculiar membranous sac at the base of\nthe front wings, which is probably connected with the production of the\nsound.  For the case of Thecophora, see 'Zoological Record,' 1869, p. 401.\nFor Mr. Buchanan White's observations, the Scottish Naturalist, July 1872,\np. 214.)\n\nSome moths also produce sounds; for instance, the males Theocophora fovea.\nOn two occasions Mr. F. Buchanan White (3.  'The Scottish Naturalist,' July\n1872, p. 213.) heard a sharp quick noise made by the male of Hylophila\nprasinana, and which he believes to be produced, as in Cicada, by an\nelastic membrane, furnished with a muscle.  He quotes, also, Guenee, that\nSetina produces a sound like the ticking of a watch, apparently by the aid\nof \"two large tympaniform vesicles, situated in the pectoral region\"; and\nthese \"are much more developed in the male than in the female.\"  Hence the\nsound-producing organs in the Lepidoptera appear to stand in some relation\nwith the sexual functions.  I have not alluded to the well-known noise made\nby the Death's Head Sphinx, for it is generally heard soon after the moth\nhas emerged from its cocoon.\n\nGiard has always observed that the musky odour, which is emitted by two\nspecies of Sphinx moths, is peculiar to the males (4.  'Zoological Record,'\n1869, p. 347.); and in the higher classes we shall meet with many instances\nof the males alone being odoriferous.\n\nEvery one must have admired the extreme beauty of many butterflies and of\nsome moths; and it may be asked, are their colours and diversified patterns\nthe result of the direct action of the physical conditions to which these\ninsects have been exposed, without any benefit being thus derived?  Or have\nsuccessive variations been accumulated and determined as a protection, or\nfor some unknown purpose, or that one sex may be attractive to the other?\nAnd, again, what is the meaning of the colours being widely different in\nthe males and females of certain species, and alike in the two sexes of\nother species of the same genus?  Before attempting to answer these\nquestions a body of facts must be given.\n\nWith our beautiful English butterflies, the admiral, peacock, and painted\nlady (Vanessae), as well as many others, the sexes are alike.  This is also\nthe case with the magnificent Heliconidae, and most of the Danaidae in the\ntropics.  But in certain other tropical groups, and in some of our English\nbutterflies, as the purple emperor, orange-tip, etc. (Apatura Iris and\nAnthocharis cardamines), the sexes differ either greatly or slightly in\ncolour.  No language suffices to describe the splendour of the males of\nsome tropical species.  Even within the same genus we often find species\npresenting extraordinary differences between the sexes, whilst others have\ntheir sexes closely alike.  Thus in the South American genus Epicalia, Mr.\nBates, to whom I am indebted for most of the following facts, and for\nlooking over this whole discussion, informs me that he knows twelve\nspecies, the two sexes of which haunt the same stations (and this is not\nalways the case with butterflies), and which, therefore, cannot have been\ndifferently affected by external conditions.  (5.  See also Mr. Bates's\npaper in 'Proc. Ent. Soc. of Philadelphia,' 1865, p. 206.  Also Mr. Wallace\non the same subject, in regard to Diadema, in 'Transactions, Entomological\nSociety of London,' 1869, p. 278.)  In nine of these twelve species the\nmales rank amongst the most brilliant of all butterflies, and differ so\ngreatly from the comparatively plain females that they were formerly placed\nin distinct genera.  The females of these nine species resemble each other\nin their general type of coloration; and they likewise resemble both sexes\nof the species in several allied genera found in various parts of the\nworld.  Hence we may infer that these nine species, and probably all the\nothers of the genus, are descended from an ancestral form which was\ncoloured in nearly the same manner.  In the tenth species the female still\nretains the same general colouring, but the male resembles her, so that he\nis coloured in a much less gaudy and contrasted manner than the males of\nthe previous species.  In the eleventh and twelfth species, the females\ndepart from the usual type, for they are gaily decorated almost like the\nmales, but in a somewhat less degree.  Hence in these two latter species\nthe bright colours of the males seem to have been transferred to the\nfemales; whilst in the tenth species the male has either retained or\nrecovered the plain colours of the female, as well as of the parent-form of\nthe genus.  The sexes in these three cases have thus been rendered nearly\nalike, though in an opposite manner.  In the allied genus Eubagis, both\nsexes of some of the species are plain-coloured and nearly alike; whilst\nwith the greater number the males are decorated with beautiful metallic\ntints in a diversified manner, and differ much from their females.  The\nfemales throughout the genus retain the same general style of colouring, so\nthat they resemble one another much more closely than they resemble their\nown males.\n\nIn the genus Papilio, all the species of the Aeneas group are remarkable\nfor their conspicuous and strongly contrasted colours, and they illustrate\nthe frequent tendency to gradation in the amount of difference between the\nsexes.  In a few species, for instance in P. ascanius, the males and\nfemales are alike; in others the males are either a little brighter, or\nvery much more superb than the females.  The genus Junonia, allied to our\nVanessae, offers a nearly parallel case, for although the sexes of most of\nthe species resemble each other, and are destitute of rich colours, yet in\ncertain species, as in J. oenone, the male is rather more bright-coloured\nthan the female, and in a few (for instance J. andremiaja) the male is so\ndifferent from the female that he might be mistaken for an entirely\ndistinct species.\n\nAnother striking case was pointed out to me in the British Museum by Mr. A.\nButler, namely, one of the tropical American Theclae, in which both sexes\nare nearly alike and wonderfully splendid; in another species the male is\ncoloured in a similarly gorgeous manner, whilst the whole upper surface of\nthe female is of a dull uniform brown.  Our common little English blue\nbutterflies of the genus Lycaena, illustrate the various differences in\ncolour between the sexes, almost as well, though not in so striking a\nmanner, as the above exotic genera.  In Lycaena agestis both sexes have\nwings of a brown colour, bordered with small ocellated orange spots, and\nare thus alike.  In L. oegon the wings of the males are of a fine blue,\nbordered with black, whilst those of the female are brown, with a similar\nborder, closely resembling the wings of L. agestis.  Lastly, in L. arion\nboth sexes are of a blue colour and are very like, though in the female the\nedges of the wings are rather duskier, with the black spots plainer; and in\na bright blue Indian species both sexes are still more alike.\n\nI have given the foregoing details in order to shew, in the first place,\nthat when the sexes of butterflies differ, the male as a general rule is\nthe more beautiful, and departs more from the usual type of colouring of\nthe group to which the species belongs.  Hence in most groups the females\nof the several species resemble each other much more closely than do the\nmales.  In some cases, however, to which I shall hereafter allude, the\nfemales are coloured more splendidly than the males.  In the second place,\nthese details have been given to bring clearly before the mind that within\nthe same genus, the two sexes frequently present every gradation from no\ndifference in colour, to so great a difference that it was long before the\ntwo were placed by entomologists in the same genus.  In the third place, we\nhave seen that when the sexes nearly resemble each other, this appears due\neither to the male having transferred his colours to the female, or to the\nmale having retained, or perhaps recovered, the primordial colours of the\ngroup.  It also deserves notice that in those groups in which the sexes\ndiffer, the females usually somewhat resemble the males, so that when the\nmales are beautiful to an extraordinary degree, the females almost\ninvariably exhibit some degree of beauty.  From the many cases of gradation\nin the amount of difference between the sexes, and from the prevalence of\nthe same general type of coloration throughout the whole of the same group,\nwe may conclude that the causes have generally been the same which have\ndetermined the brilliant colouring of the males alone of some species, and\nof both sexes of other species.\n\nAs so many gorgeous butterflies inhabit the tropics, it has often been\nsupposed that they owe their colours to the great heat and moisture of\nthese zones; but Mr. Bates (6.  'The Naturalist on the Amazons,' vol. i.\n1863, p. 19.) has shown by the comparison of various closely-allied groups\nof insects from the temperate and tropical regions, that this view cannot\nbe maintained; and the evidence becomes conclusive when brilliantly-\ncoloured males and plain-coloured females of the same species inhabit the\nsame district, feed on the same food, and follow exactly the same habits of\nlife.  Even when the sexes resemble each other, we can hardly believe that\ntheir brilliant and beautifully-arranged colours are the purposeless result\nof the nature of the tissues and of the action of the surrounding\nconditions.\n\nWith animals of all kinds, whenever colour has been modified for some\nspecial purpose, this has been, as far as we can judge, either for direct\nor indirect protection, or as an attraction between the sexes.  With many\nspecies of butterflies the upper surfaces of the wings are obscure; and\nthis in all probability leads to their escaping observation and danger.\nBut butterflies would be particularly liable to be attacked by their\nenemies when at rest; and most kinds whilst resting raise their wings\nvertically over their backs, so that the lower surface alone is exposed to\nview.  Hence it is this side which is often coloured so as to imitate the\nobjects on which these insects commonly rest.  Dr. Rossler, I believe,\nfirst noticed the similarity of the closed wings of certain Vanessae and\nother butterflies to the bark of trees.  Many analogous and striking facts\ncould be given.  The most interesting one is that recorded by Mr. Wallace\n(7.  See the interesting article in the 'Westminster Review,' July 1867, p.\n10.  A woodcut of the Kallima is given by Mr. Wallace in 'Hardwicke's\nScience Gossip,' September 1867, p. 196.) of a common Indian and Sumatran\nbutterfly (Kallima) which disappears like magic when it settles on a bush;\nfor it hides its head and antennae between its closed wings, which, in\nform, colour and veining, cannot be distinguished from a withered leaf with\nits footstalk.  In some other cases the lower surfaces of the wings are\nbrilliantly coloured, and yet are protective; thus in Thecla rubi the wings\nwhen closed are of an emerald green, and resemble the young leaves of the\nbramble, on which in spring this butterfly may often be seen seated.  It is\nalso remarkable that in very many species in which the sexes differ greatly\nin colour on their upper surface, the lower surface is closely similar or\nidentical in both sexes, and serves as a protection.  (8.  Mr. G. Fraser,\nin 'Nature,' April 1871, p. 489.)\n\nAlthough the obscure tints both of the upper and under sides of many\nbutterflies no doubt serve to conceal them, yet we cannot extend this view\nto the brilliant and conspicuous colours on the upper surface of such\nspecies as our admiral and peacock Vanessae, our white cabbage-butterflies\n(Pieris), or the great swallow-tail Papilio which haunts the open fens--for\nthese butterflies are thus rendered visible to every living creature.  In\nthese species both sexes are alike; but in the common brimstone butterfly\n(Gonepteryx rhamni), the male is of an intense yellow, whilst the female is\nmuch paler; and in the orange-tip (Anthocharis cardamines) the males alone\nhave their wings tipped with bright orange.  Both the males and females in\nthese cases are conspicuous, and it is not credible that their difference\nin colour should stand in any relation to ordinary protection.  Prof.\nWeismann remarks (9.  'Einfluss der Isolirung auf die Artbildung,' 1872, p.\n58.), that the female of one of the Lycaenae expands her brown wings when\nshe settles on the ground, and is then almost invisible; the male, on the\nother hand, as if aware of the danger incurred from the bright blue of the\nupper surface of his wings, rests with them closed; and this shows that the\nblue colour cannot be in any way protective.  Nevertheless, it is probable\nthat conspicuous colours are indirectly beneficial to many species, as a\nwarning that they are unpalatable.  For in certain other cases, beauty has\nbeen gained through the imitation of other beautiful species, which inhabit\nthe same district and enjoy an immunity from attack by being in some way\noffensive to their enemies; but then we have to account for the beauty of\nthe imitated species.\n\nAs Mr. Walsh has remarked to me, the females of our orange-tip butterfly,\nabove referred to, and of an American species (Anth. genutia) probably shew\nus the primordial colours of the parent-species of the genus; for both\nsexes of four or five widely-distributed species are coloured in nearly the\nsame manner.  As in several previous cases, we may here infer that it is\nthe males of Anth. cardamines and genutia which have departed from the\nusual type of the genus.  In the Anth. sara from California, the orange-\ntips to the wings have been partially developed in the female; but they are\npaler than in the male, and slightly different in some other respects.  In\nan allied Indian form, the Iphias glaucippe, the orange-tips are fully\ndeveloped in both sexes.  In this Iphias, as pointed out to me by Mr. A.\nButler, the under surface of the wings marvellously resembles a pale-\ncoloured leaf; and in our English orange-tip, the under surface resembles\nthe flower-head of the wild parsley, on which the butterfly often rests at\nnight.  (10.  See the interesting observations by T.W. Wood, 'The Student,'\nSept. 1868, p. 81.)  The same reason which compels us to believe that the\nlower surfaces have here been coloured for the sake of protection, leads us\nto deny that the wings have been tipped with bright orange for the same\npurpose, especially when this character is confined to the males.\n\nMost Moths rest motionless during the whole or greater part of the day with\ntheir wings depressed; and the whole upper surface is often shaded and\ncoloured in an admirable manner, as Mr. Wallace has remarked, for escaping\ndetection.  The front-wings of the Bombycidae and Noctuidae (11.  Mr.\nWallace in 'Hardwicke's Science Gossip,' September 1867, p. 193.), when at\nrest, generally overlap and conceal the hind-wings; so that the latter\nmight be brightly coloured without much risk; and they are in fact often\nthus coloured.  During flight, moths would often be able to escape from\ntheir enemies; nevertheless, as the hind-wings are then fully exposed to\nview, their bright colours must generally have been acquired at some little\nrisk.  But the following fact shews how cautious we ought to be in drawing\nconclusions on this head.  The common Yellow Under-wings (Triphaena) often\nfly about during the day or early evening, and are then conspicuous from\nthe colour of their hind-wings.  It would naturally be thought that this\nwould be a source of danger; but Mr. J. Jenner Weir believes that it\nactually serves them as a means of escape, for birds strike at these\nbrightly coloured and fragile surfaces, instead of at the body.  For\ninstance, Mr. Weir turned into his aviary a vigorous specimen of Triphaena\npronuba, which was instantly pursued by a robin; but the bird's attention\nbeing caught by the coloured wings, the moth was not captured until after\nabout fifty attempts, and small portions of the wings were repeatedly\nbroken off.  He tried the same experiment, in the open air, with a swallow\nand T. fimbria; but the large size of this moth probably interfered with\nits capture.  (12.  See also, on this subject, Mr. Weir's paper in\n'Transactions, Entomological Society,' 1869, p. 23.)  We are thus reminded\nof a statement made by Mr. Wallace (13.  'Westminster Review,' July 1867,\np. 16.), namely, that in the Brazilian forests and Malayan islands, many\ncommon and highly-decorated butterflies are weak flyers, though furnished\nwith a broad expanse of wing; and they \"are often captured with pierced and\nbroken wings, as if they had been seized by birds, from which they had\nescaped:  if the wings had been much smaller in proportion to the body, it\nseems probable that the insect would more frequently have been struck or\npierced in a vital part, and thus the increased expanse of the wings may\nhave been indirectly beneficial.\"\n\nDISPLAY.\n\nThe bright colours of many butterflies and of some moths are specially\narranged for display, so that they may be readily seen.  During the night\ncolours are not visible, and there can be no doubt that the nocturnal\nmoths, taken as a body, are much less gaily decorated than butterflies, all\nof which are diurnal in their habits.  But the moths of certain families,\nsuch as the Zygaenidae, several Sphingidae, Uraniidae, some Arctiidae and\nSaturniidae, fly about during the day or early evening, and many of these\nare extremely beautiful, being far brighter coloured than the strictly\nnocturnal kinds.  A few exceptional cases, however, of bright-coloured\nnocturnal species have been recorded.  (14.  For instance, Lithosia; but\nProf. Westwood ('Modern Class. of Insects,' vol. ii. p. 390) seems\nsurprised at this case.  On the relative colours of diurnal and nocturnal\nLepidoptera, see ibid. pp. 333 and 392; also Harris, 'Treatise on the\nInsects of New England,' 1842, p. 315.)\n\nThere is evidence of another kind in regard to display.  Butterflies, as\nbefore remarked, elevate their wings when at rest, but whilst basking in\nthe sunshine often alternately raise and depress them, thus exposing both\nsurfaces to full view; and although the lower surface is often coloured in\nan obscure manner as a protection, yet in many species it is as highly\ndecorated as the upper surface, and sometimes in a very different manner.\nIn some tropical species the lower surface is even more brilliantly\ncoloured than the upper.  (15.  Such differences between the upper and\nlower surfaces of the wings of several species of Papilio may be seen in\nthe beautiful plates to Mr. Wallace's 'Memoir on the Papilionidae of the\nMalayan Region,' in 'Transactions of the Linnean Society,' vol. xxv. part\ni. 1865.)  In the English fritillaries (Argynnis) the lower surface alone\nis ornamented with shining silver.  Nevertheless, as a general rule, the\nupper surface, which is probably more fully exposed, is coloured more\nbrightly and diversely than the lower.  Hence the lower surface generally\naffords to entomologists the more useful character for detecting the\naffinities of the various species.  Fritz Mueller informs me that three\nspecies of Castnia are found near his house in S. Brazil:  of two of them\nthe hind-wings are obscure, and are always covered by the front-wings when\nthese butterflies are at rest; but the third species has black hind-wings,\nbeautifully spotted with red and white, and these are fully expanded and\ndisplayed whenever the butterfly rests.  Other such cases could be added.\n\nIf we now turn to the enormous group of moths, which, as I hear from Mr.\nStainton, do not habitually expose the under surface of their wings to full\nview, we find this side very rarely coloured with a brightness greater\nthan, or even equal to, that of the upper side.  Some exceptions to the\nrule, either real or apparent, must be noticed, as the case of Hypopyra.\n(16.  See Mr. Wormald on this moth:  'Proceedings of the Entomological\nSociety,' March 2, 1868.)  Mr. Trimen informs me that in Guenee's great\nwork, three moths are figured, in which the under surface is much the more\nbrilliant.  For instance, in the Australian Gastrophora the upper surface\nof the fore-wing is pale greyish-ochreous, while the lower surface is\nmagnificently ornamented by an ocellus of cobalt-blue, placed in the midst\nof a black mark, surrounded by orange-yellow, and this by bluish-white.\nBut the habits of these three moths are unknown; so that no explanation can\nbe given of their unusual style of colouring.  Mr. Trimen also informs me\nthat the lower surface of the wings in certain other Geometrae (17.  See\nalso an account of the S. American genus Erateina (one of the Geometrae) in\n'Transactions, Ent. Soc.' new series, vol. v. pl. xv. and xvi.) and\nquadrifid Noctuae are either more variegated or more brightly-coloured than\nthe upper surface; but some of these species have the habit of \"holding\ntheir wings quite erect over their backs, retaining them in this position\nfor a considerable time,\" and thus exposing the under surface to view.\nOther species, when settled on the ground or herbage, now and then suddenly\nand slightly lift up their wings.  Hence the lower surface of the wings\nbeing brighter than the upper surface in certain moths is not so anomalous\nas it at first appears.  The Saturniidae include some of the most beautiful\nof all moths, their wings being decorated, as in our British Emperor moth,\nwith fine ocelli; and Mr. T.W. Wood (18.  'Proc Ent. Soc. of London,' July\n6, 1868, p. xxvii.) observes that they resemble butterflies in some of\ntheir movements; \"for instance, in the gentle waving up and down of the\nwings as if for display, which is more characteristic of diurnal than of\nnocturnal Lepidoptera.\"\n\nIt is a singular fact that no British moths which are brilliantly coloured,\nand, as far as I can discover, hardly any foreign species, differ much in\ncolour according to sex; though this is the case with many brilliant\nbutterflies.  The male, however, of one American moth, the Saturnia Io, is\ndescribed as having its fore-wings deep yellow, curiously marked with\npurplish-red spots; whilst the wings of the female are purple-brown, marked\nwith grey lines.  (19.  Harris, 'Treatise,' etc., edited by Flint, 1862, p.\n395.)  The British moths which differ sexually in colour are all brown, or\nof various dull yellow tints, or nearly white.  In several species the\nmales are much darker than the females (20.  For instance, I observe in my\nson's cabinet that the males are darker than the females in the Lasiocampa\nquercus, Odonestis potatoria, Hypogymna dispar, Dasychira pudibunda, and\nCycnia mendica.  In this latter species the difference in colour between\nthe two sexes is strongly marked; and Mr. Wallace informs me that we here\nhave, as he believes, an instance of protective mimicry confined to one\nsex, as will hereafter be more fully explained.  The white female of the\nCycnia resembles the very common Spilosoma menthrasti, both sexes of which\nare white; and Mr. Stainton observed that this latter moth was rejected\nwith utter disgust by a whole brood of young turkeys, which were fond of\neating other moths; so that if the Cycnia was commonly mistaken by British\nbirds for the Spilosoma, it would escape being devoured, and its white\ndeceptive colour would thus be highly beneficial.), and these belong to\ngroups which generally fly about during the afternoon.  On the other hand,\nin many genera, as Mr. Stainton informs me, the males have the hind-wings\nwhiter than those of the female--of which fact Agrotis exclamationis offers\na good instance.  In the Ghost Moth (Hepialus humuli) the difference is\nmore strongly marked; the males being white, and the females yellow with\ndarker markings.  (21.  It is remarkable, that in the Shetland Islands the\nmale of this moth, instead of differing widely from the female, frequently\nresembles her closely in colour (see Mr. MacLachlan, 'Transactions,\nEntomological Society,' vol. ii. 1866, p. 459).  Mr. G. Fraser suggests\n('Nature,' April 1871, p. 489) that at the season of the year when the\nghost-moth appears in these northern islands, the whiteness of the males\nwould not be needed to render them visible to the females in the twilight\nnight.)  It is probable that in these cases the males are thus rendered\nmore conspicuous, and more easily seen by the females whilst flying about\nin the dusk.\n\nFrom the several foregoing facts it is impossible to admit that the\nbrilliant colours of butterflies, and of some few moths, have commonly been\nacquired for the sake of protection.  We have seen that their colours and\nelegant patterns are arranged and exhibited as if for display.  Hence I am\nled to believe that the females prefer or are most excited by the more\nbrilliant males; for on any other supposition the males would, as far as we\ncan see, be ornamented to no purpose.  We know that ants and certain\nLamellicorn beetles are capable of feeling an attachment for each other,\nand that ants recognise their fellows after an interval of several months.\nHence there is no abstract improbability in the Lepidoptera, which probably\nstand nearly or quite as high in the scale as these insects, having\nsufficient mental capacity to admire bright colours.  They certainly\ndiscover flowers by colour.  The Humming-bird Sphinx may often be seen to\nswoop down from a distance on a bunch of flowers in the midst of green\nfoliage; and I have been assured by two persons abroad, that these moths\nrepeatedly visit flowers painted on the walls of a room, and vainly\nendeavour to insert their proboscis into them.  Fritz Mueller informs me\nthat several kinds of butterflies in S. Brazil shew an unmistakable\npreference for certain colours over others:  he observed that they very\noften visited the brilliant red flowers of five or six genera of plants,\nbut never the white or yellow flowering species of the same and other\ngenera, growing in the same garden; and I have received other accounts to\nthe same effect.  As I hear from Mr. Doubleday, the common white butterfly\noften flies down to a bit of paper on the ground, no doubt mistaking it for\none of its own species.  Mr. Collingwood (22.  'Rambles of a Naturalist in\nthe Chinese Seas,' 1868, p. 182.) in speaking of the difficulty in\ncollecting certain butterflies in the Malay Archipelago, states that \"a\ndead specimen pinned upon a conspicuous twig will often arrest an insect of\nthe same species in its headlong flight, and bring it down within easy\nreach of the net, especially if it be of the opposite sex.\"\n\nThe courtship of butterflies is, as before remarked, a prolonged affair.\nThe males sometimes fight together in rivalry; and many may be seen\npursuing or crowding round the same female.  Unless, then, the females\nprefer one male to another, the pairing must be left to mere chance, and\nthis does not appear probable.  If, on the other band, the females\nhabitually, or even occasionally, prefer the more beautiful males, the\ncolours of the latter will have been rendered brighter by degrees, and will\nhave been transmitted to both sexes or to one sex, according to the law of\ninheritance which has prevailed.  The process of sexual selection will have\nbeen much facilitated, if the conclusion can be trusted, arrived at from\nvarious kinds of evidence in the supplement to the ninth chapter; namely,\nthat the males of many Lepidoptera, at least in the imago state, greatly\nexceed the females in number.\n\nSome facts, however, are opposed to the belief that female butterflies\nprefer the more beautiful males; thus, as I have been assured by several\ncollectors, fresh females may frequently be seen paired with battered,\nfaded, or dingy males; but this is a circumstance which could hardly fail\noften to follow from the males emerging from their cocoons earlier than the\nfemales.  With moths of the family of the Bombycidae, the sexes pair\nimmediately after assuming the imago state; for they cannot feed, owing to\nthe rudimentary condition of their mouths.  The females, as several\nentomologists have remarked to me, lie in an almost torpid state, and\nappear not to evince the least choice in regard to their partners.  This is\nthe case with the common silk-moth (B. mori), as I have been told by some\ncontinental and English breeders.  Dr. Wallace, who has had great\nexperience in breeding Bombyx cynthia, is convinced that the females evince\nno choice or preference.  He has kept above 300 of these moths together,\nand has often found the most vigorous females mated with stunted males.\nThe reverse appears to occur seldom; for, as he believes, the more vigorous\nmales pass over the weakly females, and are attracted by those endowed with\nmost vitality.  Nevertheless, the Bombycidae, though obscurely-coloured,\nare often beautiful to our eyes from their elegant and mottled shades.\n\nI have as yet only referred to the species in which the males are brighter\ncoloured than the females, and I have attributed their beauty to the\nfemales for many generations having chosen and paired with the more\nattractive males.  But converse cases occur, though rarely, in which the\nfemales are more brilliant than the males; and here, as I believe, the\nmales have selected the more beautiful females, and have thus slowly added\nto their beauty.  We do not know why in various classes of animals the\nmales of some few species have selected the more beautiful females instead\nof having gladly accepted any female, as seems to be the general rule in\nthe animal kingdom:  but if, contrary to what generally occurs with the\nLepidoptera, the females were much more numerous than the males, the latter\nwould be likely to pick out the more beautiful females.  Mr. Butler shewed\nme several species of Callidryas in the British Museum, in some of which\nthe females equalled, and in others greatly surpassed the males in beauty;\nfor the females alone have the borders of their wings suffused with crimson\nand orange, and spotted with black.  The plainer males of these species\nclosely resemble each other, shewing that here the females have been\nmodified; whereas in those cases, where the males are the more ornate, it\nis these which have been modified, the females remaining closely alike.\n\nIn England we have some analogous cases, though not so marked.  The females\nalone of two species of Thecla have a bright-purple or orange patch on\ntheir fore-wings.  In Hipparchia the sexes do not differ much; but it is\nthe female of H. janira which has a conspicuous light-brown patch on her\nwings; and the females of some of the other species are brighter coloured\nthan their males.  Again, the females of Colias edusa and hyale have\n\"orange or yellow spots on the black marginal border, represented in the\nmales only by thin streaks\"; and in Pieris it is the females which \"are\nornamented with black spots on the fore-wings, and these are only partially\npresent in the males.\"  Now the males of many butterflies are known to\nsupport the females during their marriage flight; but in the species just\nnamed it is the females which support the males; so that the part which the\ntwo sexes play is reversed, as is their relative beauty.  Throughout the\nanimal kingdom the males commonly take the more active share in wooing, and\ntheir beauty seems to have been increased by the females having accepted\nthe more attractive individuals; but with these butterflies, the females\ntake the more active part in the final marriage ceremony, so that we may\nsuppose that they likewise do so in the wooing; and in this case we can\nunderstand how it is that they have been rendered the more beautiful.  Mr.\nMeldola, from whom the foregoing statements have been taken, says in\nconclusion:  \"Though I am not convinced of the action of sexual selection\nin producing the colours of insects, it cannot be denied that these facts\nare strikingly corroborative of Mr. Darwin's views.\"  (23.  'Nature,' April\n27, 1871, p. 508.  Mr. Meldola quotes Donzel, in 'Soc. Ent. de France,'\n1837, p. 77, on the flight of butterflies whilst pairing.  See also Mr. G.\nFraser, in 'Nature,' April 20, 1871, p. 489, on the sexual differences of\nseveral British butterflies.)\n\nAs sexual selection primarily depends on variability, a few words must be\nadded on this subject.  In respect to colour there is no difficulty, for\nany number of highly variable Lepidoptera could be named.  One good\ninstance will suffice.  Mr. Bates shewed me a whole series of specimens of\nPapilio sesostris and P. childrenae; in the latter the males varied much in\nthe extent of the beautifully enamelled green patch on the fore-wings, and\nin the size of the white mark, and of the splendid crimson stripe on the\nhind-wings; so that there was a great contrast amongst the males between\nthe most and the least gaudy.  The male of Papilio sesostris is much less\nbeautiful than of P. childrenae; and it likewise varies a little in the\nsize of the green patch on the fore-wings, and in the occasional appearance\nof the small crimson stripe on the hind-wings, borrowed, as it would seem,\nfrom its own female; for the females of this and of many other species in\nthe Aeneas group possess this crimson stripe.  Hence between the brightest\nspecimens of P. sesostris and the dullest of P. childrenae, there was but a\nsmall interval; and it was evident that as far as mere variability is\nconcerned, there would be no difficulty in permanently increasing the\nbeauty of either species by means of selection.  The variability is here\nalmost confined to the male sex; but Mr. Wallace and Mr. Bates have shewn\n(24.  Wallace on the Papilionidae of the Malayan Region, in 'Transact.\nLinn. Soc.' vol. xxv. 1865, pp. 8, 36.  A striking case of a rare variety,\nstrictly intermediate between two other well-marked female varieties, is\ngiven by Mr. Wallace.  See also Mr. Bates, in 'Proc. Entomolog. Soc.' Nov.\n19, 1866, p. xl.) that the females of some species are extremely variable,\nthe males being nearly constant.  In a future chapter I shall have occasion\nto shew that the beautiful eye-like spots, or ocelli, found on the wings of\nmany Lepidoptera, are eminently variable.  I may here add that these ocelli\noffer a difficulty on the theory of sexual selection; for though appearing\nto us so ornamental, they are never present in one sex and absent in the\nother, nor do they ever differ much in the two sexes.  (25.  Mr. Bates was\nso kind as to lay this subject before the Entomological Society, and I have\nreceived answers to this effect from several entomologists.)  This fact is\nat present inexplicable; but if it should hereafter be found that the\nformation of an ocellus is due to some change in the tissues of the wings,\nfor instance, occurring at a very early period of development, we might\nexpect, from what we know of the laws of inheritance, that it would be\ntransmitted to both sexes, though arising and perfected in one sex alone.\n\nOn the whole, although many serious objections may be urged, it seems\nprobable that most of the brilliantly-coloured species of Lepidoptera owe\ntheir colours to sexual selection, excepting in certain cases, presently to\nbe mentioned, in which conspicuous colours have been gained through mimicry\nas a protection.  From the ardour of the male throughout the animal\nkingdom, he is generally willing to accept any female; and it is the female\nwhich usually exerts a choice.  Hence, if sexual selection has been\nefficient with the Lepidoptera, the male, when the sexes differ, ought to\nbe the more brilliantly coloured, and this undoubtedly is the case.  When\nboth sexes are brilliantly coloured and resemble each other, the characters\nacquired by the males appear to have been transmitted to both.  We are led\nto this conclusion by cases, even within the same genus, of gradation from\nan extraordinary amount of difference to identity in colour between the two\nsexes.\n\nBut it may be asked whether the difference in colour between the sexes may\nnot be accounted for by other means besides sexual selection.  Thus the\nmales and females of the same species of butterfly are in several cases\nknown (26.  H.W. Bates, 'The Naturalist on the Amazons,' vol. ii. 1863, p.\n228.  A.R. Wallace, in 'Transactions, Linnean Society,' vol. xxv. 1865, p.\n10.) to inhabit different stations, the former commonly basking in the\nsunshine, the latter haunting gloomy forests.  It is therefore possible\nthat different conditions of life may have acted directly on the two sexes;\nbut this is not probable (27.  On this whole subject see 'The Variation of\nAnimals and Plants under Domestication,' 1868, vol. ii. chap. xxiii.) as in\nthe adult state they are exposed to different conditions during a very\nshort period; and the larvae of both are exposed to the same conditions.\nMr. Wallace believes that the difference between the sexes is due not so\nmuch to the males having been modified, as to the females having in all or\nalmost all cases acquired dull colours for the sake of protection.  It\nseems to me, on the contrary, far more probable that it is the males which\nhave been chiefly modified through sexual selection, the females having\nbeen comparatively little changed.  We can thus understand how it is that\nthe females of allied species generally resemble one another so much more\nclosely than do the males.  They thus shew us approximately the primordial\ncolouring of the parent-species of the group to which they belong.  They\nhave, however, almost always been somewhat modified by the transfer to them\nof some of the successive variations, through the accumulation of which the\nmales were rendered beautiful.  But I do not wish to deny that the females\nalone of some species may have been specially modified for protection.  In\nmost cases the males and females of distinct species will have been exposed\nduring their prolonged larval state to different conditions, and may have\nbeen thus affected; though with the males any slight change of colour thus\ncaused will generally have been masked by the brilliant tints gained\nthrough sexual selection.  When we treat of Birds, I shall have to discuss\nthe whole question, as to how far the differences in colour between the\nsexes are due to the males having been modified through sexual selection\nfor ornamental purposes, or to the females having been modified through\nnatural selection for the sake of protection, so that I will here say but\nlittle on the subject.\n\nIn all the cases in which the more common form of equal inheritance by both\nsexes has prevailed, the selection of bright-coloured males would tend to\nmake the females bright-coloured; and the selection of dull-coloured\nfemales would tend to make the males dull.  If both processes were carried\non simultaneously, they would tend to counteract each other; and the final\nresult would depend on whether a greater number of females from being well\nprotected by obscure colours, or a greater number of males by being\nbrightly-coloured and thus finding partners, succeeded in leaving more\nnumerous offspring.\n\nIn order to account for the frequent transmission of characters to one sex\nalone, Mr. Wallace expresses his belief that the more common form of equal\ninheritance by both sexes can be changed through natural selection into\ninheritance by one sex alone, but in favour of this view I can discover no\nevidence.  We know from what occurs under domestication that new characters\noften appear, which from the first are transmitted to one sex alone; and by\nthe selection of such variations there would not be the slightest\ndifficulty in giving bright colours to the males alone, and at the same\ntime or subsequently, dull colours to the females alone.  In this manner\nthe females of some butterflies and moths have, it is probable, been\nrendered inconspicuous for the sake of protection, and widely different\nfrom their males.\n\nI am, however, unwilling without distinct evidence to admit that two\ncomplex processes of selection, each requiring the transference of new\ncharacters to one sex alone, have been carried on with a multitude of\nspecies,--that the males have been rendered more brilliant by beating their\nrivals, and the females more dull-coloured by having escaped from their\nenemies.  The male, for instance, of the common brimstone butterfly\n(Gonepteryx), is of a far more intense yellow than the female, though she\nis equally conspicuous; and it does not seem probable that she specially\nacquired her pale tints as a protection, though it is probable that the\nmale acquired his bright colours as a sexual attraction.  The female of\nAnthocharis cardamines does not possess the beautiful orange wing-tips of\nthe male; consequently she closely resembles the white butterflies (Pieris)\nso common in our gardens; but we have no evidence that this resemblance is\nbeneficial to her.  As, on the other hand, she resembles both sexes of\nseveral other species of the genus inhabiting various quarters of the\nworld, it is probable that she has simply retained to a large extent her\nprimordial colours.\n\nFinally, as we have seen, various considerations lead to the conclusion\nthat with the greater number of brilliantly-coloured Lepidoptera it is the\nmale which has been chiefly modified through sexual selection; the amount\nof difference between the sexes mostly depending on the form of inheritance\nwhich has prevailed.  Inheritance is governed by so many unknown laws or\nconditions, that it seems to us to act in a capricious manner (28.  The\n'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii.\np. 17.); and we can thus, to a certain extent, understand how it is that\nwith closely allied species the sexes either differ to an astonishing\ndegree, or are identical in colour.  As all the successive steps in the\nprocess of variation are necessarily transmitted through the female, a\ngreater or less number of such steps might readily become developed in her;\nand thus we can understand the frequent gradations from an extreme\ndifference to none at all between the sexes of allied species.  These cases\nof gradation, it may be added, are much too common to favour the\nsupposition that we here see females actually undergoing the process of\ntransition and losing their brightness for the sake of protection; for we\nhave every reason to conclude that at any one time the greater number of\nspecies are in a fixed condition.\n\nMIMICRY.\n\nThis principle was first made clear in an admirable paper by Mr. Bates (29.\n'Transact. Linn. Soc.' vol. xxiii. 1862, p. 495.), who thus threw a flood\nof light on many obscure problems.  It had previously been observed that\ncertain butterflies in S. America belonging to quite distinct families,\nresembled the Heliconidae so closely in every stripe and shade of colour,\nthat they could not be distinguished save by an experienced entomologist.\nAs the Heliconidae are coloured in their usual manner, whilst the others\ndepart from the usual colouring of the groups to which they belong, it is\nclear that the latter are the imitators, and the Heliconidae the imitated.\nMr. Bates further observed that the imitating species are comparatively\nrare, whilst the imitated abound, and that the two sets live mingled\ntogether.  From the fact of the Heliconidae being conspicuous and beautiful\ninsects, yet so numerous in individuals and species, he concluded that they\nmust be protected from the attacks of enemies by some secretion or odour;\nand this conclusion has now been amply confirmed (30.  'Proc. Entomological\nSoc.' Dec. 3, 1866, p. xlv.), especially by Mr. Belt.  Hence Mr. Bates\ninferred that the butterflies which imitate the protected species have\nacquired their present marvellously deceptive appearance through variation\nand natural selection, in order to be mistaken for the protected kinds, and\nthus to escape being devoured.  No explanation is here attempted of the\nbrilliant colours of the imitated, but only of the imitating butterflies.\nWe must account for the colours of the former in the same general manner,\nas in the cases previously discussed in this chapter.  Since the\npublication of Mr. Bates' paper, similar and equally striking facts have\nbeen observed by Mr. Wallace in the Malayan region, by Mr. Trimen in South\nAfrica, and by Mr. Riley in the United States.  (31.  Wallace, 'Transact.\nLinn. Soc.' vol. xxv. 1865 p. i.; also, 'Transact. Ent. Soc.' vol. iv. (3rd\nseries), 1867, p. 301.  Trimen, 'Linn. Transact.' vol. xxvi. 1869, p. 497.\nRiley, 'Third Annual Report on the Noxious Insects of Missouri,' 1871, pp.\n163-168.  This latter essay is valuable, as Mr. Riley here discusses all\nthe objections which have been raised against Mr. Bates's theory.)\n\nAs some writers have felt much difficulty in understanding how the first\nsteps in the process of mimicry could have been effected through natural\nselection, it may be well to remark that the process probably commenced\nlong ago between forms not widely dissimilar in colour.  In this case even\na slight variation would be beneficial, if it rendered the one species more\nlike the other; and afterwards the imitated species might be modified to an\nextreme degree through sexual selection or other means, and if the changes\nwere gradual, the imitators might easily be led along the same track, until\nthey differed to an equally extreme degree from their original condition;\nand they would thus ultimately assume an appearance or colouring wholly\nunlike that of the other members of the group to which they belonged.  It\nshould also be remembered that many species of Lepidoptera are liable to\nconsiderable and abrupt variations in colour.  A few instances have been\ngiven in this chapter; and many more may be found in the papers of Mr.\nBates and Mr. Wallace.\n\nWith several species the sexes are alike, and imitate the two sexes of\nanother species.  But Mr. Trimen gives, in the paper already referred to,\nthree cases in which the sexes of the imitated form differ from each other\nin colour, and the sexes of the imitating form differ in a like manner.\nSeveral cases have also been recorded where the females alone imitate\nbrilliantly-coloured and protected species, the males retaining \"the normal\naspect of their immediate congeners.\"  It is here obvious that the\nsuccessive variations by which the female has been modified have been\ntransmitted to her alone.  It is, however, probable that some of the many\nsuccessive variations would have been transmitted to, and developed in, the\nmales had not such males been eliminated by being thus rendered less\nattractive to the females; so that only those variations were preserved\nwhich were from the first strictly limited in their transmission to the\nfemale sex.  We have a partial illustration of these remarks in a statement\nby Mr. Belt (32.  'The Naturalist in Nicaragua,' 1874, p. 385.); that the\nmales of some of the Leptalides, which imitate protected species, still\nretain in a concealed manner some of their original characters.  Thus in\nthe males \"the upper half of the lower wing is of a pure white, whilst all\nthe rest of the wings is barred and spotted with black, red and yellow,\nlike the species they mimic.  The females have not this white patch, and\nthe males usually conceal it by covering it with the upper wing, so that I\ncannot imagine its being of any other use to them than as an attraction in\ncourtship, when they exhibit it to the females, and thus gratify their\ndeep-seated preference for the normal colour of the Order to which the\nLeptalides belong.\"\n\nBRIGHT COLOURS OF CATERPILLARS.\n\nWhilst reflecting on the beauty of many butterflies, it occurred to me that\nsome caterpillars were splendidly coloured; and as sexual selection could\nnot possibly have here acted, it appeared rash to attribute the beauty of\nthe mature insect to this agency, unless the bright colours of their larvae\ncould be somehow explained.  In the first place, it may be observed that\nthe colours of caterpillars do not stand in any close correlation with\nthose of the mature insect.  Secondly, their bright colours do not serve in\nany ordinary manner as a protection.  Mr. Bates informs me, as an instance\nof this, that the most conspicuous caterpillar which he ever beheld (that\nof a Sphinx) lived on the large green leaves of a tree on the open llanos\nof South America; it was about four inches in length, transversely banded\nwith black and yellow, and with its head, legs, and tail of a bright red.\nHence it caught the eye of any one who passed by, even at the distance of\nmany yards, and no doubt that of every passing bird.\n\nI then applied to Mr. Wallace, who has an innate genius for solving\ndifficulties.  After some consideration he replied:  \"Most caterpillars\nrequire protection, as may be inferred from some kinds being furnished with\nspines or irritating hairs, and from many being coloured green like the\nleaves on which they feed, or being curiously like the twigs of the trees\non which they live.\"  Another instance of protection, furnished me by Mr.\nJ. Mansel Weale, may be added, namely, that there is a caterpillar of a\nmoth which lives on the mimosas in South Africa, and fabricates for itself\na case quite indistinguishable from the surrounding thorns.  From such\nconsiderations Mr. Wallace thought it probable that conspicuously coloured\ncaterpillars were protected by having a nauseous taste; but as their skin\nis extremely tender, and as their intestines readily protrude from a wound,\na slight peck from the beak of a bird would be as fatal to them as if they\nhad been devoured.  Hence, as Mr. Wallace remarks, \"distastefulness alone\nwould be insufficient to protect a caterpillar unless some outward sign\nindicated to its would-be destroyer that its prey was a disgusting morsel.\"\nUnder these circumstances it would be highly advantageous to a caterpillar\nto be instantaneously and certainly recognised as unpalatable by all birds\nand other animals.  Thus the most gaudy colours would be serviceable, and\nmight have been gained by variation and the survival of the most easily-\nrecognised individuals.\n\nThis hypothesis appears at first sight very bold, but when it was brought\nbefore the Entomological Society (33.  'Proceedings, Entomological\nSociety,' Dec. 3, 1866, p. xlv. and March 4, 1867, p. lxxx.) it was\nsupported by various statements; and Mr. J. Jenner Weir, who keeps a large\nnumber of birds in an aviary, informs me that he has made many trials, and\nfinds no exception to the rule, that all caterpillars of nocturnal and\nretiring habits with smooth skins, all of a green colour, and all which\nimitate twigs, are greedily devoured by his birds.  The hairy and spinose\nkinds are invariably rejected, as were four conspicuously-coloured species.\nWhen the birds rejected a caterpillar, they plainly shewed, by shaking\ntheir heads, and cleansing their beaks, that they were disgusted by the\ntaste.  (34.  See Mr. J. Jenner Weir's paper on Insects and Insectivorous\nBirds, in 'Transact. Ent. Soc.' 1869, p. 21; also Mr. Butler's paper, ibid.\np. 27.  Mr. Riley has given analogous facts in the 'Third Annual Report on\nthe Noxious Insects of Missouri,' 1871, p. 148.  Some opposed cases are,\nhowever, given by Dr. Wallace and M. H. d'Orville; see 'Zoological Record,'\n1869, p. 349.)  Three conspicuous kinds of caterpillars and moths were also\ngiven to some lizards and frogs, by Mr. A. Butler, and were rejected,\nthough other kinds were eagerly eaten.  Thus the probability of Mr.\nWallace's view is confirmed, namely, that certain caterpillars have been\nmade conspicuous for their own good, so as to be easily recognised by their\nenemies, on nearly the same principle that poisons are sold in coloured\nbottles by druggists for the good of man.  We cannot, however, at present\nthus explain the elegant diversity in the colours of many caterpillars; but\nany species which had at some former period acquired a dull, mottled, or\nstriped appearance, either in imitation of surrounding objects, or from the\ndirect action of climate, etc., almost certainly would not become uniform\nin colour, when its tints were rendered intense and bright; for in order to\nmake a caterpillar merely conspicuous, there would be no selection in any\ndefinite direction.\n\nSUMMARY AND CONCLUDING REMARKS ON INSECTS.\n\nLooking back to the several Orders, we see that the sexes often differ in\nvarious characters, the meaning of which is not in the least understood.\nThe sexes, also, often differ in their organs of sense and means of\nlocomotion, so that the males may quickly discover and reach the females.\nThey differ still oftener in the males possessing diversified contrivances\nfor retaining the females when found.  We are, however, here concerned only\nin a secondary degree with sexual differences of these kinds.\n\nIn almost all the Orders, the males of some species, even of weak and\ndelicate kinds, are known to be highly pugnacious; and some few are\nfurnished with special weapons for fighting with their rivals.  But the law\nof battle does not prevail nearly so widely with insects as with the higher\nanimals.  Hence it probably arises, that it is in only a few cases that the\nmales have been rendered larger and stronger than the females.  On the\ncontrary, they are usually smaller, so that they may be developed within a\nshorter time, to be ready in large numbers for the emergence of the\nfemales.\n\nIn two families of the Homoptera and in three of the Orthoptera, the males\nalone possess sound-producing organs in an efficient state.  These are used\nincessantly during the breeding-season, not only for calling the females,\nbut apparently for charming or exciting them in rivalry with other males.\nNo one who admits the agency of selection of any kind, will, after reading\nthe above discussion, dispute that these musical instruments have been\nacquired through sexual selection.  In four other Orders the members of one\nsex, or more commonly of both sexes, are provided with organs for producing\nvarious sounds, which apparently serve merely as call-notes.  When both\nsexes are thus provided, the individuals which were able to make the\nloudest or most continuous noise would gain partners before those which\nwere less noisy, so that their organs have probably been gained through\nsexual selection.  It is instructive to reflect on the wonderful diversity\nof the means for producing sound, possessed by the males alone, or by both\nsexes, in no less than six Orders.  We thus learn how effectual sexual\nselection has been in leading to modifications which sometimes, as with the\nHomoptera, relate to important parts of the organisation.\n\nFrom the reasons assigned in the last chapter, it is probable that the\ngreat horns possessed by the males of many Lamellicorn, and some other\nbeetles, have been acquired as ornaments.  From the small size of insects,\nwe are apt to undervalue their appearance.  If we could imagine a male\nChalcosoma (Fig. 16), with its polished bronzed coat of mail, and its vast\ncomplex horns, magnified to the size of a horse, or even of a dog, it would\nbe one of the most imposing animals in the world.\n\nThe colouring of insects is a complex and obscure subject.  When the male\ndiffers slightly from the female, and neither are brilliantly-coloured, it\nis probable that the sexes have varied in a slightly different manner, and\nthat the variations have been transmitted by each sex to the same without\nany benefit or evil thus accruing.  When the male is brilliantly-coloured\nand differs conspicuously from the female, as with some dragon-flies and\nmany butterflies, it is probable that he owes his colours to sexual\nselection; whilst the female has retained a primordial or very ancient type\nof colouring, slightly modified by the agencies before explained.  But in\nsome cases the female has apparently been made obscure by variations\ntransmitted to her alone, as a means of direct protection; and it is almost\ncertain that she has sometimes been made brilliant, so as to imitate other\nprotected species inhabiting the same district.  When the sexes resemble\neach other and both are obscurely coloured, there is no doubt that they\nhave been in a multitude of cases so coloured for the sake of protection.\nSo it is in some instances when both are brightly-coloured, for they thus\nimitate protected species, or resemble surrounding objects such as flowers;\nor they give notice to their enemies that they are unpalatable.  In other\ncases in which the sexes resemble each other and are both brilliant,\nespecially when the colours are arranged for display, we may conclude that\nthey have been gained by the male sex as an attraction, and have been\ntransferred to the female.  We are more especially led to this conclusion\nwhenever the same type of coloration prevails throughout a whole group, and\nwe find that the males of some species differ widely in colour from the\nfemales, whilst others differ slightly or not at all with intermediate\ngradations connecting these extreme states.\n\nIn the same manner as bright colours have often been partially transferred\nfrom the males to the females, so it has been with the extraordinary horns\nof many Lamellicorn and some other beetles.  So again, the sound-producing\norgans proper to the males of the Homoptera and Orthoptera have generally\nbeen transferred in a rudimentary, or even in a nearly perfect condition,\nto the females; yet not sufficiently perfect to be of any use.  It is also\nan interesting fact, as bearing on sexual selection, that the stridulating\norgans of certain male Orthoptera are not fully developed until the last\nmoult; and that the colours of certain male dragon-flies are not fully\ndeveloped until some little time after their emergence from the pupal\nstate, and when they are ready to breed.\n\nSexual selection implies that the more attractive individuals are preferred\nby the opposite sex; and as with insects, when the sexes differ, it is the\nmale which, with some rare exceptions, is the more ornamented, and departs\nmore from the type to which the species belongs;--and as it is the male\nwhich searches eagerly for the female, we must suppose that the females\nhabitually or occasionally prefer the more beautiful males, and that these\nhave thus acquired their beauty.  That the females in most or all the\nOrders would have the power of rejecting any particular male, is probable\nfrom the many singular contrivances possessed by the males, such as great\njaws, adhesive cushions, spines, elongated legs, etc., for seizing the\nfemale; for these contrivances show that there is some difficulty in the\nact, so that her concurrence would seem necessary.  Judging from what we\nknow of the perceptive powers and affections of various insects, there is\nno antecedent improbability in sexual selection having come largely into\nplay; but we have as yet no direct evidence on this head, and some facts\nare opposed to the belief.  Nevertheless, when we see many males pursuing\nthe same female, we can hardly believe that the pairing is left to blind\nchance--that the female exerts no choice, and is not influenced by the\ngorgeous colours or other ornaments with which the male is decorated.\n\nIf we admit that the females of the Homoptera and Orthoptera appreciate the\nmusical tones of their male partners, and that the various instruments have\nbeen perfected through sexual selection, there is little improbability in\nthe females of other insects appreciating beauty in form or colour, and\nconsequently in such characters having been thus gained by the males.  But\nfrom the circumstance of colour being so variable, and from its having been\nso often modified for the sake of protection, it is difficult to decide in\nhow large a proportion of cases sexual selection has played a part.  This\nis more especially difficult in those Orders, such as Orthoptera,\nHymenoptera, and Coleoptera, in which the two sexes rarely differ much in\ncolour; for we are then left to mere analogy.  With the Coleoptera,\nhowever, as before remarked, it is in the great Lamellicorn group, placed\nby some authors at the head of the Order, and in which we sometimes see a\nmutual attachment between the sexes, that we find the males of some species\npossessing weapons for sexual strife, others furnished with wonderful\nhorns, many with stridulating organs, and others ornamented with splendid\nmetallic tints.  Hence it seems probable that all these characters have\nbeen gained through the same means, namely sexual selection.  With\nbutterflies we have the best evidence, as the males sometimes take pains to\ndisplay their beautiful colours; and we cannot believe that they would act\nthus, unless the display was of use to them in their courtship.\n\nWhen we treat of Birds, we shall see that they present in their secondary\nsexual characters the closest analogy with insects.  Thus, many male birds\nare highly pugnacious, and some are furnished with special weapons for\nfighting with their rivals.  They possess organs which are used during the\nbreeding-season for producing vocal and instrumental music.  They are\nfrequently ornamented with combs, horns, wattles and plumes of the most\ndiversified kinds, and are decorated with beautiful colours, all evidently\nfor the sake of display.  We shall find that, as with insects, both sexes\nin certain groups are equally beautiful, and are equally provided with\nornaments which are usually confined to the male sex.  In other groups both\nsexes are equally plain-coloured and unornamented.  Lastly, in some few\nanomalous cases, the females are more beautiful than the males.  We shall\noften find, in the same group of birds, every gradation from no difference\nbetween the sexes, to an extreme difference.  We shall see that female\nbirds, like female insects, often possess more or less plain traces or\nrudiments of characters which properly belong to the males and are of use\nonly to them.  The analogy, indeed, in all these respects between birds and\ninsects is curiously close.  Whatever explanation applies to the one class\nprobably applies to the other; and this explanation, as we shall hereafter\nattempt to shew in further detail, is sexual selection.\n\n\nCHAPTER XII.\n\nSECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS, AND REPTILES.\n\nFISHES:   Courtship and battles of the males--Larger size of the females--\nMales, bright colours and ornamental appendages; other strange characters--\nColours and appendages acquired by the males during the breeding-season\nalone--Fishes with both sexes brilliantly coloured--Protective colours--The\nless conspicuous colours of the female cannot be accounted for on the\nprinciple of protection--Male fishes building nests, and taking charge of\nthe ova and young.\n\nAMPHIBIANS:   Differences in structure and colour between the sexes--Vocal\norgans.\n\nREPTILES:   Chelonians--Crocodiles--Snakes, colours in some cases\nprotective--Lizards, battles of--Ornamental appendages--Strange differences\nin structure between the sexes--Colours--Sexual differences almost as great\nas with birds.\n\nWe have now arrived at the great sub-kingdom of the Vertebrata, and will\ncommence with the lowest class, that of fishes.  The males of Plagiostomous\nfishes (sharks, rays) and of Chimaeroid fishes are provided with claspers\nwhich serve to retain the female, like the various structures possessed by\nmany of the lower animals.  Besides the claspers, the males of many rays\nhave clusters of strong sharp spines on their heads, and several rows along\n\"the upper outer surface of their pectoral fins.\"  These are present in the\nmales of some species, which have other parts of their bodies smooth.  They\nare only temporarily developed during the breeding-season; and Dr. Gunther\nsuspects that they are brought into action as prehensile organs by the\ndoubling inwards and downwards of the two sides of the body.  It is a\nremarkable fact that the females and not the males of some species, as of\nRaia clavata, have their backs studded with large hook-formed spines.  (1.\nYarrell's 'Hist. of British Fishes,' vol. ii. 1836, pp 417, 425, 436.  Dr.\nGunther informs me that the spines in R. clavata are peculiar to the\nfemale.)\n\nThe males alone of the capelin (Mallotus villosus, one of Salmonidae), are\nprovided with a ridge of closely-set, brush-like scales, by the aid of\nwhich two males, one on each side, hold the female, whilst she runs with\ngreat swiftness on the sandy beach, and there deposits her spawn.  (2.  The\n'American Naturalist,' April 1871, p. 119.)  The widely distinct\nMonacanthus scopas presents a somewhat analogous structure.  The male, as\nDr. Gunther informs me, has a cluster of stiff, straight spines, like those\nof a comb, on the sides of the tail; and these in a specimen six inches\nlong were nearly one and a half inches in length; the female has in the\nsame place a cluster of bristles, which may be compared with those of a\ntooth-brush.  In another species, M. peronii, the male has a brush like\nthat possessed by the female of the last species, whilst the sides of the\ntail in the female are smooth.  In some other species of the same genus the\ntail can be perceived to be a little roughened in the male and perfectly\nsmooth in the female; and lastly in others, both sexes have smooth sides.\n\nThe males of many fish fight for the possession of the females.  Thus the\nmale stickleback (Gasterosteus leiurus) has been described as \"mad with\ndelight,\" when the female comes out of her hiding-place and surveys the\nnest which he has made for her.  \"He darts round her in every direction,\nthen to his accumulated materials for the nest, then back again in an\ninstant; and as she does not advance he endeavours to push her with his\nsnout, and then tries to pull her by the tail and side-spine to the nest.\"\n(3.  See Mr. R. Warington's interesting articles in 'Annals and Magazine of\nNatural History,' October 1852, and November 1855.)  The males are said to\nbe polygamists (4.  Noel Humphreys, 'River Gardens,' 1857.); they are\nextraordinarily bold and pugnacious, whilst \"the females are quite\npacific.\"  Their battles are at times desperate; \"for these puny combatants\nfasten tight on each other for several seconds, tumbling over and over\nagain until their strength appears completely exhausted.\"  With the rough-\ntailed stickleback (G. trachurus) the males whilst fighting swim round and\nround each other, biting and endeavouring to pierce each other with their\nraised lateral spines.  The same writer adds (5.  Loudon's 'Magazine of\nNatural History,' vol. iii. 1830, p. 331.), \"the bite of these little\nfuries is very severe.  They also use their lateral spines with such fatal\neffect, that I have seen one during a battle absolutely rip his opponent\nquite open, so that he sank to the bottom and died.\"  When a fish is\nconquered, \"his gallant bearing forsakes him; his gay colours fade away;\nand he hides his disgrace among his peaceable companions, but is for some\ntime the constant object of his conqueror's persecution.\"\n\nThe male salmon is as pugnacious as the little stickleback; and so is the\nmale trout, as I hear from Dr. Gunther.  Mr. Shaw saw a violent contest\nbetween two male salmon which lasted the whole day; and Mr. R. Buist,\nSuperintendent of Fisheries, informs me that he has often watched from the\nbridge at Perth the males driving away their rivals, whilst the females\nwere spawning.  The males \"are constantly fighting and tearing each other\non the spawning-beds, and many so injure each other as to cause the death\nof numbers, many being seen swimming near the banks of the river in a state\nof exhaustion, and apparently in a dying state.\"  (6.  The 'Field,' June\n29, 1867.  For Mr. Shaw's Statement, see 'Edinburgh Review,' 1843.  Another\nexperienced observer (Scrope's 'Days of Salmon Fishing,' p. 60) remarks\nthat like the stag, the male would, if he could, keep all other males\naway.)  Mr. Buist informs me, that in June 1868, the keeper of the\nStormontfield breeding-ponds visited the northern Tyne and found about 300\ndead salmon, all of which with one exception were males; and he was\nconvinced that they had lost their lives by fighting.\n\n[Fig. 27.  Head of male common salmon (Salmo salar) during the breeding-\nseason.\n[This drawing, as well as all the others in the present chapter, have been\nexecuted by the well-known artist, Mr. G. Ford, from specimens in the\nBritish Museum, under the kind superintendence of Dr. Gunther.]\n\nFig. 28.  Head of female salmon.]\n\nThe most curious point about the male salmon is that during the breeding-\nseason, besides a slight change in colour, \"the lower jaw elongates, and a\ncartilaginous projection turns upwards from the point, which, when the jaws\nare closed, occupies a deep cavity between the intermaxillary bones of the\nupper jaw.\"  (7.  Yarrell, 'History of British Fishes,' vol. ii. 1836, p.\n10.) (Figs. 27 and 28.)  In our salmon this change of structure lasts only\nduring the breeding-season; but in the Salmo lycaodon of N.W. America the\nchange, as Mr. J.K. Lord (8.  'The Naturalist in Vancouver's Island,' vol.\ni. 1866, p. 54.) believes, is permanent, and best marked in the older males\nwhich have previously ascended the rivers.  In these old males the jaw\nbecomes developed into an immense hook-like projection, and the teeth grow\ninto regular fangs, often more than half an inch in length.  With the\nEuropean salmon, according to Mr. Lloyd (9.  'Scandinavian Adventures,'\nvol. i. 1854, pp. 100, 104.), the temporary hook-like structure serves to\nstrengthen and protect the jaws, when one male charges another with\nwonderful violence; but the greatly developed teeth of the male American\nsalmon may be compared with the tusks of many male mammals, and they\nindicate an offensive rather than a protective purpose.\n\nThe salmon is not the only fish in which the teeth differ in the two sexes;\nas this is the case with many rays.  In the thornback (Raia clavata) the\nadult male has sharp, pointed teeth, directed backwards, whilst those of\nthe female are broad and flat, and form a pavement; so that these teeth\ndiffer in the two sexes of the same species more than is usual in distinct\ngenera of the same family.  The teeth of the male become sharp only when he\nis adult:  whilst young they are broad and flat like those of the female.\nAs so frequently occurs with secondary sexual characters, both sexes of\nsome species of rays (for instance R. batis), when adult, possess sharp\npointed teeth; and here a character, proper to and primarily gained by the\nmale, appears to have been transmitted to the offspring of both sexes.  The\nteeth are likewise pointed in both sexes of R. maculata, but only when\nquite adult; the males acquiring them at an earlier age than the females.\nWe shall hereafter meet with analogous cases in certain birds, in which the\nmale acquires the plumage common to both sexes when adult, at a somewhat\nearlier age than does the female.  With other species of rays the males\neven when old never possess sharp teeth, and consequently the adults of\nboth sexes are provided with broad, flat teeth like those of the young, and\nlike those of the mature females of the above-mentioned species.  (10.  See\nYarrell's account of the rays in his 'History of British Fishes,' vol. ii.\n1836, p. 416, with an excellent figure, and pp. 422, 432.)  As the rays are\nbold, strong and voracious fish, we may suspect that the males require\ntheir sharp teeth for fighting with their rivals; but as they possess many\nparts modified and adapted for the prehension of the female, it is possible\nthat their teeth may be used for this purpose.\n\nIn regard to size, M. Carbonnier (11.  As quoted in 'The Farmer,' 1868, p.\n369.) maintains that the female of almost all fishes is larger than the\nmale; and Dr. Gunther does not know of a single instance in which the male\nis actually larger than the female.  With some Cyprinodonts the male is not\neven half as large.  As in many kinds of fishes the males habitually fight\ntogether, it is surprising that they have not generally become larger and\nstronger than the females through the effects of sexual selection.  The\nmales suffer from their small size, for according to M. Carbonnier, they\nare liable to be devoured by the females of their own species when\ncarnivorous, and no doubt by other species.  Increased size must be in some\nmanner of more importance to the females, than strength and size are to the\nmales for fighting with other males; and this perhaps is to allow of the\nproduction of a vast number of ova.\n\n[Fig. 29.  Callionymus lyra.\nUpper figure, male;\nlower figure, female.\nN.B.  The lower figure is more reduced than the upper.]\n\nIn many species the male alone is ornamented with bright colours; or these\nare much brighter in the male than the female.  The male, also, is\nsometimes provided with appendages which appear to be of no more use to him\nfor the ordinary purposes of life, than are the tail feathers to the\npeacock.  I am indebted for most of the following facts to the kindness of\nDr. Gunther.  There is reason to suspect that many tropical fishes differ\nsexually in colour and structure; and there are some striking cases with\nour British fishes.  The male Callionymus lyra has been called the gemmeous\ndragonet \"from its brilliant gem-like colours.\"  When fresh caught from the\nsea the body is yellow of various shades, striped and spotted with vivid\nblue on the head; the dorsal fins are pale brown with dark longitudinal\nbands; the ventral, caudal, and anal fins being bluish-black.  The female,\nor sordid dragonet, was considered by Linnaeus, and by many subsequent\nnaturalists, as a distinct species; it is of a dingy reddish-brown, with\nthe dorsal fin brown and the other fins white.  The sexes differ also in\nthe proportional size of the head and mouth, and in the position of the\neyes (12.  I have drawn up this description from Yarrell's 'British\nFishes,' vol. i. 1836, pp. 261 and 266.); but the most striking difference\nis the extraordinary elongation in the male (Fig. 29) of the dorsal fin.\nMr. W. Saville Kent remarks that this \"singular appendage appears from my\nobservations of the species in confinement, to be subservient to the same\nend as the wattles, crests, and other abnormal adjuncts of the male in\ngallinaceous birds, for the purpose of fascinating their mates.\"  (13.\n'Nature,' July 1873, p. 264.)  The young males resemble the adult females\nin structure and colour.  Throughout the genus Callionymus (14.  'Catalogue\nof Acanth. Fishes in the British Museum,' by Dr. Gunther, 1861, pp. 138-\n151.), the male is generally much more brightly spotted than the female,\nand in several species, not only the dorsal, but the anal fin is much\nelongated in the males.\n\nThe male of the Cottus scorpius, or sea-scorpion, is slenderer and smaller\nthan the female.  There is also a great difference in colour between them.\nIt is difficult, as Mr. Lloyd (15.  'Game Birds of Sweden,' etc., 1867, p.\n466.) remarks, \"for any one, who has not seen this fish during the\nspawning-season, when its hues are brightest, to conceive the admixture of\nbrilliant colours with which it, in other respects so ill-favoured, is at\nthat time adorned.\"  Both sexes of the Labrus mixtus, although very\ndifferent in colour, are beautiful; the male being orange with bright blue\nstripes, and the female bright red with some black spots on the back.\n\n[Fig. 30.  Xiphophorus Hellerii.\nUpper figure, male;\nlower figure, female.]\n\nIn the very distinct family of the Cyprinodontidae--inhabitants of the\nfresh waters of foreign lands--the sexes sometimes differ much in various\ncharacters.  In the male of the Mollienesia petenensis (16.  With respect\nto this and the following species I am indebted to Dr. Gunther for\ninformation:  see also his paper on the 'Fishes of Central America,' in\n'Transact. Zoological Soc.' vol. vi. 1868, p. 485.), the dorsal fin is\ngreatly developed and is marked with a row of large, round, ocellated,\nbright-coloured spots; whilst the same fin in the female is smaller, of a\ndifferent shape, and marked only with irregularly curved brown spots.  In\nthe male the basal margin of the anal fin is also a little produced and\ndark coloured.  In the male of an allied form, the Xiphophorus Hellerii\n(Fig. 30), the inferior margin of the caudal fin is developed into a long\nfilament, which, as I hear from Dr. Gunther, is striped with bright\ncolours.  This filament does not contain any muscles, and apparently cannot\nbe of any direct use to the fish.  As in the case of the Callionymus, the\nmales whilst young resemble the adult females in colour and structure.\nSexual differences such as these may be strictly compared with those which\nare so frequent with gallinaceous birds.  (17.  Dr. Gunther makes this\nremark; 'Catalogue of Fishes in the British Museum,' vol. iii. 1861, p.\n141.)\n\n[Fig.31.  Plecostomus barbatus.\nUpper figure, head of male;\nlower figure, female.]\n\nIn a siluroid fish, inhabiting the fresh waters of South America, the\nPlecostomus barbatus (18.  See Dr. Gunther on this genus, in 'Proceedings\nof the Zoological Society,' 1868, p. 232.) (Fig. 31), the male has its\nmouth and inter-operculum fringed with a beard of stiff hairs, of which the\nfemale shows hardly a trace.  These hairs are of the nature of scales.  In\nanother species of the same genus, soft flexible tentacles project from the\nfront part of the head of the male, which are absent in the female.  These\ntentacles are prolongations of the true skin, and therefore are not\nhomologous with the stiff hairs of the former species; but it can hardly be\ndoubted that both serve the same purpose.  What this purpose may be, it is\ndifficult to conjecture; ornament does not here seem probable, but we can\nhardly suppose that stiff hairs and flexible filaments can be useful in any\nordinary way to the males alone.  In that strange monster, the Chimaera\nmonstrosa, the male has a hook-shaped bone on the top of the head, directed\nforwards, with its end rounded and covered with sharp spines; in the female\n\"this crown is altogether absent,\" but what its use may be to the male is\nutterly unknown.  (19.  F. Buckland, in 'Land and Water,' July 1868, p.\n377, with a figure.  Many other cases could be added of structures peculiar\nto the male, of which the uses are not known.)\n\nThe structures as yet referred to are permanent in the male after he has\narrived at maturity; but with some Blennies, and in another allied genus\n(20.  Dr. Gunther, 'Catalogue of Fishes,' vol. iii. pp. 221 and 240.), a\ncrest is developed on the head of the male only during the breeding-season,\nand the body at the same time becomes more brightly-coloured.  There can be\nlittle doubt that this crest serves as a temporary sexual ornament, for the\nfemale does not exhibit a trace of it.  In other species of the same genus\nboth sexes possess a crest, and in at least one species neither sex is thus\nprovided.  In many of the Chromidae, for instance in Geophagus and\nespecially in Cichla, the males, as I hear from Professor Agassiz (21.  See\nalso 'A Journey in Brazil,' by Prof. and Mrs. Agassiz, 1868, p. 220.), have\na conspicuous protuberance on the forehead, which is wholly wanting in the\nfemales and in the young males.  Professor Agassiz adds, \"I have often\nobserved these fishes at the time of spawning when the protuberance is\nlargest, and at other seasons when it is totally wanting, and the two sexes\nshew no difference whatever in the outline of the profile of the head.  I\nnever could ascertain that it subserves any special function, and the\nIndians on the Amazon know nothing about its use.\"  These protuberances\nresemble, in their periodical appearance, the fleshy carbuncles on the\nheads of certain birds; but whether they serve as ornaments must remain at\npresent doubtful.\n\nI hear from Professor Agassiz and Dr. Gunther, that the males of those\nfishes, which differ permanently in colour from the females, often become\nmore brilliant during the breeding-season.  This is likewise the case with\na multitude of fishes, the sexes of which are identical in colour at all\nother seasons of the year.  The tench, roach, and perch may be given as\ninstances.  The male salmon at this season is \"marked on the cheeks with\norange-coloured stripes, which give it the appearance of a Labrus, and the\nbody partakes of a golden orange tinge.  The females are dark in colour,\nand are commonly called black-fish.\"  (22.  Yarrell, 'History of British\nFishes,' vol. ii. 1836, pp. 10, 12, 35.)  An analogous and even greater\nchange takes place with the Salmo eriox or bull trout; the males of the\nchar (S. umbla) are likewise at this season rather brighter in colour than\nthe females.  (23.  W. Thompson, in 'Annals and Magazine of Natural\nHistory,' vol. vi. 1841, p. 440.)  The colours of the pike (Esox\nreticulatus) of the United States, especially of the male, become, during\nthe breeding-season, exceedingly intense, brilliant, and iridescent. (24.\n'The American Agriculturalist,' 1868, p. 100.)  Another striking instance\nout of many is afforded by the male stickleback (Gasterosteus leiurus),\nwhich is described by Mr. Warington (25.  'Annals and Mag. of Nat. Hist.'\nOct. 1852.), as being then \"beautiful beyond description.\"  The back and\neyes of the female are simply brown, and the belly white.  The eyes of the\nmale, on the other hand, are \"of the most splendid green, having a metallic\nlustre like the green feathers of some humming-birds.  The throat and belly\nare of a bright crimson, the back of an ashy-green, and the whole fish\nappears as though it were somewhat translucent and glowed with an internal\nincandescence.\"  After the breeding season these colours all change, the\nthroat and belly become of a paler red, the back more green, and the\nglowing tints subside.\n\nWith respect to the courtship of fishes, other cases have been observed\nsince the first edition of this book appeared, besides that already given\nof the stickleback.  Mr. W.S. Kent says that the male of the Labrus mixtus,\nwhich, as we have seen, differs in colour from the female, makes \"a deep\nhollow in the sand of the tank, and then endeavours in the most persuasive\nmanner to induce a female of the same species to share it with him,\nswimming backwards and forwards between her and the completed nest, and\nplainly exhibiting the greatest anxiety for her to follow.\"  The males of\nCantharus lineatus become, during the breeding-season, of deep leaden-\nblack; they then retire from the shoal, and excavate a hollow as a nest.\n\"Each male now mounts vigilant guard over his respective hollow, and\nvigorously attacks and drives away any other fish of the same sex.  Towards\nhis companions of the opposite sex his conduct is far different; many of\nthe latter are now distended with spawn, and these he endeavours by all the\nmeans in his power to lure singly to his prepared hollow, and there to\ndeposit the myriad ova with which they are laden, which he then protects\nand guards with the greatest care.\"  (26.  'Nature,' May 1873, p. 25.)\n\nA more striking case of courtship, as well as of display, by the males of a\nChinese Macropus has been given by M. Carbonnier, who carefully observed\nthese fishes under confinement.  (27.  'Bulletin de la Societe d'Acclimat.'\nParis, July 1869, and Jan. 1870.)  The males are most beautifully coloured,\nmore so than the females.  During the breeding-season they contend for the\npossession of the females; and, in the act of courtship, expand their fins,\nwhich are spotted and ornamented with brightly coloured rays, in the same\nmanner, according to M. Carbonnier, as the peacock.  They then also bound\nabout the females with much vivacity, and appear by \"l'etalage de leurs\nvives couleurs chercher a attirer l'attention des femelles, lesquelles ne\nparaissaient indifferentes a ce manege, elles nageaient avec une molle\nlenteur vers les males et semblaient se complaire dans leur voisinage.\"\nAfter the male has won his bride, he makes a little disc of froth by\nblowing air and mucus out of his mouth.  He then collects the fertilised\nova, dropped by the female, in his mouth; and this caused M. Carbonnier\nmuch alarm, as he thought that they were going to be devoured.  But the\nmale soon deposits them in the disc of froth, afterwards guarding them,\nrepairing the froth, and taking care of the young when hatched.  I mention\nthese particulars because, as we shall presently see, there are fishes, the\nmales of which hatch their eggs in their mouths; and those who do not\nbelieve in the principle of gradual evolution might ask how could such a\nhabit have originated; but the difficulty is much diminished when we know\nthat there are fishes which thus collect and carry the eggs; for if delayed\nby any cause in depositing them, the habit of hatching them in their mouths\nmight have been acquired.\n\nTo return to our more immediate subject.  The case stands thus:  female\nfishes, as far as I can learn, never willingly spawn except in the presence\nof the males; and the males never fertilise the ova except in the presence\nof the females.  The males fight for the possession of the females.  In\nmany species, the males whilst young resemble the females in colour; but\nwhen adult become much more brilliant, and retain their colours throughout\nlife.  In other species the males become brighter than the females and\notherwise more highly ornamented, only during the season of love.  The\nmales sedulously court the females, and in one case, as we have seen, take\npains in displaying their beauty before them.  Can it be believed that they\nwould thus act to no purpose during their courtship?  And this would be the\ncase, unless the females exert some choice and select those males which\nplease or excite them most.  If the female exerts such choice, all the\nabove facts on the ornamentation of the males become at once intelligible\nby the aid of sexual selection.\n\nWe have next to inquire whether this view of the bright colours of certain\nmale fishes having been acquired through sexual selection can, through the\nlaw of the equal transmission of characters to both sexes, be extended to\nthose groups in which the males and females are brilliant in the same, or\nnearly the same degree and manner.  In such a genus as Labrus, which\nincludes some of the most splendid fishes in the world--for instance, the\nPeacock Labrus (L. pavo), described (28.  Bory Saint Vincent, in 'Dict.\nClass. d'Hist. Nat.' tom. ix. 1826, p. 151.), with pardonable exaggeration,\nas formed of polished scales of gold, encrusting lapis-lazuli, rubies,\nsapphires, emeralds, and amethysts--we may, with much probability, accept\nthis belief; for we have seen that the sexes in at least one species of the\ngenus differ greatly in colour.  With some fishes, as with many of the\nlowest animals, splendid colours may be the direct result of the nature of\ntheir tissues and of the surrounding conditions, without the aid of\nselection of any kind.  The gold-fish (Cyprinus auratus), judging from the\nanalogy of the golden variety of the common carp, is perhaps a case in\npoint, as it may owe its splendid colours to a single abrupt variation, due\nto the conditions to which this fish has been subjected under confinement.\nIt is, however, more probable that these colours have been intensified\nthrough artificial selection, as this species has been carefully bred in\nChina from a remote period.  (29.  Owing to some remarks on this subject,\nmade in my work 'On the Variation of Animals under Domestication,' Mr. W.F.\nMayers ('Chinese Notes and Queries,' Aug. 1868, p. 123) has searched the\nancient Chinese encyclopedias.  He finds that gold-fish were first reared\nin confinement during the Sung Dynasty, which commenced A.D. 960.  In the\nyear 1129 these fishes abounded.  In another place it is said that since\nthe year 1548 there has been \"produced at Hangchow a variety called the\nfire-fish, from its intensely red colour.  It is universally admired, and\nthere is not a household where it is not cultivated, IN RIVALRY AS TO ITS\nCOLOUR, and as a source of profit.\")  Under natural conditions it does not\nseem probable that beings so highly organised as fishes, and which live\nunder such complex relations, should become brilliantly coloured without\nsuffering some evil or receiving some benefit from so great a change, and\nconsequently without the intervention of natural selection.\n\nWhat, then, are we to conclude in regard to the many fishes, both sexes of\nwhich are splendidly coloured?  Mr. Wallace (30.  'Westminster Review,'\nJuly 1867, p. 7.) believes that the species which frequent reefs, where\ncorals and other brightly-coloured organisms abound, are brightly coloured\nin order to escape detection by their enemies; but according to my\nrecollection they were thus rendered highly conspicuous.  In the fresh-\nwaters of the tropics there are no brilliantly-coloured corals or other\norganisms for the fishes to resemble; yet many species in the Amazons are\nbeautifully coloured, and many of the carnivorous Cyprinidae in India are\nornamented with \"bright longitudinal lines of various tints.\"  (31.\n'Indian Cyprinidae,' by Mr. M'Clelland, 'Asiatic Researches,' vol. xix.\npart ii. 1839, p. 230.)  Mr. M'Clelland, in describing these fishes, goes\nso far as to suppose that \"the peculiar brilliancy of their colours\" serves\nas \"a better mark for king-fishers, terns, and other birds which are\ndestined to keep the number of these fishes in check\"; but at the present\nday few naturalists will admit that any animal has been made conspicuous as\nan aid to its own destruction.  It is possible that certain fishes may have\nbeen rendered conspicuous in order to warn birds and beasts of prey that\nthey were unpalatable, as explained when treating of caterpillars; but it\nis not, I believe, known that any fish, at least any fresh-water fish, is\nrejected from being distasteful to fish-devouring animals.  On the whole,\nthe most probable view in regard to the fishes, of which both sexes are\nbrilliantly coloured, is that their colours were acquired by the males as a\nsexual ornament, and were transferred equally, or nearly so, to the other\nsex.\n\nWe have now to consider whether, when the male differs in a marked manner\nfrom the female in colour or in other ornaments, he alone has been\nmodified, the variations being inherited by his male offspring alone; or\nwhether the female has been specially modified and rendered inconspicuous\nfor the sake of protection, such modifications being inherited only by the\nfemales.  It is impossible to doubt that colour has been gained by many\nfishes as a protection:  no one can examine the speckled upper surface of a\nflounder, and overlook its resemblance to the sandy bed of the sea on which\nit lives.  Certain fishes, moreover, can through the action of the nervous\nsystem change their colours in adaptation to surrounding objects, and that\nwithin a short time.  (32.  G. Pouchet, 'L'Institut.' Nov. 1, 1871, p.\n134.)  One of the most striking instances ever recorded of an animal being\nprotected by its colour (as far as it can be judged of in preserved\nspecimens), as well as by its form, is that given by Dr. Gunther (33.\n'Proc. Zoolog. Soc.' 1865, p. 327, pl. xiv. and xv.) of a pipe-fish, which,\nwith its reddish streaming filaments, is hardly distinguishable from the\nsea-weed to which it clings with its prehensile tail.  But the question now\nunder consideration is whether the females alone have been modified for\nthis object.  We can see that one sex will not be modified through natural\nselection for the sake of protection more than the other, supposing both to\nvary, unless one sex is exposed for a longer period to danger, or has less\npower of escaping from such danger than the other; and it does not appear\nthat with fishes the sexes differ in these respects.  As far as there is\nany difference, the males, from being generally smaller and from wandering\nmore about, are exposed to greater danger than the females; and yet, when\nthe sexes differ, the males are almost always the more conspicuously\ncoloured.  The ova are fertilised immediately after being deposited; and\nwhen this process lasts for several days, as in the case of the salmon (34.\nYarrell, 'British Fishes,' vol. ii. p. 11.), the female, during the whole\ntime, is attended by the male.  After the ova are fertilised they are, in\nmost cases, left unprotected by both parents, so that the males and\nfemales, as far as oviposition is concerned, are equally exposed to danger,\nand both are equally important for the production of fertile ova;\nconsequently the more or less brightly-coloured individuals of either sex\nwould be equally liable to be destroyed or preserved, and both would have\nan equal influence on the colours of their offspring.\n\nCertain fishes, belonging to several families, make nests, and some of them\ntake care of their young when hatched.  Both sexes of the bright coloured\nCrenilabrus massa and melops work together in building their nests with\nsea-weed, shells, etc.  (35.  According to the observations of M. Gerbe;\nsee Gunther's 'Record of Zoolog. Literature,' 1865, p. 194.)  But the males\nof certain fishes do all the work, and afterwards take exclusive charge of\nthe young.  This is the case with the dull-coloured gobies (36.  Cuvier,\n'Regne Animal,' vol. ii. 1829, p. 242.), in which the sexes are not known\nto differ in colour, and likewise with the sticklebacks (Gasterosteus), in\nwhich the males become brilliantly coloured during the spawning season.\nThe male of the smooth-tailed stickleback (G. leiurus) performs the duties\nof a nurse with exemplary care and vigilance during a long time, and is\ncontinually employed in gently leading back the young to the nest, when\nthey stray too far.  He courageously drives away all enemies including the\nfemales of his own species.  It would indeed be no small relief to the\nmale, if the female, after depositing her eggs, were immediately devoured\nby some enemy, for he is forced incessantly to drive her from the nest.\n(37.  See Mr. Warington's most interesting description of the habits of the\nGasterosteus leiurus in 'Annals and Magazine of Nat. History,' November\n1855.)\n\nThe males of certain other fishes inhabiting South America and Ceylon,\nbelonging to two distinct Orders, have the extraordinary habit of hatching\nwithin their mouths, or branchial cavities, the eggs laid by the females.\n(38.  Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' Sept. 15, 1857.\nAlso Prof. Turner, in 'Journal of Anatomy and Physiology,' Nov. 1, 1866, p.\n78.  Dr. Gunther has likewise described other cases.)  I am informed by\nProfessor Agassiz that the males of the Amazonian species which follow this\nhabit, \"not only are generally brighter than the females, but the\ndifference is greater at the spawning-season than at any other time.\"  The\nspecies of Geophagus act in the same manner; and in this genus, a\nconspicuous protuberance becomes developed on the forehead of the males\nduring the breeding-season.  With the various species of Chromids, as\nProfessor Agassiz likewise informs me, sexual differences in colour may be\nobserved, \"whether they lay their eggs in the water among aquatic plants,\nor deposit them in holes, leaving them to come out without further care, or\nbuild shallow nests in the river mud, over which they sit, as our Pomotis\ndoes.  It ought also to be observed that these sitters are among the\nbrightest species in their respective families; for instance, Hygrogonus is\nbright green, with large black ocelli, encircled with the most brilliant\nred.\"  Whether with all the species of Chromids it is the male alone which\nsits on the eggs is not known.  It is, however, manifest that the fact of\nthe eggs being protected or unprotected by the parents, has had little or\nno influence on the differences in colour between the sexes.  It is further\nmanifest, in all the cases in which the males take exclusive charge of the\nnests and young, that the destruction of the brighter-coloured males would\nbe far more influential on the character of the race, than the destruction\nof the brighter-coloured females; for the death of the male during the\nperiod of incubation or nursing would entail the death of the young, so\nthat they could not inherit his peculiarities; yet, in many of these very\ncases the males are more conspicuously coloured than the females.\n\nIn most of the Lophobranchii (Pipe-fish, Hippocampi, etc.) the males have\neither marsupial sacks or hemispherical depressions on the abdomen, in\nwhich the ova laid by the female are hatched.  The males also shew great\nattachment to their young.  (39.  Yarrell, 'History of British Fishes,'\nvol. ii. 1836, pp. 329, 338.)  The sexes do not commonly differ much in\ncolour; but Dr. Gunther believes that the male Hippocampi are rather\nbrighter than the females.  The genus Solenostoma, however, offers a\ncurious exceptional case (40.  Dr. Gunther, since publishing an account of\nthis species in 'The Fishes of Zanzibar,' by Col. Playfair, 1866, p. 137,\nhas re-examined the specimens, and has given me the above information.),\nfor the female is much more vividly-coloured and spotted than the male, and\nshe alone has a marsupial sack and hatches the eggs; so that the female of\nSolenostoma differs from all the other Lophobranchii in this latter\nrespect, and from almost all other fishes, in being more brightly-coloured\nthan the male.  It is improbable that this remarkable double inversion of\ncharacter in the female should be an accidental coincidence.  As the males\nof several fishes, which take exclusive charge of the eggs and young, are\nmore brightly coloured than the females, and as here the female Solenostoma\ntakes the same charge and is brighter than the male, it might be argued\nthat the conspicuous colours of that sex which is the more important of the\ntwo for the welfare of the offspring, must be in some manner protective.\nBut from the large number of fishes, of which the males are either\npermanently or periodically brighter than the females, but whose life is\nnot at all more important for the welfare of the species than that of the\nfemale, this view can hardly be maintained.  When we treat of birds we\nshall meet with analogous cases, where there has been a complete inversion\nof the usual attributes of the two sexes, and we shall then give what\nappears to be the probable explanation, namely, that the males have\nselected the more attractive females, instead of the latter having\nselected, in accordance with the usual rule throughout the animal kingdom,\nthe more attractive males.\n\nOn the whole we may conclude, that with most fishes, in which the sexes\ndiffer in colour or in other ornamental characters, the males originally\nvaried, with their variations transmitted to the same sex, and accumulated\nthrough sexual selection by attracting or exciting the females.  In many\ncases, however, such characters have been transferred, either partially or\ncompletely, to the females.  In other cases, again, both sexes have been\ncoloured alike for the sake of protection; but in no instance does it\nappear that the female alone has had her colours or other characters\nspecially modified for this latter purpose.\n\nThe last point which need be noticed is that fishes are known to make\nvarious noises, some of which are described as being musical.  Dr. Dufosse,\nwho has especially attended to this subject, says that the sounds are\nvoluntarily produced in several ways by different fishes:  by the friction\nof the pharyngeal bones--by the vibration of certain muscles attached to\nthe swim bladder, which serves as a resounding board--and by the vibration\nof the intrinsic muscles of the swim bladder.  By this latter means the\nTrigla produces pure and long-drawn sounds which range over nearly an\noctave.  But the most interesting case for us is that of two species of\nOphidium, in which the males alone are provided with a sound-producing\napparatus, consisting of small movable bones, with proper muscles, in\nconnection with the swim bladder.  (41.  'Comptes-Rendus,' tom. xlvi. 1858,\np. 353; tom. xlvii. 1858, p. 916; tom. liv. 1862, p. 393.  The noise made\nby the Umbrinas (Sciaena aquila), is said by some authors to be more like\nthat of a flute or organ, than drumming:  Dr. Zouteveen, in the Dutch\ntranslation of this work (vol. ii. p. 36), gives some further particulars\non the sounds made by fishes.)  The drumming of the Umbrinas in the\nEuropean seas is said to be audible from a depth of twenty fathoms; and the\nfishermen of Rochelle assert \"that the males alone make the noise during\nthe spawning-time; and that it is possible by imitating it, to take them\nwithout bait.\"  (42.  The Rev. C. Kingsley, in 'Nature,' May 1870, p. 40.)\nFrom this statement, and more especially from the case of Ophidium, it is\nalmost certain that in this, the lowest class of the Vertebrata, as with so\nmany insects and spiders, sound-producing instruments have, at least in\nsome cases, been developed through sexual selection, as a means for\nbringing the sexes together.\n\nAMPHIBIANS.\n\nURODELA.\n\n[Fig. 32.  Triton cristatus (half natural size, from Bell's 'British\nReptiles').\nUpper figure, male during the breeding season;\nlower figure, female.]\n\nI will begin with the tailed amphibians.  The sexes of salamanders or newts\noften differ much both in colour and structure.  In some species prehensile\nclaws are developed on the fore-legs of the males during the breeding-\nseason:  and at this season in the male Triton palmipes the hind-feet are\nprovided with a swimming-web, which is almost completely absorbed during\nthe winter; so that their feet then resemble those of the female.  (43.\nBell, 'History of British Reptiles,' 2nd ed., 1849, pp. 156-159.)  This\nstructure no doubt aids the male in his eager search and pursuit of the\nfemale.  Whilst courting her he rapidly vibrates the end of his tail.  With\nour common newts (Triton punctatus and cristatus) a deep, much indented\ncrest is developed along the back and tail of the male during the breeding-\nseason, which disappears during the winter.  Mr. St. George Mivart informs\nme that it is not furnished with muscles, and therefore cannot be used for\nlocomotion.  As during the season of courtship it becomes edged with bright\ncolours, there can hardly be a doubt that it is a masculine ornament.  In\nmany species the body presents strongly contrasted, though lurid tints, and\nthese become more vivid during the breeding-season.  The male, for\ninstance, of our common little newt (Triton punctatus) is \"brownish-grey\nabove, passing into yellow beneath, which in the spring becomes a rich\nbright orange, marked everywhere with round dark spots.\"  The edge of the\ncrest also is then tipped with bright red or violet.  The female is usually\nof a yellowish-brown colour with scattered brown dots, and the lower\nsurface is often quite plain.  (44.  Bell, 'History of British Reptiles,'\n2nd ed., 1849, pp. 146, 151.)  The young are obscurely tinted.  The ova are\nfertilised during the act of deposition, and are not subsequently tended by\neither parent.  We may therefore conclude that the males have acquired\ntheir strongly-marked colours and ornamental appendages through sexual\nselection; these being transmitted either to the male offspring alone, or\nto both sexes.\n\nANURA OR BATRACHIA.\n\nWith many frogs and toads the colours evidently serve as a protection, such\nas the bright green tints of tree frogs and the obscure mottled shades of\nmany terrestrial species.  The most conspicuously-coloured toad which I\never saw, the Phryniscus nigricans (45.  'Zoology of the Voyage of the\n\"Beagle,\"' 1843.  Bell, ibid. p. 49.), had the whole upper surface of the\nbody as black as ink, with the soles of the feet and parts of the abdomen\nspotted with the brightest vermilion.  It crawled about the bare sandy or\nopen grassy plains of La Plata under a scorching sun, and could not fail to\ncatch the eye of every passing creature.  These colours are probably\nbeneficial by making this animal known to all birds of prey as a nauseous\nmouthful.\n\nIn Nicaragua there is a little frog \"dressed in a bright livery of red and\nblue\" which does not conceal itself like most other species, but hops about\nduring the daytime, and Mr. Belt says (46.  'The Naturalist in Nicaragua,'\n1874, p. 321.) that as soon as he saw its happy sense of security, he felt\nsure that it was uneatable.  After several trials he succeeded in tempting\na young duck to snatch up a young one, but it was instantly rejected; and\nthe duck \"went about jerking its head, as if trying to throw off some\nunpleasant taste.\"\n\nWith respect to sexual differences of colour, Dr. Gunther does not know of\nany striking instance either with frogs or toads; yet he can often\ndistinguish the male from the female by the tints of the former being a\nlittle more intense.  Nor does he know of any striking difference in\nexternal structure between the sexes, excepting the prominences which\nbecome developed during the breeding-season on the front legs of the male,\nby which he is enabled to hold the female.  (47.  The male alone of the\nBufo sikimmensis (Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 204) has two\nplate-like callosities on the thorax and certain rugosities on the fingers,\nwhich perhaps subserve the same end as the above-mentioned prominences.)\nIt is surprising that these animals have not acquired more strongly-marked\nsexual characters; for though cold-blooded their passions are strong.  Dr.\nGunther informs me that he has several times found an unfortunate female\ntoad dead and smothered from having been so closely embraced by three or\nfour males.  Frogs have been observed by Professor Hoffman in Giessen\nfighting all day long during the breeding-season, and with so much violence\nthat one had its body ripped open.\n\nFrogs and toads offer one interesting sexual difference, namely, in the\nmusical powers possessed by the males; but to speak of music, when applied\nto the discordant and overwhelming sounds emitted by male bull-frogs and\nsome other species, seems, according to our taste, a singularly\ninappropriate expression.  Nevertheless, certain frogs sing in a decidedly\npleasing manner.  Near Rio Janeiro I used often to sit in the evening to\nlisten to a number of little Hylae, perched on blades of grass close to the\nwater, which sent forth sweet chirping notes in harmony.  The various\nsounds are emitted chiefly by the males during the breeding-season, as in\nthe case of the croaking of our common frog.  (48.  Bell, 'History British\nReptiles,' 1849, p. 93.)  In accordance with this fact the vocal organs of\nthe males are more highly-developed than those of the females.  In some\ngenera the males alone are provided with sacs which open into the larynx.\n(49.  J. Bishop, in 'Todd's Cyclopaedia of Anatomy and Physiology,' vol.\niv. p. 1503.)  For instance, in the edible frog (Rana esculenta) \"the sacs\nare peculiar to the males, and become, when filled with air in the act of\ncroaking, large globular bladders, standing out one on each side of the\nhead, near the corners of the mouth.\"  The croak of the male is thus\nrendered exceedingly powerful; whilst that of the female is only a slight\ngroaning noise.  (50.  Bell, ibid. pp. 112-114.)  In the several genera of\nthe family the vocal organs differ considerably in structure, and their\ndevelopment in all cases may be attributed to sexual selection.\n\nREPTILES.\n\nCHELONIA.\n\nTortoises and turtles do not offer well-marked sexual differences.  In some\nspecies, the tail of the male is longer than that of the female.  In some,\nthe plastron or lower surface of the shell of the male is slightly concave\nin relation to the back of the female.  The male of the mud-turtle of the\nUnited States (Chrysemys picta) has claws on its front feet twice as long\nas those of the female; and these are used when the sexes unite.  (51.  Mr.\nC.J. Maynard, 'The American Naturalist,' Dec. 1869, p. 555.)  With the huge\ntortoise of the Galapagos Islands (Testudo nigra) the males are said to\ngrow to a larger size than the females:  during the pairing-season, and at\nno other time, the male utters a hoarse bellowing noise, which can be heard\nat the distance of more than a hundred yards; the female, on the other\nhand, never uses her voice.  (52.  See my 'Journal of Researches during the\nVoyage of the \"Beagle,\"' 1845, p. 384.)\n\nWith the Testudo elegans of India, it is said \"that the combats of the\nmales may be heard at some distance, from the noise they produce in butting\nagainst each other.\"  (53.  Dr. Gunther, 'Reptiles of British India,' 1864,\np. 7.)\n\nCROCODILIA.\n\nThe sexes apparently do not differ in colour; nor do I know that the males\nfight together, though this is probable, for some kinds make a prodigious\ndisplay before the females.  Bartram (54.  'Travels through Carolina,'\netc., 1791, p. 128.) describes the male alligator as striving to win the\nfemale by splashing and roaring in the midst of a lagoon, \"swollen to an\nextent ready to burst, with its head and tail lifted up, he springs or\ntwirls round on the surface of the water, like an Indian chief rehearsing\nhis feats of war.\"  During the season of love, a musky odour is emitted by\nthe submaxillary glands of the crocodile, and pervades their haunts.  (55.\nOwen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.)\n\nOPHIDIA.\n\nDr. Gunther informs me that the males are always smaller than the females,\nand generally have longer and slenderer tails; but he knows of no other\ndifference in external structure.  In regard to colour, be can almost\nalways distinguish the male from the female, by his more strongly-\npronounced tints; thus the black zigzag band on the back of the male\nEnglish viper is more distinctly defined than in the female.  The\ndifference is much plainer in the rattle-snakes of N. America, the male of\nwhich, as the keeper in the Zoological Gardens shewed me, can at once be\ndistinguished from the female by having more lurid yellow about its whole\nbody.  In S. Africa the Bucephalus capensis presents an analogous\ndifference, for the female \"is never so fully variegated with yellow on the\nsides as the male.\"  (56.  Sir Andrew Smith, 'Zoology of S. Africa:\nReptilia,' 1849, pl. x.)  The male of the Indian Dipsas cynodon, on the\nother hand, is blackish-brown, with the belly partly black, whilst the\nfemale is reddish or yellowish-olive, with the belly either uniform\nyellowish or marbled with black.  In the Tragops dispar of the same country\nthe male is bright green, and the female bronze-coloured.  (57.  Dr. A.\nGunther, 'Reptiles of British India,' Ray Soc., 1864, pp. 304, 308.)  No\ndoubt the colours of some snakes are protective, as shewn by the green\ntints of tree-snakes, and the various mottled shades of the species which\nlive in sandy places; but it is doubtful whether the colours of many kinds,\nfor instance of the common English snake and viper, serve to conceal them;\nand this is still more doubtful with the many foreign species which are\ncoloured with extreme elegance.  The colours of certain species are very\ndifferent in the adult and young states. (58.  Dr. Stoliczka, 'Journal of\nAsiatic Society of Bengal,' vol. xxxix, 1870, pp. 205, 211.)\n\nDuring the breeding-season the anal scent-glands of snakes are in active\nfunction (59.  Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.); and\nso it is with the same glands in lizards, and as we have seen with the\nsubmaxillary glands of crocodiles.  As the males of most animals search for\nthe females, these odoriferous glands probably serve to excite or charm the\nfemale, rather than to guide her to the spot where the male may be found.\nMale snakes, though appearing so sluggish, are amorous; for many have been\nobserved crowding round the same female, and even round her dead body.\nThey are not known to fight together from rivalry.  Their intellectual\npowers are higher than might have been anticipated.  In the Zoological\nGardens they soon learn not to strike at the iron bar with which their\ncages are cleaned; and Dr. Keen of Philadelphia informs me that some snakes\nwhich he kept learned after four or five times to avoid a noose, with which\nthey were at first easily caught.  An excellent observer in Ceylon, Mr. E.\nLayard, saw (60.  'Rambles in Ceylon,' in 'Annals and Magazine of Natural\nHistory,' 2nd series, vol. ix. 1852, p. 333.) a cobra thrust its head\nthrough a narrow hole and swallow a toad.  \"With this encumbrance he could\nnot withdraw himself; finding this, he reluctantly disgorged the precious\nmorsel, which began to move off; this was too much for snake philosophy to\nbear, and the toad was again seized, and again was the snake, after violent\nefforts to escape, compelled to part with its prey.  This time, however, a\nlesson had been learnt, and the toad was seized by one leg, withdrawn, and\nthen swallowed in triumph.\"\n\nThe keeper in the Zoological Gardens is positive that certain snakes, for\ninstance Crotalus and Python, distinguish him from all other persons.\nCobras kept together in the same cage apparently feel some attachment\ntowards each other.  (61.  Dr. Gunther, 'Reptiles of British India,' 1864,\np. 340.)\n\nIt does not, however, follow because snakes have some reasoning power,\nstrong passions and mutual affection, that they should likewise be endowed\nwith sufficient taste to admire brilliant colours in their partners, so as\nto lead to the adornment of the species through sexual selection.\nNevertheless, it is difficult to account in any other manner for the\nextreme beauty of certain species; for instance, of the coral-snakes of S.\nAmerica, which are of a rich red with black and yellow transverse bands.  I\nwell remember how much surprise I felt at the beauty of the first coral-\nsnake which I saw gliding across a path in Brazil.  Snakes coloured in this\npeculiar manner, as Mr. Wallace states on the authority of Dr. Gunther (62.\n'Westminster Review,' July 1st, 1867, p. 32.), are found nowhere else in\nthe world except in S. America, and here no less than four genera occur.\nOne of these, Elaps, is venomous; a second and widely-distinct genus is\ndoubtfully venomous, and the two others are quite harmless.  The species\nbelonging to these distinct genera inhabit the same districts, and are so\nlike each other that no one \"but a naturalist would distinguish the\nharmless from the poisonous kinds.\"  Hence, as Mr. Wallace believes, the\ninnocuous kinds have probably acquired their colours as a protection, on\nthe principle of imitation; for they would naturally be thought dangerous\nby their enemies.  The cause, however, of the bright colours of the\nvenomous Elaps remains to be explained, and this may perhaps be sexual\nselection.\n\nSnakes produce other sounds besides hissing.  The deadly Echis carinata has\non its sides some oblique rows of scales of a peculiar structure with\nserrated edges; and when this snake is excited these scales are rubbed\nagainst each other, which produces \"a curious prolonged, almost hissing\nsound.\"  (63.  Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 196.)  With\nrespect to the rattling of the rattle-snake, we have at last some definite\ninformation:  for Professor Aughey states (64.  The 'American Naturalist,'\n1873, p. 85.), that on two occasions, being himself unseen, he watched from\na little distance a rattle-snake coiled up with head erect, which continued\nto rattle at short intervals for half an hour:  and at last he saw another\nsnake approach, and when they met they paired.  Hence he is satisfied that\none of the uses of the rattle is to bring the sexes together.\nUnfortunately he did not ascertain whether it was the male or the female\nwhich remained stationary and called for the other.  But it by no means\nfollows from the above fact that the rattle may not be of use to these\nsnakes in other ways, as a warning to animals which would otherwise attack\nthem.  Nor can I quite disbelieve the several accounts which have appeared\nof their thus paralysing their prey with fear.  Some other snakes also make\na distinct noise by rapidly vibrating their tails against the surrounding\nstalks of plants; and I have myself heard this in the case of a\nTrigonocephalus in S. America.\n\nLACERTILIA.\n\nThe males of some, probably of many kinds of lizards, fight together from\nrivalry.  Thus the arboreal Anolis cristatellus of S. America is extremely\npugnacious:  \"During the spring and early part of the summer, two adult\nmales rarely meet without a contest.  On first seeing one another, they nod\ntheir heads up and down three or four times, and at the same time expanding\nthe frill or pouch beneath the throat; their eyes glisten with rage, and\nafter waving their tails from side to side for a few seconds, as if to\ngather energy, they dart at each other furiously, rolling over and over,\nand holding firmly with their teeth.  The conflict generally ends in one of\nthe combatants losing his tail, which is often devoured by the victor.\"\nThe male of this species is considerably larger than the female (65.  Mr.\nN.L. Austen kept these animals alive for a considerable time; see 'Land and\nWater,' July 1867, p. 9.); and this, as far as Dr. Gunther has been able to\nascertain, is the general rule with lizards of all kinds.  The male alone\nof the Cyrtodactylus rubidus of the Andaman Islands possesses pre-anal\npores; and these pores, judging from analogy, probably serve to emit an\nodour. (66.  Stoliczka, 'Journal of the Asiatic Society of Bengal,' vol.\nxxxiv. 1870, p. 166.)\n\n[Fig.33.  Sitana minor.\nMale with the gular pouch expanded (from Gunther's 'Reptiles of India')']\n\nThe sexes often differ greatly in various external characters.  The male of\nthe above-mentioned Anolis is furnished with a crest which runs along the\nback and tail, and can be erected at pleasure; but of this crest the female\ndoes not exhibit a trace.  In the Indian Cophotis ceylanica, the female has\na dorsal crest, though much less developed than in the male; and so it is,\nas Dr. Gunther informs me, with the females of many Iguanas, Chameleons,\nand other lizards.  In some species, however, the crest is equally\ndeveloped in both sexes, as in the Iguana tuberculata.  In the genus\nSitana, the males alone are furnished with a large throat pouch (Fig. 33),\nwhich can be folded up like a fan, and is coloured blue, black, and red;\nbut these splendid colours are exhibited only during the pairing-season.\nThe female does not possess even a rudiment of this appendage.  In the\nAnolis cristatellus, according to Mr. Austen, the throat pouch, which is\nbright red marbled with yellow, is present in the female, though in a\nrudimental condition.  Again, in certain other lizards, both sexes are\nequally well provided with throat pouches.  Here we see with species\nbelonging to the same group, as in so many previous cases, the same\ncharacter either confined to the males, or more largely developed in them\nthan in the females, or again equally developed in both sexes.  The little\nlizards of the genus Draco, which glide through the air on their rib-\nsupported parachutes, and which in the beauty of their colours baffle\ndescription, are furnished with skinny appendages to the throat \"like the\nwattles of gallinaceous birds.\"  These become erected when the animal is\nexcited.  They occur in both sexes, but are best developed when the male\narrives at maturity, at which age the middle appendage is sometimes twice\nas long as the head.  Most of the species likewise have a low crest running\nalong the neck; and this is much more developed in the full-grown males\nthan in the females or young males.  (67.  All the foregoing statements and\nquotations, in regard to Cophotis, Sitana and Draco, as well as the\nfollowing facts in regard to Ceratophora and Chamaeleon, are from Dr.\nGunther himself, or from his magnificent work on the 'Reptiles of British\nIndia,' Ray Soc., 1864, pp. 122, 130, 135.)\n\nA Chinese species is said to live in pairs during the spring; \"and if one\nis caught, the other falls from the tree to the ground, and allows itself\nto be captured with impunity\"--I presume from despair.  (68.  Mr. Swinhoe,\n'Proc. Zoolog. Soc.' 1870, p. 240.)\n\n[Fig. 34.  Ceratophora Stoddartii.\nUpper figure;\nlower figure, female.]\n\nThere are other and much more remarkable differences between the sexes of\ncertain lizards.  The male of Ceratophora aspera bears on the extremity of\nhis snout an appendage half as long as the head.  It is cylindrical,\ncovered with scales, flexible, and apparently capable of erection:  in the\nfemale it is quite rudimental.  In a second species of the same genus a\nterminal scale forms a minute horn on the summit of the flexible appendage;\nand in a third species (C. Stoddartii, fig. 34) the whole appendage is\nconverted into a horn, which is usually of a white colour, but assumes a\npurplish tint when the animal is excited.  In the adult male of this latter\nspecies the horn is half an inch in length, but it is of quite minute size\nin the female and in the young.  These appendages, as Dr. Gunther has\nremarked to me, may be compared with the combs of gallinaceous birds, and\napparently serve as ornaments.\n\n[Fig. 35.  Chamaeleo bifurcus.\nUpper figure, male;\nlower figure, female.\n\nFig. 36.  Chamaeleo Owenii.\nUpper figure, male;\nlower figure, female.]\n\nIn the genus Chamaeleon we come to the acme of difference between the\nsexes.  The upper part of the skull of the male C. bifurcus (Fig. 35), an\ninhabitant of Madagascar, is produced into two great, solid, bony\nprojections, covered with scales like the rest of the head; and of this\nwonderful modification of structure the female exhibits only a rudiment.\nAgain, in Chamaeleo Owenii (Fig. 36), from the West Coast of Africa, the\nmale bears on his snout and forehead three curious horns, of which the\nfemale has not a trace.  These horns consist of an excrescence of bone\ncovered with a smooth sheath, forming part of the general integuments of\nthe body, so that they are identical in structure with those of a bull,\ngoat, or other sheath-horned ruminant.  Although the three horns differ so\nmuch in appearance from the two great prolongations of the skull in C.\nbifurcus, we can hardly doubt that they serve the same general purpose in\nthe economy of these two animals.  The first conjecture, which will occur\nto every one, is that they are used by the males for fighting together; and\nas these animals are very quarrelsome (69.  Dr. Buchholz, 'Monatsbericht K.\nPreuss. Akad.' Jan. 1874, p. 78.), this is probably a correct view.  Mr.\nT.W. Wood also informs me that he once watched two individuals of C.\npumilus fighting violently on the branch of a tree; they flung their heads\nabout and tried to bite each other; they then rested for a time and\nafterwards continued their battle.\n\nWith many lizards the sexes differ slightly in colour, the tints and\nstripes of the males being brighter and more distinctly defined than in the\nfemales.  This, for instance, is the case with the above Cophotis and with\nthe Acanthodactylus capensis of S. Africa.  In a Cordylus of the latter\ncountry, the male is either much redder or greener than the female.  In the\nIndian Calotes nigrilabris there is a still greater difference; the lips\nalso of the male are black, whilst those of the female are green.  In our\ncommon little viviparous lizard (Zootoca vivipara) \"the under side of the\nbody and base of the tail in the male are bright orange, spotted with\nblack; in the female these parts are pale-greyish-green without spots.\"\n(70.  Bell, 'History of British Reptiles,' 2nd ed., 1849, p. 40.)  We have\nseen that the males alone of Sitana possess a throat-pouch; and this is\nsplendidly tinted with blue, black, and red.  In the Proctotretus tenuis of\nChile the male alone is marked with spots of blue, green, and coppery-red.\n(71.  For Proctotretus, see 'Zoology of the Voyage of the \"Beagle\";\nReptiles,' by Mr. Bell, p. 8.  For the Lizards of S. Africa, see 'Zoology\nof S. Africa:  Reptiles,' by Sir Andrew Smith, pl. 25 and 39.  For the\nIndian Calotes, see 'Reptiles of British India,' by Dr. Gunther, p. 143.)\nIn many cases the males retain the same colours throughout the year, but in\nothers they become much brighter during the breeding-season; I may give as\nan additional instance the Calotes maria, which at this season has a bright\nred head, the rest of the body being green.  (72.  Gunther in 'Proceedings,\nZoological Society,' 1870, p. 778, with a coloured figure.)\n\nBoth sexes of many species are beautifully coloured exactly alike; and\nthere is no reason to suppose that such colours are protective.  No doubt\nwith the bright green kinds which live in the midst of vegetation, this\ncolour serves to conceal them; and in N. Patagonia I saw a lizard\n(Proctotretus multimaculatus) which, when frightened, flattened its body,\nclosed its eyes, and then from its mottled tints was hardly distinguishable\nfrom the surrounding sand.  But the bright colours with which so many\nlizards are ornamented, as well as their various curious appendages, were\nprobably acquired by the males as an attraction, and then transmitted\neither to their male offspring alone, or to both sexes.  Sexual selection,\nindeed, seems to have played almost as important a part with reptiles as\nwith birds; and the less conspicuous colours of the females in comparison\nwith the males cannot be accounted for, as Mr. Wallace believes to be the\ncase with birds, by the greater exposure of the females to danger during\nincubation.\n\n\nCHAPTER XIII.\n\nSECONDARY SEXUAL CHARACTERS OF BIRDS.\n\nSexual differences--Law of battle--Special weapons--Vocal organs--\nInstrumental music--Love-antics and dances--Decorations, permanent and\nseasonal--Double and single annual moults--Display of ornaments by the\nmales.\n\nSecondary sexual characters are more diversified and conspicuous in birds,\nthough not perhaps entailing more important changes of structure, than in\nany other class of animals.  I shall, therefore, treat the subject at\nconsiderable length.  Male birds sometimes, though rarely, possess special\nweapons for fighting with each other.  They charm the female by vocal or\ninstrumental music of the most varied kinds.  They are ornamented by all\nsorts of combs, wattles, protuberances, horns, air-distended sacks, top-\nknots, naked shafts, plumes and lengthened feathers gracefully springing\nfrom all parts of the body.  The beak and naked skin about the head, and\nthe feathers, are often gorgeously coloured.  The males sometimes pay their\ncourt by dancing, or by fantastic antics performed either on the ground or\nin the air.  In one instance, at least, the male emits a musky odour, which\nwe may suppose serves to charm or excite the female; for that excellent\nobserver, Mr. Ramsay (1.  'Ibis,' vol. iii. (new series), 1867, p. 414.),\nsays of the Australian musk-duck (Biziura lobata) that \"the smell which the\nmale emits during the summer months is confined to that sex, and in some\nindividuals is retained throughout the year; I have never, even in the\nbreeding-season, shot a female which had any smell of musk.\"  So powerful\nis this odour during the pairing-season, that it can be detected long\nbefore the bird can be seen.  (2. Gould, 'Handbook of the Birds of\nAustralia,' 1865, vol. ii. p. 383.)  On the whole, birds appear to be the\nmost aesthetic of all animals, excepting of course man, and they have\nnearly the same taste for the beautiful as we have.  This is shewn by our\nenjoyment of the singing of birds, and by our women, both civilised and\nsavage, decking their heads with borrowed plumes, and using gems which are\nhardly more brilliantly coloured than the naked skin and wattles of certain\nbirds.  In man, however, when cultivated, the sense of beauty is manifestly\na far more complex feeling, and is associated with various intellectual\nideas.\n\nBefore treating of the sexual characters with which we are here more\nparticularly concerned, I may just allude to certain differences between\nthe sexes which apparently depend on differences in their habits of life;\nfor such cases, though common in the lower, are rare in the higher classes.\nTwo humming-birds belonging to the genus Eustephanus, which inhabit the\nisland of Juan Fernandez, were long thought to be specifically distinct,\nbut are now known, as Mr. Gould informs me, to be the male and female of\nthe same species, and they differ slightly in the form of the beak.  In\nanother genus of humming-birds (Grypus), the beak of the male is serrated\nalong the margin and hooked at the extremity, thus differing much from that\nof the female.  In the Neomorpha of New Zealand, there is, as we have seen,\na still wider difference in the form of the beak in relation to the manner\nof feeding of the two sexes.  Something of the same kind has been observed\nwith the goldfinch (Carduelis elegans), for I am assured by Mr. J. Jenner\nWeir that the bird-catchers can distinguish the males by their slightly\nlonger beaks.  The flocks of males are often found feeding on the seeds of\nthe teazle (Dipsacus), which they can reach with their elongated beaks,\nwhilst the females more commonly feed on the seeds of the betony or\nScrophularia.  With a slight difference of this kind as a foundation, we\ncan see how the beaks of the two sexes might be made to differ greatly\nthrough natural selection.  In some of the above cases, however, it is\npossible that the beaks of the males may have been first modified in\nrelation to their contests with other males; and that this afterwards led\nto slightly changed habits of life.\n\nLAW OF BATTLE.\n\nAlmost all male birds are extremely pugnacious, using their beaks, wings,\nand legs for fighting together.  We see this every spring with our robins\nand sparrows.  The smallest of all birds, namely the humming-bird, is one\nof the most quarrelsome.  Mr. Gosse (3.  Quoted by Mr. Gould, 'Introduction\nto the Trochilidae,' 1861, page 29.) describes a battle in which a pair\nseized hold of each other's beaks, and whirled round and round, till they\nalmost fell to the ground; and M. Montes de Oca, in speaking or another\ngenus of humming-bird, says that two males rarely meet without a fierce\naerial encounter:  when kept in cages \"their fighting has mostly ended in\nthe splitting of the tongue of one of the two, which then surely dies from\nbeing unable to feed.\"  (4.  Gould, ibid. p. 52.)  With waders, the males\nof the common water-hen (Gallinula chloropus) \"when pairing, fight\nviolently for the females:  they stand nearly upright in the water and\nstrike with their feet.\"  Two were seen to be thus engaged for half an\nhour, until one got hold of the head of the other, which would have been\nkilled had not the observer interfered; the female all the time looking on\nas a quiet spectator.  (5.  W. Thompson, 'Natural History of Ireland:\nBirds,' vol. ii. 1850, p. 327.)  Mr. Blyth informs me that the males of an\nallied bird (Gallicrex cristatus) are a third larger than the females, and\nare so pugnacious during the breeding-season that they are kept by the\nnatives of Eastern Bengal for the sake of fighting.  Various other birds\nare kept in India for the same purpose, for instance, the bulbuls\n(Pycnonotus hoemorrhous) which \"fight with great spirit.\"  (6.  Jerdon,\n'Birds of India,' 1863, vol. ii. p. 96.)\n\n[Fig. 37.  The Ruff or Machetes pugnax (from Brehm's 'Thierleben').]\n\nThe polygamous ruff (Machetes pugnax, Fig. 37) is notorious for his extreme\npugnacity; and in the spring, the males, which are considerably larger than\nthe females, congregate day after day at a particular spot, where the\nfemales propose to lay their eggs.  The fowlers discover these spots by the\nturf being trampled somewhat bare.  Here they fight very much like game-\ncocks, seizing each other with their beaks and striking with their wings.\nThe great ruff of feathers round the neck is then erected, and according to\nCol. Montagu \"sweeps the ground as a shield to defend the more tender\nparts\"; and this is the only instance known to me in the case of birds of\nany structure serving as a shield.  The ruff of feathers, however, from its\nvaried and rich colours probably serves in chief part as an ornament.  Like\nmost pugnacious birds, they seem always ready to fight, and when closely\nconfined, often kill each other; but Montagu observed that their pugnacity\nbecomes greater during the spring, when the long feathers on their necks\nare fully developed; and at this period the least movement by any one bird\nprovokes a general battle.  (7.  Macgillivray, 'History of British Birds,'\nvol. iv. 1852, pp. 177-181.)  Of the pugnacity of web-footed birds, two\ninstances will suffice:  in Guiana \"bloody fights occur during the\nbreeding-season between the males of the wild musk-duck (Cairina moschata);\nand where these fights have occurred the river is covered for some distance\nwith feathers.\"  (8.  Sir R. Schomburgk, in 'Journal of Royal Geographic\nSociety,' vol. xiii. 1843, p. 31.)  Birds which seem ill-adapted for\nfighting engage in fierce conflicts; thus the stronger males of the pelican\ndrive away the weaker ones, snapping with their huge beaks and giving heavy\nblows with their wings.  Male snipe fight together, \"tugging and pushing\neach other with their bills in the most curious manner imaginable.\"  Some\nfew birds are believed never to fight; this is the case, according to\nAudubon, with one of the woodpeckers of the United States (Picu sauratus),\nalthough \"the hens are followed by even half a dozen of their gay suitors.\"\n(9.  'Ornithological Biography,' vol. i. p. 191.  For pelicans and snipes,\nsee vol. iii. pp. 138, 477.)\n\nThe males of many birds are larger than the females, and this no doubt is\nthe result of the advantage gained by the larger and stronger males over\ntheir rivals during many generations.  The difference in size between the\ntwo sexes is carried to an extreme point in several Australian species;\nthus the male musk-duck (Biziura), and the male Cincloramphus cruralis\n(allied to our pipits) are by measurement actually twice as large as their\nrespective females.  (10.  Gould, 'Handbook of Birds of Australia,' vol. i.\np. 395; vol. ii. p. 383.)  With many other birds the females are larger\nthan the males; and, as formerly remarked, the explanation often given,\nnamely, that the females have most of the work in feeding their young, will\nnot suffice.  In some few cases, as we shall hereafter see, the females\napparently have acquired their greater size and strength for the sake of\nconquering other females and obtaining possession of the males.\n\nThe males of many gallinaceous birds, especially of the polygamous kinds,\nare furnished with special weapons for fighting with their rivals, namely\nspurs, which can be used with fearful effect.  It has been recorded by a\ntrustworthy writer (11.  Mr. Hewitt, in the 'Poultry Book' by Tegetmeier,\n1866, p. 137.) that in Derbyshire a kite struck at a game-hen accompanied\nby her chickens, when the cock rushed to the rescue, and drove his spur\nright through the eye and skull of the aggressor.  The spur was with\ndifficulty drawn from the skull, and as the kite, though dead, retained his\ngrasp, the two birds were firmly locked together; but the cock when\ndisentangled was very little injured.  The invincible courage of the game-\ncock is notorious:  a gentleman who long ago witnessed the brutal scene,\ntold me that a bird had both its legs broken by some accident in the\ncockpit, and the owner laid a wager that if the legs could be spliced so\nthat the bird could stand upright, he would continue fighting.  This was\neffected on the spot, and the bird fought with undaunted courage until he\nreceived his death-stroke.  In Ceylon a closely allied, wild species, the\nGallus Stanleyi, is known to fight desperately \"in defence of his\nseraglio,\" so that one of the combatants is frequently found dead.  (12.\nLayard, 'Annals and Magazine of Natural History,' vol. xiv. 1854, p. 63.)\nAn Indian partridge (Ortygornis gularis), the male of which is furnished\nwith strong and sharp spurs, is so quarrelsome \"that the scars of former\nfights disfigure the breast of almost every bird you kill.\"  (13.  Jerdon,\n'Birds of India,' vol. iii. p. 574.)\n\nThe males of almost all gallinaceous birds, even those which are not\nfurnished with spurs, engage during the breeding-season in fierce\nconflicts.  The Capercailzie and Black-cock (Tetrao urogallus and T.\ntetrix), which are both polygamists, have regular appointed places, where\nduring many weeks they congregate in numbers to fight together and to\ndisplay their charms before the females.  Dr. W. Kovalevsky informs me that\nin Russia he has seen the snow all bloody on the arenas where the\ncapercailzie have fought; and the black-cocks \"make the feathers fly in\nevery direction,\" when several \"engage in a battle royal.\"  The elder Brehm\ngives a curious account of the Balz, as the love-dances and love-songs of\nthe Black-cock are called in Germany.  The bird utters almost continuously\nthe strangest noises:  \"he holds his tail up and spreads it out like a fan,\nhe lifts up his head and neck with all the feathers erect, and stretches\nhis wings from the body.  Then he takes a few jumps in different\ndirections, sometimes in a circle, and presses the under part of his beak\nso hard against the ground that the chin feathers are rubbed off.  During\nthese movements he beats his wings and turns round and round.  The more\nardent he grows the more lively he becomes, until at last the bird appears\nlike a frantic creature.\"  At such times the black-cocks are so absorbed\nthat they become almost blind and deaf, but less so than the capercailzie:\nhence bird after bird may be shot on the same spot, or even caught by the\nhand.  After performing these antics the males begin to fight:  and the\nsame black-cock, in order to prove his strength over several antagonists,\nwill visit in the course of one morning several Balz-places, which remain\nthe same during successive years.  (14.  Brehm, 'Thierleben,' 1867, B. iv.\ns. 351.  Some of the foregoing statements are taken from L. Lloyd, 'The\nGame Birds of Sweden,' etc., 1867, p. 79.)\n\nThe peacock with his long train appears more like a dandy than a warrior,\nbut he sometimes engages in fierce contests:  the Rev. W. Darwin Fox\ninforms me that at some little distance from Chester two peacocks became so\nexcited whilst fighting, that they flew over the whole city, still engaged,\nuntil they alighted on the top of St. John's tower.\n\nThe spur, in those gallinaceous birds which are thus provided, is generally\nsingle; but Polyplectron (Fig. 51) has two or more on each leg; and one of\nthe Blood-pheasants (Ithaginis cruentus) has been seen with five spurs.\nThe spurs are generally confined to the male, being represented by mere\nknobs or rudiments in the female; but the females of the Java peacock (Pavo\nmuticus) and, as I am informed by Mr. Blyth, of the small fire-backed\npheasant (Euplocamus erythrophthalmus) possess spurs.  In Galloperdix it is\nusual for the males to have two spurs, and for the females to have only one\non each leg.  (15.  Jerdon, 'Birds of India':  on Ithaginis, vol. iii. p.\n523; on Galloperdix, p. 541.)  Hence spurs may be considered as a masculine\nstructure, which has been occasionally more or less transferred to the\nfemales.  Like most other secondary sexual characters, the spurs are highly\nvariable, both in number and development, in the same species.\n\n[Fig.38.  Palamedea cornuta (from Brehm), shewing the double wing-spurs,\nand the filament on the head.]\n\nVarious birds have spurs on their wings.  But the Egyptian goose\n(Chenalopex aegyptiacus) has only \"bare obtuse knobs,\" and these probably\nshew us the first steps by which true spurs have been developed in other\nspecies.  In the spur-winged goose, Plectropterus gambensis, the males have\nmuch larger spurs than the females; and they use them, as I am informed by\nMr. Bartlett, in fighting together, so that, in this case, the wing-spurs\nserve as sexual weapons; but according to Livingstone, they are chiefly\nused in the defence of the young.  The Palamedea (Fig. 38) is armed with a\npair of spurs on each wing; and these are such formidable weapons that a\nsingle blow has been known to drive a dog howling away.  But it does not\nappear that the spurs in this case, or in that of some of the spur-winged\nrails, are larger in the male than in the female.  (16.  For the Egyptian\ngoose, see Macgillivray, 'British Birds,' vol. iv. p. 639.  For\nPlectropterus, Livingstone's 'Travels,' p. 254.  For Palamedea, Brehm's\n'Thierleben,' B. iv. s. 740.  See also on this bird Azara, 'Voyages dans\nl'Amerique merid.' tom. iv. 1809, pp. 179, 253.)  In certain plovers,\nhowever, the wing-spurs must be considered as a sexual character.  Thus in\nthe male of our common peewit (Vanellus cristatus) the tubercle on the\nshoulder of the wing becomes more prominent during the breeding-season, and\nthe males fight together.  In some species of Lobivanellus a similar\ntubercle becomes developed during the breeding-season \"into a short horny\nspur.\"  In the Australian L. lobatus both sexes have spurs, but these are\nmuch larger in the males than in the females.  In an allied bird, the\nHoplopterus armatus, the spurs do not increase in size during the breeding-\nseason; but these birds have been seen in Egypt to fight together, in the\nsame manner as our peewits, by turning suddenly in the air and striking\nsideways at each other, sometimes with fatal results.  Thus also they drive\naway other enemies.  (17.  See, on our peewit, Mr. R. Carr in 'Land and\nWater,' Aug. 8th, 1868, p. 46.  In regard to Lobivanellus, see Jerdon's\n'Birds of India,' vol. iii. p. 647, and Gould's 'Handbook of Birds of\nAustralia,' vol. ii. p. 220.  For the Hoplopterus, see Mr. Allen in the\n'Ibis,' vol. v. 1863, p. 156.)\n\nThe season of love is that of battle; but the males of some birds, as of\nthe game-fowl and ruff, and even the young males of the wild turkey and\ngrouse (18.  Audubon, 'Ornithological Biography,' vol. ii. p. 492; vol. i.\npp. 4-13.), are ready to fight whenever they meet.  The presence of the\nfemale is the teterrima belli causa.  The Bengali baboos make the pretty\nlittle males of the amadavat (Estrelda amandava) fight together by placing\nthree small cages in a row, with a female in the middle; after a little\ntime the two males are turned loose, and immediately a desperate battle\nensues.  (19.  Mr. Blyth, 'Land and Water,' 1867, p. 212.)  When many males\ncongregate at the same appointed spot and fight together, as in the case of\ngrouse and various other birds, they are generally attended by the females\n(20.  Richardson on Tetrao umbellus, 'Fauna Bor. Amer.:  Birds,' 1831, p.\n343.  L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 22, 79, on the\ncapercailzie and black-cock.  Brehm, however, asserts ('Thierleben,' B. iv.\ns. 352) that in Germany the grey-hens do not generally attend the Balzen of\nthe black-cocks, but this is an exception to the common rule; possibly the\nhens may lie hidden in the surrounding bushes, as is known to be the case\nwith the gray-hens in Scandinavia, and with other species in N. America.),\nwhich afterwards pair with the victorious combatants.  But in some cases\nthe pairing precedes instead of succeeding the combat:  thus according to\nAudubon (21.  'Ornithological Biography,' vol. ii. p. 275.), several males\nof the Virginian goat-sucker (Caprimulgus virgianus) \"court, in a highly\nentertaining manner the female, and no sooner has she made her choice, than\nher approved gives chase to all intruders, and drives them beyond his\ndominions.\"  Generally the males try to drive away or kill their rivals\nbefore they pair.  It does not, however, appear that the females invariably\nprefer the victorious males.  I have indeed been assured by Dr. W.\nKovalevsky that the female capercailzie sometimes steals away with a young\nmale who has not dared to enter the arena with the older cocks, in the same\nmanner as occasionally happens with the does of the red-deer in Scotland.\nWhen two males contend in presence of a single female, the victor, no\ndoubt, commonly gains his desire; but some of these battles are caused by\nwandering males trying to distract the peace of an already mated pair.\n(22.  Brehm, 'Thierleben,' etc., B. iv. 1867, p. 990.  Audubon,\n'Ornithological Biography,' vol. ii. p. 492.)\n\nEven with the most pugnacious species it is probable that the pairing does\nnot depend exclusively on the mere strength and courage of the male; for\nsuch males are generally decorated with various ornaments, which often\nbecome more brilliant during the breeding-season, and which are sedulously\ndisplayed before the females.  The males also endeavour to charm or excite\ntheir mates by love-notes, songs, and antics; and the courtship is, in many\ninstances, a prolonged affair.  Hence it is not probable that the females\nare indifferent to the charms of the opposite sex, or that they are\ninvariably compelled to yield to the victorious males.  It is more probable\nthat the females are excited, either before or after the conflict, by\ncertain males, and thus unconsciously prefer them.  In the case of Tetrao\numbellus, a good observer (23.  'Land and Water,' July 25, 1868, p. 14.)\ngoes so far as to believe that the battles of the male \"are all a sham,\nperformed to show themselves to the greatest advantage before the admiring\nfemales who assemble around; for I have never been able to find a maimed\nhero, and seldom more than a broken feather.\"  I shall have to recur to\nthis subject, but I may here add that with the Tetrao cupido of the United\nStates, about a score of males assemble at a particular spot, and,\nstrutting about, make the whole air resound with their extraordinary\nnoises.  At the first answer from a female the males begin to fight\nfuriously, and the weaker give way; but then, according to Audubon, both\nthe victors and vanquished search for the female, so that the females must\neither then exert a choice, or the battle must be renewed.  So, again, with\none of the field-starlings of the United States (Sturnella ludoviciana) the\nmales engage in fierce conflicts, \"but at the sight of a female they all\nfly after her as if mad.\"  (24.  Audubon's 'Ornithological Biography;' on\nTetrao cupido, vol. ii. p. 492; on the Sturnus, vol. ii. p. 219.)\n\nVOCAL AND INSTRUMENTAL MUSIC.\n\nWith birds the voice serves to express various emotions, such as distress,\nfear, anger, triumph, or mere happiness.  It is apparently sometimes used\nto excite terror, as in the case of the hissing noise made by some\nnestling-birds.  Audubon (25.  'Ornithological Biography,' vol. v. p.\n601.), relates that a night-heron (Ardea nycticorax, Linn.), which he kept\ntame, used to hide itself when a cat approached, and then \"suddenly start\nup uttering one of the most frightful cries, apparently enjoying the cat's\nalarm and flight.\"  The common domestic cock clucks to the hen, and the hen\nto her chickens, when a dainty morsel is found.  The hen, when she has laid\nan egg, \"repeats the same note very often, and concludes with the sixth\nabove, which she holds for a longer time\" (26.  The Hon. Daines Barrington,\n'Philosophical Transactions,' 1773, p. 252.); and thus she expresses her\njoy.  Some social birds apparently call to each other for aid; and as they\nflit from tree to tree, the flock is kept together by chirp answering\nchirp.  During the nocturnal migrations of geese and other water-fowl,\nsonorous clangs from the van may be heard in the darkness overhead,\nanswered by clangs in the rear.  Certain cries serve as danger signals,\nwhich, as the sportsman knows to his cost, are understood by the same\nspecies and by others.  The domestic cock crows, and the humming-bird\nchirps, in triumph over a defeated rival.  The true song, however, of most\nbirds and various strange cries are chiefly uttered during the breeding-\nseason, and serve as a charm, or merely as a call-note, to the other sex.\n\nNaturalists are much divided with respect to the object of the singing of\nbirds.  Few more careful observers ever lived than Montagu, and he\nmaintained that the \"males of song-birds and of many others do not in\ngeneral search for the female, but, on the contrary, their business in the\nspring is to perch on some conspicuous spot, breathing out their full and\namorous notes, which, by instinct, the female knows, and repairs to the\nspot to choose her mate.\"  (27.  'Ornithological Dictionary,' 1833, p.\n475.)  Mr. Jenner Weir informs me that this is certainly the case with the\nnightingale.  Bechstein, who kept birds during his whole life, asserts,\n\"that the female canary always chooses the best singer, and that in a state\nof nature the female finch selects that male out of a hundred whose notes\nplease her most.  (28.  'Naturgeschichte der Stubenvoegel,' 1840, s. 4.\nMr. Harrison Weir likewise writes to me:--\"I am informed that the best\nsinging males generally get a mate first, when they are bred in the same\nroom.\")  There can be no doubt that birds closely attend to each other's\nsong.  Mr. Weir has told me of the case of a bullfinch which had been\ntaught to pipe a German waltz, and who was so good a performer that he cost\nten guineas; when this bird was first introduced into a room where other\nbirds were kept and he began to sing, all the others, consisting of about\ntwenty linnets and canaries, ranged themselves on the nearest side of their\ncages, and listened with the greatest interest to the new performer.  Many\nnaturalists believe that the singing of birds is almost exclusively \"the\neffect of rivalry and emulation,\" and not for the sake of charming their\nmates.  This was the opinion of Daines Barrington and White of Selborne,\nwho both especially attended to this subject.  (29.  'Philosophical\nTransactions,' 1773, p. 263.  White's 'Natural History of Selborne,' 1825,\nvol. i. p. 246.)  Barrington, however, admits that \"superiority in song\ngives to birds an amazing ascendancy over others, as is well known to bird-\ncatchers.\"\n\nIt is certain that there is an intense degree of rivalry between the males\nin their singing.  Bird-fanciers match their birds to see which will sing\nlongest; and I was told by Mr. Yarrell that a first-rate bird will\nsometimes sing till he drops down almost dead, or according to Bechstein\n(30.  'Naturgesch. der Stubenvoegel,' 1840, s. 252.), quite dead from\nrupturing a vessel in the lungs.  Whatever the cause may be, male birds, as\nI hear from Mr. Weir, often die suddenly during the season of song.  That\nthe habit of singing is sometimes quite independent of love is clear, for a\nsterile, hybrid canary-bird has been described (31.  Mr. Bold, 'Zoologist,'\n1843-44, p. 659.) as singing whilst viewing itself in a mirror, and then\ndashing at its own image; it likewise attacked with fury a female canary,\nwhen put into the same cage.  The jealousy excited by the act of singing is\nconstantly taken advantage of by bird-catchers; a male, in good song, is\nhidden and protected, whilst a stuffed bird, surrounded by limed twigs, is\nexposed to view.  In this manner, as Mr. Weir informs me, a man has in the\ncourse of a single day caught fifty, and in one instance, seventy, male\nchaffinches.  The power and inclination to sing differ so greatly with\nbirds that although the price of an ordinary male chaffinch is only\nsixpence, Mr. Weir saw one bird for which the bird-catcher asked three\npounds; the test of a really good singer being that it will continue to\nsing whilst the cage is swung round the owner's head.\n\nThat male birds should sing from emulation as well as for charming the\nfemale, is not at all incompatible; and it might have been expected that\nthese two habits would have concurred, like those of display and pugnacity.\nSome authors, however, argue that the song of the male cannot serve to\ncharm the female, because the females of some few species, such as of the\ncanary, robin, lark, and bullfinch, especially when in a state of\nwidowhood, as Bechstein remarks, pour forth fairly melodious strains.  In\nsome of these cases the habit of singing may be in part attributed to the\nfemales having been highly fed and confined (32.  D. Barrington,\n'Philosophical Transactions,' 1773, p. 262.  Bechstein, 'Stubenvoegel,'\n1840, s. 4.), for this disturbs all the functions connected with the\nreproduction of the species.  Many instances have already been given of the\npartial transference of secondary masculine characters to the female, so\nthat it is not at all surprising that the females of some species should\npossess the power of song.  It has also been argued, that the song of the\nmale cannot serve as a charm, because the males of certain species, for\ninstance of the robin, sing during the autumn.  (33.  This is likewise the\ncase with the water-ouzel; see Mr. Hepburn in the 'Zoologist,' 1845-46, p.\n1068.)  But nothing is more common than for animals to take pleasure in\npractising whatever instinct they follow at other times for some real good.\nHow often do we see birds which fly easily, gliding and sailing through the\nair obviously for pleasure?  The cat plays with the captured mouse, and the\ncormorant with the captured fish.  The weaver-bird (Ploceus), when confined\nin a cage, amuses itself by neatly weaving blades of grass between the\nwires of its cage.  Birds which habitually fight during the breeding-season\nare generally ready to fight at all times; and the males of the\ncapercailzie sometimes hold their Balzen or leks at the usual place of\nassemblage during the autumn.  (34.  L. Lloyd, 'Game Birds of Sweden,'\n1867, p. 25.)  Hence it is not at all surprising that male birds should\ncontinue singing for their own amusement after the season for courtship is\nover.\n\nAs shewn in a previous chapter, singing is to a certain extent an art, and\nis much improved by practice.  Birds can be taught various tunes, and even\nthe unmelodious sparrow has learnt to sing like a linnet.  They acquire the\nsong of their foster parents (35.  Barrington, ibid. p. 264, Bechstein,\nibid. s. 5.), and sometimes that of their neighbours.  (36.  Dureau de la\nMalle gives a curious instance ('Annales des Sc. Nat.' 3rd series, Zoolog.,\ntom. x. p. 118) of some wild blackbirds in his garden in Paris, which\nnaturally learnt a republican air from a caged bird.)  All the common\nsongsters belong to the Order of Insessores, and their vocal organs are\nmuch more complex than those of most other birds; yet it is a singular fact\nthat some of the Insessores, such as ravens, crows, and magpies, possess\nthe proper apparatus (37.  Bishop, in 'Todd's Cyclopaedia of Anatomy and\nPhysiology,' vol. iv. p. 1496.), though they never sing, and do not\nnaturally modulate their voices to any great extent.  Hunter asserts (38.\nAs stated by Barrington in 'Philosophical Transactions,' 1773, p. 262.)\nthat with the true songsters the muscles of the larynx are stronger in the\nmales than in the females; but with this slight exception there is no\ndifference in the vocal organs of the two sexes, although the males of most\nspecies sing so much better and more continuously than the females.\n\nIt is remarkable that only small birds properly sing.  The Australian genus\nMenura, however, must be excepted; for the Menura Alberti, which is about\nthe size of a half-grown turkey, not only mocks other birds, but \"its own\nwhistle is exceedingly beautiful and varied.\"  The males congregate and\nform \"corroborying places,\" where they sing, raising and spreading their\ntails like peacocks, and drooping their wings.  (39.  Gould, 'Handbook to\nthe Birds of Australia,' vol. i. 1865, pp. 308-310.  See also Mr. T.W. Wood\nin the 'Student,' April 1870, p. 125.)  It is also remarkable that birds\nwhich sing well are rarely decorated with brilliant colours or other\nornaments.  Of our British birds, excepting the bullfinch and goldfinch,\nthe best songsters are plain-coloured.  The kingfisher, bee-eater, roller,\nhoopoe, woodpeckers, etc., utter harsh cries; and the brilliant birds of\nthe tropics are hardly ever songsters.  (40.  See remarks to this effect in\nGould's 'Introduction to the Trochilidae,' 1861, p. 22.)  Hence bright\ncolours and the power of song seem to replace each other.  We can perceive\nthat if the plumage did not vary in brightness, or if bright colours were\ndangerous to the species, other means would be employed to charm the\nfemales; and melody of voice offers one such means.\n\n[Fig. 39.  Tetrao cupido:  male.  (T.W. Wood.)]\n\nIn some birds the vocal organs differ greatly in the two sexes.  In the\nTetrao cupido (Fig. 39) the male has two bare, orange-coloured sacks, one\non each side of the neck; and these are largely inflated when the male,\nduring the breeding-season, makes his curious hollow sound, audible at a\ngreat distance.  Audubon proved that the sound was intimately connected\nwith this apparatus (which reminds us of the air-sacks on each side of the\nmouth of certain male frogs), for he found that the sound was much\ndiminished when one of the sacks of a tame bird was pricked, and when both\nwere pricked it was altogether stopped.  The female has \"a somewhat\nsimilar, though smaller naked space of skin on the neck; but this is not\ncapable of inflation.\"  (41.  'The Sportsman and Naturalist in Canada,' by\nMajor W. Ross King, 1866, pp. 144-146.  Mr. T.W. Wood gives in the\n'Student' (April 1870, p. 116) an excellent account of the attitude and\nhabits of this bird during its courtship.  He states that the ear-tufts or\nneck-plumes are erected, so that they meet over the crown of the head.  See\nhis drawing, Fig. 39.)  The male of another kind of grouse (Tetrao\nurophasianus), whilst courting the female, has his \"bare yellow oesophagus\ninflated to a prodigious size, fully half as large as the body\"; and he\nthen utters various grating, deep, hollow tones.  With his neck-feathers\nerect, his wings lowered, and buzzing on the ground, and his long pointed\ntail spread out like a fan, he displays a variety of grotesque attitudes.\nThe oesophagus of the female is not in any way remarkable.  (42.\nRichardson, 'Fauna Bor. Americana:  Birds,' 1831, p. 359.  Audubon, ibid.\nvol. iv. p. 507.)\n\n[Fig. 40.  The Umbrella-bird or Cephalopterus ornatus, male (from Brehm).]\n\nIt seems now well made out that the great throat pouch of the European male\nbustard (Otis tarda), and of at least four other species, does not, as was\nformerly supposed, serve to hold water, but is connected with the utterance\nduring the breeding-season of a peculiar sound resembling \"oak.\"  (43.  The\nfollowing papers have been lately written on this subject:  Prof. A.\nNewton, in the 'Ibis,' 1862, p. 107; Dr. Cullen, ibid. 1865, p. 145; Mr.\nFlower, in 'Proc. Zool. Soc.' 1865, p. 747; and Dr. Murie, in 'Proc. Zool.\nSoc.' 1868, p. 471.  In this latter paper an excellent figure is given of\nthe male Australian Bustard in full display with the sack distended.  It is\na singular fact that the sack is not developed in all the males of the same\nspecies.)  A crow-like bird inhabiting South America (see Cephalopterus\nornatus, Fig. 40) is called the umbrella-bird, from its immense top knot,\nformed of bare white quills surmounted by dark-blue plumes, which it can\nelevate into a great dome no less than five inches in diameter, covering\nthe whole head.  This bird has on its neck a long, thin, cylindrical fleshy\nappendage, which is thickly clothed with scale-like blue feathers.  It\nprobably serves in part as an ornament, but likewise as a resounding\napparatus; for Mr. Bates found that it is connected \"with an unusual\ndevelopment of the trachea and vocal organs.\"  It is dilated when the bird\nutters its singularly deep, loud and long sustained fluty note.  The head-\ncrest and neck-appendage are rudimentary in the female.  (44.  Bates, 'The\nNaturalist on the Amazons,' 1863, vol. ii. p. 284; Wallace, in\n'Proceedings, Zoological Society,' 1850, p. 206.  A new species, with a\nstill larger neck-appendage (C. penduliger), has lately been discovered,\nsee 'Ibis,' vol. i. p. 457.)\n\nThe vocal organs of various web-footed and wading birds are extraordinarily\ncomplex, and differ to a certain extent in the two sexes.  In some cases\nthe trachea is convoluted, like a French horn, and is deeply embedded in\nthe sternum.  In the wild swan (Cygnus ferus) it is more deeply embedded in\nthe adult male than in the adult female or young male.  In the male\nMerganser the enlarged portion of the trachea is furnished with an\nadditional pair of muscles.  (45.  Bishop, in Todd's 'Cyclopaedia of\nAnatomy and Physiology,' vol. iv. p. 1499.)  In one of the ducks, however,\nnamely Anas punctata, the bony enlargement is only a little more developed\nin the male than in the female.  (46.  Prof. Newton, 'Proc. Zoolog. Soc.'\n1871, p. 651.)  But the meaning of these differences in the trachea of the\ntwo sexes of the Anatidae is not understood; for the male is not always the\nmore vociferous; thus with the common duck, the male hisses, whilst the\nfemale utters a loud quack.  (47.  The spoonbill (Platalea) has its trachea\nconvoluted into a figure of eight, and yet this bird (Jerdon, 'Birds of\nIndia,' vol. iii. p. 763) is mute; but Mr. Blyth informs me that the\nconvolutions are not constantly present, so that perhaps they are now\ntending towards abortion.)  In both sexes of one of the cranes (Grus virgo)\nthe trachea penetrates the sternum, but presents \"certain sexual\nmodifications.\"  In the male of the black stork there is also a well-marked\nsexual difference in the length and curvature of the bronchi.  (48.\n'Elements of Comparative Anatomy,' by R. Wagner, Eng. translat. 1845, p.\n111.  With respect to the swan, as given above, Yarrell's 'History of\nBritish Birds,' 2nd edition, 1845, vol. iii. p. 193.)  Highly important\nstructures have, therefore, in these cases been modified according to sex.\n\nIt is often difficult to conjecture whether the many strange cries and\nnotes uttered by male birds during the breeding-season serve as a charm or\nmerely as a call to the female.  The soft cooing of the turtle-dove and of\nmany pigeons, it may be presumed, pleases the female.  When the female of\nthe wild turkey utters her call in the morning, the male answers by a note\nwhich differs from the gobbling noise made, when with erected feathers,\nrustling wings and distended wattles, he puffs and struts before her.  (49.\nC.L. Bonaparte, quoted in the 'Naturalist Library:  Birds,' vol. xiv. p.\n126.)  The spel of the black-cock certainly serves as a call to the female,\nfor it has been known to bring four or five females from a distance to a\nmale under confinement; but as the black-cock continues his spel for hours\nduring successive days, and in the case of the capercailzie \"with an agony\nof passion,\" we are led to suppose that the females which are present are\nthus charmed.  (50.  L. Lloyd, 'The Game Birds of Sweden,' etc., 1867, pp.\n22, 81.)  The voice of the common rook is known to alter during the\nbreeding-season, and is therefore in some way sexual.  (51.  Jenner,\n'Philosophical Transactions,' 1824, p. 20.)  But what shall we say about\nthe harsh screams of, for instance, some kinds of macaws; have these birds\nas bad taste for musical sounds as they apparently have for colour, judging\nby the inharmonious contrast of their bright yellow and blue plumage?  It\nis indeed possible that without any advantage being thus gained, the loud\nvoices of many male birds may be the result of the inherited effects of the\ncontinued use of their vocal organs when excited by the strong passions of\nlove, jealousy and rage; but to this point we shall recur when we treat of\nquadrupeds.\n\nWe have as yet spoken only of the voice, but the males of various birds\npractise, during their courtship, what may be called instrumental music.\nPeacocks and Birds of Paradise rattle their quills together.  Turkey-cocks\nscrape their wings against the ground, and some kinds of grouse thus\nproduce a buzzing sound.  Another North American grouse, the Tetrao\numbellus, when with his tail erect, his ruffs displayed, \"he shows off his\nfinery to the females, who lie hid in the neighbourhood,\" drums by rapidly\nstriking his wings together above his back, according to Mr. R. Haymond,\nand not, as Audubon thought, by striking them against his sides.  The sound\nthus produced is compared by some to distant thunder, and by others to the\nquick roll of a drum.  The female never drums, \"but flies directly to the\nplace where the male is thus engaged.\"  The male of the Kalij-pheasant, in\nthe Himalayas, often makes a singular drumming noise with his wings, not\nunlike the sound produced by shaking a stiff piece of cloth.\"  On the west\ncoast of Africa the little black-weavers (Ploceus?) congregate in a small\nparty on the bushes round a small open space, and sing and glide through\nthe air with quivering wings, \"which make a rapid whirring sound like a\nchild's rattle.\"  One bird after another thus performs for hours together,\nbut only during the courting-season.  At this season, and at no other time,\nthe males of certain night-jars (Caprimulgus) make a strange booming noise\nwith their wings.  The various species of woodpeckers strike a sonorous\nbranch with their beaks, with so rapid a vibratory movement that \"the head\nappears to be in two places at once.\"  The sound thus produced is audible\nat a considerable distance but cannot be described; and I feel sure that\nits source would never be conjectured by any one hearing it for the first\ntime.  As this jarring sound is made chiefly during the breeding-season, it\nhas been considered as a love-song; but it is perhaps more strictly a love-\ncall.  The female, when driven from her nest, has been observed thus to\ncall her mate, who answered in the same manner and soon appeared.  Lastly,\nthe male hoopoe (Upupa epops) combines vocal and instrumental music; for\nduring the breeding-season this bird, as Mr. Swinhoe observed, first draws\nin air, and then taps the end of its beak perpendicularly down against a\nstone or the trunk of a tree, \"when the breath being forced down the\ntubular bill produces the correct sound.\"  If the beak is not thus struck\nagainst some object, the sound is quite different.  Air is at the same time\nswallowed, and the oesophagus thus becomes much swollen; and this probably\nacts as a resonator, not only with the hoopoe, but with pigeons and other\nbirds.  (52.   For the foregoing facts see, on Birds of Paradise, Brehm,\n'Thierleben,' Band iii. s. 325.  On Grouse, Richardson, 'Fauna Bor.\nAmeric.:  Birds,' pp. 343 and 359; Major W. Ross King, 'The Sportsman in\nCanada,' 1866, p. 156; Mr. Haymond, in Prof. Cox's 'Geol. Survey of\nIndiana,' p. 227; Audubon, 'American Ornitholog. Biograph.' vol. i. p. 216.\nOn the Kalij-pheasant, Jerdon, 'Birds of India,' vol. iii. p. 533.  On the\nWeavers, Livingstone's 'Expedition to the Zambesi,' 1865, p. 425.  On\nWoodpeckers, Macgillivray, 'Hist. of British Birds,' vol. iii. 1840, pp.\n84, 88, 89, and 95.  On the Hoopoe, Mr. Swinhoe, in 'Proc. Zoolog. Soc.'\nJune 23, 1863 and 1871, p. 348.  On the Night-jar, Audubon, ibid. vol. ii.\np. 255, and 'American Naturalist,' 1873, p. 672.  The English Night-jar\nlikewise makes in the spring a curious noise during its rapid flight.)\n\n[Fig. 41.  Outer tail-feather of Scolopax gallinago (from 'Proc. Zool.\nSoc.' 1858).\n\nFig. 42.  Outer tail-feather of Scolopax frenata.\n\nFig. 43.  Outer tail-feather of Scolopax javensis.]\n\nIn the foregoing cases sounds are made by the aid of structures already\npresent and otherwise necessary; but in the following cases certain\nfeathers have been specially modified for the express purpose of producing\nsounds.  The drumming, bleating, neighing, or thundering noise (as\nexpressed by different observers) made by the common snipe (Scolopax\ngallinago) must have surprised every one who has ever heard it.  This bird,\nduring the pairing-season, flies to \"perhaps a thousand feet in height,\"\nand after zig-zagging about for a time descends to the earth in a curved\nline, with outspread tail and quivering pinions, and surprising velocity.\nThe sound is emitted only during this rapid descent.  No one was able to\nexplain the cause until M. Meves observed that on each side of the tail the\nouter feathers are peculiarly formed (Fig. 41), having a stiff sabre-shaped\nshaft with the oblique barbs of unusual length, the outer webs being\nstrongly bound together.  He found that by blowing on these feathers, or by\nfastening them to a long thin stick and waving them rapidly through the\nair, he could reproduce the drumming noise made by the living bird.  Both\nsexes are furnished with these feathers, but they are generally larger in\nthe male than in the female, and emit a deeper note.  In some species, as\nin S. frenata (Fig. 42), four feathers, and in S. javensis (Fig. 43), no\nless than eight on each side of the tail are greatly modified.  Different\ntones are emitted by the feathers of the different species when waved\nthrough the air; and the Scolopax Wilsonii of the United States makes a\nswitching noise whilst descending rapidly to the earth.  (53.  See M.\nMeves' interesting paper in 'Proc. Zool. Soc.' 1858, p. 199.  For the\nhabits of the snipe, Macgillivray, 'History of British Birds,' vol. iv. p.\n371.  For the American snipe, Capt. Blakiston, 'Ibis,' vol. v. 1863, p.\n131.)\n\n[Fig. 44.  Primary wing-feather of a Humming-bird, the Selasphorus\nplatycercus (from a sketch by Mr. Salvin).\nUpper figure, that of male;\nlower figure, corresponding feather of female.]\n\nIn the male of the Chamaepetes unicolor (a large gallinaceous bird of\nAmerica), the first primary wing-feather is arched towards the tip and is\nmuch more attenuated than in the female.  In an allied bird, the Penelope\nnigra, Mr. Salvin observed a male, which, whilst it flew downwards \"with\noutstretched wings, gave forth a kind of crashing rushing noise,\" like the\nfalling of a tree.  (54.  Mr. Salvin, in 'Proceedings, Zoological Society,'\n1867, p. 160.  I am much indebted to this distinguished ornithologist for\nsketches of the feathers of the Chamaepetes, and for other information.)\nThe male alone of one of the Indian bustards (Sypheotides auritus) has its\nprimary wing-feathers greatly acuminated; and the male of an allied species\nis known to make a humming noise whilst courting the female.  (55.  Jerdon,\n'Birds of India,' vol. iii. pp. 618, 621.)  In a widely different group of\nbirds, namely Humming-birds, the males alone of certain kinds have either\nthe shafts of their primary wing-feathers broadly dilated, or the webs\nabruptly excised towards the extremity.  The male, for instance, of\nSelasphorus platycercus, when adult, has the first primary wing-feather\n(Fig. 44), thus excised.  Whilst flying from flower to flower he makes \"a\nshrill, almost whistling noise\" (56.  Gould, 'Introduction to the\nTrochilidae,' 1861, p. 49.  Salvin, 'Proceedings, Zoological Society,'\n1867, p. 160.); but it did not appear to Mr. Salvin that the noise was\nintentionally made.\n\n[Fig. 45.  Secondary wing-feathers of Pipra deliciosa (from Mr. Sclater, in\n'Proc. Zool. Soc.' 1860).\nThe three upper feathers, a, b, c, from the male;\nthe three lower corresponding feathers, d, e, f, from the female.\na and d, fifth secondary wing-feather of male and female, upper surface.\nb and e, sixth secondary, upper surface.\nc and f, seventh secondary, lower surface.]\n\nLastly, in several species of a sub-genus of Pipra or Manakin, the males,\nas described by Mr. Sclater, have their SECONDARY wing-feathers modified in\na still more remarkable manner.  In the brilliantly-coloured P. deliciosa\nthe first three secondaries are thick-stemmed and curved towards the body;\nin the fourth and fifth (Fig. 45, a) the change is greater; and in the\nsixth and seventh (b, c) the shaft \"is thickened to an extraordinary\ndegree, forming a solid horny lump.\"  The barbs also are greatly changed in\nshape, in comparison with the corresponding feathers (d, e, f) in the\nfemale.  Even the bones of the wing, which support these singular feathers\nin the male, are said by Mr. Fraser to be much thickened.  These little\nbirds make an extraordinary noise, the first \"sharp note being not unlike\nthe crack of a whip.\"  (57.  Sclater, in 'Proceedings, Zoological Society,'\n1860, p. 90, and in 'Ibis,' vol. iv. 1862, p. 175.  Also Salvin, in 'Ibis,'\n1860, p. 37.)\n\nThe diversity of the sounds, both vocal and instrumental, made by the males\nof many birds during the breeding-season, and the diversity of the means\nfor producing such sounds, are highly remarkable.  We thus gain a high idea\nof their importance for sexual purposes, and are reminded of the conclusion\narrived at as to insects.  It is not difficult to imagine the steps by\nwhich the notes of a bird, primarily used as a mere call or for some other\npurpose, might have been improved into a melodious love song.  In the case\nof the modified feathers, by which the drumming, whistling, or roaring\nnoises are produced, we know that some birds during their courtship\nflutter, shake, or rattle their unmodified feathers together; and if the\nfemales were led to select the best performers, the males which possessed\nthe strongest or thickest, or most attenuated feathers, situated on any\npart of the body, would be the most successful; and thus by slow degrees\nthe feathers might be modified to almost any extent.  The females, of\ncourse, would not notice each slight successive alteration in shape, but\nonly the sounds thus produced.  It is a curious fact that in the same class\nof animals, sounds so different as the drumming of the snipe's tail, the\ntapping of the woodpecker's beak, the harsh trumpet-like cry of certain\nwater-fowl, the cooing of the turtle-dove, and the song of the nightingale,\nshould all be pleasing to the females of the several species.  But we must\nnot judge of the tastes of distinct species by a uniform standard; nor must\nwe judge by the standard of man's taste.  Even with man, we should remember\nwhat discordant noises, the beating of tom-toms and the shrill notes of\nreeds, please the ears of savages.  Sir S. Baker remarks (58.  'The Nile\nTributaries of Abyssinia,' 1867, p. 203.), that \"as the stomach of the Arab\nprefers the raw meat and reeking liver taken hot from the animal, so does\nhis ear prefer his equally coarse and discordant music to all other.\"\n\nLOVE ANTICS AND DANCES.\n\nThe curious love gestures of some birds have already been incidentally\nnoticed; so that little need here be added.  In Northern America large\nnumbers of a grouse, the Tetrao phasianellus, meet every morning during the\nbreeding-season on a selected level spot, and here they run round and round\nin a circle of about fifteen or twenty feet in diameter, so that the ground\nis worn quite bare, like a fairy-ring.  In these Partridge-dances, as they\nare called by the hunters, the birds assume the strangest attitudes, and\nrun round, some to the left and some to the right.  Audubon describes the\nmales of a heron (Ardea herodias) as walking about on their long legs with\ngreat dignity before the females, bidding defiance to their rivals.  With\none of the disgusting carrion-vultures (Cathartes jota) the same naturalist\nstates that \"the gesticulations and parade of the males at the beginning of\nthe love-season are extremely ludicrous.\"  Certain birds perform their\nlove-antics on the wing, as we have seen with the black African weaver,\ninstead of on the ground.  During the spring our little white-throat\n(Sylvia cinerea) often rises a few feet or yards in the air above some\nbush, and \"flutters with a fitful and fantastic motion, singing all the\nwhile, and then drops to its perch.\"  The great English bustard throws\nhimself into indescribably odd attitudes whilst courting the female, as has\nbeen figured by Wolf.  An allied Indian bustard (Otis bengalensis) at such\ntimes \"rises perpendicularly into the air with a hurried flapping of his\nwings, raising his crest and puffing out the feathers of his neck and\nbreast, and then drops to the ground;\" he repeats this manoeuvre several\ntimes, at the same time humming in a peculiar tone.  Such females as happen\nto be near \"obey this saltatory summons,\" and when they approach he trails\nhis wings and spreads his tail like a turkey-cock.  (59.  For Tetrao\nphasianellus, see Richardson, 'Fauna, Bor. America,' p. 361, and for\nfurther particulars Capt. Blakiston, 'Ibis,' 1863, p. 125.  For the\nCathartes and Ardea, Audubon, 'Ornithological Biography,' vol. ii. p. 51,\nand vol. iii. p. 89.  On the White-throat, Macgillivray, 'History of\nBritish Birds,' vol. ii. p. 354.  On the Indian Bustard, Jerdon, 'Birds of\nIndia,' vol. iii. p. 618.)\n\n[Fig. 46.  Bower-bird, Chlamydera maculata, with bower (from Brehm).]\n\nBut the most curious case is afforded by three allied genera of Australian\nbirds, the famous Bower-birds,--no doubt the co-descendants of some ancient\nspecies which first acquired the strange instinct of constructing bowers\nfor performing their love-antics.  The bowers (Fig. 46), which, as we shall\nhereafter see, are decorated with feathers, shells, bones, and leaves, are\nbuilt on the ground for the sole purpose of courtship, for their nests are\nformed in trees.  Both sexes assist in the erection of the bowers, but the\nmale is the principal workman.  So strong is this instinct that it is\npractised under confinement, and Mr. Strange has described (60.  Gould,\n'Handbook to the Birds of Australia,' vol. i. pp. 444, 449, 455.  The bower\nof the Satin Bower-bird may be seen in the Zoological Society's Gardens,\nRegent's Park.) the habits of some Satin Bower-birds which he kept in an\naviary in New South Wales.  \"At times the male will chase the female all\nover the aviary, then go to the bower, pick up a gay feather or a large\nleaf, utter a curious kind of note, set all his feathers erect, run round\nthe bower and become so excited that his eyes appear ready to start from\nhis head; he continues opening first one wing then the other, uttering a\nlow, whistling note, and, like the domestic cock, seems to be picking up\nsomething from the ground, until at last the female goes gently towards\nhim.\"  Captain Stokes has described the habits and \"play-houses\" of another\nspecies, the Great Bower-bird, which was seen \"amusing itself by flying\nbackwards and forwards, taking a shell alternately from each side, and\ncarrying it through the archway in its mouth.\"  These curious structures,\nformed solely as halls of assemblage, where both sexes amuse themselves and\npay their court, must cost the birds much labour.  The bower, for instance,\nof the Fawn-breasted species, is nearly four feet in length, eighteen\ninches in height, and is raised on a thick platform of sticks.\n\nDECORATION.\n\nI will first discuss the cases in which the males are ornamented either\nexclusively or in a much higher degree than the females, and in a\nsucceeding chapter those in which both sexes are equally ornamented, and\nfinally the rare cases in which the female is somewhat more brightly-\ncoloured than the male.  As with the artificial ornaments used by savage\nand civilised men, so with the natural ornaments of birds, the head is the\nchief seat of decoration.  (61.  See remarks to this effect, on the\n'Feeling of Beauty among Animals,' by Mr. J. Shaw, in the 'Athenaeum,' Nov.\n24th, 1866, p. 681.)  The ornaments, as mentioned at the commencement of\nthis chapter, are wonderfully diversified.  The plumes on the front or back\nof the head consist of variously-shaped feathers, sometimes capable of\nerection or expansion, by which their beautiful colours are fully\ndisplayed.  Elegant ear-tufts (Fig. 39) are occasionally present.  The head\nis sometimes covered with velvety down, as with the pheasant; or is naked\nand vividly coloured.  The throat, also, is sometimes ornamented with a\nbeard, wattles, or caruncles.  Such appendages are generally brightly-\ncoloured, and no doubt serve as ornaments, though not always ornamental in\nour eyes; for whilst the male is in the act of courting the female, they\noften swell and assume vivid tints, as in the male turkey.  At such times\nthe fleshy appendages about the head of the male Tragopan pheasant\n(Ceriornis Temminckii) swell into a large lappet on the throat and into two\nhorns, one on each side of the splendid top-knot; and these are then\ncoloured of the most intense blue which I have ever beheld.  (62.  See Dr.\nMurie's account with coloured figures in 'Proceedings, Zoological Society,'\n1872, p. 730.)  The African hornbill (Bucorax abyssinicus) inflates the\nscarlet bladder-like wattle on its neck, and with its wings drooping and\ntail expanded \"makes quite a grand appearance.\"  (63.  Mr. Monteiro,\n'Ibis,' vol. iv. 1862, p. 339.)  Even the iris of the eye is sometimes more\nbrightly-coloured in the male than in the female; and this is frequently\nthe case with the beak, for instance, in our common blackbird.  In Buceros\ncorrugatus, the whole beak and immense casque are coloured more\nconspicuously in the male than in the female; and \"the oblique grooves upon\nthe sides of the lower mandible are peculiar to the male sex.\"  (64.  'Land\nand Water,' 1868, p. 217.)\n\nThe head, again, often supports fleshy appendages, filaments, and solid\nprotuberances.  These, if not common to both sexes, are always confined to\nthe males.  The solid protuberances have been described in detail by Dr. W.\nMarshall (65.  'Ueber die Schaedelhoecker,' etc., 'Niederland. Archiv. fur\nZoologie,' B. I. Heft 2, 1872.), who shews that they are formed either of\ncancellated bone coated with skin, or of dermal and other tissues.  With\nmammals true horns are always supported on the frontal bones, but with\nbirds various bones have been modified for this purpose; and in species of\nthe same group the protuberances may have cores of bone, or be quite\ndestitute of them, with intermediate gradations connecting these two\nextremes.  Hence, as Dr. Marshall justly remarks, variations of the most\ndifferent kinds have served for the development through sexual selection of\nthese ornamental appendages.  Elongated feathers or plumes spring from\nalmost every part of the body.  The feathers on the throat and breast are\nsometimes developed into beautiful ruffs and collars.  The tail-feathers\nare frequently increased in length; as we see in the tail-coverts of the\npeacock, and in the tail itself of the Argus pheasant.  With the peacock\neven the bones of the tail have been modified to support the heavy tail-\ncoverts.  (66.  Dr. W. Marshall, 'Ueber den Vogelschwanz,' ibid. B. I. Heft\n2, 1872.)  The body of the Argus is not larger than that of a fowl; yet the\nlength from the end of the beak to the extremity of the tail is no less\nthan five feet three inches (67.  Jardine's 'Naturalist Library:  Birds,'\nvol. xiv. p. 166.), and that of the beautifully ocellated secondary wing-\nfeathers nearly three feet.  In a small African night-jar (Cosmetornis\nvexillarius) one of the primary wing-feathers, during the breeding-season,\nattains a length of twenty-six inches, whilst the bird itself is only ten\ninches in length.  In another closely-allied genus of night-jars, the\nshafts of the elongated wing-feathers are naked, except at the extremity,\nwhere there is a disc.  (68.  Sclater, in the 'Ibis,' vol. vi. 1864, p.\n114; Livingstone, 'Expedition to the Zambesi,' 1865, p. 66.)  Again, in\nanother genus of night-jars, the tail-feathers are even still more\nprodigiously developed.  In general the feathers of the tail are more often\nelongated than those of the wings, as any great elongation of the latter\nimpedes flight.  We thus see that in closely-allied birds ornaments of the\nsame kind have been gained by the males through the development of widely\ndifferent feathers.\n\nIt is a curious fact that the feathers of species belonging to very\ndistinct groups have been modified in almost exactly the same peculiar\nmanner.  Thus the wing-feathers in one of the above-mentioned night-jars\nare bare along the shaft, and terminate in a disc; or are, as they are\nsometimes called, spoon or racket-shaped.  Feathers of this kind occur in\nthe tail of a motmot (Eumomota superciliaris), of a king-fisher, finch,\nhumming-bird, parrot, several Indian drongos (Dicrurus and Edolius, in one\nof which the disc stands vertically), and in the tail of certain birds of\nparadise.  In these latter birds, similar feathers, beautifully ocellated,\nornament the head, as is likewise the case with some gallinaceous birds.\nIn an Indian bustard (Sypheotides auritus) the feathers forming the ear-\ntufts, which are about four inches in length, also terminate in discs.\n(69.  Jerdon, 'Birds of India,' vol. iii. p. 620.)  It is a most singular\nfact that the motmots, as Mr. Salvin has clearly shewn (70.  'Proceedings,\nZoological Society,' 1873, p. 429.), give to their tail feathers the\nracket-shape by biting off the barbs, and, further, that this continued\nmutilation has produced a certain amount of inherited effect.\n\n[Fig. 47.  Paradisea Papuana (T.W. Wood).]\n\nAgain, the barbs of the feathers in various widely-distinct birds are\nfilamentous or plumose, as with some herons, ibises, birds of paradise, and\nGallinaceae.  In other cases the barbs disappear, leaving the shafts bare\nfrom end to end; and these in the tail of the Paradisea apoda attain a\nlength of thirty-four inches (71.  Wallace, in 'Annals and Magazine of\nNatural History,' vol. xx. 1857, p. 416, and in his 'Malay Archipelago,'\nvol. ii. 1869, p. 390.):  in P. Papuana (Fig. 47) they are much shorter and\nthin.  Smaller feathers when thus denuded appear like bristles, as on the\nbreast of the turkey-cock.  As any fleeting fashion in dress comes to be\nadmired by man, so with birds a change of almost any kind in the structure\nor colouring of the feathers in the male appears to have been admired by\nthe female.  The fact of the feathers in widely distinct groups having been\nmodified in an analogous manner no doubt depends primarily on all the\nfeathers having nearly the same structure and manner of development, and\nconsequently tending to vary in the same manner.  We often see a tendency\nto analogous variability in the plumage of our domestic breeds belonging to\ndistinct species.  Thus top-knots have appeared in several species.  In an\nextinct variety of the turkey, the top-knot consisted of bare quills\nsurmounted with plumes of down, so that they somewhat resembled the racket-\nshaped feathers above described.  In certain breeds of the pigeon and fowl\nthe feathers are plumose, with some tendency in the shafts to be naked.  In\nthe Sebastopol goose the scapular feathers are greatly elongated, curled,\nor even spirally twisted, with the margins plumose.  (72.  See my work on\n'The Variation of Animals and Plants under Domestication,' vol. i. pp. 289,\n293.)\n\nIn regard to colour, hardly anything need here be said, for every one knows\nhow splendid are the tints of many birds, and how harmoniously they are\ncombined.  The colours are often metallic and iridescent.  Circular spots\nare sometimes surrounded by one or more differently shaded zones, and are\nthus converted into ocelli.  Nor need much be said on the wonderful\ndifference between the sexes of many birds.  The common peacock offers a\nstriking instance.  Female birds of paradise are obscurely coloured and\ndestitute of all ornaments, whilst the males are probably the most highly\ndecorated of all birds, and in so many different ways that they must be\nseen to be appreciated.  The elongated and golden-orange plumes which\nspring from beneath the wings of the Paradisea apoda, when vertically\nerected and made to vibrate, are described as forming a sort of halo, in\nthe centre of which the head \"looks like a little emerald sun with its rays\nformed by the two plumes.\"  (73.  Quoted from M. de Lafresnaye in 'Annals\nand Mag. of Natural History,' vol. xiii. 1854, p. 157:  see also Mr.\nWallace's much fuller account in vol. xx. 1857, p. 412, and in his 'Malay\nArchipelago.')  In another most beautiful species the head is bald, \"and\nof a rich cobalt blue, crossed by several lines of black velvety feathers.\"\n(74.  Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 405.)\n\n[Fig. 48.  Lophornis ornatus, male and female (from Brehm).\n\nFig. 49.  Spathura underwoodi, male and female (from Brehm).]\n\nMale humming-birds (Figs. 48 and 49) almost vie with birds of paradise in\ntheir beauty, as every one will admit who has seen Mr. Gould's splendid\nvolumes, or his rich collection.  It is very remarkable in how many\ndifferent ways these birds are ornamented.  Almost every part of their\nplumage has been taken advantage of, and modified; and the modifications\nhave been carried, as Mr. Gould shewed me, to a wonderful extreme in some\nspecies belonging to nearly every sub-group.  Such cases are curiously like\nthose which we see in our fancy breeds, reared by man for the sake of\nornament; certain individuals originally varied in one character, and other\nindividuals of the same species in other characters; and these have been\nseized on by man and much augmented--as shewn by the tail of the fantail-\npigeon, the hood of the jacobin, the beak and wattle of the carrier, and so\nforth.  The sole difference between these cases is that in the one, the\nresult is due to man's selection, whilst in the other, as with humming-\nbirds, birds of paradise, etc., it is due to the selection by the females\nof the more beautiful males.\n\nI will mention only one other bird, remarkable from the extreme contrast in\ncolour between the sexes, namely the famous bell-bird (Chasmorhynchus\nniveus) of S. America, the note of which can be distinguished at the\ndistance of nearly three miles, and astonishes every one when first hearing\nit.  The male is pure white, whilst the female is dusky-green; and white is\na very rare colour in terrestrial species of moderate size and inoffensive\nhabits.  The male, also, as described by Waterton, has a spiral tube,\nnearly three inches in length, which rises from the base of the beak.  It\nis jet-black, dotted over with minute downy feathers.  This tube can be\ninflated with air, through a communication with the palate; and when not\ninflated hangs down on one side.  The genus consists of four species, the\nmales of which are very distinct, whilst the females, as described by Mr.\nSclater in a very interesting paper, closely resemble each other, thus\noffering an excellent instance of the common rule that within the same\ngroup the males differ much more from each other than do the females.  In a\nsecond species (C. nudicollis) the male is likewise snow-white, with the\nexception of a large space of naked skin on the throat and round the eyes,\nwhich during the breeding-season is of a fine green colour.  In a third\nspecies (C. tricarunculatus) the head and neck alone of the male are white,\nthe rest of the body being chestnut-brown, and the male of this species is\nprovided with three filamentous projections half as long as the body--one\nrising from the base of the beak, and the two others from the corners of\nthe mouth.   (75.  Mr. Sclater, 'Intellectual Observer,' Jan. 1867.\nWaterton's 'Wanderings,' p. 118.  See also Mr. Salvin's interesting paper,\nwith a plate, in the 'Ibis,' 1865, p. 90.)\n\nThe coloured plumage and certain other ornaments of the adult males are\neither retained for life, or are periodically renewed during the summer and\nbreeding-season.  At this same season the beak and naked skin about the\nhead frequently change colour, as with some herons, ibises, gulls, one of\nthe bell-birds just noticed, etc.  In the white ibis, the cheeks, the\ninflatable skin of the throat, and the basal portion of the beak then\nbecome crimson.  (76.  'Land and Water,' 1867, p. 394.)  In one of the\nrails, Gallicrex cristatus, a large red caruncle is developed during this\nperiod on the head of the male.  So it is with a thin horny crest on the\nbeak of one of the pelicans, P. erythrorhynchus; for, after the breeding-\nseason, these horny crests are shed, like horns from the heads of stags,\nand the shore of an island in a lake in Nevada was found covered with these\ncurious exuviae.  (77.  Mr. D.G. Elliot, in 'Proc. Zool. Soc.' 1869, p.\n589.)\n\nChanges of colour in the plumage according to the season depend, firstly on\na double annual moult, secondly on an actual change of colour in the\nfeathers themselves, and thirdly on their dull-coloured margins being\nperiodically shed, or on these three processes more or less combined.  The\nshedding of the deciduary margins may be compared with the shedding of\ntheir down by very young birds; for the down in most cases arises from the\nsummits of the first true feathers.  (78.  Nitzsch's 'Pterylography,'\nedited by P.L. Sclater, Ray Society, 1867, p. 14.)\n\nWith respect to the birds which annually undergo a double moult, there are,\nfirstly, some kinds, for instance snipes, swallow-plovers (Glareolae), and\ncurlews, in which the two sexes resemble each other, and do not change\ncolour at any season.  I do not know whether the winter plumage is thicker\nand warmer than the summer plumage, but warmth seems the most probable end\nattained of a double moult, where there is no change of colour.  Secondly,\nthere are birds, for instance, certain species of Totanus and other\nGrallatores, the sexes of which resemble each other, but in which the\nsummer and winter plumage differ slightly in colour.  The difference,\nhowever, in these cases is so small that it can hardly be an advantage to\nthem; and it may, perhaps, be attributed to the direct action of the\ndifferent conditions to which the birds are exposed during the two seasons.\nThirdly, there are many other birds the sexes of which are alike, but which\nare widely different in their summer and winter plumage.  Fourthly, there\nare birds the sexes of which differ from each other in colour; but the\nfemales, though moulting twice, retain the same colours throughout the\nyear, whilst the males undergo a change of colour, sometimes a great one,\nas with certain bustards.  Fifthly and lastly, there are birds the sexes of\nwhich differ from each other in both their summer and winter plumage; but\nthe male undergoes a greater amount of change at each recurrent season than\nthe female--of which the ruff (Machetes pugnax) offers a good instance.\n\nWith respect to the cause or purpose of the differences in colour between\nthe summer and winter plumage, this may in some instances, as with the\nptarmigan (79.  The brown mottled summer plumage of the ptarmigan is of as\nmuch importance to it, as a protection, as the white winter plumage; for in\nScandinavia during the spring, when the snow has disappeared, this bird is\nknown to suffer greatly from birds of prey, before it has acquired its\nsummer dress:  see Wilhelm von Wright, in Lloyd, 'Game Birds of Sweden,'\n1867, p. 125.), serve during both seasons as a protection.  When the\ndifference between the two plumages is slight it may perhaps be attributed,\nas already remarked, to the direct action of the conditions of life.  But\nwith many birds there can hardly be a doubt that the summer plumage is\nornamental, even when both sexes are alike.  We may conclude that this is\nthe case with many herons, egrets, etc., for they acquire their beautiful\nplumes only during the breeding-season.  Moreover, such plumes, top-knots,\netc., though possessed by both sexes, are occasionally a little more\ndeveloped in the male than in the female; and they resemble the plumes and\nornaments possessed by the males alone of other birds.  It is also known\nthat confinement, by affecting the reproductive system of male birds,\nfrequently checks the development of their secondary sexual characters, but\nhas no immediate influence on any other characters; and I am informed by\nMr. Bartlett that eight or nine specimens of the Knot (Tringa canutus)\nretained their unadorned winter plumage in the Zoological Gardens\nthroughout the year, from which fact we may infer that the summer plumage,\nthough common to both sexes, partakes of the nature of the exclusively\nmasculine plumage of many other birds.  (80.  In regard to the previous\nstatements on moulting, see, on snipes, etc., Macgillivray, 'Hist. Brit.\nBirds,' vol. iv. p. 371; on Glareolae, curlews, and bustards, Jerdon,\n'Birds of India,' vol. iii. pp. 615, 630, 683; on Totanus, ibid. p. 700; on\nthe plumes of herons, ibid. p. 738, and Macgillivray, vol. iv. pp. 435 and\n444, and Mr. Stafford Allen, in the 'Ibis,' vol. v. 1863, p. 33.)\n\nFrom the foregoing facts, more especially from neither sex of certain birds\nchanging colour during either annual moult, or changing so slightly that\nthe change can hardly be of any service to them, and from the females of\nother species moulting twice yet retaining the same colours throughout the\nyear, we may conclude that the habit of annually moulting twice has not\nbeen acquired in order that the male should assume an ornamental character\nduring the breeding-season; but that the double moult, having been\noriginally acquired for some distinct purpose, has subsequently been taken\nadvantage of in certain cases for gaining a nuptial plumage.\n\nIt appears at first sight a surprising circumstance that some closely-\nallied species should regularly undergo a double annual moult, and others\nonly a single one.  The ptarmigan, for instance, moults twice or even\nthrice in the year, and the blackcock only once:  some of the splendidly\ncoloured honey-suckers (Nectariniae) of India and some sub-genera of\nobscurely coloured pipits (Anthus) have a double, whilst others have only a\nsingle annual moult.  (81.  On the moulting of the ptarmigan, see Gould's\n'Birds of Great Britain.'  On the honey-suckers, Jerdon, 'Birds of India,'\nvol. i. pp. 359, 365, 369.  On the moulting of Anthus, see Blyth, in\n'Ibis,' 1867, p. 32.)  But the gradations in the manner of moulting, which\nare known to occur with various birds, shew us how species, or whole\ngroups, might have originally acquired their double annual moult, or having\nonce gained the habit, have again lost it.  With certain bustards and\nplovers the vernal moult is far from complete, some feathers being renewed,\nand some changed in colour.  There is also reason to believe that with\ncertain bustards and rail-like birds, which properly undergo a double\nmoult, some of the older males retain their nuptial plumage throughout the\nyear.  A few highly modified feathers may merely be added during the spring\nto the plumage, as occurs with the disc-formed tail-feathers of certain\ndrongos (Bhringa) in India, and with the elongated feathers on the back,\nneck, and crest of certain herons.  By such steps as these, the vernal\nmoult might be rendered more and more complete, until a perfect double\nmoult was acquired.  Some of the birds of paradise retain their nuptial\nfeathers throughout the year, and thus have only a single moult; others\ncast them directly after the breeding-season, and thus have a double moult;\nand others again cast them at this season during the first year, but not\nafterwards; so that these latter species are intermediate in their manner\nof moulting.  There is also a great difference with many birds in the\nlength of time during which the two annual plumages are retained; so that\nthe one might come to be retained for the whole year, and the other\ncompletely lost.  Thus in the spring Machetes pugnax retains his ruff for\nbarely two months.  In Natal the male widow-bird (Chera progne) acquires\nhis fine plumage and long tail-feathers in December or January, and loses\nthem in March; so that they are retained only for about three months.  Most\nspecies, which undergo a double moult, keep their ornamental feathers for\nabout six months.  The male, however, of the wild Gallus bankiva retains\nhis neck-hackles for nine or ten months; and when these are cast off, the\nunderlying black feathers on the neck are fully exposed to view.  But with\nthe domesticated descendant of this species, the neck-hackles of the male\nare immediately replaced by new ones; so that we here see, as to part of\nthe plumage, a double moult changed under domestication into a single\nmoult.  (82.  For the foregoing statements in regard to partial moults, and\non old males retaining their nuptial plumage, see Jerdon, on bustards and\nplovers, in 'Birds of India,' vol. iii. pp. 617, 637, 709, 711.  Also Blyth\nin 'Land and Water,' 1867, p. 84.  On the moulting of Paradisea, see an\ninteresting article by Dr. W. Marshall, 'Archives Neerlandaises,' tom. vi.\n1871.  On the Vidua, 'Ibis,' vol. iii. 1861, p. 133.  On the Drongo-\nshrikes, Jerdon, ibid. vol. i. p. 435.  On the vernal moult of the Herodias\nbubulcus, Mr. S.S. Allen, in 'Ibis,' 1863, p. 33.  On Gallus bankiva,\nBlyth, in 'Annals and Mag. of Natural History,' vol. i. 1848, p. 455; see,\nalso, on this subject, my 'Variation of Animals under Domestication,' vol.\ni. p. 236.)\n\nThe common drake (Anas boschas), after the breeding-season, is well known\nto lose his male plumage for a period of three months, during which time he\nassumes that of the female.  The male pin-tail duck (Anas acuta) loses his\nplumage for the shorter period of six weeks or two months; and Montagu\nremarks that \"this double moult within so short a time is a most\nextraordinary circumstance, that seems to bid defiance to all human\nreasoning.\"  But the believer in the gradual modification of species will\nbe far from feeling surprise at finding gradations of all kinds.  If the\nmale pin-tail were to acquire his new plumage within a still shorter\nperiod, the new male feathers would almost necessarily be mingled with the\nold, and both with some proper to the female; and this apparently is the\ncase with the male of a not distantly-allied bird, namely the Merganser\nserrator, for the males are said to \"undergo a change of plumage, which\nassimilates them in some measure to the female.\"  By a little further\nacceleration in the process, the double moult would be completely lost.\n(83.  See Macgillivray, 'Hist. British Birds' (vol. v. pp. 34, 70, and\n223), on the moulting of the Anatidae, with quotations from Waterton and\nMontagu.  Also Yarrell, 'History of British Birds,' vol. iii. p. 243.)\n\nSome male birds, as before stated, become more brightly coloured in the\nspring, not by a vernal moult, but either by an actual change of colour in\nthe feathers, or by their obscurely-coloured deciduary margins being shed.\nChanges of colour thus caused may last for a longer or shorter time.  In\nthe Pelecanus onocrotalus a beautiful rosy tint, with lemon-coloured marks\non the breast, overspreads the whole plumage in the spring; but these\ntints, as Mr. Sclater states, \"do not last long, disappearing generally in\nabout six weeks or two months after they have been attained.\"  Certain\nfinches shed the margins of their feathers in the spring, and then become\nbrighter coloured, while other finches undergo no such change.  Thus the\nFringilla tristis of the United States (as well as many other American\nspecies) exhibits its bright colours only when the winter is past, whilst\nour goldfinch, which exactly represents this bird in habits, and our\nsiskin, which represents it still more closely in structure, undergo no\nsuch annual change.  But a difference of this kind in the plumage of allied\nspecies is not surprising, for with the common linnet, which belongs to the\nsame family, the crimson forehead and breast are displayed only during the\nsummer in England, whilst in Madeira these colours are retained throughout\nthe year.  (84.  On the pelican, see Sclater, in 'Proc. Zool. Soc.' 1868,\np. 265.  On the American finches, see Audubon, 'Ornithological Biography,'\nvol. i. pp. 174, 221, and Jerdon, 'Birds of India,' vol. ii. p. 383.  On\nthe Fringilla cannabina of Madeira, Mr. E. Vernon Harcourt, 'Ibis,' vol. v.\n1863, p. 230.)\n\nDISPLAY BY MALE BIRDS OF THEIR PLUMAGE.\n\nOrnaments of all kinds, whether permanently or temporarily gained, are\nsedulously displayed by the males, and apparently serve to excite, attract,\nor fascinate the females.  But the males will sometimes display their\nornaments, when not in the presence of the females, as occasionally occurs\nwith grouse at their balz-places, and as may be noticed with the peacock;\nthis latter bird, however, evidently wishes for a spectator of some kind,\nand, as I have often seen, will shew off his finery before poultry, or even\npigs.  (85.  See also 'Ornamental Poultry,' by Rev. E.S. Dixon, 1848, p.\n8.)  All naturalists who have closely attended to the habits of birds,\nwhether in a state of nature or under confinement, are unanimously of\nopinion that the males take delight in displaying their beauty.  Audubon\nfrequently speaks of the male as endeavouring in various ways to charm the\nfemale.  Mr. Gould, after describing some peculiarities in a male humming-\nbird, says he has no doubt that it has the power of displaying them to the\ngreatest advantage before the female.  Dr. Jerdon (86.  'Birds of India,'\nintroduct., vol. i. p. xxiv.; on the peacock, vol. iii. p. 507.  See\nGould's 'Introduction to Trochilidae,' 1861, pp. 15 and 111.) insists that\nthe beautiful plumage of the male serves \"to fascinate and attract the\nfemale.\"  Mr. Bartlett, at the Zoological Gardens, expressed himself to me\nin the strongest terms to the same effect.\n\n[Fig. 50.  Rupicola crocea, male (T.W. Wood).]\n\nIt must be a grand sight in the forests of India \"to come suddenly on\ntwenty or thirty pea-fowl, the males displaying their gorgeous trains, and\nstrutting about in all the pomp of pride before the gratified females.\"\nThe wild turkey-cock erects his glittering plumage, expands his finely-\nzoned tail and barred wing-feathers, and altogether, with his crimson and\nblue wattles, makes a superb, though, to our eyes, grotesque appearance.\nSimilar facts have already been given with respect to grouse of various\nkinds.  Turning to another Order:  The male Rupicola crocea (Fig. 50) is\none of the most beautiful birds in the world, being of a splendid orange,\nwith some of the feathers curiously truncated and plumose.  The female is\nbrownish-green, shaded with red, and has a much smaller crest.  Sir R.\nSchomburgk has described their courtship; he found one of their meeting-\nplaces where ten males and two females were present.  The space was from\nfour to five feet in diameter, and appeared to have been cleared of every\nblade of grass and smoothed as if by human hands.  A male \"was capering, to\nthe apparent delight of several others.  Now spreading its wings, throwing\nup its head, or opening its tail like a fan; now strutting about with a\nhopping gait until tired, when it gabbled some kind of note, and was\nrelieved by another.  Thus three of them successively took the field, and\nthen, with self-approbation, withdrew to rest.\"  The Indians, in order to\nobtain their skins, wait at one of the meeting-places till the birds are\neagerly engaged in dancing, and then are able to kill with their poisoned\narrows four or five males, one after the other.  (87.  'Journal of R.\nGeograph. Soc.' vol. x. 1840, p. 236.)  With birds of paradise a dozen or\nmore full-plumaged males congregate in a tree to hold a dancing-party, as\nit is called by the natives:  and here they fly about, raise their wings,\nelevate their exquisite plumes, and make them vibrate, and the whole tree\nseems, as Mr. Wallace remarks, to be filled with waving plumes.  When thus\nengaged, they become so absorbed that a skilful archer may shoot nearly the\nwhole party.  These birds, when kept in confinement in the Malay\nArchipelago, are said to take much care in keeping their feathers clean;\noften spreading them out, examining them, and removing every speck of dirt.\nOne observer, who kept several pairs alive, did not doubt that the display\nof the male was intended to please the female.  (88.  'Annals and Mag. of\nNat. Hist.' vol. xiii. 1854, p. 157; also Wallace, ibid. vol. xx. 1857, p.\n412, and 'The Malay Archipelago,' vol. ii. 1869, p. 252.  Also Dr. Bennett,\nas quoted by Brehm, 'Thierleben,' B. iii. s. 326.)\n\n[Fig. 51.  Polyplectron chinquis, male (T.W. Wood).]\n\nThe Gold and Amherst pheasants during their courtship not only expand and\nraise their splendid frills, but twist them, as I have myself seen,\nobliquely towards the female on whichever side she may be standing,\nobviously in order that a large surface may be displayed before her.  (89.\nMr. T.W. Wood has given ('The Student,' April 1870, p. 115) a full account\nof this manner of display, by the Gold pheasant and by the Japanese\npheasant, Ph. versicolor; and he calls it the lateral or one-sided\ndisplay.)  They likewise turn their beautiful tails and tail-coverts a\nlittle towards the same side.  Mr. Bartlett has observed a male\nPolyplectron (Fig. 51) in the act of courtship, and has shewn me a specimen\nstuffed in the attitude then assumed.  The tail and wing-feathers of this\nbird are ornamented with beautiful ocelli, like those on the peacock's\ntrain.  Now when the peacock displays himself, he expands and erects his\ntail transversely to his body, for he stands in front of the female, and\nhas to shew off, at the same time, his rich blue throat and breast.  But\nthe breast of the Polyplectron is obscurely coloured, and the ocelli are\nnot confined to the tail-feathers.  Consequently the Polyplectron does not\nstand in front of the female; but he erects and expands his tail-feathers a\nlittle obliquely, lowering the expanded wing on the same side, and raising\nthat on the opposite side.  In this attitude the ocelli over the whole body\nare exposed at the same time before the eyes of the admiring female in one\ngrand bespangled expanse.  To whichever side she may turn, the expanded\nwings and the obliquely-held tail are turned towards her.  The male\nTragopan pheasant acts in nearly the same manner, for he raises the\nfeathers of the body, though not the wing itself, on the side which is\nopposite to the female, and which would otherwise be concealed, so that\nnearly all the beautifully spotted feathers are exhibited at the same time.\n\n[Fig. 52.  Side view of male Argus pheasant, whilst displaying before the\nfemale.  Observed and sketched from nature by T.W. Wood.]\n\nThe Argus pheasant affords a much more remarkable case.  The immensely\ndeveloped secondary wing-feathers are confined to the male; and each is\nornamented with a row of from twenty to twenty-three ocelli, above an inch\nin diameter.  These feathers are also elegantly marked with oblique stripes\nand rows of spots of a dark colour, like those on the skin of a tiger and\nleopard combined.  These beautiful ornaments are hidden until the male\nshows himself off before the female.  He then erects his tail, and expands\nhis wing-feathers into a great, almost upright, circular fan or shield,\nwhich is carried in front of the body.  The neck and head are held on one\nside, so that they are concealed by the fan; but the bird in order to see\nthe female, before whom he is displaying himself, sometimes pushes his head\nbetween two of the long wing-feathers (as Mr. Bartlett has seen), and then\npresents a grotesque appearance.  This must be a frequent habit with the\nbird in a state of nature, for Mr. Bartlett and his son on examining some\nperfect skins sent from the East, found a place between two of the feathers\nwhich was much frayed, as if the head had here frequently been pushed\nthrough.  Mr. Wood thinks that the male can also peep at the female on one\nside, beyond the margin of the fan.\n\nThe ocelli on the wing-feathers are wonderful objects; for they are so\nshaded that, as the Duke of Argyll remarks (90.  'The Reign of Law,' 1867,\np. 203.), they stand out like balls lying loosely within sockets.  When I\nlooked at the specimen in the British Museum, which is mounted with the\nwings expanded and trailing downwards, I was however greatly disappointed,\nfor the ocelli appeared flat, or even concave.  But Mr. Gould soon made the\ncase clear to me, for he held the feathers erect, in the position in which\nthey would naturally be displayed, and now, from the light shining on them\nfrom above, each ocellus at once resembled the ornament called a ball and\nsocket.  These feathers have been shown to several artists, and all have\nexpressed their admiration at the perfect shading.  It may well be asked,\ncould such artistically shaded ornaments have been formed by means of\nsexual selection?  But it will be convenient to defer giving an answer to\nthis question until we treat in the next chapter of the principle of\ngradation.\n\nThe foregoing remarks relate to the secondary wing-feathers, but the\nprimary wing-feathers, which in most gallinaceous birds are uniformly\ncoloured, are in the Argus pheasant equally wonderful.  They are of a soft\nbrown tint with numerous dark spots, each of which consists of two or three\nblack dots with a surrounding dark zone.  But the chief ornament is a space\nparallel to the dark-blue shaft, which in outline forms a perfect second\nfeather lying within the true feather.  This inner part is coloured of a\nlighter chestnut, and is thickly dotted with minute white points.  I have\nshewn this feather to several persons, and many have admired it even more\nthan the ball and socket feathers, and have declared that it was more like\na work of art than of nature.  Now these feathers are quite hidden on all\nordinary occasions, but are fully displayed, together with the long\nsecondary feathers, when they are all expanded together so as to form the\ngreat fan or shield.\n\nThe case of the male Argus pheasant is eminently interesting, because it\naffords good evidence that the most refined beauty may serve as a sexual\ncharm, and for no other purpose.  We must conclude that this is the case,\nas the secondary and primary wing-feathers are not at all displayed, and\nthe ball and socket ornaments are not exhibited in full perfection until\nthe male assumes the attitude of courtship.  The Argus pheasant does not\npossess brilliant colours, so that his success in love appears to depend on\nthe great size of his plumes, and on the elaboration of the most elegant\npatterns.  Many will declare that it is utterly incredible that a female\nbird should be able to appreciate fine shading and exquisite patterns.  It\nis undoubtedly a marvellous fact that she should possess this almost human\ndegree of taste.  He who thinks that he can safely gauge the discrimination\nand taste of the lower animals may deny that the female Argus pheasant can\nappreciate such refined beauty; but he will then be compelled to admit that\nthe extraordinary attitudes assumed by the male during the act of\ncourtship, by which the wonderful beauty of his plumage is fully displayed,\nare purposeless; and this is a conclusion which I for one will never admit.\n\nAlthough so many pheasants and allied gallinaceous birds carefully display\ntheir plumage before the females, it is remarkable, as Mr. Bartlett informs\nme, that this is not the case with the dull-coloured Eared and Cheer\npheasants (Crossoptilon auritum and Phasianus wallichii); so that these\nbirds seem conscious that they have little beauty to display.  Mr. Bartlett\nhas never seen the males of either of these species fighting together,\nthough he has not had such good opportunities for observing the Cheer as\nthe Eared pheasant.  Mr. Jenner Weir, also, finds that all male birds with\nrich or strongly-characterised plumage are more quarrelsome than the dull-\ncoloured species belonging to the same groups.  The goldfinch, for\ninstance, is far more pugnacious than the linnet, and the blackbird than\nthe thrush.  Those birds which undergo a seasonal change of plumage\nlikewise become much more pugnacious at the period when they are most gaily\nornamented.  No doubt the males of some obscurely-coloured birds fight\ndesperately together, but it appears that when sexual selection has been\nhighly influential, and has given bright colours to the males of any\nspecies, it has also very often given a strong tendency to pugnacity.  We\nshall meet with nearly analogous cases when we treat of mammals.  On the\nother hand, with birds the power of song and brilliant colours have rarely\nbeen both acquired by the males of the same species; but in this case the\nadvantage gained would have been the same, namely success in charming the\nfemale.  Nevertheless it must be owned that the males of several\nbrilliantly coloured birds have had their feathers specially modified for\nthe sake of producing instrumental music, though the beauty of this cannot\nbe compared, at least according to our taste, with that of the vocal music\nof many songsters.\n\nWe will now turn to male birds which are not ornamented in any high degree,\nbut which nevertheless display during their courtship whatever attractions\nthey may possess.  These cases are in some respects more curious than the\nforegoing, and have been but little noticed.  I owe the following facts to\nMr. Weir, who has long kept confined birds of many kinds, including all the\nBritish Fringillidae and Emberizidae.  The facts have been selected from a\nlarge body of valuable notes kindly sent me by him.  The bullfinch makes\nhis advances in front of the female, and then puffs out his breast, so that\nmany more of the crimson feathers are seen at once than otherwise would be\nthe case.  At the same time he twists and bows his black tail from side to\nside in a ludicrous manner.  The male chaffinch also stands in front of the\nfemale, thus shewing his red breast and \"blue bell,\" as the fanciers call\nhis head; the wings at the same time being slightly expanded, with the pure\nwhite bands on the shoulders thus rendered conspicuous.  The common linnet\ndistends his rosy breast, slightly expands his brown wings and tail, so as\nto make the best of them by exhibiting their white edgings.  We must,\nhowever, be cautious in concluding that the wings are spread out solely for\ndisplay, as some birds do so whose wings are not beautiful.  This is the\ncase with the domestic cock, but it is always the wing on the side opposite\nto the female which is expanded, and at the same time scraped on the\nground.  The male goldfinch behaves differently from all other finches:\nhis wings are beautiful, the shoulders being black, with the dark-tipped\nwing-feathers spotted with white and edged with golden yellow.  When he\ncourts the female, he sways his body from side to side, and quickly turns\nhis slightly expanded wings first to one side, then to the other, with a\ngolden flashing effect.  Mr. Weir informs me that no other British finch\nturns thus from side to side during his courtship, not even the closely-\nallied male siskin, for he would not thus add to his beauty.\n\nMost of the British Buntings are plain coloured birds; but in the spring\nthe feathers on the head of the male reed-bunting (Emberiza schoeniculus)\nacquire a fine black colour by the abrasion of the dusky tips; and these\nare erected during the act of courtship.  Mr. Weir has kept two species of\nAmadina from Australia:  the A. castanotis is a very small and chastely\ncoloured finch, with a dark tail, white rump, and jet-black upper tail-\ncoverts, each of the latter being marked with three large conspicuous oval\nspots of white.  (91.  For the description of these birds, see Gould's\n'Handbook to the Birds of Australia,' vol. i. 1865, p. 417.)  This species,\nwhen courting the female, slightly spreads out and vibrates these parti-\ncoloured tail-coverts in a very peculiar manner.  The male Amadina Lathami\nbehaves very differently, exhibiting before the female his brilliantly\nspotted breast, scarlet rump, and scarlet upper tail-coverts.  I may here\nadd from Dr. Jerdon that the Indian bulbul (Pycnonotus hoemorrhous) has its\nunder tail-coverts of a crimson colour, and these, it might be thought,\ncould never be well exhibited; but the bird \"when excited often spreads\nthem out laterally, so that they can be seen even from above.\"  (92.\n'Birds of India,' vol. ii. p. 96.)  The crimson under tail-coverts of some\nother birds, as with one of the woodpeckers, Picus major, can be seen\nwithout any such display.  The common pigeon has iridescent feathers on the\nbreast, and every one must have seen how the male inflates his breast\nwhilst courting the female, thus shewing them off to the best advantage.\nOne of the beautiful bronze-winged pigeons of Australia (Ocyphaps lophotes)\nbehaves, as described to me by Mr. Weir, very differently:  the male,\nwhilst standing before the female, lowers his head almost to the ground,\nspreads out and raises his tail, and half expands his wings.  He then\nalternately and slowly raises and depresses his body, so that the\niridescent metallic feathers are all seen at once, and glitter in the sun.\n\nSufficient facts have now been given to shew with what care male birds\ndisplay their various charms, and this they do with the utmost skill.\nWhilst preening their feathers, they have frequent opportunities for\nadmiring themselves, and of studying how best to exhibit their beauty.  But\nas all the males of the same species display themselves in exactly the same\nmanner, it appears that actions, at first perhaps intentional, have become\ninstinctive.  If so, we ought not to accuse birds of conscious vanity; yet\nwhen we see a peacock strutting about, with expanded and quivering tail-\nfeathers, he seems the very emblem of pride and vanity.\n\nThe various ornaments possessed by the males are certainly of the highest\nimportance to them, for in some cases they have been acquired at the\nexpense of greatly impeded powers of flight or of running.  The African\nnight-jar (Cosmetornis), which during the pairing-season has one of its\nprimary wing-feathers developed into a streamer of very great length, is\nthereby much retarded in its flight, although at other times remarkable for\nits swiftness.  The \"unwieldy size\" of the secondary wing-feathers of the\nmale Argus pheasant is said \"almost entirely to deprive the bird of\nflight.\"  The fine plumes of male birds of paradise trouble them during a\nhigh wind.  The extremely long tail-feathers of the male widow-birds\n(Vidua) of Southern Africa render \"their flight heavy;\" but as soon as\nthese are cast off they fly as well as the females.  As birds always breed\nwhen food is abundant, the males probably do not suffer much inconvenience\nin searching for food from their impeded powers of movement; but there can\nhardly be a doubt that they must be much more liable to be struck down by\nbirds of prey.  Nor can we doubt that the long train of the peacock and the\nlong tail and wing-feathers of the Argus pheasant must render them an\neasier prey to any prowling tiger-cat than would otherwise be the case.\nEven the bright colours of many male birds cannot fail to make them\nconspicuous to their enemies of all kinds.  Hence, as Mr. Gould has\nremarked, it probably is that such birds are generally of a shy\ndisposition, as if conscious that their beauty was a source of danger, and\nare much more difficult to discover or approach, than the sombre coloured\nand comparatively tame females or than the young and as yet unadorned\nmales.  (93.  On the Cosmetornis, see Livingstone's 'Expedition to the\nZambesi,' 1865, p. 66.  On the Argus pheasant, Jardine's 'Nat. Hist. Lib.:\nBirds,' vol. xiv. p. 167.  On Birds of Paradise, Lesson, quoted by Brehm,\n'Thierleben,' B. iii. s. 325.  On the widow-bird, Barrow's 'Travels in\nAfrica,' vol. i. p. 243, and 'Ibis,' vol. iii. 1861 p. 133.  Mr. Gould, on\nthe shyness of male birds, 'Handbook to Birds of Australia,' vol. i. 1865,\npp. 210, 457.)\n\nIt is a more curious fact that the males of some birds which are provided\nwith special weapons for battle, and which in a state of nature are so\npugnacious that they often kill each other, suffer from possessing certain\nornaments.  Cock-fighters trim the hackles and cut off the combs and gills\nof their cocks; and the birds are then said to be dubbed.  An undubbed\nbird, as Mr. Tegetmeier insists, \"is at a fearful disadvantage; the comb\nand gills offer an easy hold to his adversary's beak, and as a cock always\nstrikes where he holds, when once he has seized his foe, he has him\nentirely in his power.  Even supposing that the bird is not killed, the\nloss of blood suffered by an undubbed cock is much greater than that\nsustained by one that has been trimmed.\"  (94.  Tegetmeier, 'The Poultry\nBook,' 1866, p. 139.)  Young turkey-cocks in fighting always seize hold of\neach other's wattles; and I presume that the old birds fight in the same\nmanner.  It may perhaps be objected that the comb and wattles are not\nornamental, and cannot be of service to the birds in this way; but even to\nour eyes, the beauty of the glossy black Spanish cock is much enhanced by\nhis white face and crimson comb; and no one who has ever seen the splendid\nblue wattles of the male Tragopan pheasant distended in courtship can for a\nmoment doubt that beauty is the object gained.  From the foregoing facts we\nclearly see that the plumes and other ornaments of the males must be of the\nhighest importance to them; and we further see that beauty is even\nsometimes more important than success in battle.\n\n\nCHAPTER XIV.\n\nBIRDS--continued.\n\nChoice exerted by the female--Length of courtship--Unpaired birds--Mental\nqualities and taste for the beautiful--Preference or antipathy shewn by the\nfemale for particular males--Variability of birds--Variations sometimes\nabrupt--Laws of variation--Formation of ocelli--Gradations of character--\nCase of Peacock, Argus pheasant, and Urosticte.\n\nWhen the sexes differ in beauty or in the power of singing, or in producing\nwhat I have called instrumental music, it is almost invariably the male who\nsurpasses the female.  These qualities, as we have just seen, are evidently\nof high importance to the male.  When they are gained for only a part of\nthe year it is always before the breeding-season.  It is the male alone who\nelaborately displays his varied attractions, and often performs strange\nantics on the ground or in the air, in the presence of the female.  Each\nmale drives away, or if he can, kills his rivals.  Hence we may conclude\nthat it is the object of the male to induce the female to pair with him,\nand for this purpose he tries to excite or charm her in various ways; and\nthis is the opinion of all those who have carefully studied the habits of\nliving birds.  But there remains a question which has an all important\nbearing on sexual selection, namely, does every male of the same species\nexcite and attract the female equally?  Or does she exert a choice, and\nprefer certain males?  This latter question can be answered in the\naffirmative by much direct and indirect evidence.  It is far more difficult\nto decide what qualities determine the choice of the females; but here\nagain we have some direct and indirect evidence that it is to a large\nextent the external attractions of the male; though no doubt his vigour,\ncourage, and other mental qualities come into play.  We will begin with the\nindirect evidence.\n\nLENGTH OF COURTSHIP.\n\nThe lengthened period during which both sexes of certain birds meet day\nafter day at an appointed place probably depends partly on the courtship\nbeing a prolonged affair, and partly on reiteration in the act of pairing.\nThus in Germany and Scandinavia the balzen or leks of the black-cocks last\nfrom the middle of March, all through April into May.  As many as forty or\nfifty, or even more birds congregate at the leks; and the same place is\noften frequented during successive years.  The lek of the capercailzie\nlasts from the end of March to the middle or even end of May.  In North\nAmerica \"the partridge dances\" of the Tetrao phasianellus \"last for a month\nor more.\"  Other kinds of grouse, both in North America and Eastern Siberia\n(1.  Nordman describes ('Bull. Soc. Imp. des Nat. Moscou,' 1861, tom.\nxxxiv. p. 264) the balzen of Tetrao urogalloides in Amur Land.  He\nestimated the number of birds assembled at above a hundred, not counting\nthe females, which lie hid in the surrounding bushes.  The noises uttered\ndiffer from those of T. urogallus.), follow nearly the same habits.  The\nfowlers discover the hillocks where the ruffs congregate by the grass being\ntrampled bare, and this shews that the same spot is long frequented.  The\nIndians of Guiana are well acquainted with the cleared arenas, where they\nexpect to find the beautiful cocks of the Rock; and the natives of New\nGuinea know the trees where from ten to twenty male birds of paradise in\nfull plumage congregate.  In this latter case it is not expressly stated\nthat the females meet on the same trees, but the hunters, if not specially\nasked, would probably not mention their presence, as their skins are\nvalueless.  Small parties of an African weaver (Ploceus) congregate, during\nthe breeding-season, and perform for hours their graceful evolutions.\nLarge numbers of the Solitary snipe (Scolopax major) assemble during dusk\nin a morass; and the same place is frequented for the same purpose during\nsuccessive years; here they may be seen running about \"like so many large\nrats,\" puffing out their feathers, flapping their wings, and uttering the\nstrangest cries.  (2.  With respect to the assemblages of the above named\ngrouse, see Brehm, 'Thierleben,' B. iv. s. 350; also L. Lloyd, 'Game Birds\nof Sweden,' 1867, pp. 19, 78.  Richardson, 'Fauna Bor. Americana:  Birds,'\np. 362.  References in regard to the assemblages of other birds have\nalready been given.  On Paradisea, see Wallace, in 'Annals and Mag. of Nat.\nHist.' vol. xx. 1857, p. 412.  On the snipe, Lloyd, ibid. p. 221.)\n\nSome of the above birds,--the black-cock, capercailzie, pheasant-grouse,\nruff, solitary snipe, and perhaps others,--are, as is believed,\npolygamists.  With such birds it might have been thought that the stronger\nmales would simply have driven away the weaker, and then at once have taken\npossession of as many females as possible; but if it be indispensable for\nthe male to excite or please the female, we can understand the length of\nthe courtship and the congregation of so many individuals of both sexes at\nthe same spot.  Certain strictly monogamous species likewise hold nuptial\nassemblages; this seems to be the case in Scandinavia with one of the\nptarmigans, and their leks last from the middle of March to the middle of\nMay.  In Australia the lyre-bird (Menura superba) forms \"small round\nhillocks,\" and the M. Alberti scratches for itself shallow holes, or, as\nthey are called by the natives, \"corroborying places,\" where it is believed\nboth sexes assemble.  The meetings of the M. superba are sometimes very\nlarge; and an account has lately been published (3.  Quoted by Mr. T.W.\nWood, in the 'Student,' April 1870, p. 125.) by a traveller, who heard in a\nvalley beneath him, thickly covered with scrub, \"a din which completely\nastonished\" him; on crawling onwards he beheld, to his amazement, about one\nhundred and fifty of the magnificent lyre-cocks, \"ranged in order of\nbattle, and fighting with indescribable fury.\"  The bowers of the Bower-\nbirds are the resort of both sexes during the breeding-season; and \"here\nthe males meet and contend with each other for the favours of the female,\nand here the latter assemble and coquet with the males.\"  With two of the\ngenera, the same bower is resorted to during many years.  (4.  Gould,\n'Handbook to the Birds of Australia,' vol. i. pp. 300, 308, 448, 451.  On\nthe ptarmigan, above alluded to, see Lloyd, ibid. p. 129.)\n\nThe common magpie (Corvus pica, Linn.), as I have been informed by the Rev.\nW. Darwin Fox, used to assemble from all parts of Delamere Forest, in order\nto celebrate the \"great magpie marriage.\"  Some years ago these birds\nabounded in extraordinary numbers, so that a gamekeeper killed in one\nmorning nineteen males, and another killed by a single shot seven birds at\nroost together.  They then had the habit of assembling very early in the\nspring at particular spots, where they could be seen in flocks, chattering,\nsometimes fighting, bustling and flying about the trees.  The whole affair\nwas evidently considered by the birds as one of the highest importance.\nShortly after the meeting they all separated, and were then observed by Mr.\nFox and others to be paired for the season.  In any district in which a\nspecies does not exist in large numbers, great assemblages cannot, of\ncourse, be held, and the same species may have different habits in\ndifferent countries.  For instance, I have heard of only one instance, from\nMr. Wedderburn, of a regular assemblage of black game in Scotland, yet\nthese assemblages are so well known in Germany and Scandinavia that they\nhave received special names.\n\nUNPAIRED BIRDS.\n\nFrom the facts now given, we may conclude that the courtship of birds\nbelonging to widely different groups, is often a prolonged, delicate, and\ntroublesome affair.  There is even reason to suspect, improbable as this\nwill at first appear, that some males and females of the same species,\ninhabiting the same district, do not always please each other, and\nconsequently do not pair.  Many accounts have been published of either the\nmale or female of a pair having been shot, and quickly replaced by another.\nThis has been observed more frequently with the magpie than with any other\nbird, owing perhaps to its conspicuous appearance and nest.  The\nillustrious Jenner states that in Wiltshire one of a pair was daily shot no\nless than seven times successively, \"but all to no purpose, for the\nremaining magpie soon found another mate\"; and the last pair reared their\nyoung.  A new partner is generally found on the succeeding day; but Mr.\nThompson gives the case of one being replaced on the evening of the same\nday.  Even after the eggs are hatched, if one of the old birds is destroyed\na mate will often be found; this occurred after an interval of two days, in\na case recently observed by one of Sir J. Lubbock's keepers.  (5.  On\nmagpies, Jenner, in 'Philosophical Transactions,' 1824, p. 21.\nMacgillivray, 'Hist. British Birds,' vol. i. p. 570.  Thompson, in 'Annals\nand Magazine of Natural History,' vol. viii. 1842, p. 494.)  The first and\nmost obvious conjecture is that male magpies must be much more numerous\nthan females; and that in the above cases, as well as in many others which\ncould be given, the males alone had been killed.  This apparently holds\ngood in some instances, for the gamekeepers in Delamere Forest assured Mr.\nFox that the magpies and carrion-crows which they formerly killed in\nsuccession in large numbers near their nests, were all males; and they\naccounted for this fact by the males being easily killed whilst bringing\nfood to the sitting females.  Macgillivray, however, gives, on the\nauthority of an excellent observer, an instance of three magpies\nsuccessively killed on the same nest, which were all females; and another\ncase of six magpies successively killed whilst sitting on the same eggs,\nwhich renders it probable that most of them were females; though, as I hear\nfrom Mr. Fox, the male will sit on the eggs when the female is killed.\n\nSir J. Lubbock's gamekeeper has repeatedly shot, but how often he could not\nsay, one of a pair of jays (Garrulus glandarius), and has never failed\nshortly afterwards to find the survivor re-matched.  Mr. Fox, Mr. F. Bond,\nand others have shot one of a pair of carrion-crows (Corvus corone), but\nthe nest was soon again tenanted by a pair.  These birds are rather common;\nbut the peregrine-falcon (Falco peregrinus) is rare, yet Mr. Thompson\nstates that in Ireland \"if either an old male or female be killed in the\nbreeding-season (not an uncommon circumstance), another mate is found\nwithin a very few days, so that the eyries, notwithstanding such\ncasualties, are sure to turn out their complement of young.\"  Mr. Jenner\nWeir has known the same thing with the peregrine-falcons at Beachy Head.\nThe same observer informs me that three kestrels (Falco tinnunculus), all\nmales, were killed one after the other whilst attending the same nest; two\nof these were in mature plumage, but the third was in the plumage of the\nprevious year.  Even with the rare golden eagle (Aquila chrysaetos), Mr.\nBirkbeck was assured by a trustworthy gamekeeper in Scotland, that if one\nis killed, another is soon found.  So with the white owl (Strix flammea),\n\"the survivor readily found a mate, and the mischief went on.\"\n\nWhite of Selborne, who gives the case of the owl, adds that he knew a man,\nwho from believing that partridges when paired were disturbed by the males\nfighting, used to shoot them; and though he had widowed the same female\nseveral times, she always soon found a fresh partner.  This same naturalist\nordered the sparrows, which deprived the house-martins of their nests, to\nbe shot; but the one which was left, \"be it cock or hen, presently procured\na mate, and so for several times following.\"  I could add analogous cases\nrelating to the chaffinch, nightingale, and redstart.  With respect to the\nlatter bird (Phoenicura ruticilla), a writer expresses much surprise how\nthe sitting female could so soon have given effectual notice that she was a\nwidow, for the species was not common in the neighbourhood.  Mr. Jenner\nWeir has mentioned to me a nearly similar case; at Blackheath he never sees\nor hears the note of the wild bullfinch, yet when one of his caged males\nhas died, a wild one in the course of a few days has generally come and\nperched near the widowed female, whose call-note is not loud.  I will give\nonly one other fact, on the authority of this same observer; one of a pair\nof starlings (Sturnus vulgaris) was shot in the morning; by noon a new mate\nwas found; this was again shot, but before night the pair was complete; so\nthat the disconsolate widow or widower was thrice consoled during the same\nday.  Mr. Engleheart also informs me that he used during several years to\nshoot one of a pair of starlings which built in a hole in a house at\nBlackheath; but the loss was always immediately repaired.  During one\nseason he kept an account, and found that he had shot thirty-five birds\nfrom the same nest; these consisted of both males and females, but in what\nproportion he could not say:  nevertheless, after all this destruction, a\nbrood was reared.  (6.  On the peregrine falcon, see Thompson, 'Nat. Hist.\nof Ireland:  Birds,' vol. i. 1849, p. 39.  On owls, sparrows, and\npartridges, see White, 'Nat. Hist. of Selborne,' edit. of 1825, vol. i. p.\n139.  On the Phoenicura, see Loudon's 'Mag. of Nat. Hist.' vol. vii. 1834,\np. 245.  Brehm ('Thierleben,' B. iv. s. 991) also alludes to cases of birds\nthrice mated during the same day.)\n\nThese facts well deserve attention.  How is it that there are birds enough\nready to replace immediately a lost mate of either sex?  Magpies, jays,\ncarrion-crows, partridges, and some other birds, are always seen during the\nspring in pairs, and never by themselves; and these offer at first sight\nthe most perplexing cases.  But birds of the same sex, although of course\nnot truly paired, sometimes live in pairs or in small parties, as is known\nto be the case with pigeons and partridges.  Birds also sometimes live in\ntriplets, as has been observed with starlings, carrion-crows, parrots, and\npartridges.  With partridges two females have been known to live with one\nmale, and two males with one female.  In all such cases it is probable that\nthe union would be easily broken; and one of the three would readily pair\nwith a widow or widower.  The males of certain birds may occasionally be\nheard pouring forth their love-song long after the proper time, shewing\nthat they have either lost or never gained a mate.  Death from accident or\ndisease of one of a pair would leave the other free and single; and there\nis reason to believe that female birds during the breeding-season are\nespecially liable to premature death.  Again, birds which have had their\nnests destroyed, or barren pairs, or retarded individuals, would easily be\ninduced to desert their mates, and would probably be glad to take what\nshare they could of the pleasures and duties of rearing offspring although\nnot their own.  (7.  See White ('Nat. Hist. of Selborne,' 1825, vol. i. p.\n140) on the existence, early in the season, of small coveys of male\npartridges, of which fact I have heard other instances.  See Jenner, on the\nretarded state of the generative organs in certain birds, in 'Phil.\nTransact.' 1824.  In regard to birds living in triplets, I owe to Mr.\nJenner Weir the cases of the starlings and parrots, and to Mr. Fox, of\npartridges; on carrion-crows, see the 'Field,' 1868, p. 415.  On various\nmale birds singing after the proper period, see Rev. L. Jenyns,\n'Observations in Natural History,' 1846, p. 87.)  Such contingencies as\nthese probably explain most of the foregoing cases.  (8.  The following\ncase has been given ('The Times,' Aug. 6, 1868) by the Rev. F.O. Morris, on\nthe authority of the Hon. and Rev. O.W. Forester.  \"The gamekeeper here\nfound a hawk's nest this year, with five young ones on it.  He took four\nand killed them, but left one with its wings clipped as a decoy to destroy\nthe old ones by.  They were both shot next day, in the act of feeding the\nyoung one, and the keeper thought it was done with.  The next day he came\nagain and found two other charitable hawks, who had come with an adopted\nfeeling to succour the orphan.  These two he killed, and then left the\nnest.  On returning afterwards he found two more charitable individuals on\nthe same errand of mercy.  One of these he killed; the other he also shot,\nbut could not find.  No more came on the like fruitless errand.\")\nNevertheless, it is a strange fact that within the same district, during\nthe height of the breeding-season, there should be so many males and\nfemales always ready to repair the loss of a mated bird.  Why do not such\nspare birds immediately pair together?  Have we not some reason to suspect,\nand the suspicion has occurred to Mr. Jenner Weir, that as the courtship of\nbirds appears to be in many cases prolonged and tedious, so it occasionally\nhappens that certain males and females do not succeed, during the proper\nseason, in exciting each other's love, and consequently do not pair?  This\nsuspicion will appear somewhat less improbable after we have seen what\nstrong antipathies and preferences female birds occasionally evince towards\nparticular males.\n\nMENTAL QUALITIES OF BIRDS, AND THEIR TASTE FOR THE BEAUTIFUL.\n\nBefore we further discuss the question whether the females select the more\nattractive males or accept the first whom they may encounter, it will be\nadvisable briefly to consider the mental powers of birds.  Their reason is\ngenerally, and perhaps justly, ranked as low; yet some facts could be given\nleading to an opposite conclusion.  (9.  I am indebted to Prof. Newton for\nthe following passage from Mr. Adam's 'Travels of a Naturalist,' 1870, p.\n278.  Speaking of Japanese nut-hatches in confinement, he says:  \"Instead\nof the more yielding fruit of the yew, which is the usual food of the nut-\nhatch of Japan, at one time I substituted hard hazel-nuts.  As the bird was\nunable to crack them, he placed them one by one in his water-glass,\nevidently with the notion that they would in time become softer--an\ninteresting proof of intelligence on the part of these birds.\")  Low powers\nof reasoning, however, are compatible, as we see with mankind, with strong\naffections, acute perception, and a taste for the beautiful; and it is with\nthese latter qualities that we are here concerned.  It has often been said\nthat parrots become so deeply attached to each other that when one dies the\nother pines for a long time; but Mr. Jenner Weir thinks that with most\nbirds the strength of their affection has been much exaggerated.\nNevertheless when one of a pair in a state of nature has been shot, the\nsurvivor has been heard for days afterwards uttering a plaintive call; and\nMr. St. John gives various facts proving the attachment of mated birds.\n(10.  'A Tour in Sutherlandshire,' vol. i. 1849, p. 185.  Dr. Buller says\n('Birds of New Zealand,' 1872, p. 56) that a male King Lory was killed; and\nthe female \"fretted and moped, refused her food, and died of a broken\nheart.\")  Mr. Bennett relates (11.  'Wanderings in New South Wales,' vol.\nii. 1834, p. 62.) that in China after a drake of the beautiful mandarin\nTeal had been stolen, the duck remained disconsolate, though sedulously\ncourted by another mandarin drake, who displayed before her all his charms.\nAfter an interval of three weeks the stolen drake was recovered, and\ninstantly the pair recognised each other with extreme joy.  On the other\nhand, starlings, as we have seen, may be consoled thrice in the same day\nfor the loss of their mates.  Pigeons have such excellent local memories,\nthat they have been known to return to their former homes after an interval\nof nine months, yet, as I hear from Mr. Harrison Weir, if a pair which\nnaturally would remain mated for life be separated for a few weeks during\nthe winter, and afterwards matched with other birds, the two when brought\ntogether again, rarely, if ever, recognise each other.\n\nBirds sometimes exhibit benevolent feelings; they will feed the deserted\nyoung ones even of distinct species, but this perhaps ought to be\nconsidered as a mistaken instinct.  They will feed, as shewn in an earlier\npart of this work, adult birds of their own species which have become\nblind.  Mr. Buxton gives a curious account of a parrot which took care of a\nfrost-bitten and crippled bird of a distinct species, cleansed her\nfeathers, and defended her from the attacks of the other parrots which\nroamed freely about his garden.  It is a still more curious fact that these\nbirds apparently evince some sympathy for the pleasures of their fellows.\nWhen a pair of cockatoos made a nest in an acacia tree, \"it was ridiculous\nto see the extravagant interest taken in the matter by the others of the\nsame species.\"  These parrots, also, evinced unbounded curiosity, and\nclearly had \"the idea of property and possession.\"  (12.  'Acclimatization\nof Parrots,' by C. Buxton, M.P., 'Annals and Mag. of Nat. Hist.' Nov. 1868,\np. 381.)  They have good memories, for in the Zoological Gardens they have\nplainly recognised their former masters after an interval of some months.\n\nBirds possess acute powers of observation.  Every mated bird, of course,\nrecognises its fellow.  Audubon states that a certain number of mocking-\nthrushes (Mimus polyglottus) remain all the year round in Louisiana, whilst\nothers migrate to the Eastern States; these latter, on their return, are\ninstantly recognised, and always attacked, by their southern brethren.\nBirds under confinement distinguish different persons, as is proved by the\nstrong and permanent antipathy or affection which they shew, without any\napparent cause, towards certain individuals.  I have heard of numerous\ninstances with jays, partridges, canaries, and especially bullfinches.  Mr.\nHussey has described in how extraordinary a manner a tamed partridge\nrecognised everybody:  and its likes and dislikes were very strong.  This\nbird seemed \"fond of gay colours, and no new gown or cap could be put on\nwithout catching his attention.\"  (13.  The 'Zoologist,' 1847-48, p. 1602.)\nMr. Hewitt has described the habits of some ducks (recently descended from\nwild birds), which, at the approach of a strange dog or cat, would rush\nheadlong into the water, and exhaust themselves in their attempts to\nescape; but they knew Mr. Hewitt's own dogs and cats so well that they\nwould lie down and bask in the sun close to them.  They always moved away\nfrom a strange man, and so they would from the lady who attended them if\nshe made any great change in her dress.  Audubon relates that he reared and\ntamed a wild turkey which always ran away from any strange dog; this bird\nescaped into the woods, and some days afterwards Audubon saw, as he\nthought, a wild turkey, and made his dog chase it; but, to his\nastonishment, the bird did not run away, and the dog, when he came up, did\nnot attack the bird, for they mutually recognised each other as old\nfriends.  (14.  Hewitt on wild ducks, 'Journal of Horticulture,' Jan. 13,\n1863, p. 39.  Audubon on the wild turkey, 'Ornithological Biography,' vol.\ni. p. 14.  On the mocking-thrush, ibid. vol. i. p. 110.)\n\nMr. Jenner Weir is convinced that birds pay particular attention to the\ncolours of other birds, sometimes out of jealousy, and sometimes as a sign\nof kinship.  Thus he turned a reed-bunting (Emberiza schoeniculus), which\nhad acquired its black head-dress, into his aviary, and the new-comer was\nnot noticed by any bird, except by a bullfinch, which is likewise black-\nheaded.  This bullfinch was a very quiet bird, and had never before\nquarrelled with any of its comrades, including another reed-bunting, which\nhad not as yet become black-headed:  but the reed-bunting with a black head\nwas so unmercifully treated that it had to be removed.  Spiza cyanea,\nduring the breeding-season, is of a bright blue colour; and though\ngenerally peaceable, it attacked S. ciris, which has only the head blue,\nand completely scalped the unfortunate bird.  Mr. Weir was also obliged to\nturn out a robin, as it fiercely attacked all the birds in his aviary with\nany red in their plumage, but no other kinds; it actually killed a red-\nbreasted crossbill, and nearly killed a goldfinch.  On the other hand, he\nhas observed that some birds, when first introduced, fly towards the\nspecies which resemble them most in colour, and settle by their sides.\n\nAs male birds display their fine plumage and other ornaments with so much\ncare before the females, it is obviously probable that these appreciate the\nbeauty of their suitors.  It is, however, difficult to obtain direct\nevidence of their capacity to appreciate beauty.  When birds gaze at\nthemselves in a looking-glass (of which many instances have been recorded)\nwe cannot feel sure that it is not from jealousy of a supposed rival,\nthough this is not the conclusion of some observers.  In other cases it is\ndifficult to distinguish between mere curiosity and admiration.  It is\nperhaps the former feeling which, as stated by Lord Lilford (15.  The\n'Ibis,' vol. ii. 1860, p. 344.), attracts the ruff towards any bright\nobject, so that, in the Ionian Islands, \"it will dart down to a bright-\ncoloured handkerchief, regardless of repeated shots.\"  The common lark is\ndrawn down from the sky, and is caught in large numbers, by a small mirror\nmade to move and glitter in the sun.  Is it admiration or curiosity which\nleads the magpie, raven, and some other birds to steal and secrete bright\nobjects, such as silver articles or jewels?\n\nMr. Gould states that certain humming-birds decorate the outsides of their\nnests \"with the utmost taste; they instinctively fasten thereon beautiful\npieces of flat lichen, the larger pieces in the middle, and the smaller on\nthe part attached to the branch.  Now and then a pretty feather is\nintertwined or fastened to the outer sides, the stem being always so placed\nthat the feather stands out beyond the surface.\"  The best evidence,\nhowever, of a taste for the beautiful is afforded by the three genera of\nAustralian bower-birds already mentioned.  Their bowers (Fig. 46), where\nthe sexes congregate and play strange antics, are variously constructed,\nbut what most concerns us is, that they are decorated by the several\nspecies in a different manner.  The Satin bower-bird collects gaily-\ncoloured articles, such as the blue tail-feathers of parrakeets, bleached\nbones and shells, which it sticks between the twigs or arranges at the\nentrance.  Mr. Gould found in one bower a neatly-worked stone tomahawk and\na slip of blue cotton, evidently procured from a native encampment.  These\nobjects are continually re-arranged, and carried about by the birds whilst\nat play.  The bower of the Spotted bower-bird \"is beautifully lined with\ntall grasses, so disposed that the heads nearly meet, and the decorations\nare very profuse.\"  Round stones are used to keep the grass-stems in their\nproper places, and to make divergent paths leading to the bower.  The\nstones and shells are often brought from a great distance.  The Regent\nbird, as described by Mr. Ramsay, ornaments its short bower with bleached\nland-shells belonging to five or six species, and with \"berries of various\ncolours, blue, red, and black, which give it when fresh a very pretty\nappearance.  Besides these there were several newly-picked leaves and young\nshoots of a pinkish colour, the whole showing a decided taste for the\nbeautiful.\"  Well may Mr. Gould say that \"these highly decorated halls of\nassembly must be regarded as the most wonderful instances of bird-\narchitecture yet discovered;\" and the taste, as we see, of the several\nspecies certainly differs.  (16.  On the ornamented nests of humming-birds,\nGould, 'Introduction to the Trochilidae,' 1861, p. 19.  On the bower-birds,\nGould, 'Handbook to the Birds of Australia,' 1865, vol. i. pp. 444-461.\nRamsay, in the 'Ibis,' 1867, p. 456.)\n\nPREFERENCE FOR PARTICULAR MALES BY THE FEMALES.\n\nHaving made these preliminary remarks on the discrimination and taste of\nbirds, I will give all the facts known to me which bear on the preference\nshewn by the female for particular males.  It is certain that distinct\nspecies of birds occasionally pair in a state of nature and produce\nhybrids.  Many instances could be given:  thus Macgillivray relates how a\nmale blackbird and female thrush \"fell in love with each other,\" and\nproduced offspring.  (17.  'History of Brit. Birds,' vol. ii. p. 92.)\nSeveral years ago eighteen cases had been recorded of the occurrence in\nGreat Britain of hybrids between the black grouse and pheasant (18.\n'Zoologist,' 1853-1854, p. 3946.); but most of these cases may perhaps be\naccounted for by solitary birds not finding one of their own species to\npair with.  With other birds, as Mr. Jenner Weir has reason to believe,\nhybrids are sometimes the result of the casual intercourse of birds\nbuilding in close proximity.  But these remarks do not apply to the many\nrecorded instances of tamed or domestic birds, belonging to distinct\nspecies, which have become absolutely fascinated with each other, although\nliving with their own species.  Thus Waterton (19.  Waterton, 'Essays on\nNat. Hist.' 2nd series, pp. 42 and 117.  For the following statements see\non the wigeon, 'Loudon's Mag. of Nat. Hist.' vol. ix. p. 616; L. Lloyd,\n'Scandinavian Adventures,' vol. i. 1854, p. 452.  Dixon, 'Ornamental and\nDomestic Poultry,' p. 137; Hewitt, in 'Journal of Horticulture,' Jan. 13,\n1863, p. 40; Bechstein, 'Stubenvoegel,' 1840, s. 230.  Mr. J. Jenner Weir\nhas lately given me an analogous case with ducks of two species.) states\nthat out of a flock of twenty-three Canada geese, a female paired with a\nsolitary Bernicle gander, although so different in appearance and size; and\nthey produced hybrid offspring.  A male wigeon (Mareca penelope), living\nwith females of the same species, has been known to pair with a pintail\nduck, Querquedula acuta.  Lloyd describes the remarkable attachment between\na shield-drake (Tadorna vulpanser) and a common duck.  Many additional\ninstances could be given; and the Rev. E.S. Dixon remarks that \"those who\nhave kept many different species of geese together well know what\nunaccountable attachments they are frequently forming, and that they are\nquite as likely to pair and rear young with individuals of a race (species)\napparently the most alien to themselves as with their own stock.\"\n\nThe Rev. W.D. Fox informs me that he possessed at the same time a pair of\nChinese geese (Anser cygnoides), and a common gander with three geese.  The\ntwo lots kept quite separate, until the Chinese gander seduced one of the\ncommon geese to live with him.  Moreover, of the young birds hatched from\nthe eggs of the common geese, only four were pure, the other eighteen\nproving hybrids; so that the Chinese gander seems to have had prepotent\ncharms over the common gander.  I will give only one other case; Mr. Hewitt\nstates that a wild duck, reared in captivity, \"after breeding a couple of\nseasons with her own mallard, at once shook him off on my placing a male\nPintail on the water.  It was evidently a case of love at first sight, for\nshe swam about the new-comer caressingly, though he appeared evidently\nalarmed and averse to her overtures of affection.  From that hour she\nforgot her old partner.  Winter passed by, and the next spring the pintail\nseemed to have become a convert to her blandishments, for they nested and\nproduced seven or eight young ones.\"\n\nWhat the charm may have been in these several cases, beyond mere novelty,\nwe cannot even conjecture.  Colour, however, sometimes comes into play; for\nin order to raise hybrids from the siskin (Fringilla spinus) and the\ncanary, it is much the best plan, according to Bechstein, to place birds of\nthe same tint together.  Mr. Jenner Weir turned a female canary into his\naviary, where there were male linnets, goldfinches, siskins, greenfinches,\nchaffinches, and other birds, in order to see which she would choose; but\nthere never was any doubt, and the greenfinch carried the day.  They paired\nand produced hybrid offspring.\n\nThe fact of the female preferring to pair with one male rather than with\nanother of the same species is not so likely to excite attention, as when\nthis occurs, as we have just seen, between distinct species.  The former\ncases can best be observed with domesticated or confined birds; but these\nare often pampered by high feeding, and sometimes have their instincts\nvitiated to an extreme degree.  Of this latter fact I could give sufficient\nproofs with pigeons, and especially with fowls, but they cannot be here\nrelated.  Vitiated instincts may also account for some of the hybrid unions\nabove mentioned; but in many of these cases the birds were allowed to range\nfreely over large ponds, and there is no reason to suppose that they were\nunnaturally stimulated by high feeding.\n\nWith respect to birds in a state of nature, the first and most obvious\nsupposition which will occur to every one is that the female at the proper\nseason accepts the first male whom she may encounter; but she has at least\nthe opportunity for exerting a choice, as she is almost invariably pursued\nby many males.  Audubon--and we must remember that he spent a long life in\nprowling about the forests of the United States and observing the birds--\ndoes not doubt that the female deliberately chooses her mate; thus,\nspeaking of a woodpecker, he says the hen is followed by half-a-dozen gay\nsuitors, who continue performing strange antics, \"until a marked preference\nis shewn for one.\"  The female of the red-winged starling (Agelaeus\nphoeniceus) is likewise pursued by several males, \"until, becoming\nfatigued, she alights, receives their addresses, and soon makes a choice.\"\nHe describes also how several male night-jars repeatedly plunge through the\nair with astonishing rapidity, suddenly turning, and thus making a singular\nnoise; \"but no sooner has the female made her choice than the other males\nare driven away.\"  With one of the vultures (Cathartes aura) of the United\nStates, parties of eight, ten, or more males and females assemble on fallen\nlogs, \"exhibiting the strongest desire to please mutually,\" and after many\ncaresses, each male leads off his partner on the wing.  Audubon likewise\ncarefully observed the wild flocks of Canada geese (Anser canadensis), and\ngives a graphic description of their love-antics; he says that the birds\nwhich had been previously mated \"renewed their courtship as early as the\nmonth of January, while the others would be contending or coquetting for\nhours every day, until all seemed satisfied with the choice they had made,\nafter which, although they remained together, any person could easily\nperceive that they were careful to keep in pairs.  I have observed also\nthat the older the birds the shorter were the preliminaries of their\ncourtship.  The bachelors and old maids whether in regret, or not caring to\nbe disturbed by the bustle, quietly moved aside and lay down at some\ndistance from the rest.\"  (20.  Audubon, 'Ornithological Biography,' vol.\ni. pp. 191, 349; vol. ii. pp. 42, 275; vol. iii. p. 2.)  Many similar\nstatements with respect to other birds could be cited from this same\nobserver.\n\nTurning now to domesticated and confined birds, I will commence by giving\nwhat little I have learnt respecting the courtship of fowls.  I have\nreceived long letters on this subject from Messrs. Hewitt and Tegetmeier,\nand almost an essay from the late Mr. Brent.  It will be admitted by every\none that these gentlemen, so well known from their published works, are\ncareful and experienced observers.  They do not believe that the females\nprefer certain males on account of the beauty of their plumage; but some\nallowance must be made for the artificial state under which these birds\nhave long been kept.  Mr. Tegetmeier is convinced that a gamecock, though\ndisfigured by being dubbed and with his hackles trimmed, would be accepted\nas readily as a male retaining all his natural ornaments.  Mr. Brent,\nhowever, admits that the beauty of the male probably aids in exciting the\nfemale; and her acquiescence is necessary.  Mr. Hewitt is convinced that\nthe union is by no means left to mere chance, for the female almost\ninvariably prefers the most vigorous, defiant, and mettlesome male; hence\nit is almost useless, as he remarks, \"to attempt true breeding if a game-\ncock in good health and condition runs the locality, for almost every hen\non leaving the roosting-place will resort to the game-cock, even though\nthat bird may not actually drive away the male of her own variety.\"  Under\nordinary circumstances the males and females of the fowl seem to come to a\nmutual understanding by means of certain gestures, described to me by Mr.\nBrent.  But hens will often avoid the officious attentions of young males.\nOld hens, and hens of a pugnacious disposition, as the same writer informs\nme, dislike strange males, and will not yield until well beaten into\ncompliance.  Ferguson, however, describes how a quarrelsome hen was subdued\nby the gentle courtship of a Shanghai cock.  (21.  'Rare and Prize\nPoultry,' 1854, p. 27.)\n\nThere is reason to believe that pigeons of both sexes prefer pairing with\nbirds of the same breed; and dovecot-pigeons dislike all the highly\nimproved breeds.  (22.  'Variation of Animals and Plants under\nDomestication,' vol. ii. p. 103.)  Mr. Harrison Weir has lately heard from\na trustworthy observer, who keeps blue pigeons, that these drive away all\nother coloured varieties, such as white, red, and yellow; and from another\nobserver, that a female dun carrier could not, after repeated trials, be\nmatched with a black male, but immediately paired with a dun.  Again, Mr.\nTegetmeier had a female blue turbit that obstinately refused to pair with\ntwo males of the same breed, which were successively shut up with her for\nweeks; but on being let out she would have immediately accepted the first\nblue dragon that offered.  As she was a valuable bird, she was then shut up\nfor many weeks with a silver (i.e., very pale blue) male, and at last mated\nwith him.  Nevertheless, as a general rule, colour appears to have little\ninfluence on the pairing of pigeons.  Mr. Tegetmeier, at my request,\nstained some of his birds with magenta, but they were not much noticed by\nthe others.\n\nFemale pigeons occasionally feel a strong antipathy towards certain males,\nwithout any assignable cause.  Thus MM. Boitard and Corbie, whose\nexperience extended over forty-five years, state:  \"Quand une femelle\neprouve de l'antipathie pour un male avec lequel on veut l'accoupler,\nmalgre tous les feux de l'amour, malgre l'alpiste et le chenevis dont on la\nnourrit pour augmenter son ardeur, malgre un emprisonnement de six mois et\nmeme d'un an, elle refuse constamment ses caresses; les avances empressees,\nles agaceries, les tournoiemens, les tendres roucoulemens, rien ne peut lui\nplaire ni l'emouvoir; gonflee, boudeuse, blottie dans un coin de sa prison,\nelle n'en sort que pour boire et manger, ou pour repousser avec une espece\nde rage des caresses devenues trop pressantes.\"  (23.  Boitard and Corbie,\n'Les Pigeons,' etc., 1824, p. 12.  Prosper Lucas ('Traite de l'Hered. Nat.'\ntom. ii. 1850, p. 296) has himself observed nearly similar facts with\npigeons.)  On the other hand, Mr. Harrison Weir has himself observed, and\nhas heard from several breeders, that a female pigeon will occasionally\ntake a strong fancy for a particular male, and will desert her own mate for\nhim.  Some females, according to another experienced observer, Riedel (24.\nDie Taubenzucht, 1824, s. 86.), are of a profligate disposition, and prefer\nalmost any stranger to their own mate.  Some amorous males, called by our\nEnglish fanciers \"gay birds,\" are so successful in their gallantries, that,\nas Mr. H. Weir informs me, they must be shut up on account of the mischief\nwhich they cause.\n\nWild turkeys in the United States, according to Audubon, \"sometimes pay\ntheir addresses to the domesticated females, and are generally received by\nthem with great pleasure.\"  So that these females apparently prefer the\nwild to their own males.  (25.  'Ornithological Biography,' vol. i. p. 13.\nSee to the same effect, Dr. Bryant, in Allen's 'Mammals and Birds of\nFlorida,' p. 344.)\n\nHere is a more curious case.  Sir R. Heron during many years kept an\naccount of the habits of the peafowl, which he bred in large numbers.  He\nstates that \"the hens have frequently great preference to a particular\npeafowl.  They were all so fond of an old pied cock, that one year, when he\nwas confined, though still in view, they were constantly assembled close to\nthe trellice-walls of his prison, and would not suffer a japanned peacock\nto touch them.  On his being let out in the autumn, the oldest of the hens\ninstantly courted him and was successful in her courtship.  The next year\nhe was shut up in a stable, and then the hens all courted his rival.\"  (26.\n'Proceedings, Zoological Society,' 1835, p. 54.  The japanned peacock is\nconsidered by Mr. Sclater as a distinct species, and has been named Pavo\nnigripennis; but the evidence seems to me to show that it is only a\nvariety.)  This rival was a japanned or black-winged peacock, to our eyes a\nmore beautiful bird than the common kind.\n\nLichtenstein, who was a good observer and had excellent opportunities of\nobservation at the Cape of Good Hope, assured Rudolphi that the female\nwidow-bird (Chera progne) disowns the male when robbed of the long tail-\nfeathers with which he is ornamented during the breeding-season.  I presume\nthat this observation must have been made on birds under confinement.  (27.\nRudolphi, 'Beitraege zur Anthropologie,' 1812, s. 184.)  Here is an\nanalogous case; Dr. Jaeger (28.  'Die Darwin'sche Theorie, und ihre\nStellung zu Moral und Religion,' 1869, s. 59.), director of the Zoological\nGardens of Vienna, states that a male silver-pheasant, who had been\ntriumphant over all other males and was the accepted lover of the females,\nhad his ornamental plumage spoiled.  He was then immediately superseded by\na rival, who got the upper hand and afterwards led the flock.\n\nIt is a remarkable fact, as shewing how important colour is in the\ncourtship of birds, that Mr. Boardman, a well-known collector and observer\nof birds for many years in the Northern United States, has never in his\nlarge experience seen an albino paired with another bird; yet he has had\nopportunities of observing many albinos belonging to several species.  (29.\nThis statement is given by Mr. A. Leith Adams, in his 'Field and Forest\nRambles,' 1873, p. 76, and accords with his own experience.)  It can hardly\nbe maintained that albinos in a state of nature are incapable of breeding,\nas they can be raised with the greatest facility under confinement.  It\nappears, therefore, that we must attribute the fact that they do not pair\nto their rejection by their normally coloured comrades.\n\nFemale birds not only exert a choice, but in some few cases they court the\nmale, or even fight together for his possession.  Sir R. Heron states that\nwith peafowl, the first advances are always made by the female; something\nof the same kind takes place, according to Audubon, with the older females\nof the wild turkey.  With the capercailzie, the females flit round the male\nwhilst he is parading at one of the places of assemblage, and solicit his\nattention.  (30.  In regard to peafowl, see Sir R. Heron, 'Proc. Zoolog.\nSoc.' 1835, p. 54, and the Rev. E.S. Dixon, 'Ornamental Poultry,' 1848, p.\n8.  For the turkey, Audubon, ibid. p. 4.  For the capercailzie, Lloyd,\n'Game Birds of Sweden,' 1867, p. 23.)  We have seen that a tame wild-duck\nseduced an unwilling pintail drake after a long courtship.  Mr. Bartlett\nbelieves that the Lophophorus, like many other gallinaceous birds, is\nnaturally polygamous, but two females cannot be placed in the same cage\nwith a male, as they fight so much together.  The following instance of\nrivalry is more surprising as it relates to bullfinches, which usually pair\nfor life.  Mr. Jenner Weir introduced a dull-coloured and ugly female into\nhis aviary, and she immediately attacked another mated female so\nunmercifully that the latter had to be separated.  The new female did all\nthe courtship, and was at last successful, for she paired with the male;\nbut after a time she met with a just retribution, for, ceasing to be\npugnacious, she was replaced by the old female, and the male then deserted\nhis new and returned to his old love.\n\nIn all ordinary cases the male is so eager that he will accept any female,\nand does not, as far as we can judge, prefer one to the other; but, as we\nshall hereafter see, exceptions to this rule apparently occur in some few\ngroups.  With domesticated birds, I have heard of only one case of males\nshewing any preference for certain females, namely, that of the domestic\ncock, who, according to the high authority of Mr. Hewitt, prefers the\nyounger to the older hens.  On the other hand, in effecting hybrid unions\nbetween the male pheasant and common hens, Mr. Hewitt is convinced that the\npheasant invariably prefers the older birds.  He does not appear to be in\nthe least influenced by their colour; but \"is most capricious in his\nattachments\" (31.  Mr. Hewitt, quoted in Tegetmeier's 'Poultry Book,' 1866,\np. 165.):  from some inexplicable cause he shews the most determined\naversion to certain hens, which no care on the part of the breeder can\novercome.  Mr. Hewitt informs me that some hens are quite unattractive even\nto the males of their own species, so that they may be kept with several\ncocks during a whole season, and not one egg out of forty or fifty will\nprove fertile.  On the other hand, with the long-tailed duck (Harelda\nglacialis), \"it has been remarked,\" says M. Ekstrom, \"that certain females\nare much more courted than the rest.  Frequently, indeed, one sees an\nindividual surrounded by six or eight amorous males.\"  Whether this\nstatement is credible, I know not; but the native sportsmen shoot these\nfemales in order to stuff them as decoys.  (32.  Quoted in Lloyd's 'Game\nBirds of Sweden,' p. 345.)\n\nWith respect to female birds feeling a preference for particular males, we\nmust bear in mind that we can judge of choice being exerted only by\nanalogy.  If an inhabitant of another planet were to behold a number of\nyoung rustics at a fair courting a pretty girl, and quarrelling about her\nlike birds at one of their places of assemblage, he would, by the eagerness\nof the wooers to please her and to display their finery, infer that she had\nthe power of choice.  Now with birds the evidence stands thus:  they have\nacute powers of observation, and they seem to have some taste for the\nbeautiful both in colour and sound.  It is certain that the females\noccasionally exhibit, from unknown causes, the strongest antipathies and\npreferences for particular males.  When the sexes differ in colour or in\nother ornaments the males with rare exceptions are the more decorated,\neither permanently or temporarily during the breeding-season.  They\nsedulously display their various ornaments, exert their voices, and perform\nstrange antics in the presence of the females.  Even well-armed males, who,\nit might be thought, would altogether depend for success on the law of\nbattle, are in most cases highly ornamented; and their ornaments have been\nacquired at the expense of some loss of power.  In other cases ornaments\nhave been acquired, at the cost of increased risk from birds and beasts of\nprey.  With various species many individuals of both sexes congregate at\nthe same spot, and their courtship is a prolonged affair.  There is even\nreason to suspect that the males and females within the same district do\nnot always succeed in pleasing each other and pairing.\n\nWhat then are we to conclude from these facts and considerations?  Does the\nmale parade his charms with so much pomp and rivalry for no purpose?  Are\nwe not justified in believing that the female exerts a choice, and that she\nreceives the addresses of the male who pleases her most?  It is not\nprobable that she consciously deliberates; but she is most excited or\nattracted by the most beautiful, or melodious, or gallant males.  Nor need\nit be supposed that the female studies each stripe or spot of colour; that\nthe peahen, for instance, admires each detail in the gorgeous train of the\npeacock--she is probably struck only by the general effect.  Nevertheless,\nafter hearing how carefully the male Argus pheasant displays his elegant\nprimary wing-feathers, and erects his ocellated plumes in the right\nposition for their full effect; or again, how the male goldfinch\nalternately displays his gold-bespangled wings, we ought not to feel too\nsure that the female does not attend to each detail of beauty.  We can\njudge, as already remarked, of choice being exerted, only from analogy; and\nthe mental powers of birds do not differ fundamentally from ours.  From\nthese various considerations we may conclude that the pairing of birds is\nnot left to chance; but that those males, which are best able by their\nvarious charms to please or excite the female, are under ordinary\ncircumstances accepted.  If this be admitted, there is not much difficulty\nin understanding how male birds have gradually acquired their ornamental\ncharacters.  All animals present individual differences, and as man can\nmodify his domesticated birds by selecting the individuals which appear to\nhim the most beautiful, so the habitual or even occasional preference by\nthe female of the more attractive males would almost certainly lead to\ntheir modification; and such modifications might in the course of time be\naugmented to almost any extent, compatible with the existence of the\nspecies.\n\nVARIABILITY OF BIRDS, AND ESPECIALLY OF THEIR SECONDARY SEXUAL CHARACTERS.\n\nVariability and inheritance are the foundations for the work of selection.\nThat domesticated birds have varied greatly, their variations being\ninherited, is certain.  That birds in a state of nature have been modified\ninto distinct races is now universally admitted.  (33.  According to Dr.\nBlasius ('Ibis,' vol. ii. 1860, p. 297), there are 425 indubitable species\nof birds which breed in Europe, besides sixty forms, which are frequently\nregarded as distinct species.  Of the latter, Blasius thinks that only ten\nare really doubtful, and that the other fifty ought to be united with their\nnearest allies; but this shews that there must be a considerable amount of\nvariation with some of our European birds.  It is also an unsettled point\nwith naturalists, whether several North American birds ought to be ranked\nas specifically distinct from the corresponding European species.  So again\nmany North American forms which until lately were named as distinct\nspecies, are now considered to be local races.)  Variations may be divided\ninto two classes; those which appear to our ignorance to arise\nspontaneously, and those which are directly related to the surrounding\nconditions, so that all or nearly all the individuals of the same species\nare similarly modified.  Cases of the latter kind have recently been\nobserved with care by Mr. J.A. Allen (34.  'Mammals and Birds of East\nFlorida,' also an 'Ornithological Reconnaissance of Kansas,' etc.\nNotwithstanding the influence of climate on the colours of birds, it is\ndifficult to account for the dull or dark tints of almost all the species\ninhabiting certain countries, for instance, the Galapagos Islands under the\nequator, the wide temperate plains of Patagonia, and, as it appears, Egypt\n(see Mr. Hartshorne in the 'American Naturalist,' 1873, p. 747).  These\ncountries are open, and afford little shelter to birds; but it seems\ndoubtful whether the absence of brightly coloured species can be explained\non the principle of protection, for on the Pampas, which are equally open,\nthough covered by green grass, and where the birds would be equally exposed\nto danger, many brilliant and conspicuously coloured species are common.  I\nhave sometimes speculated whether the prevailing dull tints of the scenery\nin the above named countries may not have affected the appreciation of\nbright colours by the birds inhabiting them.), who shews that in the United\nStates many species of birds gradually become more strongly coloured in\nproceeding southward, and more lightly coloured in proceeding westward to\nthe arid plains of the interior.  Both sexes seem generally to be affected\nin a like manner, but sometimes one sex more than the other.  This result\nis not incompatible with the belief that the colours of birds are mainly\ndue to the accumulation of successive variations through sexual selection;\nfor even after the sexes have been greatly differentiated, climate might\nproduce an equal effect on both sexes, or a greater effect on one sex than\non the other, owing to some constitutional difference.\n\nIndividual differences between the members of the same species are admitted\nby every one to occur under a state of nature.  Sudden and strongly marked\nvariations are rare; it is also doubtful whether if beneficial they would\noften be preserved through selection and transmitted to succeeding\ngenerations.  (35.  'Origin of Species' fifth edit. 1869, p.104.  I had\nalways perceived, that rare and strongly-marked deviations of structure,\ndeserving to be called monstrosities, could seldom be preserved through\nnatural selection, and that the preservation of even highly-beneficial\nvariations would depend to a certain extent on chance.  I had also fully\nappreciated the importance of mere individual differences, and this led me\nto insist so strongly on the importance of that unconscious form of\nselection by man, which follows from the preservation of the most valued\nindividuals of each breed, without any intention on his part to modify the\ncharacters of the breed.  But until I read an able article in the 'North\nBritish Review' (March 1867, p. 289, et seq.), which has been of more use\nto me than any other Review, I did not see how great the chances were\nagainst the preservation of variations, whether slight or strongly\npronounced, occurring only in single individuals.)  Nevertheless, it may be\nworth while to give the few cases which I have been able to collect,\nrelating chiefly to colour,--simple albinism and melanism being excluded.\nMr. Gould is well known to admit the existence of few varieties, for he\nesteems very slight differences as specific; yet he states (36.\n'Introduction to the Trochlidae,' p. 102.) that near Bogota certain\nhumming-birds belonging to the genus Cynanthus are divided into two or\nthree races or varieties, which differ from each other in the colouring of\nthe tail--\"some having the whole of the feathers blue, while others have\nthe eight central ones tipped with beautiful green.\"  It does not appear\nthat intermediate gradations have been observed in this or the following\ncases.  In the males alone of one of the Australian parrakeets \"the thighs\nin some are scarlet, in others grass-green.\"  In another parrakeet of the\nsame country \"some individuals have the band across the wing-coverts\nbright-yellow, while in others the same part is tinged with red.\"  (37.\nGould, 'Handbook to Birds of Australia,' vol. ii. pp. 32 and 68.)  In the\nUnited States some few of the males of the scarlet tanager (Tanagra rubra)\nhave \"a beautiful transverse band of glowing red on the smaller wing-\ncoverts\" (38.  Audubon, 'Ornithological Biography,' 1838, vol. iv. p.\n389.); but this variation seems to be somewhat rare, so that its\npreservation through sexual selection would follow only under usually\nfavourable circumstances.  In Bengal the Honey buzzard (Pernis cristata)\nhas either a small rudimental crest on its head, or none at all:  so slight\na difference, however, would not have been worth notice, had not this same\nspecies possessed in Southern India a well-marked occipital crest formed of\nseveral graduated feathers.\"  (39.  Jerdon, 'Birds of India,' vol. i. p.\n108; and Mr. Blyth, in 'Land and Water,' 1868, p. 381.)\n\nThe following case is in some respects more interesting.  A pied variety of\nthe raven, with the head, breast, abdomen, and parts of the wings and tail-\nfeathers white, is confined to the Feroe Islands.  It is not very rare\nthere, for Graba saw during his visit from eight to ten living specimens.\nAlthough the characters of this variety are not quite constant, yet it has\nbeen named by several distinguished ornithologists as a distinct species.\nThe fact of the pied birds being pursued and persecuted with much clamour\nby the other ravens of the island was the chief cause which led Brunnich to\nconclude that they were specifically distinct; but this is now known to be\nan error.  (40.  Graba, 'Tagebuch Reise nach Faro,' 1830, ss. 51-54.\nMacgillivray, 'History of British Birds,' vol. iii. p. 745, 'Ibis,' vol. v.\n1863, p. 469.)  This case seems analogous to that lately given of albino\nbirds not pairing from being rejected by their comrades.\n\nIn various parts of the northern seas a remarkable variety of the common\nGuillemot (Uria troile) is found; and in Feroe, one out of every five\nbirds, according to Graba's estimation, presents this variation.  It is\ncharacterised (41.  Graba, ibid. s. 54.  Macgillivray, ibid. vol. v. p.\n327.) by a pure white ring round the eye, with a curved narrow white line,\nan inch and a half in length, extending back from the ring.  This\nconspicuous character has caused the bird to be ranked by several\nornithologists as a distinct species under the name of U. lacrymans, but it\nis now known to be merely a variety.  It often pairs with the common kind,\nyet intermediate gradations have never been seen; nor is this surprising,\nfor variations which appear suddenly, are often, as I have elsewhere shewn\n(42.  'Variation of Animals and Plants under Domestication,' vol. ii. p.\n92.), transmitted either unaltered or not at all.  We thus see that two\ndistinct forms of the same species may co-exist in the same district, and\nwe cannot doubt that if the one had possessed any advantage over the other,\nit would soon have been multiplied to the exclusion of the latter.  If, for\ninstance, the male pied ravens, instead of being persecuted by their\ncomrades, had been highly attractive (like the above pied peacock) to the\nblack female ravens their numbers would have rapidly increased.  And this\nwould have been a case of sexual selection.\n\nWith respect to the slight individual differences which are common, in a\ngreater or less degree, to all the members of the same species, we have\nevery reason to believe that they are by far the most important for the\nwork of selection.  Secondary sexual characters are eminently liable to\nvary, both with animals in a state of nature and under domestication.  (43.\nOn these points see also 'Variation of Animals and Plants under\nDomestication,' vol. i. p. 253; vol ii. pp. 73, 75.)  There is also reason\nto believe, as we have seen in our eighth chapter, that variations are more\napt to occur in the male than in the female sex.  All these contingencies\nare highly favourable for sexual selection.  Whether characters thus\nacquired are transmitted to one sex or to both sexes, depends, as we shall\nsee in the following chapter, on the form of inheritance which prevails.\n\nIt is sometimes difficult to form an opinion whether certain slight\ndifferences between the sexes of birds are simply the result of variability\nwith sexually-limited inheritance, without the aid of sexual selection, or\nwhether they have been augmented through this latter process.  I do not\nhere refer to the many instances where the male displays splendid colours\nor other ornaments, of which the female partakes to a slight degree; for\nthese are almost certainly due to characters primarily acquired by the male\nhaving been more or less transferred to the female.  But what are we to\nconclude with respect to certain birds in which, for instance, the eyes\ndiffer slightly in colour in the two sexes?  (44.  See, for instance, on\nthe irides of a Podica and Gallicrex in 'Ibis,' vol. ii. 1860, p. 206; and\nvol. v. 1863, p. 426.)  In some cases the eyes differ conspicuously; thus\nwith the storks of the genus Xenorhynchus, those of the male are blackish-\nhazel, whilst those of the females are gamboge-yellow; with many hornbills\n(Buceros), as I hear from Mr. Blyth (45.  See also Jerdon, 'Birds of\nIndia,' vol. i. pp. 243-245.), the males have intense crimson eyes, and\nthose of the females are white.  In the Buceros bicornis, the hind margin\nof the casque and a stripe on the crest of the beak are black in the male,\nbut not so in the female.  Are we to suppose that these black marks and the\ncrimson colour of the eyes have been preserved or augmented through sexual\nselection in the males?  This is very doubtful; for Mr. Bartlett shewed me\nin the Zoological Gardens that the inside of the mouth of this Buceros is\nblack in the male and flesh-coloured in the female; and their external\nappearance or beauty would not be thus affected.  I observed in Chile (46.\n'Zoology of the Voyage of H.M.S. \"Beagle,\"' 1841, p. 6.) that the iris in\nthe condor, when about a year old, is dark-brown, but changes at maturity\ninto yellowish-brown in the male, and into bright red in the female.  The\nmale has also a small, longitudinal, leaden-coloured, fleshy crest or comb.\nThe comb of many gallinaceous birds is highly ornamental, and assumes vivid\ncolours during the act of courtship; but what are we to think of the dull-\ncoloured comb of the condor, which does not appear to us in the least\nornamental?  The same question may be asked in regard to various other\ncharacters, such as the knob on the base of the beak of the Chinese goose\n(Anser cygnoides), which is much larger in the male than in the female.  No\ncertain answer can be given to these questions; but we ought to be cautious\nin assuming that knobs and various fleshy appendages cannot be attractive\nto the female, when we remember that with savage races of man various\nhideous deformities--deep scars on the face with the flesh raised into\nprotuberances, the septum of the nose pierced by sticks or bones, holes in\nthe ears and lips stretched widely open--are all admired as ornamental.\n\nWhether or not unimportant differences between the sexes, such as those\njust specified, have been preserved through sexual selection, these\ndifferences, as well as all others, must primarily depend on the laws of\nvariation.  On the principle of correlated development, the plumage often\nvaries on different parts of the body, or over the whole body, in the same\nmanner.  We see this well illustrated in certain breeds of the fowl.  In\nall the breeds the feathers on the neck and loins of the males are\nelongated, and are called hackles; now when both sexes acquire a top-knot,\nwhich is a new character in the genus, the feathers on the head of the male\nbecome hackle-shaped, evidently on the principle of correlation; whilst\nthose on the head of the female are of the ordinary shape.  The colour also\nof the hackles forming the top-knot of the male, is often correlated with\nthat of the hackles on the neck and loins, as may be seen by comparing\nthese feathers in the golden and silver-spangled Polish, the Houdans, and\nCreve-coeur breeds.  In some natural species we may observe exactly the\nsame correlation in the colours of these same feathers, as in the males of\nthe splendid Gold and Amherst pheasants.\n\nThe structure of each individual feather generally causes any change in its\ncolouring to be symmetrical; we see this in the various laced, spangled,\nand pencilled breeds of the fowl; and on the principle of correlation the\nfeathers over the whole body are often coloured in the same manner.  We are\nthus enabled without much trouble to rear breeds with their plumage marked\nalmost as symmetrically as in natural species.  In laced and spangled fowls\nthe coloured margins of the feathers are abruptly defined; but in a mongrel\nraised by me from a black Spanish cock glossed with green, and a white\ngame-hen, all the feathers were greenish-black, excepting towards their\nextremities, which were yellowish-white; but between the white extremities\nand the black bases, there was on each feather a symmetrical, curved zone\nof dark-brown.  In some instances the shaft of the feather determines the\ndistribution of the tints; thus with the body-feathers of a mongrel from\nthe same black Spanish cock and a silver-spangled Polish hen, the shaft,\ntogether with a narrow space on each side, was greenish-black, and this was\nsurrounded by a regular zone of dark-brown, edged with brownish-white.  In\nthese cases we have feathers symmetrically shaded, like those which give so\nmuch elegance to the plumage of many natural species.  I have also noticed\na variety of the common pigeon with the wing-bars symmetrically zoned with\nthree bright shades, instead of being simply black on a slaty-blue ground,\nas in the parent-species.\n\nIn many groups of birds the plumage is differently coloured in the several\nspecies, yet certain spots, marks, or stripes are retained by all.\nAnalogous cases occur with the breeds of the pigeon, which usually retain\nthe two wing-bars, though they may be coloured red, yellow, white, black,\nor blue, the rest of the plumage being of some wholly different tint.  Here\nis a more curious case, in which certain marks are retained, though\ncoloured in a manner almost exactly the opposite of what is natural; the\naboriginal pigeon has a blue tail, with the terminal halves of the outer\nwebs of the two outer tail feathers white; now there is a sub-variety\nhaving a white instead of a blue tail, with precisely that part black which\nis white in the parent-species.  (47.  Bechstein, 'Naturgeschichte\nDeutschlands,' B. iv. 1795, s. 31, on a sub-variety of the Monck pigeon.)\n\nFORMATION AND VARIABILITY OF THE OCELLI OR EYE-LIKE SPOTS ON THE PLUMAGE OF\nBIRDS.\n\n[Fig. 53.  Cyllo leda, Linn., from a drawing by Mr. Trimen, shewing the\nextreme range of variation in the ocelli.\nA.  Specimen, from Mauritius, upper surface of fore-wing.\nA1.  Specimen, from Natal, ditto.\nB.  Specimen, from Java, upper surface of hind-wing.\nB1.  Specimen, from Mauritius, ditto.]\n\nAs no ornaments are more beautiful than the ocelli on the feathers of\nvarious birds, on the hairy coats of some mammals, on the scales of\nreptiles and fishes, on the skin of amphibians, on the wings of many\nLepidoptera and other insects, they deserve to be especially noticed.  An\nocellus consists of a spot within a ring of another colour, like the pupil\nwithin the iris, but the central spot is often surrounded by additional\nconcentric zones.  The ocelli on the tail-coverts of the peacock offer a\nfamiliar example, as well as those on the wings of the peacock-butterfly\n(Vanessa).  Mr. Trimen has given me a description of a S. African moth\n(Gynanisa isis), allied to our Emperor moth, in which a magnificent ocellus\noccupies nearly the whole surface of each hinder wing; it consists of a\nblack centre, including a semi-transparent crescent-shaped mark, surrounded\nby successive, ochre-yellow, black, ochre-yellow, pink, white, pink, brown,\nand whitish zones.  Although we do not know the steps by which these\nwonderfully beautiful and complex ornaments have been developed, the\nprocess has probably been a simple one, at least with insects; for, as Mr.\nTrimen writes to me, \"no characters of mere marking or coloration are so\nunstable in the Lepidoptera as the ocelli, both in number and size.\"  Mr.\nWallace, who first called my attention to this subject, shewed me a series\nof specimens of our common meadow-brown butterfly (Hipparchia janira)\nexhibiting numerous gradations from a simple minute black spot to an\nelegantly-shaded ocellus.  In a S. African butterfly (Cyllo leda, Linn.),\nbelonging to the same family, the ocelli are even still more variable.  In\nsome specimens (A, Fig. 53) large spaces on the upper surface of the wings\nare coloured black, and include irregular white marks; and from this state\na complete gradation can be traced into a tolerably perfect ocellus (A1),\nand this results from the contraction of the irregular blotches of colour.\nIn another series of specimens a gradation can be followed from excessively\nminute white dots, surrounded by a scarcely visible black line (B), into\nperfectly symmetrical and large ocelli (B1).  (48.  This woodcut has been\nengraved from a beautiful drawing, most kindly made for me by Mr. Trimen;\nsee also his description of the wonderful amount of variation in the\ncoloration and shape of the wings of this butterfly, in his 'Rhopalocera\nAfricae Australis,' p. 186.)  In cases like these, the development of a\nperfect ocellus does not require a long course of variation and selection.\n\nWith birds and many other animals, it seems to follow from the comparison\nof allied species that circular spots are often generated by the breaking\nup and contraction of stripes.  In the Tragopan pheasant faint white lines\nin the female represent the beautiful white spots in the male (49.  Jerdon,\n'Birds of India,' vol. iii. p. 517.); and something of the same kind may be\nobserved in the two sexes of the Argus pheasant.  However this may be,\nappearances strongly favour the belief that on the one hand, a dark spot is\noften formed by the colouring matter being drawn towards a central point\nfrom a surrounding zone, which latter is thus rendered lighter; and, on the\nother hand, that a white spot is often formed by the colour being driven\naway from a central point, so that it accumulates in a surrounding darker\nzone.  In either case an ocellus is the result.  The colouring matter seems\nto be a nearly constant quantity, but is redistributed, either\ncentripetally or centrifugally.  The feathers of the common guinea-fowl\noffer a good instance of white spots surrounded by darker zones; and\nwherever the white spots are large and stand near each other, the\nsurrounding dark zones become confluent.  In the same wing-feather of the\nArgus pheasant dark spots may be seen surrounded by a pale zone, and white\nspots by a dark zone.  Thus the formation of an ocellus in its most\nelementary state appears to be a simple affair.  By what further steps the\nmore complex ocelli, which are surrounded by many successive zones of\ncolour, have been generated, I will not pretend to say.  But the zoned\nfeathers of the mongrels from differently coloured fowls, and the\nextraordinary variability of the ocelli on many Lepidoptera, lead us to\nconclude that their formation is not a complex process, but depends on some\nslight and graduated change in the nature of the adjoining tissues.\n\nGRADATION OF SECONDARY SEXUAL CHARACTERS.\n\n[Fig. 54.  Feather of Peacock, about two-thirds of natural size, drawn by\nMr. Ford.  The transparent zone is represented by the outermost white zone,\nconfined to the upper end of the disc.]\n\nCases of gradation are important, as shewing us that highly complex\nornaments may be acquired by small successive steps.  In order to discover\nthe actual steps by which the male of any existing bird has acquired his\nmagnificent colours or other ornaments, we ought to behold the long line of\nhis extinct progenitors; but this is obviously impossible.  We may,\nhowever, generally gain a clue by comparing all the species of the same\ngroup, if it be a large one; for some of them will probably retain, at\nleast partially, traces of their former characters.  Instead of entering on\ntedious details respecting various groups, in which striking instances of\ngradation could be given, it seems the best plan to take one or two\nstrongly marked cases, for instance that of the peacock, in order to see if\nlight can be thrown on the steps by which this bird has become so\nsplendidly decorated.  The peacock is chiefly remarkable from the\nextraordinary length of his tail-coverts; the tail itself not being much\nelongated.  The barbs along nearly the whole length of these feathers stand\nseparate or are decomposed; but this is the case with the feathers of many\nspecies, and with some varieties of the domestic fowl and pigeon.  The\nbarbs coalesce towards the extremity of the shaft forming the oval disc or\nocellus, which is certainly one of the most beautiful objects in the world.\nIt consists of an iridescent, intensely blue, indented centre, surrounded\nby a rich green zone, this by a broad coppery-brown zone, and this by five\nother narrow zones of slightly different iridescent shades.  A trifling\ncharacter in the disc deserves notice; the barbs, for a space along one of\nthe concentric zones are more or less destitute of their barbules, so that\na part of the disc is surrounded by an almost transparent zone, which gives\nit a highly finished aspect.  But I have elsewhere described (50.\n'Variation of Animals and Plants under Domestication,' vol. i. p. 254.) an\nexactly analogous variation in the hackles of a sub-variety of the game-\ncock, in which the tips, having a metallic lustre, \"are separated from the\nlower part of the feather by a symmetrically shaped transparent zone,\ncomposed of the naked portions of the barbs.\"  The lower margin or base of\nthe dark-blue centre of the ocellus is deeply indented on the line of the\nshaft.  The surrounding zones likewise shew traces, as may be seen in the\ndrawing (Fig. 54), of indentations, or rather breaks.  These indentations\nare common to the Indian and Javan peacocks (Pavo cristatus and P.\nmuticus); and they seem to deserve particular attention, as probably\nconnected with the development of the ocellus; but for a long time I could\nnot conjecture their meaning.\n\nIf we admit the principle of gradual evolution, there must formerly have\nexisted many species which presented every successive step between the\nwonderfully elongated tail-coverts of the peacock and the short tail-\ncoverts of all ordinary birds; and again between the magnificent ocelli of\nthe former, and the simpler ocelli or mere coloured spots on other birds;\nand so with all the other characters of the peacock.  Let us look to the\nallied Gallinaceae for any still-existing gradations.  The species and sub-\nspecies of Polyplectron inhabit countries adjacent to the native land of\nthe peacock; and they so far resemble this bird that they are sometimes\ncalled peacock-pheasants.  I am also informed by Mr. Bartlett that they\nresemble the peacock in their voice and in some of their habits.  During\nthe spring the males, as previously described, strut about before the\ncomparatively plain-coloured females, expanding and erecting their tail and\nwing-feathers, which are ornamented with numerous ocelli.  I request the\nreader to turn back to the drawing (Fig. 51) of a Polyplectron; In P.\nnapoleonis the ocelli are confined to the tail, and the back is of a rich\nmetallic blue; in which respects this species approaches the Java peacock.\nP. hardwickii possesses a peculiar top-knot, which is also somewhat like\nthat of the Java peacock.  In all the species the ocelli on the wings and\ntail are either circular or oval, and consist of a beautiful, iridescent,\ngreenish-blue or greenish-purple disc, with a black border.  This border in\nP. chinquis shades into brown, edged with cream colour, so that the ocellus\nis here surrounded with variously shaded, though not bright, concentric\nzones.  The unusual length of the tail-coverts is another remarkable\ncharacter in Polyplectron; for in some of the species they are half, and in\nothers two-thirds as long as the true tail-feathers.  The tail-coverts are\nocellated as in the peacock.  Thus the several species of Polyplectron\nmanifestly make a graduated approach to the peacock in the length of their\ntail-coverts, in the zoning of the ocelli, and in some other characters.\n\n[Fig. 55.  Part of a tail-covert of Polyplectron chinquis, with the two\nocelli of natural size.\n\nFig. 56.  Part of a tail-covert of Polyplectron malaccense, with the two\nocelli, partially confluent, of natural size.]\n\nNotwithstanding this approach, the first species of Polyplectron which I\nexamined almost made me give up the search; for I found not only that the\ntrue tail-feathers, which in the peacock are quite plain, were ornamented\nwith ocelli, but that the ocelli on all the feathers differed fundamentally\nfrom those of the peacock, in there being two on the same feather (Fig.\n55), one on each side of the shaft.  Hence I concluded that the early\nprogenitors of the peacock could not have resembled a Polyplectron.  But on\ncontinuing my search, I observed that in some of the species the two ocelli\nstood very near each other; that in the tail-feathers of P. hardwickii they\ntouched each other; and, finally, that on the tail-coverts of this same\nspecies as well as of P. malaccense (Fig. 56) they were actually confluent.\nAs the central part alone is confluent, an indentation is left at both the\nupper and lower ends; and the surrounding coloured zones are likewise\nindented.  A single ocellus is thus formed on each tail-covert, though\nstill plainly betraying its double origin.  These confluent ocelli differ\nfrom the single ocelli of the peacock in having an indentation at both\nends, instead of only at the lower or basal end.  The explanation, however,\nof this difference is not difficult; in some species of Polyplectron the\ntwo oval ocelli on the same feather stand parallel to each other; in other\nspecies (as in P. chinquis) they converge towards one end; now the partial\nconfluence of two convergent ocelli would manifestly leave a much deeper\nindentation at the divergent than at the convergent end.  It is also\nmanifest that if the convergence were strongly pronounced and the\nconfluence complete, the indentation at the convergent end would tend to\ndisappear.\n\nThe tail-feathers in both species of the peacock are entirely destitute of\nocelli, and this apparently is related to their being covered up and\nconcealed by the long tail-coverts.  In this respect they differ remarkably\nfrom the tail-feathers of Polyplectron, which in most of the species are\nornamented with larger ocelli than those on the tail-coverts.  Hence I was\nled carefully to examine the tail-feathers of the several species, in order\nto discover whether their ocelli shewed any tendency to disappear; and to\nmy great satisfaction, this appeared to be so.  The central tail-feathers\nof P. napoleonis have the two ocelli on each side of the shaft perfectly\ndeveloped; but the inner ocellus becomes less and less conspicuous on the\nmore exterior tail-feathers, until a mere shadow or rudiment is left on the\ninner side of the outermost feather.  Again, in P. malaccense, the ocelli\non the tail-coverts are, as we have seen, confluent; and these feathers are\nof unusual length, being two-thirds of the length of the tail-feathers, so\nthat in both these respects they approach the tail-coverts of the peacock.\nNow in P. malaccense, the two central tail-feathers alone are ornamented,\neach with two brightly-coloured ocelli, the inner ocellus having completely\ndisappeared from all the other tail-feathers.  Consequently the tail-\ncoverts and tail-feathers of this species of Polyplectron make a near\napproach in structure and ornamentation to the corresponding feathers of\nthe peacock.\n\nAs far, then, as gradation throws light on the steps by which the\nmagnificent train of the peacock has been acquired, hardly anything more is\nneeded.  If we picture to ourselves a progenitor of the peacock in an\nalmost exactly intermediate condition between the existing peacock, with\nhis enormously elongated tail-coverts, ornamented with single ocelli, and\nan ordinary gallinaceous bird with short tail-coverts, merely spotted with\nsome colour, we shall see a bird allied to Polyplectron--that is, with\ntail-coverts, capable of erection and expansion, ornamented with two\npartially confluent ocelli, and long enough almost to conceal the tail-\nfeathers, the latter having already partially lost their ocelli.  The\nindentation of the central disc and of the surrounding zones of the\nocellus, in both species of peacock, speaks plainly in favour of this view,\nand is otherwise inexplicable.  The males of Polyplectron are no doubt\nbeautiful birds, but their beauty, when viewed from a little distance,\ncannot be compared with that of the peacock.  Many female progenitors of\nthe peacock must, during a long line of descent, have appreciated this\nsuperiority; for they have unconsciously, by the continued preference for\nthe most beautiful males, rendered the peacock the most splendid of living\nbirds.\n\nARGUS PHEASANT.\n\nAnother excellent case for investigation is offered by the ocelli on the\nwing-feathers of the Argus pheasant, which are shaded in so wonderful a\nmanner as to resemble balls lying loose within sockets, and consequently\ndiffer from ordinary ocelli.  No one, I presume, will attribute the\nshading, which has excited the admiration of many experienced artists, to\nchance--to the fortuitous concourse of atoms of colouring matter.  That\nthese ornaments should have been formed through the selection of many\nsuccessive variations, not one of which was originally intended to produce\nthe ball-and-socket effect, seems as incredible as that one of Raphael's\nMadonnas should have been formed by the selection of chance daubs of paint\nmade by a long succession of young artists, not one of whom intended at\nfirst to draw the human figure.  In order to discover how the ocelli have\nbeen developed, we cannot look to a long line of progenitors, nor to many\nclosely-allied forms, for such do not now exist.  But fortunately the\nseveral feathers on the wing suffice to give us a clue to the problem, and\nthey prove to demonstration that a gradation is at least possible from a\nmere spot to a finished ball-and-socket ocellus.\n\n[Fig. 57.  Part of secondary wing-feather of Argus pheasant, shewing two\nperfect ocelli, a and b.  A, B, C, D, etc., are dark stripes running\nobliquely down, each to an ocellus.\n[Much of the web on both sides, especially to the left of the shaft, has\nbeen cut off.]\n\nFig.59.  Portion of one of the secondary wing-feathers near to the body,\nshewing the so-called elliptic ornaments.  The right-hand figure is given\nmerely as a diagram for the sake of the letters of reference.\nA, B, C, D, etc.  Rows of spots running down to and forming the elliptic\nornaments.\nb.  Lowest spot or mark in row B.\nc.  The next succeeding spot or mark in the same row.\nd.  Apparently a broken prolongation of the spot c. in the same row B.]\n\nThe wing-feathers, bearing the ocelli, are covered with dark stripes (Fig.\n57) or with rows of dark spots (Fig. 59), each stripe or row of spots\nrunning obliquely down the outer side of the shaft to one of the ocelli.\nThe spots are generally elongated in a line transverse to the row in which\nthey stand.  They often become confluent either in the line of the row--and\nthen they form a longitudinal stripe--or transversely, that is, with the\nspots in the adjoining rows, and then they form transverse stripes.  A spot\nsometimes breaks up into smaller spots, which still stand in their proper\nplaces.\n\nIt will be convenient first to describe a perfect ball-and-socket ocellus.\nThis consists of an intensely black circular ring, surrounding a space\nshaded so as exactly to resemble a ball.  The figure here given has been\nadmirably drawn by Mr. Ford and well engraved, but a woodcut cannot exhibit\nthe exquisite shading of the original.  The ring is almost always slightly\nbroken or interrupted (Fig. 57) at a point in the upper half, a little to\nthe right of and above the white shade on the enclosed ball; it is also\nsometimes broken towards the base on the right hand.  These little breaks\nhave an important meaning.  The ring is always much thickened, with the\nedges ill-defined towards the left-hand upper corner, the feather being\nheld erect, in the position in which it is here drawn.  Beneath this\nthickened part there is on the surface of the ball an oblique almost pure-\nwhite mark, which shades off downwards into a pale-leaden hue, and this\ninto yellowish and brown tints, which insensibly become darker and darker\ntowards the lower part of the ball.  It is this shading which gives so\nadmirably the effect of light shining on a convex surface.  If one of the\nballs be examined, it will be seen that the lower part is of a brown tint\nand is indistinctly separated by a curved oblique line from the upper part,\nwhich is yellower and more leaden; this curved oblique line runs at right\nangles to the longer axis of the white patch of light, and indeed of all\nthe shading; but this difference in colour, which cannot of course be shewn\nin the woodcut, does not in the least interfere with the perfect shading of\nthe ball.  It should be particularly observed that each ocellus stands in\nobvious connection either with a dark stripe, or with a longitudinal row of\ndark spots, for both occur indifferently on the same feather.  Thus in Fig.\n57 stripe A runs to ocellus a; B runs to ocellus b; stripe C is broken in\nthe upper part, and runs down to the next succeeding ocellus, not\nrepresented in the woodcut; D to the next lower one, and so with the\nstripes E and F.  Lastly, the several ocelli are separated from each other\nby a pale surface bearing irregular black marks.\n\n[Fig. 58.  Basal part of the secondary wing feather, nearest to the body.]\n\nI will next describe the other extreme of the series, namely, the first\ntrace of an ocellus.  The short secondary wing-feather (Fig. 58), nearest\nto the body, is marked like the other feathers, with oblique, longitudinal,\nrather irregular, rows of very dark spots.  The basal spot, or that nearest\nthe shaft, in the five lower rows (excluding the lowest one) is a little\nlarger than the other spots of the same row, and a little more elongated in\na transverse direction.  It differs also from the other spots by being\nbordered on its upper side with some dull fulvous shading.  But this spot\nis not in any way more remarkable than those on the plumage of many birds,\nand might easily be overlooked.  The next higher spot does not differ at\nall from the upper ones in the same row.  The larger basal spots occupy\nexactly the same relative position on these feathers as do the perfect\nocelli on the longer wing-feathers.\n\nBy looking to the next two or three succeeding wing-feathers, an absolutely\ninsensible gradation can be traced from one of the last-described basal\nspots, together with the next higher one in the same row, to a curious\nornament, which cannot be called an ocellus, and which I will name, from\nthe want of a better term, an \"elliptic ornament.\"  These are shewn in the\naccompanying figure (Fig. 59).  We here see several oblique rows, A, B, C,\nD, etc. (see the lettered diagram on the right hand), of dark spots of the\nusual character.  Each row of spots runs down to and is connected with one\nof the elliptic ornaments, in exactly the same manner as each stripe in\nFig. 57 runs down to and is connected with one of the ball-and-socket\nocelli.  Looking to any one row, for instance, B, in Fig. 59, the lowest\nmark (b) is thicker and considerably longer than the upper spots, and has\nits left extremity pointed and curved upwards.  This black mark is abruptly\nbordered on its upper side by a rather broad space of richly shaded tints,\nbeginning with a narrow brown zone, which passes into orange, and this into\na pale leaden tint, with the end towards the shaft much paler.  These\nshaded tints together fill up the whole inner space of the elliptic\nornament.  The mark (b) corresponds in every respect with the basal shaded\nspot of the simple feather described in the last paragraph (Fig. 58), but\nis more highly developed and more brightly coloured.  Above and to the\nright of this spot (b, Fig. 59), with its bright shading, there is a long\nnarrow, black mark (c), belonging to the same row, and which is arched a\nlittle downwards so as to face (b).  This mark is sometimes broken into two\nportions.  It is also narrowly edged on the lower side with a fulvous tint.\nTo the left of and above c, in the same oblique direction, but always more\nor less distinct from it, there is another black mark (d).  This mark is\ngenerally sub-triangular and irregular in shape, but in the one lettered in\nthe diagram it is unusually narrow, elongated, and regular.  It apparently\nconsists of a lateral and broken prolongation of the mark (c), together\nwith its confluence with a broken and prolonged part of the next spot\nabove; but I do not feel sure of this.  These three marks, b, c, and d,\nwith the intervening bright shades, form together the so-called elliptic\nornament.  These ornaments placed parallel to the shaft, manifestly\ncorrespond in position with the ball-and-socket ocelli.  Their extremely\nelegant appearance cannot be appreciated in the drawing, as the orange and\nleaden tints, contrasting so well with the black marks, cannot be shewn.\n\n[Fig. 60.  An ocellus in an intermediate condition between the elliptic\nornament and the perfect ball-and-socket ocellus.]\n\nBetween one of the elliptic ornaments and a perfect ball-and-socket\nocellus, the gradation is so perfect that it is scarcely possible to decide\nwhen the latter term ought to be used.  The passage from the one into the\nother is effected by the elongation and greater curvature in opposite\ndirections of the lower black mark (b, Fig. 59), and more especially of the\nupper one (c), together with the contraction of the elongated sub-\ntriangular or narrow mark (d), so that at last these three marks become\nconfluent, forming an irregular elliptic ring.  This ring is gradually\nrendered more and more circular and regular, increasing at the same time in\ndiameter.  I have here given a drawing (Fig. 60) of the natural size of an\nocellus not as yet quite perfect.  The lower part of the black ring is much\nmore curved than is the lower mark in the elliptic ornament (b, Fig. 59).\nThe upper part of the ring consists of two or three separate portions; and\nthere is only a trace of the thickening of the portion which forms the\nblack mark above the white shade.  This white shade itself is not as yet\nmuch concentrated; and beneath it the surface is brighter coloured than in\na perfect ball-and-socket ocellus.  Even in the most perfect ocelli traces\nof the junction of three or four elongated black marks, by which the ring\nhas been formed, may often be detected.  The irregular sub-triangular or\nnarrow mark (d, Fig. 59), manifestly forms, by its contraction and\nequalisation, the thickened portion of the ring above the white shade on a\nperfect ball-and-socket ocellus.  The lower part of the ring is invariably\na little thicker than the other parts (Fig. 57), and this follows from the\nlower black mark of the elliptic ornament (b, Fig. 59) having originally\nbeen thicker than the upper mark (c).  Every step can be followed in the\nprocess of confluence and modification; and the black ring which surrounds\nthe ball of the ocellus is unquestionably formed by the union and\nmodification of the three black marks, b, c, d, of the elliptic ornament.\nThe irregular zigzag black marks between the successive ocelli (Fig. 57)\nare plainly due to the breaking up of the somewhat more regular but similar\nmarks between the elliptic ornaments.\n\nThe successive steps in the shading of the ball-and-socket ocelli can be\nfollowed out with equal clearness.  The brown, orange, and pale-leadened\nnarrow zones, which border the lower black mark of the elliptic ornament,\ncan be seen gradually to become more and more softened and shaded into each\nother, with the upper lighter part towards the left-hand corner rendered\nstill lighter, so as to become almost white, and at the same time more\ncontracted.  But even in the most perfect ball-and-socket ocelli a slight\ndifference in the tints, though not in the shading, between the upper and\nlower parts of the ball can be perceived, as before noticed; and the line\nof separation is oblique, in the same direction as the bright coloured\nshades of the elliptic ornaments.  Thus almost every minute detail in the\nshape and colouring of the ball-and-socket ocelli can be shewn to follow\nfrom gradual changes in the elliptic ornaments; and the development of the\nlatter can be traced by equally small steps from the union of two almost\nsimple spots, the lower one (Fig. 58) having some dull fulvous shading on\nits upper side.\n\n[Fig. 61.  Portion near summit of one of the secondary wing-feathers,\nbearing perfect ball-and-socket ocelli.\na.  Ornamented upper part.\nb.  Uppermost, imperfect ball-and-socket ocellus.  (The shading above the\nwhite mark on the summit of the ocellus is here a little too dark.)\nc.  Perfect ocellus.]\n\nThe extremities of the longer secondary feathers which bear the perfect\nball-and-socket ocelli, are peculiarly ornamented (Fig. 61).  The oblique\nlongitudinal stripes suddenly cease upwards and become confused; and above\nthis limit the whole upper end of the feather (a) is covered with white\ndots, surrounded by little black rings, standing on a dark ground.  The\noblique stripe belonging to the uppermost ocellus (b) is barely represented\nby a very short irregular black mark with the usual, curved, transverse\nbase.  As this stripe is thus abruptly cut off, we can perhaps understand\nfrom what has gone before, how it is that the upper thickened part of the\nring is here absent; for, as before stated, this thickened part apparently\nstands in some relation with a broken prolongation from the next higher\nspot.  From the absence of the upper and thickened part of the ring, the\nuppermost ocellus, though perfect in all other respects, appears as if its\ntop had been obliquely sliced off.  It would, I think, perplex any one, who\nbelieves that the plumage of the Argus pheasant was created as we now see\nit, to account for the imperfect condition of the uppermost ocellus.  I\nshould add that on the secondary wing-feather farthest from the body all\nthe ocelli are smaller and less perfect than on the other feathers, and\nhave the upper part of the ring deficient, as in the case just mentioned.\nThe imperfection here seems to be connected with the fact that the spots on\nthis feather shew less tendency than usual to become confluent into\nstripes; they are, on the contrary, often broken up into smaller spots, so\nthat two or three rows run down to the same ocellus.\n\nThere still remains another very curious point, first observed by Mr. T.W.\nWood (51.  The 'Field,' May 28, 1870.), which deserves attention.  In a\nphotograph, given me by Mr. Ward, of a specimen mounted as in the act of\ndisplay, it may be seen that on the feathers which are held\nperpendicularly, the white marks on the ocelli, representing light\nreflected from a convex surface, are at the upper or further end, that is,\nare directed upwards; and the bird whilst displaying himself on the ground\nwould naturally be illuminated from above.  But here comes the curious\npoint; the outer feathers are held almost horizontally, and their ocelli\nought likewise to appear as if illuminated from above, and consequently the\nwhite marks ought to be placed on the upper sides of the ocelli; and,\nwonderful as is the fact, they are thus placed!  Hence the ocelli on the\nseveral feathers, though occupying very different positions with respect to\nthe light, all appear as if illuminated from above, just as an artist would\nhave shaded them.  Nevertheless they are not illuminated from strictly the\nsame point as they ought to be; for the white marks on the ocelli of the\nfeathers which are held almost horizontally, are placed rather too much\ntowards the further end; that is, they are not sufficiently lateral.  We\nhave, however, no right to expect absolute perfection in a part rendered\nornamental through sexual selection, any more than we have in a part\nmodified through natural selection for real use; for instance, in that\nwondrous organ the human eye.  And we know what Helmholtz, the highest\nauthority in Europe on the subject, has said about the human eye; that if\nan optician had sold him an instrument so carelessly made, he would have\nthought himself fully justified in returning it.  (52.  'Popular Lectures\non Scientific Subjects,' Eng. trans. 1873, pp. 219, 227, 269, 390.)\n\nWe have now seen that a perfect series can be followed, from simple spots\nto the wonderful ball-and-socket ornaments.  Mr. Gould, who kindly gave me\nsome of these feathers, fully agrees with me in the completeness of the\ngradation.  It is obvious that the stages in development exhibited by the\nfeathers on the same bird do not at all necessarily shew us the steps\npassed through by the extinct progenitors of the species; but they probably\ngive us the clue to the actual steps, and they at least prove to\ndemonstration that a gradation is possible.  Bearing in mind how carefully\nthe male Argus pheasant displays his plumes before the female, as well as\nthe many facts rendering it probable that female birds prefer the more\nattractive males, no one who admits the agency of sexual selection in any\ncase will deny that a simple dark spot with some fulvous shading might be\nconverted, through the approximation and modification of two adjoining\nspots, together with some slight increase of colour, into one of the so-\ncalled elliptic ornaments.  These latter ornaments have been shewn to many\npersons, and all have admitted that they are beautiful, some thinking them\neven more so than the ball-and-socket ocelli.  As the secondary plumes\nbecame lengthened through sexual selection, and as the elliptic ornaments\nincreased in diameter, their colours apparently became less bright; and\nthen the ornamentation of the plumes had to be gained by an improvement in\nthe pattern and shading; and this process was carried on until the\nwonderful ball-and-socket ocelli were finally developed.  Thus we can\nunderstand--and in no other way as it seems to me--the present condition\nand origin of the ornaments on the wing-feathers of the Argus pheasant.\n\nFrom the light afforded by the principle of gradation--from what we know of\nthe laws of variation--from the changes which have taken place in many of\nour domesticated birds--and, lastly, from the character (as we shall\nhereafter see more clearly) of the immature plumage of young birds--we can\nsometimes indicate, with a certain amount of confidence, the probable steps\nby which the males have acquired their brilliant plumage and various\nornaments; yet in many cases we are involved in complete darkness.  Mr.\nGould several years ago pointed out to me a humming-bird, the Urosticte\nbenjamini, remarkable for the curious differences between the sexes.  The\nmale, besides a splendid gorget, has greenish-black tail-feathers, with the\nfour CENTRAL ones tipped with white; in the female, as with most of the\nallied species, the three OUTER tail-feathers on each side are tipped with\nwhite, so that the male has the four central, whilst the female has the six\nexterior feathers ornamented with white tips.  What makes the case more\ncurious is that, although the colouring of the tail differs remarkably in\nboth sexes of many kinds of humming-birds, Mr. Gould does not know a single\nspecies, besides the Urosticte, in which the male has the four central\nfeathers tipped with white.\n\nThe Duke of Argyll, in commenting on this case (53.  'The Reign of Law,'\n1867, p. 247.), passes over sexual selection, and asks, \"What explanation\ndoes the law of natural selection give of such specific varieties as\nthese?\"  He answers \"none whatever\"; and I quite agree with him.  But can\nthis be so confidently said of sexual selection?  Seeing in how many ways\nthe tail-feathers of humming-birds differ, why should not the four central\nfeathers have varied in this one species alone, so as to have acquired\nwhite tips?  The variations may have been gradual, or somewhat abrupt as in\nthe case recently given of the humming-birds near Bogota, in which certain\nindividuals alone have the \"central tail-feathers tipped with beautiful\ngreen.\"  In the female of the Urosticte I noticed extremely minute or\nrudimental white tips to the two outer of the four central black tail-\nfeathers; so that here we have an indication of change of some kind in the\nplumage of this species.  If we grant the possibility of the central tail-\nfeathers of the male varying in whiteness, there is nothing strange in such\nvariations having been sexually selected.  The white tips, together with\nthe small white ear-tufts, certainly add, as the Duke of Argyll admits, to\nthe beauty of the male; and whiteness is apparently appreciated by other\nbirds, as may be inferred from such cases as the snow-white male of the\nBell-bird.  The statement made by Sir R. Heron should not be forgotten,\nnamely, that his peahens, when debarred from access to the pied peacock,\nwould not unite with any other male, and during that season produced no\noffspring.  Nor is it strange that variations in the tail-feathers of the\nUrosticte should have been specially selected for the sake of ornament, for\nthe next succeeding genus in the family takes its name of Metallura from\nthe splendour of these feathers.  We have, moreover, good evidence that\nhumming-birds take especial pains in displaying their tail-feathers; Mr.\nBelt (54.  'The Naturalist in Nicaragua,' 1874, p. 112.), after describing\nthe beauty of the Florisuga mellivora, says, \"I have seen the female\nsitting on a branch, and two males displaying their charms in front of her.\nOne would shoot up like a rocket, then suddenly expanding the snow-white\ntail, like an inverted parachute, slowly descend in front of her, turning\nround gradually to shew off back and front...The expanded white tail\ncovered more space than all the rest of the bird, and was evidently the\ngrand feature in the performance.  Whilst one male was descending, the\nother would shoot up and come slowly down expanded.  The entertainment\nwould end in a fight between the two performers; but whether the most\nbeautiful or the most pugnacious was the accepted suitor, I know not.\"  Mr.\nGould, after describing the peculiar plumage of the Urosticte, adds, \"that\nornament and variety is the sole object, I have myself but little doubt.\"\n(55.  'Introduction to the Trochilidae,' 1861, p. 110.)  If this be\nadmitted, we can perceive that the males which during former times were\ndecked in the most elegant and novel manner would have gained an advantage,\nnot in the ordinary struggle for life, but in rivalry with other males, and\nwould have left a larger number of offspring to inherit their newly-\nacquired beauty.\n\n\nCHAPTER XV.\n\nBirds--continued.\n\nDiscussion as to why the males alone of some species, and both sexes of\nothers, are brightly coloured--On sexually-limited inheritance, as applied\nto various structures and to brightly-coloured plumage--Nidification in\nrelation to colour--Loss of nuptial plumage during the winter.\n\nWe have in this chapter to consider why the females of many birds have not\nacquired the same ornaments as the male; and why, on the other hand, both\nsexes of many other birds are equally, or almost equally, ornamented?  In\nthe following chapter we shall consider the few cases in which the female\nis more conspicuously coloured than the male.\n\nIn my 'Origin of Species' (1.  Fourth edition, 1866, p. 241.) I briefly\nsuggested that the long tail of the peacock would be inconvenient and the\nconspicuous black colour of the male capercailzie dangerous, to the female\nduring the period of incubation:  and consequently that the transmission of\nthese characters from the male to the female offspring had been checked\nthrough natural selection.  I still think that this may have occurred in\nsome few instances:  but after mature reflection on all the facts which I\nhave been able to collect, I am now inclined to believe that when the sexes\ndiffer, the successive variations have generally been from the first\nlimited in their transmission to the same sex in which they first arose.\nSince my remarks appeared, the subject of sexual coloration has been\ndiscussed in some very interesting papers by Mr. Wallace (2.  'Westminster\nReview,' July 1867.  'Journal of Travel,' vol. i. 1868, p. 73.), who\nbelieves that in almost all cases the successive variations tended at first\nto be transmitted equally to both sexes; but that the female was saved,\nthrough natural selection, from acquiring the conspicuous colours of the\nmale, owing to the danger which she would thus have incurred during\nincubation.\n\nThis view necessitates a tedious discussion on a difficult point, namely,\nwhether the transmission of a character, which is at first inherited by\nboth sexes can be subsequently limited in its transmission to one sex alone\nby means of natural selection.  We must bear in mind, as shewn in the\npreliminary chapter on sexual selection, that characters which are limited\nin their development to one sex are always latent in the other.  An\nimaginary illustration will best aid us in seeing the difficulty of the\ncase; we may suppose that a fancier wished to make a breed of pigeons, in\nwhich the males alone should be coloured of a pale blue, whilst the females\nretained their former slaty tint.  As with pigeons characters of all kinds\nare usually transmitted to both sexes equally, the fancier would have to\ntry to convert this latter form of inheritance into sexually-limited\ntransmission.  All that he could do would be to persevere in selecting\nevery male pigeon which was in the least degree of a paler blue; and the\nnatural result of this process, if steadily carried on for a long time, and\nif the pale variations were strongly inherited or often recurred, would be\nto make his whole stock of a lighter blue.  But our fancier would be\ncompelled to match, generation after generation, his pale blue males with\nslaty females, for he wishes to keep the latter of this colour.  The result\nwould generally be the production either of a mongrel piebald lot, or more\nprobably the speedy and complete loss of the pale-blue tint; for the\nprimordial slaty colour would be transmitted with prepotent force.\nSupposing, however, that some pale-blue males and slaty females were\nproduced during each successive generation, and were always crossed\ntogether, then the slaty females would have, if I may use the expression,\nmuch blue blood in their veins, for their fathers, grandfathers, etc., will\nall have been blue birds.  Under these circumstances it is conceivable\n(though I know of no distinct facts rendering it probable) that the slaty\nfemales might acquire so strong a latent tendency to pale-blueness, that\nthey would not destroy this colour in their male offspring, their female\noffspring still inheriting the slaty tint.  If so, the desired end of\nmaking a breed with the two sexes permanently different in colour might be\ngained.\n\nThe extreme importance, or rather necessity in the above case of the\ndesired character, namely, pale-blueness, being present though in a latent\nstate in the female, so that the male offspring should not be deteriorated,\nwill be best appreciated as follows:  the male of Soemmerring's pheasant\nhas a tail thirty-seven inches in length, whilst that of the female is only\neight inches; the tail of the male common pheasant is about twenty inches,\nand that of the female twelve inches long.  Now if the female Soemmerring\npheasant with her SHORT tail were crossed with the male common pheasant,\nthere can be no doubt that the male hybrid offspring would have a much\nLONGER tail than that of the pure offspring of the common pheasant.  On the\nother hand, if the female common pheasant, with a tail much longer than\nthat of the female Soemmerring pheasant, were crossed with the male of the\nlatter, the male hybrid offspring would have a much SHORTER tail than that\nof the pure offspring of Soemmerring's pheasant.  (3.  Temminck says that\nthe tail of the female Phasianus Soemmerringii is only six inches long,\n'Planches coloriees,' vol. v. 1838, pp. 487 and 488:  the measurements\nabove given were made for me by Mr. Sclater.  For the common pheasant, see\nMacgillivray, 'History of British Birds,' vol. i. pp. 118-121.)\n\nOur fancier, in order to make his new breed with the males of a pale-blue\ntint, and the females unchanged, would have to continue selecting the males\nduring many generations; and each stage of paleness would have to be fixed\nin the males, and rendered latent in the females.  The task would be an\nextremely difficult one, and has never been tried, but might possibly be\nsuccessfully carried out.  The chief obstacle would be the early and\ncomplete loss of the pale-blue tint, from the necessity of reiterated\ncrosses with the slaty female, the latter not having at first any LATENT\ntendency to produce pale-blue offspring.\n\nOn the other hand, if one or two males were to vary ever so slightly in\npaleness, and the variations were from the first limited in their\ntransmission to the male sex, the task of making a new breed of the desired\nkind would be easy, for such males would simply have to be selected and\nmatched with ordinary females.  An analogous case has actually occurred,\nfor there are breeds of the pigeon in Belgium (4.  Dr. Chapuis, 'Le Pigeon\nVoyageur Belge,' 1865, p. 87.) in which the males alone are marked with\nblack striae.  So again Mr. Tegetmeier has recently shewn (5.  The 'Field,'\nSept. 1872.) that dragons not rarely produce silver-coloured birds, which\nare almost always hens; and he himself has bred ten such females.  It is on\nthe other hand a very unusual event when a silver male is produced; so that\nnothing would be easier, if desired, than to make a breed of dragons with\nblue males and silver females.  This tendency is indeed so strong that when\nMr. Tegetmeier at last got a silver male and matched him with one of the\nsilver females, he expected to get a breed with both sexes thus coloured;\nhe was however disappointed, for the young male reverted to the blue colour\nof his grandfather, the young female alone being silver.  No doubt with\npatience this tendency to reversion in the males, reared from an occasional\nsilver male matched with a silver hen, might be eliminated, and then both\nsexes would be coloured alike; and this very process has been followed with\nsuccess by Mr. Esquilant in the case of silver turbits.\n\nWith fowls, variations of colour, limited in their transmission to the male\nsex, habitually occur.  When this form of inheritance prevails, it might\nwell happen that some of the successive variations would be transferred to\nthe female, who would then slightly resemble the male, as actually occurs\nin some breeds.  Or again, the greater number, but not all, of the\nsuccessive steps might be transferred to both sexes, and the female would\nthen closely resemble the male.  There can hardly be a doubt that this is\nthe cause of the male pouter pigeon having a somewhat larger crop, and of\nthe male carrier pigeon having somewhat larger wattles, than their\nrespective females; for fanciers have not selected one sex more than the\nother, and have had no wish that these characters should be more strongly\ndisplayed in the male than in the female, yet this is the case with both\nbreeds.\n\nThe same process would have to be followed, and the same difficulties\nencountered, if it were desired to make a breed with the females alone of\nsome new colour.\n\nLastly, our fancier might wish to make a breed with the two sexes differing\nfrom each other, and both from the parent species.  Here the difficulty\nwould be extreme, unless the successive variations were from the first\nsexually limited on both sides, and then there would be no difficulty.  We\nsee this with the fowl; thus the two sexes of the pencilled Hamburghs\ndiffer greatly from each other, and from the two sexes of the aboriginal\nGallus bankiva; and both are now kept constant to their standard of\nexcellence by continued selection, which would be impossible unless the\ndistinctive characters of both were limited in their transmission.\n\nThe Spanish fowl offers a more curious case; the male has an immense comb,\nbut some of the successive variations, by the accumulation of which it was\nacquired, appear to have been transferred to the female; for she has a comb\nmany times larger than that of the females of the parent species.  But the\ncomb of the female differs in one respect from that of the male, for it is\napt to lop over; and within a recent period it has been ordered by the\nfancy that this should always be the case, and success has quickly followed\nthe order.  Now the lopping of the comb must be sexually limited in its\ntransmission, otherwise it would prevent the comb of the male from being\nperfectly upright, which would be abhorrent to every fancier.  On the other\nhand, the uprightness of the comb in the male must likewise be a sexually-\nlimited character, otherwise it would prevent the comb of the female from\nlopping over.\n\nFrom the foregoing illustrations, we see that even with almost unlimited\ntime at command, it would be an extremely difficult and complex, perhaps an\nimpossible process, to change one form of transmission into the other\nthrough selection.  Therefore, without distinct evidence in each case, I am\nunwilling to admit that this has been effected in natural species.  On the\nother hand, by means of successive variations, which were from the first\n\nsexually limited in their transmission, there would not be the least\ndifficulty in rendering a male bird widely different in colour or in any\nother character from the female; the latter being left unaltered, or\nslightly altered, or specially modified for the sake of protection.\n\nAs bright colours are of service to the males in their rivalry with other\nmales, such colours would be selected whether or not they were transmitted\nexclusively to the same sex.  Consequently the females might be expected\noften to partake of the brightness of the males to a greater or less\ndegree; and this occurs with a host of species.  If all the successive\nvariations were transmitted equally to both sexes, the females would be\nindistinguishable from the males; and this likewise occurs with many birds.\nIf, however, dull colours were of high importance for the safety of the\nfemale during incubation, as with many ground birds, the females which\nvaried in brightness, or which received through inheritance from the males\nany marked accession of brightness, would sooner or later be destroyed.\nBut the tendency in the males to continue for an indefinite period\ntransmitting to their female offspring their own brightness, would have to\nbe eliminated by a change in the form of inheritance; and this, as shewn by\nour previous illustration, would be extremely difficult.  The more probable\nresult of the long-continued destruction of the more brightly-coloured\nfemales, supposing the equal form of transmission to prevail, would be the\nlessening or annihilation of the bright colours of the males, owing to\ntheir continual crossing with the duller females.  It would be tedious to\nfollow out all the other possible results; but I may remind the reader that\nif sexually-limited variations in brightness occurred in the females, even\nif they were not in the least injurious to them and consequently were not\neliminated, yet they would not be favoured or selected, for the male\nusually accepts any female, and does not select the more attractive\nindividuals; consequently these variations would be liable to be lost, and\nwould have little influence on the character of the race; and this will aid\nin accounting for the females being commonly duller-coloured than the\nmales.\n\nIn the eighth chapter instances were given, to which many might here be\nadded, of variations occurring at various ages, and inherited at the\ncorresponding age.  It was also shewn that variations which occur late in\nlife are commonly transmitted to the same sex in which they first appear;\nwhilst variations occurring early in life are apt to be transmitted to both\nsexes; not that all the cases of sexually-limited transmission can thus be\naccounted for.  It was further shewn that if a male bird varied by becoming\nbrighter whilst young, such variations would be of no service until the age\nfor reproduction had arrived, and there was competition between rival\nmales.  But in the case of birds living on the ground and commonly in need\nof the protection of dull colours, bright tints would be far more dangerous\nto the young and inexperienced than to the adult males.  Consequently the\nmales which varied in brightness whilst young would suffer much destruction\nand be eliminated through natural selection; on the other hand, the males\nwhich varied in this manner when nearly mature, notwithstanding that they\nwere exposed to some additional danger, might survive, and from being\nfavoured through sexual selection, would procreate their kind.  As a\nrelation often exists between the period of variation and the form of\ntransmission, if the bright-coloured young males were destroyed and the\nmature ones were successful in their courtship, the males alone would\nacquire brilliant colours and would transmit them exclusively to their male\noffspring.  But I by no means wish to maintain that the influence of age on\nthe form of transmission, is the sole cause of the great difference in\nbrilliancy between the sexes of many birds.\n\nWhen the sexes of birds differ in colour, it is interesting to determine\nwhether the males alone have been modified by sexual selection, the females\nhaving been left unchanged, or only partially and indirectly thus changed;\nor whether the females have been specially modified through natural\nselection for the sake of protection.  I will therefore discuss this\nquestion at some length, even more fully than its intrinsic importance\ndeserves; for various curious collateral points may thus be conveniently\nconsidered.\n\nBefore we enter on the subject of colour, more especially in reference to\nMr. Wallace's conclusions, it may be useful to discuss some other sexual\ndifferences under a similar point of view.  A breed of fowls formerly\nexisted in Germany (6.  Bechstein, 'Naturgeschichte Deutschlands,' 1793, B.\niii. 339.) in which the hens were furnished with spurs; they were good\nlayers, but they so greatly disturbed their nests with their spurs that\nthey could not be allowed to sit on their own eggs.  Hence at one time it\nappeared to me probable that with the females of the wild Gallinaceae the\ndevelopment of spurs had been checked through natural selection, from the\ninjury thus caused to their nests.  This seemed all the more probable, as\nwing-spurs, which would not be injurious during incubation, are often as\nwell-developed in the female as in the male; though in not a few cases they\nare rather larger in the male.  When the male is furnished with leg-spurs\nthe female almost always exhibits rudiments of them,--the rudiment\nsometimes consisting of a mere scale, as in Gallus.  Hence it might be\nargued that the females had aboriginally been furnished with well-developed\nspurs, but that these had subsequently been lost through disuse or natural\nselection.  But if this view be admitted, it would have to be extended to\ninnumerable other cases; and it implies that the female progenitors of the\nexisting spur-bearing species were once encumbered with an injurious\nappendage.\n\nIn some few genera and species, as in Galloperdix, Acomus, and the Javan\npeacock (Pavo muticus), the females, as well as the males, possess well-\ndeveloped leg-spurs.  Are we to infer from this fact that they construct a\ndifferent sort of nest from that made by their nearest allies, and not\nliable to be injured by their spurs; so that the spurs have not been\nremoved?  Or are we to suppose that the females of these several species\nespecially require spurs for their defence?  It is a more probable\nconclusion that both the presence and absence of spurs in the females\nresult from different laws of inheritance having prevailed, independently\nof natural selection.  With the many females in which spurs appear as\nrudiments, we may conclude that some few of the successive variations,\nthrough which they were developed in the males, occurred very early in\nlife, and were consequently transferred to the females.  In the other and\nmuch rarer cases, in which the females possess fully developed spurs, we\nmay conclude that all the successive variations were transferred to them;\nand that they gradually acquired and inherited the habit of not disturbing\ntheir nests.\n\nThe vocal organs and the feathers variously modified for producing sound,\nas well as the proper instincts for using them, often differ in the two\nsexes, but are sometimes the same in both.  Can such differences be\naccounted for by the males having acquired these organs and instincts,\nwhilst the females have been saved from inheriting them, on account of the\ndanger to which they would have been exposed by attracting the attention of\nbirds or beasts of prey?  This does not seem to me probable, when we think\nof the multitude of birds which with impunity gladden the country with\ntheir voices during the spring.  (7.  Daines Barrington, however, thought\nit probable ('Philosophical Transactions,' 1773, p. 164) that few female\nbirds sing, because the talent would have been dangerous to them during\nincubation.  He adds, that a similar view may possibly account for the\ninferiority of the female to the male in plumage.)  It is a safer\nconclusion that, as vocal and instrumental organs are of special service\nonly to the males during their courtship, these organs were developed\nthrough sexual selection and their constant use in that sex alone--the\nsuccessive variations and the effects of use having been from the first\nmore or less limited in transmission to the male offspring.\n\nMany analogous cases could be adduced; those for instance of the plumes on\nthe head being generally longer in the male than in the female, sometimes\nof equal length in both sexes, and occasionally absent in the female,--\nthese several cases occurring in the same group of birds.  It would be\ndifficult to account for such a difference between the sexes by the female\nhaving been benefited by possessing a slightly shorter crest than the male,\nand its consequent diminution or complete suppression through natural\nselection.  But I will take a more favourable case, namely the length of\nthe tail.  The long train of the peacock would have been not only\ninconvenient but dangerous to the peahen during the period of incubation\nand whilst accompanying her young.  Hence there is not the least a priori\nimprobability in the development of her tail having been checked through\nnatural selection.  But the females of various pheasants, which apparently\nare exposed on their open nests to as much danger as the peahen, have tails\nof considerable length.  The females as well as the males of the Menura\nsuperba have long tails, and they build a domed nest, which is a great\nanomaly in so large a bird.  Naturalists have wondered how the female\nMenura could manage her tail during incubation; but it is now known (8.\nMr. Ramsay, in 'Proc. Zoolog. Soc.' 1868, p. 50.) that she \"enters the nest\nhead first, and then turns round with her tail sometimes over her back, but\nmore often bent round by her side.  Thus in time the tail becomes quite\naskew, and is a tolerable guide to the length of time the bird has been\nsitting.\"  Both sexes of an Australian kingfisher (Tanysiptera sylvia) have\nthe middle tail-feathers greatly lengthened, and the female makes her nest\nin a hole; and as I am informed by Mr. R.B. Sharpe these feathers become\nmuch crumpled during incubation.\n\nIn these two latter cases the great length of the tail-feathers must be in\nsome degree inconvenient to the female; and as in both species the tail-\nfeathers of the female are somewhat shorter than those of the male, it\nmight be argued that their full development had been prevented through\nnatural selection.  But if the development of the tail of the peahen had\nbeen checked only when it became inconveniently or dangerously great, she\nwould have retained a much longer tail than she actually possesses; for her\ntail is not nearly so long, relatively to the size of her body, as that of\nmany female pheasants, nor longer than that of the female turkey.  It must\nalso be borne in mind that, in accordance with this view, as soon as the\ntail of the peahen became dangerously long, and its development was\nconsequently checked, she would have continually reacted on her male\nprogeny, and thus have prevented the peacock from acquiring his present\nmagnificent train.  We may therefore infer that the length of the tail in\nthe peacock and its shortness in the peahen are the result of the requisite\nvariations in the male having been from the first transmitted to the male\noffspring alone.\n\nWe are led to a nearly similar conclusion with respect to the length of the\ntail in the various species of pheasants.  In the Eared pheasant\n(Crossoptilon auritum) the tail is of equal length in both sexes, namely\nsixteen or seventeen inches; in the common pheasant it is about twenty\ninches long in the male and twelve in the female; in Soemmerring's\npheasant, thirty-seven inches in the male and only eight in the female; and\nlastly in Reeve's pheasant it is sometimes actually seventy-two inches long\nin the male and sixteen in the female.  Thus in the several species, the\ntail of the female differs much in length, irrespectively of that of the\nmale; and this can be accounted for, as it seems to me, with much more\nprobability, by the laws of inheritance,--that is by the successive\nvariations having been from the first more or less closely limited in their\ntransmission to the male sex than by the agency of natural selection,\nresulting from the length of tail being more or less injurious to the\nfemales of these several allied species.\n\nWe may now consider Mr. Wallace's arguments in regard to the sexual\ncoloration of birds.  He believes that the bright tints originally acquired\nthrough sexual selection by the males would in all, or almost all cases,\nhave been transmitted to the females, unless the transference had been\nchecked through natural selection.  I may here remind the reader that\nvarious facts opposed to this view have already been given under reptiles,\namphibians, fishes and lepidoptera.  Mr. Wallace rests his belief chiefly,\nbut not exclusively, as we shall see in the next chapter, on the following\nstatement (9.  'Journal of Travel,' edited by A. Murray, vol. i. 1868, p.\n78.), that when both sexes are coloured in a very conspicuous manner, the\nnest is of such a nature as to conceal the sitting bird; but when there is\na marked contrast of colour between the sexes, the male being gay and the\nfemale dull-coloured, the nest is open and exposes the sitting bird to\nview.  This coincidence, as far as it goes, certainly seems to favour the\nbelief that the females which sit on open nests have been specially\nmodified for the sake of protection; but we shall presently see that there\nis another and more probable explanation, namely, that conspicuous females\nhave acquired the instinct of building domed nests oftener than dull-\ncoloured birds.  Mr. Wallace admits that there are, as might have been\nexpected, some exceptions to his two rules, but it is a question whether\nthe exceptions are not so numerous as seriously to invalidate them.\n\nThere is in the first place much truth in the Duke of Argyll's remark (10.\n'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. 281.) that a\nlarge domed nest is more conspicuous to an enemy, especially to all tree-\nhaunting carnivorous animals, than a smaller open nest.  Nor must we forget\nthat with many birds which build open nests, the male sits on the eggs and\naids the female in feeding the young:  this is the case, for instance, with\nPyranga aestiva (11.  Audubon, 'Ornithological Biography,' vol. i. p.\n233.), one of the most splendid birds in the United States, the male being\nvermilion, and the female light brownish-green.  Now if brilliant colours\nhad been extremely dangerous to birds whilst sitting on their open nests,\nthe males in these cases would have suffered greatly.  It might, however,\nbe of such paramount importance to the male to be brilliantly coloured, in\norder to beat his rivals, that this may have more than compensated some\nadditional danger.\n\nMr. Wallace admits that with the King-crows (Dicrurus), Orioles, and\nPittidae, the females are conspicuously coloured, yet build open nests; but\nhe urges that the birds of the first group are highly pugnacious and could\ndefend themselves; that those of the second group take extreme care in\nconcealing their open nests, but this does not invariably hold good (12.\nJerdon, 'Birds of India,' vol. ii. p. 108.  Gould's 'Handbook of the Birds\nof Australia,' vol. i. p. 463.); and that with the birds of the third group\nthe females are brightly coloured chiefly on the under surface.  Besides\nthese cases, pigeons which are sometimes brightly, and almost always\nconspicuously coloured, and which are notoriously liable to the attacks of\nbirds of prey, offer a serious exception to the rule, for they almost\nalways build open and exposed nests.  In another large family, that of the\nhumming-birds, all the species build open nests, yet with some of the most\ngorgeous species the sexes are alike; and in the majority, the females,\nthough less brilliant than the males, are brightly coloured.  Nor can it be\nmaintained that all female humming-birds, which are brightly coloured,\nescape detection by their tints being green, for some display on their\nupper surfaces red, blue, and other colours.  (13.  For instance, the\nfemale Eupetomena macroura has the head and tail dark blue with reddish\nloins; the female Lampornis porphyrurus is blackish-green on the upper\nsurface, with the lores and sides of the throat crimson; the female\nEulampis jugularis has the top of the head and back green, but the loins\nand the tail are crimson.  Many other instances of highly conspicuous\nfemales could be given.  See Mr. Gould's magnificent work on this family.)\n\nIn regard to birds which build in holes or construct domed nests, other\nadvantages, as Mr. Wallace remarks, besides concealment are gained, such as\nshelter from the rain, greater warmth, and in hot countries protection from\nthe sun (14.  Mr. Salvin noticed in Guatemala ('Ibis,' 1864, p. 375) that\nhumming-birds were much more unwilling to leave their nests during very hot\nweather, when the sun was shining brightly, as if their eggs would be thus\ninjured, than during cool, cloudy, or rainy weather.); so that it is no\nvalid objection to his view that many birds having both sexes obscurely\ncoloured build concealed nests.  (15.  I may specify, as instances of dull-\ncoloured birds building concealed nests, the species belonging to eight\nAustralian genera described in Gould's 'Handbook of the Birds of\nAustralia,' vol. i. pp. 340, 362, 365, 383, 387, 389, 391, 414.)  The\nfemale Horn-bill (Buceros), for instance, of India and Africa is protected\nduring incubation with extraordinary care, for she plasters up with her own\nexcrement the orifice of the hole in which she sits on her eggs, leaving\nonly a small orifice through which the male feeds her; she is thus kept a\nclose prisoner during the whole period of incubation (16.  Mr. C. Horne,\n'Proc. Zoolog. Soc.' 1869. p. 243.); yet female horn-bills are not more\nconspicuously coloured than many other birds of equal size which build open\nnests.  It is a more serious objection to Mr. Wallace's view, as is\nadmitted by him, that in some few groups the males are brilliantly coloured\nand the females obscure, and yet the latter hatch their eggs in domed\nnests.  This is the case with the Grallinae of Australia, the Superb\nWarblers (Maluridae) of the same country, the Sun-birds (Nectariniae), and\nwith several of the Australian Honey-suckers or Meliphagidae.  (17.  On the\nnidification and colours of these latter species, see Gould's 'Handbook to\nthe Birds of Australia,' vol. i. pp. 504, 527.)\n\nIf we look to the birds of England we shall see that there is no close and\ngeneral relation between the colours of the female and the nature of the\nnest which is constructed.  About forty of our British birds (excluding\nthose of large size which could defend themselves) build in holes in banks,\nrocks, or trees, or construct domed nests.  If we take the colours of the\nfemale goldfinch, bullfinch, or blackbird, as a standard of the degree of\nconspicuousness, which is not highly dangerous to the sitting female, then\nout of the above forty birds the females of only twelve can be considered\nas conspicuous to a dangerous degree, the remaining twenty-eight being\ninconspicuous.  (18.  I have consulted, on this subject, Macgillivray's\n'British Birds,' and though doubts may be entertained in some cases in\nregard to the degree of concealment of the nest, and to the degree of\nconspicuousness of the female, yet the following birds, which all lay their\neggs in holes or in domed nests, can hardly be considered, by the above\nstandard, as conspicuous:  Passer, 2 species; Sturnus, of which the female\nis considerably less brilliant than the male; Cinclus; Motallica boarula\n(?); Erithacus (?); Fruticola, 2 sp.; Saxicola; Ruticilla, 2 sp.; Sylvia, 3\nsp.; Parus, 3 sp.; Mecistura; Anorthura; Certhia; Sitta; Yunx; Muscicapa, 2\nsp.; Hirundo, 3 sp.; and Cypselus.  The females of the following 12 birds\nmay be considered as conspicuous according to the same standard, viz.,\nPastor, Motacilla alba, Parus major and P. caeruleus, Upupa, Picus, 4 sp.,\nCoracias, Alcedo, and Merops.)  Nor is there any close relation within the\nsame genus between a well-pronounced difference in colour between the\nsexes, and the nature of the nest constructed.  Thus the male house sparrow\n(Passer domesticus) differs much from the female, the male tree-sparrow (P.\nmontanus) hardly at all, and yet both build well-concealed nests.  The two\nsexes of the common fly-catcher (Muscicapa grisola) can hardly be\ndistinguished, whilst the sexes of the pied fly-catcher (M. luctuosa)\ndiffer considerably, and both species build in holes or conceal their\nnests.  The female blackbird (Turdus merula) differs much, the female ring-\nouzel (T. torquatus) differs less, and the female common thrush (T.\nmusicus) hardly at all from their respective males; yet all build open\nnests.  On the other hand, the not very distantly-allied water-ouzel\n(Cinclus aquaticus) builds a domed nest, and the sexes differ about as much\nas in the ring-ouzel.  The black and red grouse (Tetrao tetrix and T.\nscoticus) build open nests in equally well-concealed spots, but in the one\nspecies the sexes differ greatly, and in the other very little.\n\nNotwithstanding the foregoing objections, I cannot doubt, after reading Mr.\nWallace's excellent essay, that looking to the birds of the world, a large\nmajority of the species in which the females are conspicuously coloured\n(and in this case the males with rare exceptions are equally conspicuous),\nbuild concealed nests for the sake of protection.  Mr. Wallace enumerates\n(19.  'Journal of Travel,' edited by A. Murray, vol. i. p. 78.) a long\nseries of groups in which this rule holds good; but it will suffice here to\ngive, as instances, the more familiar groups of kingfishers, toucans,\ntrogons, puff-birds (Capitonidae), plantain-eaters (Musophagae,\nwoodpeckers, and parrots.  Mr. Wallace believes that in these groups, as\nthe males gradually acquired through sexual selection their brilliant\ncolours, these were transferred to the females and were not eliminated by\nnatural selection, owing to the protection which they already enjoyed from\ntheir manner of nidification.  According to this view, their present manner\nof nesting was acquired before their present colours.  But it seems to me\nmuch more probable that in most cases, as the females were gradually\nrendered more and more brilliant from partaking of the colours of the male,\nthey were gradually led to change their instincts (supposing that they\noriginally built open nests), and to seek protection by building domed or\nconcealed nests.  No one who studies, for instance, Audubon's account of\nthe differences in the nests of the same species in the Northern and\nSouthern United States (20.  See many statements in the 'Ornithological\nBiography.'  See also some curious observations on the nests of Italian\nbirds by Eugenio Bettoni, in the 'Atti della Societa Italiana,' vol. xi.\n1869, p. 487.), will feel any great difficulty in admitting that birds,\neither by a change (in the strict sense of the word) of their habits, or\nthrough the natural selection of so-called spontaneous variations of\ninstinct, might readily be led to modify their manner of nesting.\n\nThis way of viewing the relation, as far as it holds good, between the\nbright colours of female birds and their manner of nesting, receives some\nsupport from certain cases occurring in the Sahara Desert.  Here, as in\nmost other deserts, various birds, and many other animals, have had their\ncolours adapted in a wonderful manner to the tints of the surrounding\nsurface.  Nevertheless there are, as I am informed by the Rev. Mr.\nTristram, some curious exceptions to the rule; thus the male of the\nMonticola cyanea is conspicuous from his bright blue colour, and the female\nalmost equally conspicuous from her mottled brown and white plumage; both\nsexes of two species of Dromolaea are of a lustrous black; so that these\nthree species are far from receiving protection from their colours, yet\nthey are able to survive, for they have acquired the habit of taking refuge\nfrom danger in holes or crevices in the rocks.\n\nWith respect to the above groups in which the females are conspicuously\ncoloured and build concealed nests, it is not necessary to suppose that\neach separate species had its nidifying instinct specially modified; but\nonly that the early progenitors of each group were gradually led to build\ndomed or concealed nests, and afterwards transmitted this instinct,\ntogether with their bright colours, to their modified descendants.  As far\nas it can be trusted, the conclusion is interesting, that sexual selection\ntogether with equal or nearly equal inheritance by both sexes, have\nindirectly determined the manner of nidification of whole groups of birds.\n\nAccording to Mr. Wallace, even in the groups in which the females, from\nbeing protected in domed nests during incubation, have not had their bright\ncolours eliminated through natural selection, the males often differ in a\nslight, and occasionally in a considerable degree from the females.  This\nis a significant fact, for such differences in colour must be accounted for\nby some of the variations in the males having been from the first limited\nin transmission to the same sex; as it can hardly be maintained that these\ndifferences, especially when very slight, serve as a protection to the\nfemale.  Thus all the species in the splendid group of the Trogons build in\nholes; and Mr. Gould gives figures (21.  See his Monograph of the\nTrogonidae, 1st edition.) of both sexes of twenty-five species, in all of\nwhich, with one partial exception, the sexes differ sometimes slightly,\nsometimes conspicuously, in colour,--the males being always finer than the\nfemales, though the latter are likewise beautiful.  All the species of\nkingfishers build in holes, and with most of the species the sexes are\nequally brilliant, and thus far Mr. Wallace's rule holds good; but in some\nof the Australian species the colours of the females are rather less vivid\nthan those of the male; and in one splendidly-coloured species, the sexes\ndiffer so much that they were at first thought to be specifically distinct.\n(22.  Namely, Cyanalcyon, Gould's 'Handbook to the Birds of Australia,'\nvol. i. p. 133; see, also, pp. 130, 136.)  Mr. R.B. Sharpe, who has\nespecially studied this group, has shewn me some American species (Ceryle)\nin which the breast of the male is belted with black.  Again, in\nCarcineutes, the difference between the sexes is conspicuous:  in the male\nthe upper surface is dull-blue banded with black, the lower surface being\npartly fawn-coloured, and there is much red about the head; in the female\nthe upper surface is reddish-brown banded with black, and the lower surface\nwhite with black markings.  It is an interesting fact, as shewing how the\nsame peculiar style of sexual colouring often characterises allied forms,\nthat in three species of Dacelo the male differs from the female only in\nthe tail being dull-blue banded with black, whilst that of the female is\nbrown with blackish bars; so that here the tail differs in colour in the\ntwo sexes in exactly the same manner as the whole upper surface in the two\nsexes of Carcineutes.\n\nWith parrots, which likewise build in holes, we find analogous cases:  in\nmost of the species, both sexes are brilliantly coloured and\nindistinguishable, but in not a few species the males are coloured rather\nmore vividly than the females, or even very differently from them.  Thus,\nbesides other strongly-marked differences, the whole under surface of the\nmale King Lory (Aprosmictus scapulatus) is scarlet, whilst the throat and\nchest of the female is green tinged with red:  in the Euphema splendida\nthere is a similar difference, the face and wing coverts moreover of the\nfemale being of a paler blue than in the male.  (23.  Every gradation of\ndifference between the sexes may be followed in the parrots of Australia.\nSee Gould's 'Handbook,' etc., vol. ii. pp. 14-102.)  In the family of the\ntits (Parinae), which build concealed nests, the female of our common blue\ntomtit (Parus caeruleus), is \"much less brightly coloured\" than the male:\nand in the magnificent Sultan yellow tit of India the difference is\ngreater.  (24.  Macgillivray's 'British Birds,' vol. ii. p. 433.  Jerdon,\n'Birds of India,' vol. ii. p. 282.)\n\nAgain, in the great group of the woodpeckers (25.  All the following facts\nare taken from M. Malherbe's magnificent 'Monographie des Picidees,'\n1861.), the sexes are generally nearly alike, but in the Megapicus validus\nall those parts of the head, neck, and breast, which are crimson in the\nmale are pale brown in the female.  As in several woodpeckers the head of\nthe male is bright crimson, whilst that of the female is plain, it occurred\nto me that this colour might possibly make the female dangerously\nconspicuous, whenever she put her head out of the hole containing her nest,\nand consequently that this colour, in accordance with Mr. Wallace's belief,\nhad been eliminated.  This view is strengthened by what Malherbe states\nwith respect to Indopicus carlotta; namely, that the young females, like\nthe young males, have some crimson about their heads, but that this colour\ndisappears in the adult female, whilst it is intensified in the adult male.\nNevertheless the following considerations render this view extremely\ndoubtful:  the male takes a fair share in incubation (26.  Audubon's\n'Ornithological Biography,' vol. ii. p. 75; see also the 'Ibis,' vol. i. p.\n268.), and would be thus almost equally exposed to danger; both sexes of\nmany species have their heads of an equally bright crimson; in other\nspecies the difference between the sexes in the amount of scarlet is so\nslight that it can hardly make any appreciable difference in the danger\nincurred; and lastly, the colouring of the head in the two sexes often\ndiffers slightly in other ways.\n\nThe cases, as yet given, of slight and graduated differences in colour\nbetween the males and females in the groups, in which as a general rule the\nsexes resemble each other, all relate to species which build domed or\nconcealed nests.  But similar gradations may likewise be observed in groups\nin which the sexes as a general rule resemble each other, but which build\nopen nests.\n\nAs I have before instanced the Australian parrots, so I may here instance,\nwithout giving any details, the Australian pigeons.  (27.  Gould's\n'Handbook to the Birds of Australia,' vol. ii. pp. 109-149.)  It deserves\nespecial notice that in all these cases the slight differences in plumage\nbetween the sexes are of the same general nature as the occasionally\ngreater differences.  A good illustration of this fact has already been\nafforded by those kingfishers in which either the tail alone or the whole\nupper surface of the plumage differs in the same manner in the two sexes.\nSimilar cases may be observed with parrots and pigeons.  The differences in\ncolour between the sexes of the same species are, also, of the same general\nnature as the differences in colour between the distinct species of the\nsame group.  For when in a group in which the sexes are usually alike, the\nmale differs considerably from the female, he is not coloured in a quite\nnew style.  Hence we may infer that within the same group the special\ncolours of both sexes when they are alike, and the colours of the male,\nwhen he differs slightly or even considerably from the female, have been in\nmost cases determined by the same general cause; this being sexual\nselection.\n\nIt is not probable, as has already been remarked, that differences in\ncolour between the sexes, when very slight, can be of service to the female\nas a protection.  Assuming, however, that they are of service, they might\nbe thought to be cases of transition; but we have no reason to believe that\nmany species at any one time are undergoing change.  Therefore we can\nhardly admit that the numerous females which differ very slightly in colour\nfrom their males are now all commencing to become obscure for the sake of\nprotection.  Even if we consider somewhat more marked sexual differences,\nis it probable, for instance, that the head of the female chaffinch,--the\ncrimson on the breast of the female bullfinch,--the green of the female\ngreenfinch,--the crest of the female golden-crested wren, have all been\nrendered less bright by the slow process of selection for the sake of\nprotection?  I cannot think so; and still less with the slight differences\nbetween the sexes of those birds which build concealed nests.  On the other\nhand, the differences in colour between the sexes, whether great or small,\nmay to a large extent be explained on the principle of the successive\nvariations, acquired by the males through sexual selection, having been\nfrom the first more or less limited in their transmission to the females.\nThat the degree of limitation should differ in different species of the\nsame group will not surprise any one who has studied the laws of\ninheritance, for they are so complex that they appear to us in our\nignorance to be capricious in their action.  (28.  See remarks to this\neffect in 'Variation of Animals and Plants under Domestication,' vol. ii.\nchap. xii.)\n\nAs far as I can discover there are few large groups of birds in which all\nthe species have both sexes alike and brilliantly coloured, but I hear from\nMr. Sclater, that this appears to be the case with the Musophagae or\nplantain-eaters.  Nor do I believe that any large group exists in which the\nsexes of all the species are widely dissimilar in colour:  Mr. Wallace\ninforms me that the chatterers of S. America (Cotingidae) offer one of the\nbest instances; but with some of the species, in which the male has a\nsplendid red breast, the female exhibits some red on her breast; and the\nfemales of other species shew traces of the green and other colours of the\nmales.  Nevertheless we have a near approach to close sexual similarity or\ndissimilarity throughout several groups:  and this, from what has just been\nsaid of the fluctuating nature of inheritance, is a somewhat surprising\ncircumstance.  But that the same laws should largely prevail with allied\nanimals is not surprising.  The domestic fowl has produced a great number\nof breeds and sub-breeds, and in these the sexes generally differ in\nplumage; so that it has been noticed as an unusual circumstance when in\ncertain sub-breeds they resemble each other.  On the other hand, the\ndomestic pigeon has likewise produced a vast number of distinct breeds and\nsub-breeds, and in these, with rare exceptions, the two sexes are\nidentically alike.\n\nTherefore if other species of Gallus and Columba were domesticated and\nvaried, it would not be rash to predict that similar rules of sexual\nsimilarity and dissimilarity, depending on the form of transmission, would\nhold good in both cases.  In like manner the same form of transmission has\ngenerally prevailed under nature throughout the same groups, although\nmarked exceptions to this rule occur.  Thus within the same family or even\ngenus, the sexes may be identically alike, or very different in colour.\nInstances have already been given in the same genus, as with sparrows, fly-\ncatchers, thrushes and grouse.  In the family of pheasants the sexes of\nalmost all the species are wonderfully dissimilar, but are quite alike in\nthe eared pheasant or Crossoptilon auritum.  In two species of Chloephaga,\na genus of geese, the male cannot be distinguished from the females, except\nby size; whilst in two others, the sexes are so unlike that they might\neasily be mistaken for distinct species.  (29.  The 'Ibis,' vol. vi. 1864,\np. 122.)\n\nThe laws of inheritance can alone account for the following cases, in which\nthe female acquires, late in life, certain characters proper to the male,\nand ultimately comes to resemble him more or less completely.  Here\nprotection can hardly have come into play.  Mr. Blyth informs me that the\nfemales of Oriolus melanocephalus and of some allied species, when\nsufficiently mature to breed, differ considerably in plumage from the adult\nmales; but after the second or third moults they differ only in their beaks\nhaving a slight greenish tinge.  In the dwarf bitterns (Ardetta), according\nto the same authority, \"the male acquires his final livery at the first\nmoult, the female not before the third or fourth moult; in the meanwhile\nshe presents an intermediate garb, which is ultimately exchanged for the\nsame livery as that of the male.\"  So again the female Falco peregrinus\nacquires her blue plumage more slowly than the male.  Mr. Swinhoe states\nthat with one of the Drongo shrikes (Dicrurus macrocercus) the male, whilst\nalmost a nestling, moults his soft brown plumage and becomes of a uniform\nglossy greenish-black; but the female retains for a long time the white\nstriae and spots on the axillary feathers; and does not completely assume\nthe uniform black colour of the male for three years.  The same excellent\nobserver remarks that in the spring of the second year the female spoon-\nbill (Platalea) of China resembles the male of the first year, and that\napparently it is not until the third spring that she acquires the same\nadult plumage as that possessed by the male at a much earlier age.  The\nfemale Bombycilla carolinensis differs very little from the male, but the\nappendages, which like beads of red sealing-wax ornament the wing-feathers\n(30.  When the male courts the female, these ornaments are vibrated, and\n\"are shewn off to great advantage,\" on the outstretched wings:  A. Leith\nAdams, 'Field and Forest Rambles,' 1873, p. 153.), are not developed in her\nso early in life as in the male.  In the male of an Indian parrakeet\n(Palaeornis javanicus) the upper mandible is coral-red from his earliest\nyouth, but in the female, as Mr. Blyth has observed with caged and wild\nbirds, it is at first black and does not become red until the bird is at\nleast a year old, at which age the sexes resemble each other in all\nrespects.  Both sexes of the wild turkey are ultimately furnished with a\ntuft of bristles on the breast, but in two-year-old birds the tuft is about\nfour inches long in the male and hardly apparent in the female; when,\nhowever, the latter has reached her fourth year, it is from four to five\ninches in length.  (31.  On Ardetta, Translation of Cuvier's 'Regne\nAnimal,' by Mr. Blyth, footnote, p. 159.  On the Peregrine Falcon, Mr.\nBlyth, in Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304.  On\nDicrurus, 'Ibis,' 1863, p. 44.  On the Platalea, 'Ibis,' vol. vi. 1864, p.\n366.  On the Bombycilla, Audubon's 'Ornitholog.  Biography,' vol. i. p.\n229.  On the Palaeornis, see, also, Jerdon, 'Birds of India,' vol. i. p.\n263.  On the wild turkey, Audubon, ibid. vol. i. p. 15; but I hear from\nJudge Caton that in Illinois the female very rarely acquires a tuft.\nAnalogous cases with the females of Petrocossyphus are given by Mr. R.\nSharpe, 'Proceedings of the Zoological Society,' 1872, p. 496.)\n\n\nThese cases must not be confounded with those where diseased or old females\nabnormally assume masculine characters, nor with those where fertile\nfemales, whilst young, acquire the characters of the male, through\nvariation or some unknown cause.  (32.  Of these latter cases Mr. Blyth has\nrecorded (Translation of Cuvier's 'Regne Animal,' p. 158) various instances\nwith Lanius, Ruticilla, Linaria, and Anas.  Audubon has also recorded a\nsimilar case ('Ornitholog. Biography,' vol. v. p. 519) with Pyranga\naestiva.)  But all these cases have so much in common that they depend,\naccording to the hypothesis of pangenesis, on gemmules derived from each\npart of the male being present, though latent, in the female; their\ndevelopment following on some slight change in the elective affinities of\nher constituent tissues.\n\nA few words must be added on changes of plumage in relation to the season\nof the year.  From reasons formerly assigned there can be little doubt that\nthe elegant plumes, long pendant feathers, crests, etc., of egrets, herons,\nand many other birds, which are developed and retained only during the\nsummer, serve for ornamental and nuptial purposes, though common to both\nsexes.  The female is thus rendered more conspicuous during the period of\nincubation than during the winter; but such birds as herons and egrets\nwould be able to defend themselves.  As, however, plumes would probably be\ninconvenient and certainly of no use during the winter, it is possible that\nthe habit of moulting twice in the year may have been gradually acquired\nthrough natural selection for the sake of casting off inconvenient\nornaments during the winter.  But this view cannot be extended to the many\nwaders, whose summer and winter plumages differ very little in colour.\nWith defenceless species, in which both sexes, or the males alone, become\nextremely conspicuous during the breeding-season,--or when the males\nacquire at this season such long wing or tail-feathers as to impede their\nflight, as with Cosmetornis and Vidua,--it certainly at first appears\nhighly probable that the second moult has been gained for the special\npurpose of throwing off these ornaments.  We must, however, remember that\nmany birds, such as some of the Birds of Paradise, the Argus pheasant and\npeacock, do not cast their plumes during the winter; and it can hardly be\nmaintained that the constitution of these birds, at least of the\nGallinaceae, renders a double moult impossible, for the ptarmigan moults\nthrice in the year.  (33.  See Gould's 'Birds of Great Britain.')  Hence it\nmust be considered as doubtful whether the many species which moult their\nornamental plumes or lose their bright colours during the winter, have\nacquired this habit on account of the inconvenience or danger which they\nwould otherwise have suffered.\n\nI conclude, therefore, that the habit of moulting twice in the year was in\nmost or all cases first acquired for some distinct purpose, perhaps for\ngaining a warmer winter covering; and that variations in the plumage\noccurring during the summer were accumulated through sexual selection, and\ntransmitted to the offspring at the same season of the year; that such\nvariations were inherited either by both sexes or by the males alone,\naccording to the form of inheritance which prevailed.  This appears more\nprobable than that the species in all cases originally tended to retain\ntheir ornamental plumage during the winter, but were saved from this\nthrough natural selection, resulting from the inconvenience or danger thus\ncaused.\n\nI have endeavoured in this chapter to shew that the arguments are not\ntrustworthy in favour of the view that weapons, bright colours, and various\nornaments, are now confined to the males owing to the conversion, by\nnatural selection, of the equal transmission of characters to both sexes,\ninto transmission to the male sex alone.  It is also doubtful whether the\ncolours of many female birds are due to the preservation, for the sake of\nprotection, of variations which were from the first limited in their\ntransmission to the female sex.  But it will be convenient to defer any\nfurther discussion on this subject until I treat, in the following chapter,\nof the differences in plumage between the young and old.\n\n\nCHAPTER XVI.\n\nBIRDS--concluded.\n\nThe immature plumage in relation to the character of the plumage in both\nsexes when adult--Six classes of cases--Sexual differences between the\nmales of closely-allied or representative species--The female assuming the\ncharacters of the male--Plumage of the young in relation to the summer and\nwinter plumage of the adults--On the increase of beauty in the birds of the\nworld--Protective colouring--Conspicuously coloured birds--Novelty\nappreciated--Summary of the four chapters on Birds.\n\nWe must now consider the transmission of characters, as limited by age, in\nreference to sexual selection.  The truth and importance of the principle\nof inheritance at corresponding ages need not here be discussed, as enough\nhas already been said on the subject.  Before giving the several rather\ncomplex rules or classes of cases, under which the differences in plumage\nbetween the young and the old, as far as known to me, may be included, it\nwill be well to make a few preliminary remarks.\n\nWith animals of all kinds when the adults differ in colour from the young,\nand the colours of the latter are not, as far as we can see, of any special\nservice, they may generally be attributed, like various embryological\nstructures, to the retention of a former character.  But this view can be\nmaintained with confidence, only when the young of several species resemble\neach other closely, and likewise resemble other adult species belonging to\nthe same group; for the latter are the living proofs that such a state of\nthings was formerly possible.  Young lions and pumas are marked with feeble\nstripes or rows of spots, and as many allied species both young and old are\nsimilarly marked, no believer in evolution will doubt that the progenitor\nof the lion and puma was a striped animal, and that the young have retained\nvestiges of the stripes, like the kittens of black cats, which are not in\nthe least striped when grown up.  Many species of deer, which when mature\nare not spotted, are whilst young covered with white spots, as are likewise\nsome few species in the adult state.  So again the young in the whole\nfamily of pigs (Suidae), and in certain rather distantly allied animals,\nsuch as the tapir, are marked with dark longitudinal stripes; but here we\nhave a character apparently derived from an extinct progenitor, and now\npreserved by the young alone.  In all such cases the old have had their\ncolours changed in the course of time, whilst the young have remained but\nlittle altered, and this has been effected through the principle of\ninheritance at corresponding ages.\n\nThis same principle applies to many birds belonging to various groups, in\nwhich the young closely resemble each other, and differ much from their\nrespective adult parents.  The young of almost all the Gallinaceae, and of\nsome distantly allied birds such as ostriches, are covered with\nlongitudinally striped down; but this character points back to a state of\nthings so remote that it hardly concerns us.  Young cross-bills (Loxia)\nhave at first straight beaks like those of other finches, and in their\nimmature striated plumage they resemble the mature red-pole and female\nsiskin, as well as the young of the goldfinch, greenfinch, and some other\nallied species.  The young of many kinds of buntings (Emberiza) resemble\none another, and likewise the adult state of the common bunting, E.\nmiliaria.  In almost the whole large group of thrushes the young have their\nbreasts spotted--a character which is retained throughout life by many\nspecies, but is quite lost by others, as by the Turdus migratorius.  So\nagain with many thrushes, the feathers on the back are mottled before they\nare moulted for the first time, and this character is retained for life by\ncertain eastern species.  The young of many species of shrikes (Lanius), of\nsome woodpeckers, and of an Indian pigeon (Chalcophaps indicus), are\ntransversely striped on the under surface; and certain allied species or\nwhole genera are similarly marked when adult.  In some closely-allied and\nresplendent Indian cuckoos (Chrysococcyx), the mature species differ\nconsiderably from one another in colour, but the young cannot be\ndistinguished.  The young of an Indian goose (Sarkidiornis melanonotus)\nclosely resemble in plumage an allied genus, Dendrocygna, when mature.  (1.\nIn regard to thrushes, shrikes, and woodpeckers, see Mr. Blyth, in\nCharlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304; also footnote to\nhis translation of Cuvier's 'Regne Animal,' p. 159.  I give the case of\nLoxia on Mr. Blyth's information.  On thrushes, see also Audubon, 'Ornith.\nBiog.' vol. ii. p. 195.  On Chrysococcyx and Chalcophaps, Blyth, as quoted\nin Jerdon's 'Birds of India,' vol. iii. p. 485.  On Sarkidiornis, Blyth, in\n'Ibis,' 1867, p. 175.)  Similar facts will hereafter be given in regard to\ncertain herons.  Young black-grouse (Tetrao tetrix) resemble the young as\nwell as the old of certain other species, for instance the red-grouse or T.\nscoticus.  Finally, as Mr. Blyth, who has attended closely to this subject,\nhas well remarked, the natural affinities of many species are best\nexhibited in their immature plumage; and as the true affinities of all\norganic beings depend on their descent from a common progenitor, this\nremark strongly confirms the belief that the immature plumage approximately\nshews us the former or ancestral condition of the species.\n\nAlthough many young birds, belonging to various families, thus give us a\nglimpse of the plumage of their remote progenitors, yet there are many\nother birds, both dull-coloured and bright-coloured, in which the young\nclosely resemble their parents.  In such cases the young of the different\nspecies cannot resemble each other more closely than do the parents; nor\ncan they strikingly resemble allied forms when adult.  They give us but\nlittle insight into the plumage of their progenitors, excepting in so far\nthat, when the young and the old are coloured in the same general manner\nthroughout a whole group of species, it is probable that their progenitors\nwere similarly coloured.\n\nWe may now consider the classes of cases, under which the differences and\nresemblances between the plumage of the young and the old, in both sexes or\nin one sex alone, may be grouped.  Rules of this kind were first enounced\nby Cuvier; but with the progress of knowledge they require some\nmodification and amplification.  This I have attempted to do, as far as the\nextreme complexity of the subject permits, from information derived from\nvarious sources; but a full essay on this subject by some competent\nornithologist is much needed.  In order to ascertain to what extent each\nrule prevails, I have tabulated the facts given in four great works,\nnamely, by Macgillivray on the birds of Britain, Audubon on those of North\nAmerica, Jerdon on those of India, and Gould on those of Australia.  I may\nhere premise, first, that the several cases or rules graduate into each\nother; and secondly, that when the young are said to resemble their\nparents, it is not meant that they are identically alike, for their colours\nare almost always less vivid, and the feathers are softer and often of a\ndifferent shape.\n\nRULES OR CLASSES OF CASES.\n\nI.  When the adult male is more beautiful or conspicuous than the adult\nfemale, the young of both sexes in their first plumage closely resemble the\nadult female, as with the common fowl and peacock; or, as occasionally\noccurs, they resemble her much more closely than they do the adult male.\n\nII.  When the adult female is more conspicuous than the adult male, as\nsometimes though rarely occurs, the young of both sexes in their first\nplumage resemble the adult male.\n\nIII.  When the adult male resembles the adult female, the young of both\nsexes have a peculiar first plumage of their own, as with the robin.\n\nIV.  When the adult male resembles the adult female, the young of both\nsexes in their first plumage resemble the adults, as with the kingfisher,\nmany parrots, crows, hedge-warblers.\n\nV.  When the adults of both sexes have a distinct winter and summer\nplumage, whether or not the male differs from the female, the young\nresemble the adults of both sexes in their winter dress, or much more\nrarely in their summer dress, or they resemble the females alone.  Or the\nyoung may have an intermediate character; or again they may differ greatly\nfrom the adults in both their seasonal plumages.\n\nVI.  In some few cases the young in their first plumage differ from each\nother according to sex; the young males resembling more or less closely the\nadult males, and the young females more or less closely the adult females.\n\nCLASS I.\n\nIn this class, the young of both sexes more or less closely resemble the\nadult female, whilst the adult male differs from the adult female, often in\nthe most conspicuous manner.  Innumerable instances in all Orders could be\ngiven; it will suffice to call to mind the common pheasant, duck, and\nhouse-sparrow.  The cases under this class graduate into others.  Thus the\ntwo sexes when adult may differ so slightly, and the young so slightly from\nthe adults, that it is doubtful whether such cases ought to come under the\npresent, or under the third or fourth classes.  So again the young of the\ntwo sexes, instead of being quite alike, may differ in a slight degree from\neach other, as in our sixth class.  These transitional cases, however, are\nfew, or at least are not strongly pronounced, in comparison with those\nwhich come strictly under the present class.\n\nThe force of the present law is well shewn in those groups, in which, as a\ngeneral rule, the two sexes and the young are all alike; for when in these\ngroups the male does differ from the female, as with certain parrots,\nkingfishers, pigeons, etc., the young of both sexes resemble the adult\nfemale.  (2.  See, for instance, Mr. Gould's account ('Handbook to the\nBirds of Australia,' vol. i. p. 133) of Cyanalcyon (one of the\nKingfishers), in which, however, the young male, though resembling the\nadult female, is less brilliantly coloured.  In some species of Dacelo the\nmales have blue tails, and the females brown ones; and Mr. R.B. Sharpe\ninforms me that the tail of the young male of D. gaudichaudi is at first\nbrown.  Mr. Gould has described (ibid. vol. ii. pp. 14, 20, 37) the sexes\nand the young of certain black Cockatoos and of the King Lory, with which\nthe same rule prevails.  Also Jerdon ('Birds of India,' vol. i. p. 260) on\nthe Palaeornis rosa, in which the young are more like the female than the\nmale.  See Audubon ('Ornithological Biography,' vol. ii. p. 475) on the two\nsexes and the young of Columba passerina.)  We see the same fact exhibited\nstill more clearly in certain anomalous cases; thus the male of Heliothrix\nauriculata (one of the humming-birds) differs conspicuously from the female\nin having a splendid gorget and fine ear-tufts, but the female is\nremarkable from having a much longer tail than that of the male; now the\nyoung of both sexes resemble (with the exception of the breast being\nspotted with bronze) the adult female in all other respects, including the\nlength of her tail, so that the tail of the male actually becomes shorter\nas he reaches maturity, which is a most unusual circumstance.  (3.  I owe\nthis information to Mr. Gould, who shewed me the specimens; see also his\n'Introduction to the Trochilidae,' 1861, p. 120.)  Again, the plumage of\nthe male goosander (Mergus merganser) is more conspicuously coloured than\nthat of the female, with the scapular and secondary wing-feathers much\nlonger; but differently from what occurs, as far as I know, in any other\nbird, the crest of the adult male, though broader than that of the female,\nis considerably shorter, being only a little above an inch in length; the\ncrest of the female being two and a half inches long.  Now the young of\nboth sexes entirely resemble the adult female, so that their crests are\nactually of greater length, though narrower, than in the adult male.  (4.\nMacgillivray, 'Hist. Brit. Birds,' vol. v. pp. 207-214.)\n\nWhen the young and the females closely resemble each other and both differ\nfrom the males, the most obvious conclusion is that the males alone have\nbeen modified.  Even in the anomalous cases of the Heliothrix and Mergus,\nit is probable that originally both adult sexes were furnished--the one\nspecies with a much elongated tail, and the other with a much elongated\ncrest--these characters having since been partially lost by the adult males\nfrom some unexplained cause, and transmitted in their diminished state to\ntheir male offspring alone, when arrived at the corresponding age of\nmaturity.  The belief that in the present class the male alone has been\nmodified, as far as the differences between the male and the female\ntogether with her young are concerned, is strongly supported by some\nremarkable facts recorded by Mr. Blyth (5.  See his admirable paper in the\n'Journal of the Asiatic Soc. of Bengal,' vol. xix. 1850, p. 223; see also\nJerdon, 'Birds of India,' vol. i. introduction, p. xxix.  In regard to\nTanysiptera, Prof. Schlegel told Mr. Blyth that he could distinguish\nseveral distinct races, solely by comparing the adult males.), with respect\nto closely-allied species which represent each other in distinct countries.\nFor with several of these representative species the adult males have\nundergone a certain amount of change and can be distinguished; the females\nand the young from the distinct countries being indistinguishable, and\ntherefore absolutely unchanged.  This is the case with certain Indian chats\n(Thamnobia), with certain honey-suckers (Nectarinia), shrikes\n(Tephrodornis), certain kingfishers (Tanysiptera), Kalij pheasants\n(Gallophasis), and tree-partridges (Arboricola).\n\nIn some analogous cases, namely with birds having a different summer and\nwinter plumage, but with the two sexes nearly alike, certain closely-allied\nspecies can easily be distinguished in their summer or nuptial plumage, yet\nare indistinguishable in their winter as well as in their immature plumage.\nThis is the case with some of the closely-allied Indian wagtails or\nMotacillae.  Mr. Swinhoe (6.  See also Mr. Swinhoe, in 'Ibis,' July 1863,\np. 131; and a previous paper, with an extract from a note by Mr. Blyth, in\n'Ibis,' January, 1861, p. 25.) informs me that three species of Ardeola, a\ngenus of herons, which represent one another on separate continents, are\n\"most strikingly different\" when ornamented with their summer plumes, but\nare hardly, if at all, distinguishable during the winter.  The young also\nof these three species in their immature plumage closely resemble the\nadults in their winter dress.  This case is all the more interesting,\nbecause with two other species of Ardeola both sexes retain, during the\nwinter and summer, nearly the same plumage as that possessed by the three\nfirst species during the winter and in their immature state; and this\nplumage, which is common to several distinct species at different ages and\nseasons, probably shews us how the progenitors of the genus were coloured.\nIn all these cases, the nuptial plumage which we may assume was originally\nacquired by the adult males during the breeding-season, and transmitted to\nthe adults of both sexes at the corresponding season, has been modified,\nwhilst the winter and immature plumages have been left unchanged.\n\nThe question naturally arises, how is it that in these latter cases the\nwinter plumage of both sexes, and in the former cases the plumage of the\nadult females, as well as the immature plumage of the young, have not been\nat all affected?  The species which represent each other in distinct\ncountries will almost always have been exposed to somewhat different\nconditions, but we can hardly attribute to this action the modification of\nthe plumage in the males alone, seeing that the females and the young,\nthough similarly exposed, have not been affected.  Hardly any fact shews us\nmore clearly how subordinate in importance is the direct action of the\nconditions of life, in comparison with the accumulation through selection\nof indefinite variations, than the surprising difference between the sexes\nof many birds; for both will have consumed the same food, and have been\nexposed to the same climate.  Nevertheless we are not precluded from\nbelieving that in the course of time new conditions may produce some direct\neffect either on both sexes, or from their constitutional differences\nchiefly on one sex.  We see only that this is subordinate in importance to\nthe accumulated results of selection.  Judging, however, from a wide-spread\nanalogy, when a species migrates into a new country (and this must precede\nthe formation of representative species), the changed conditions to which\nthey will almost always have been exposed will cause them to undergo a\ncertain amount of fluctuating variability.  In this case sexual selection,\nwhich depends on an element liable to change--the taste or admiration of\nthe female--will have had new shades of colour or other differences to act\non and accumulate; and as sexual selection is always at work, it would\n(from what we know of the results on domestic animals of man's\nunintentional selection), be surprising if animals inhabiting separate\ndistricts, which can never cross and thus blend their newly-acquired\ncharacters, were not, after a sufficient lapse of time, differently\nmodified.  These remarks likewise apply to the nuptial or summer plumage,\nwhether confined to the males, or common to both sexes.\n\nAlthough the females of the above closely-allied or representative species,\ntogether with their young, differ hardly at all from one another, so that\nthe males alone can be distinguished, yet the females of most species\nwithin the same genus obviously differ from each other.  The differences,\nhowever, are rarely as great as between the males.  We see this clearly in\nthe whole family of the Gallinaceae:  the females, for instance, of the\ncommon and Japan pheasant, and especially of the gold and Amherst pheasant\n--of the silver pheasant and the wild fowl--resemble one another very\nclosely in colour, whilst the males differ to an extraordinary degree.  So\nit is with the females of most of the Cotingidae, Fringillidae, and many\nother families.  There can indeed be no doubt that, as a general rule, the\nfemales have been less modified than the males.  Some few birds, however,\noffer a singular and inexplicable exception; thus the females of Paradisea\napoda and P. papuana differ from each other more than do their respective\nmales (7.  Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 394.); the\nfemale of the latter species having the under surface pure white, whilst\nthe female P. apoda is deep brown beneath.  So, again, as I hear from\nProfessor Newton, the males of two species of Oxynotus (shrikes), which\nrepresent each other in the islands of Mauritius and Bourbon (8.  These\nspecies are described with coloured figures, by M. F. Pollen, in 'Ibis,'\n1866, p. 275.), differ but little in colour, whilst the females differ\nmuch.  In the Bourbon species the female appears to have partially retained\nan immature condition of plumage, for at first sight she \"might be taken\nfor the young of the Mauritian species.\"  These differences may be compared\nwith those inexplicable ones, which occur independently of man's selection\nin certain sub-breeds of the game-fowl, in which the females are very\ndifferent, whilst the males can hardly be distinguished.  (9.  'Variation\nof Animals,' etc., vol. i. p. 251.)\n\nAs I account so largely by sexual selection for the differences between the\nmales of allied species, how can the differences between the females be\naccounted for in all ordinary cases?  We need not here consider the species\nwhich belong to distinct genera; for with these, adaptation to different\nhabits of life, and other agencies, will have come into play.  In regard to\nthe differences between the females within the same genus, it appears to me\nalmost certain, after looking through various large groups, that the chief\nagent has been the greater or less transference to the female of the\ncharacters acquired by the males through sexual selection.  In the several\nBritish finches, the two sexes differ either very slightly or considerably;\nand if we compare the females of the greenfinch, chaffinch, goldfinch,\nbullfinch, crossbill, sparrow, etc., we shall see that they differ from one\nanother chiefly in the points in which they partially resemble their\nrespective males; and the colours of the males may safely be attributed to\nsexual selection.  With many gallinaceous species the sexes differ to an\nextreme degree, as with the peacock, pheasant, and fowl, whilst with other\nspecies there has been a partial or even complete transference of character\nfrom the male to the female.  The females of the several species of\nPolyplectron exhibit in a dim condition, and chiefly on the tail, the\nsplendid ocelli of their males.  The female partridge differs from the male\nonly in the red mark on her breast being smaller; and the female wild\nturkey only in her colours being much duller.  In the guinea-fowl the two\nsexes are indistinguishable.  There is no improbability in the plain,\nthough peculiarly spotted plumage of this latter bird having been acquired\nthrough sexual selection by the males, and then transmitted to both sexes;\nfor it is not essentially different from the much more beautifully spotted\nplumage, characteristic of the males alone of the Tragopan pheasants.\n\nIt should be observed that, in some instances, the transference of\ncharacters from the male to the female has been effected apparently at a\nremote period, the male having subsequently undergone great changes,\nwithout transferring to the female any of his later-gained characters.  For\ninstance, the female and the young of the black-grouse (Tetrao tetrix)\nresemble pretty closely both sexes and the young of the red-grouse (T.\nscoticus); and we may consequently infer that the black-grouse is descended\nfrom some ancient species, of which both sexes were coloured in nearly the\nsame manner as the red-grouse.  As both sexes of this latter species are\nmore distinctly barred during the breeding-season than at any other time,\nand as the male differs slightly from the female in his more strongly-\npronounced red and brown tints (10.  Macgillivray, 'History of British\nBirds,' vol. i. pp. 172-174.), we may conclude that his plumage has been\ninfluenced by sexual selection, at least to a certain extent.  If so, we\nmay further infer that nearly similar plumage of the female black-grouse\nwas similarly produced at some former period.  But since this period the\nmale black-grouse has acquired his fine black plumage, with his forked and\noutwardly-curled tail-feathers; but of these characters there has hardly\nbeen any transference to the female, excepting that she shews in her tail a\ntrace of the curved fork.\n\nWe may therefore conclude that the females of distinct though allied\nspecies have often had their plumage rendered more or less different by the\ntransference in various degrees of characters acquired by the males through\nsexual selection, both during former and recent times.  But it deserves\nespecial attention that brilliant colours have been transferred much more\nrarely than other tints.  For instance, the male of the red-throated blue-\nbreast (Cyanecula suecica) has a rich blue breast, including a sub-\ntriangular red mark; now marks of nearly the same shape have been\ntransferred to the female, but the central space is fulvous instead of red,\nand is surrounded by mottled instead of blue feathers.  The Gallinaceae\noffer many analogous cases; for none of the species, such as partridges,\nquails, guinea-fowls, etc., in which the colours of the plumage have been\nlargely transferred from the male to the female, are brilliantly coloured.\nThis is well exemplified with the pheasants, in which the male is generally\nso much more brilliant than the female; but with the Eared and Cheer\npheasants (Crossoptilon auritum and Phasianus wallichii) the sexes closely\nresemble each other and their colours are dull.  We may go so far as to\nbelieve that if any part of the plumage in the males of these two pheasants\nhad been brilliantly coloured, it would not have been transferred to the\nfemales.  These facts strongly support Mr. Wallace's view that with birds\nwhich are exposed to much danger during incubation, the transference of\nbright colours from the male to the female has been checked through natural\nselection.  We must not, however, forget that another explanation, before\ngiven, is possible; namely, that the males which varied and became bright,\nwhilst they were young and inexperienced, would have been exposed to much\ndanger, and would generally have been destroyed; the older and more\ncautious males, on the other hand, if they varied in a like manner, would\nnot only have been able to survive, but would have been favoured in their\nrivalry with other males.  Now variations occurring late in life tend to be\ntransmitted exclusively to the same sex, so that in this case extremely\nbright tints would not have been transmitted to the females.  On the other\nhand, ornaments of a less conspicuous kind, such as those possessed by the\nEared and Cheer pheasants, would not have been dangerous, and if they\nappeared during early youth, would generally have been transmitted to both\nsexes.\n\nIn addition to the effects of the partial transference of characters from\nthe males to the females, some of the differences between the females of\nclosely allied species may be attributed to the direct or definite action\nof the conditions of life.  (11.  See, on this subject, chap. xxiii. in the\n'Variation of Animals and Plants under Domestication.')  With the males,\nany such action would generally have been masked by the brilliant colours\ngained through sexual selection; but not so with the females.  Each of the\nendless diversities in plumage which we see in our domesticated birds is,\nof course, the result of some definite cause; and under natural and more\nuniform conditions, some one tint, assuming that it was in no way\ninjurious, would almost certainly sooner or later prevail.  The free\nintercrossing of the many individuals belonging to the same species would\nultimately tend to make any change of colour, thus induced, uniform in\ncharacter.\n\nNo one doubts that both sexes of many birds have had their colours adapted\nfor the sake of protection; and it is possible that the females alone of\nsome species may have been modified for this end.  Although it would be a\ndifficult, perhaps an impossible process, as shewn in the last chapter, to\nconvert one form of transmission into another through selection, there\nwould not be the least difficulty in adapting the colours of the female,\nindependently of those of the male, to surrounding objects, through the\naccumulation of variations which were from the first limited in their\ntransmission to the female sex.  If the variations were not thus limited,\nthe bright tints of the male would be deteriorated or destroyed.  Whether\nthe females alone of many species have been thus specially modified, is at\npresent very doubtful.  I wish I could follow Mr. Wallace to the full\nextent; for the admission would remove some difficulties.  Any variations\nwhich were of no service to the female as a protection would be at once\nobliterated, instead of being lost simply by not being selected, or from\nfree intercrossing, or from being eliminated when transferred to the male\nand in any way injurious to him.  Thus the plumage of the female would be\nkept constant in character.  It would also be a relief if we could admit\nthat the obscure tints of both sexes of many birds had been acquired and\npreserved for the sake of protection,--for example, of the hedge-warbler or\nkitty-wren (Accentor modularis and Troglodytes vulgaris), with respect to\nwhich we have no sufficient evidence of the action of sexual selection.  We\nought, however, to be cautious in concluding that colours which appear to\nus dull, are not attractive to the females of certain species; we should\nbear in mind such cases as that of the common house-sparrow, in which the\nmale differs much from the female, but does not exhibit any bright tints.\nNo one probably will dispute that many gallinaceous birds which live on the\nopen ground, have acquired their present colours, at least in part, for the\nsake of protection.  We know how well they are thus concealed; we know that\nptarmigans, whilst changing from their winter to their summer plumage, both\nof which are protective, suffer greatly from birds of prey.  But can we\nbelieve that the very slight differences in tints and markings between, for\ninstance, the female black-grouse and red-grouse serve as a protection?\nAre partridges, as they are now coloured, better protected than if they had\nresembled quails?  Do the slight differences between the females of the\ncommon pheasant, the Japan and gold pheasants, serve as a protection, or\nmight not their plumages have been interchanged with impunity?  From what\nMr. Wallace has observed of the habits of certain gallinaceous birds in the\nEast, he thinks that such slight differences are beneficial.  For myself, I\nwill only say that I am not convinced.\n\nFormerly when I was inclined to lay much stress on protection as accounting\nfor the duller colours of female birds, it occurred to me that possibly\nboth sexes and the young might aboriginally have been equally bright\ncoloured; but that subsequently, the females from the danger incurred\nduring incubation, and the young from being inexperienced, had been\nrendered dull as a protection.  But this view is not supported by any\nevidence, and is not probable; for we thus in imagination expose during\npast times the females and the young to danger, from which it has\nsubsequently been necessary to shield their modified descendants.  We have,\nalso, to reduce, through a gradual process of selection, the females and\nthe young to almost exactly the same tints and markings, and to transmit\nthem to the corresponding sex and period of life.  On the supposition that\nthe females and the young have partaken during each stage of the process of\nmodification of a tendency to be as brightly coloured as the males, it is\nalso a somewhat strange fact that the females have never been rendered\ndull-coloured without the young participating in the same change; for there\nare no instances, as far as I can discover, of species with the females\ndull and the young bright coloured.  A partial exception, however, is\noffered by the young of certain woodpeckers, for they have \"the whole upper\npart of the head tinged with red,\" which afterwards either decreases into a\nmere circular red line in the adults of both sexes, or quite disappears in\nthe adult females.  (12.  Audubon, 'Ornith. Biography,' vol. i. p. 193.\nMacgillivray, 'History of British Birds,' vol. iii. p. 85.  See also the\ncase before given of Indopicus carlotta.)\n\nFinally, with respect to our present class of cases, the most probable view\nappears to be that successive variations in brightness or in other\nornamental characters, occurring in the males at a rather late period of\nlife have alone been preserved; and that most or all of these variations,\nowing to the late period of life at which they appeared, have been from the\nfirst transmitted only to the adult male offspring.  Any variations in\nbrightness occurring in the females or in the young, would have been of no\nservice to them, and would not have been selected; and moreover, if\ndangerous, would have been eliminated.  Thus the females and the young will\neither have been left unmodified, or (as is much more common) will have\nbeen partially modified by receiving through transference from the males\nsome of his successive variations.  Both sexes have perhaps been directly\nacted on by the conditions of life to which they have long been exposed:\nbut the females from not being otherwise much modified, will best exhibit\nany such effects.  These changes and all others will have been kept uniform\nby the free intercrossing of many individuals.  In some cases, especially\nwith ground birds, the females and the young may possibly have been\nmodified, independently of the males, for the sake of protection, so as to\nhave acquired the same dull-coloured plumage.\n\nCLASS II.\n\nWHEN THE ADULT FEMALE IS MORE CONSPICUOUS THAN THE ADULT MALE, THE YOUNG OF\nBOTH SEXES IN THEIR FIRST PLUMAGE RESEMBLE THE ADULT MALE.\n\nThis class is exactly the reverse of the last, for the females are here\nbrighter coloured or more conspicuous than the males; and the young, as far\nas they are known, resemble the adult males instead of the adult females.\nBut the difference between the sexes is never nearly so great as with many\nbirds in the first class, and the cases are comparatively rare.  Mr.\nWallace, who first called attention to the singular relation which exists\nbetween the less bright colours of the males and their performing the\nduties of incubation, lays great stress on this point (13.  'Westminster\nReview,' July 1867, and A. Murray, 'Journal of Travel,' 1868, p. 83.), as a\ncrucial test that obscure colours have been acquired for the sake of\nprotection during the period of nesting.  A different view seems to me more\nprobable.  As the cases are curious and not numerous, I will briefly give\nall that I have been able to find.\n\nIn one section of the genus Turnix, quail-like birds, the female is\ninvariably larger than the male (being nearly twice as large in one of the\nAustralian species), and this is an unusual circumstance with the\nGallinaceae.  In most of the species the female is more distinctly coloured\nand brighter than the male (14.  For the Australian species, see Gould's\n'Handbook,' etc., vol. ii. pp. 178, 180, 186, and 188.  In the British\nMuseum specimens of the Australian Plain-wanderer (Pedionomus torquatus)\nmay be seen, shewing similar sexual differences.), but in some few species\nthe sexes are alike.  In Turnix taigoor of India the male \"wants the black\non the throat and neck, and the whole tone of the plumage is lighter and\nless pronounced than that of the female.\"  The female appears to be\nnoisier, and is certainly much more pugnacious than the male; so that the\nfemales and not the males are often kept by the natives for fighting, like\ngame-cocks.  As male birds are exposed by the English bird-catchers for a\ndecoy near a trap, in order to catch other males by exciting their rivalry,\nso the females of this Turnix are employed in India.  When thus exposed the\nfemales soon begin their \"loud purring call, which can be heard a long way\noff, and any females within ear-shot run rapidly to the spot, and commence\nfighting with the caged bird.\"  In this way from twelve to twenty birds,\nall breeding females, may be caught in the course of a single day.  The\nnatives assert that the females after laying their eggs associate in\nflocks, and leave the males to sit on them.  There is no reason to doubt\nthe truth of this assertion, which is supported by some observations made\nin China by Mr. Swinhoe.  (15.  Jerdon, 'Birds of India,' vol. iii. p. 596.\nMr. Swinhoe, in 'Ibis,' 1865, p. 542; 1866, pp. 131, 405.)  Mr. Blyth\nbelieves, that the young of both sexes resemble the adult male.\n\n[Fig. 62.  Rhynchaea capensis (from Brehm).]\n\nThe females of the three species of Painted Snipes (Rhynchaea, Fig. 62)\n\"are not only larger but much more richly coloured than the males.\"  (16.\nJerdon, 'Birds of India,' vol. iii. p. 677.)  With all other birds in which\nthe trachea differs in structure in the two sexes it is more developed and\ncomplex in the male than in the female; but in the Rhynchaea australis it\nis simple in the male, whilst in the female it makes four distinct\nconvolutions before entering the lungs.  (17.  Gould's 'Handbook to the\nBirds of Australia,' vol. ii. p. 275.)  The female therefore of this\nspecies has acquired an eminently masculine character.  Mr. Blyth\nascertained, by examining many specimens, that the trachea is not\nconvoluted in either sex of R. bengalensis, which species resembles R.\naustralis so closely, that it can hardly be distinguished except by its\nshorter toes.  This fact is another striking instance of the law that\nsecondary sexual characters are often widely different in closely-allied\nforms, though it is a very rare circumstance when such differences relate\nto the female sex.  The young of both sexes of R. bengalensis in their\nfirst plumage are said to resemble the mature male.  (18.  'The Indian\nField,' Sept. 1858, p. 3.)  There is also reason to believe that the male\nundertakes the duty of incubation, for Mr. Swinhoe (19.  'Ibis,' 1866, p.\n298.) found the females before the close of the summer associated in\nflocks, as occurs with the females of the Turnix.\n\nThe females of Phalaropus fulicarius and P. hyperboreus are larger, and in\ntheir summer plumage \"more gaily attired than the males.\"  But the\ndifference in colour between the sexes is far from conspicuous.  According\nto Professor Steenstrup, the male alone of P. fulicarius undertakes the\nduty of incubation; this is likewise shewn by the state of his breast-\nfeathers during the breeding-season.  The female of the dotterel plover\n(Eudromias morinellus) is larger than the male, and has the red and black\ntints on the lower surface, the white crescent on the breast, and the\nstripes over the eyes, more strongly pronounced.  The male also takes at\nleast a share in hatching the eggs; but the female likewise attends to the\nyoung.  (20.  For these several statements, see Mr. Gould's 'Birds of Great\nBritain.'  Prof. Newton informs me that he has long been convinced, from\nhis own observations and from those of others, that the males of the above-\nnamed species take either the whole or a large share of the duties of\nincubation, and that they \"shew much greater devotion towards their young,\nwhen in danger, than do the females.\"  So it is, as he informs me, with\nLimosa lapponica and some few other Waders, in which the females are larger\nand have more strongly contrasted colours than the males.)  I have not been\nable to discover whether with these species the young resemble the adult\nmales more closely than the adult females; for the comparison is somewhat\ndifficult to make on account of the double moult.\n\nTurning now to the ostrich Order:  the male of the common cassowary\n(Casuarius galeatus) would be thought by any one to be the female, from his\nsmaller size and from the appendages and naked skin about his head being\nmuch less brightly coloured; and I am informed by Mr. Bartlett that in the\nZoological Gardens, it is certainly the male alone who sits on the eggs and\ntakes care of the young.  (21.  The natives of Ceram (Wallace, 'Malay\nArchipelago,' vol. ii. p. 150) assert that the male and female sit\nalternately on the eggs; but this assertion, as Mr. Bartlett thinks, may be\naccounted for by the female visiting the nest to lay her eggs.)  The female\nis said by Mr. T.W. Wood (22.  The 'Student,' April 1870, p. 124.) to\nexhibit during the breeding-season a most pugnacious disposition; and her\nwattles then become enlarged and more brilliantly coloured.  So again the\nfemale of one of the emus (Dromoeus irroratus) is considerably larger than\nthe male, and she possesses a slight top-knot, but is otherwise\nindistinguishable in plumage.  She appears, however, \"to have greater\npower, when angry or otherwise excited, of erecting, like a turkey-cock,\nthe feathers of her neck and breast.  She is usually the more courageous\nand pugilistic.  She makes a deep hollow guttural boom especially at night,\nsounding like a small gong.  The male has a slenderer frame and is more\ndocile, with no voice beyond a suppressed hiss when angry, or a croak.\"  He\nnot only performs the whole duty of incubation, but has to defend the young\nfrom their mother; \"for as soon as she catches sight of her progeny she\nbecomes violently agitated, and notwithstanding the resistance of the\nfather appears to use her utmost endeavours to destroy them.  For months\nafterwards it is unsafe to put the parents together, violent quarrels being\nthe inevitable result, in which the female generally comes off conqueror.\"\n(23.  See the excellent account of the habits of this bird under\nconfinement, by Mr. A.W. Bennett, in 'Land and Water,' May 1868, p. 233.)\nSo that with this emu we have a complete reversal not only of the parental\nand incubating instincts, but of the usual moral qualities of the two\nsexes; the females being savage, quarrelsome, and noisy, the males gentle\nand good.  The case is very different with the African ostrich, for the\nmale is somewhat larger than the female and has finer plumes with more\nstrongly contrasted colours; nevertheless he undertakes the whole duty of\nincubation.  (24.  Mr. Sclater, on the incubation of the Struthiones,\n'Proc. Zool. Soc.' June 9, 1863.  So it is with the Rhea darwinii:  Captain\nMusters says ('At Home with the Patagonians,' 1871, p. 128), that the male\nis larger, stronger and swifter than the female, and of slightly darker\ncolours; yet he takes sole charge of the eggs and of the young, just as\ndoes the male of the common species of Rhea.)\n\nI will specify the few other cases known to me, in which the female is more\nconspicuously coloured than the male, although nothing is known about the\nmanner of incubation.  With the carrion-hawk of the Falkland Islands\n(Milvago leucurus) I was much surprised to find by dissection that the\nindividuals, which had all their tints strongly pronounced, with the cere\nand legs orange-coloured, were the adult females; whilst those with duller\nplumage and grey legs were the males or the young.  In an Australian tree-\ncreeper (Climacteris erythrops) the female differs from the male in \"being\nadorned with beautiful, radiated, rufous markings on the throat, the male\nhaving this part quite plain.\"  Lastly, in an Australian night-jar \"the\nfemale always exceeds the male in size and in the brilliance of her tints;\nthe males, on the other hand, have two white spots on the primaries more\nconspicuous than in the female.\"  (25.  For the Milvago, see 'Zoology of\nthe Voyage of the \"Beagle,\"  Birds,' 1841, p. 16.  For the Climacteris and\nnight-jar (Eurostopodus), see Gould's 'Handbook to the Birds of Australia,'\nvol. i. pp. 602 and 97.  The New Zealand shieldrake (Tadorna variegata)\noffers a quite anomalous case; the head of the female is pure white, and\nher back is redder than that of the male; the head of the male is of a rich\ndark bronzed colour, and his back is clothed with finely pencilled slate-\ncoloured feathers, so that altogether he may be considered as the more\nbeautiful of the two.  He is larger and more pugnacious than the female,\nand does not sit on the eggs.  So that in all these respects this species\ncomes under our first class of cases; but Mr. Sclater ('Proceedings of the\nZoological Society,' 1866, p. 150) was much surprised to observe that the\nyoung of both sexes, when about three months old, resembled in their dark\nheads and necks the adult males, instead of the adult females; so that it\nwould appear in this case that the females have been modified, whilst the\nmales and the young have retained a former state of plumage.)\n\nWe thus see that the cases in which female birds are more conspicuously\ncoloured than the males, with the young in their immature plumage\nresembling the adult males instead of the adult females, as in the previous\nclass, are not numerous, though they are distributed in various Orders.\nThe amount of difference, also, between the sexes is incomparably less than\nthat which frequently occurs in the last class; so that the cause of the\ndifference, whatever it may have been, has here acted on the females either\nless energetically or less persistently than on the males in the last\nclass.  Mr. Wallace believes that the males have had their colours rendered\nless conspicuous for the sake of protection during the period of\nincubation; but the difference between the sexes in hardly any of the\nforegoing cases appears sufficiently great for this view to be safely\naccepted.  In some of the cases, the brighter tints of the female are\nalmost confined to the lower surface, and the males, if thus coloured,\nwould not have been exposed to danger whilst sitting on the eggs.  It\nshould also be borne in mind that the males are not only in a slight degree\nless conspicuously coloured than the females, but are smaller and weaker.\nThey have, moreover, not only acquired the maternal instinct of incubation,\nbut are less pugnacious and vociferous than the females, and in one\ninstance have simpler vocal organs.  Thus an almost complete transposition\nof the instincts, habits, disposition, colour, size, and of some points of\nstructure, has been effected between the two sexes.\n\nNow if we might assume that the males in the present class have lost some\nof that ardour which is usual to their sex, so that they no longer search\neagerly for the females; or, if we might assume that the females have\nbecome much more numerous than the males--and in the case of one Indian\nTurnix the females are said to be \"much more commonly met with than the\nmales\" (26.  Jerdon, 'Birds of India,' vol. iii. p. 598.)--then it is not\nimprobable that the females would have been led to court the males, instead\nof being courted by them.  This indeed is the case to a certain extent with\nsome birds, as we have seen with the peahen, wild turkey, and certain kinds\nof grouse.  Taking as our guide the habits of most male birds, the greater\nsize and strength as well as the extraordinary pugnacity of the females of\nthe Turnix and emu, must mean that they endeavour to drive away rival\nfemales, in order to gain possession of the male; and on this view all the\nfacts become clear; for the males would probably be most charmed or excited\nby the females which were the most attractive to them by their bright\ncolours, other ornaments, or vocal powers.  Sexual selection would then do\nits work, steadily adding to the attractions of the females; the males and\nthe young being left not at all, or but little modified.\n\nCLASS III.\n\nWHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES\nHAVE A PECULIAR FIRST PLUMAGE OF THEIR OWN.\n\nIn this class the sexes when adult resemble each other, and differ from the\nyoung.  This occurs with many birds of many kinds.  The male robin can\nhardly be distinguished from the female, but the young are widely\ndifferent, with their mottled dusky-olive and brown plumage.  The male and\nfemale of the splendid scarlet ibis are alike, whilst the young are brown;\nand the scarlet colour, though common to both sexes, is apparently a sexual\ncharacter, for it is not well developed in either sex under confinement;\nand a loss of colour often occurs with brilliant males when they are\nconfined.  With many species of herons the young differ greatly from the\nadults; and the summer plumage of the latter, though common to both sexes,\nclearly has a nuptial character.  Young swans are slate-coloured, whilst\nthe mature birds are pure white; but it would be superfluous to give\nadditional instances.  These differences between the young and the old\napparently depend, as in the last two classes, on the young having retained\na former or ancient state of plumage, whilst the old of both sexes have\nacquired a new one.  When the adults are bright coloured, we may conclude\nfrom the remarks just made in relation to the scarlet ibis and to many\nherons, and from the analogy of the species in the first class, that such\ncolours have been acquired through sexual selection by the nearly mature\nmales; but that, differently from what occurs in the first two classes, the\ntransmission, though limited to the same age, has not been limited to the\nsame sex.  Consequently, the sexes when mature resemble each other and\ndiffer from the young.\n\nCLASS IV.\n\nWHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES IN\nTHEIR FIRST PLUMAGE RESEMBLE THE ADULTS.\n\nIn this class the young and the adults of both sexes, whether brilliantly\nor obscurely coloured, resemble each other.  Such cases are, I think, more\ncommon than those in the last class.  We have in England instances in the\nkingfisher, some woodpeckers, the jay, magpie, crow, and many small dull-\ncoloured birds, such as the hedge-warbler or kitty-wren.  But the\nsimilarity in plumage between the young and the old is never complete, and\ngraduates away into dissimilarity.  Thus the young of some members of the\nkingfisher family are not only less vividly coloured than the adults, but\nmany of the feathers on the lower surface are edged with brown (27.\nJerdon, 'Birds of India,' vol. i. pp. 222, 228.  Gould's 'Handbook to the\nBirds of Australia,' vol. i. pp. 124, 130.),--a vestige probably of a\nformer state of the plumage.  Frequently in the same group of birds, even\nwithin the same genus, for instance in an Australian genus of parrakeets\n(Platycercus), the young of some species closely resemble, whilst the young\nof other species differ considerably, from their parents of both sexes,\nwhich are alike.  (28.  Gould, ibid. vol. ii. pp. 37, 46, 56.)  Both sexes\nand the young of the common jay are closely similar; but in the Canada jay\n(Perisoreus canadensis) the young differ so much from their parents that\nthey were formerly described as distinct species.  (29.  Audubon, 'Ornith.\nBiography,' vol. ii. p. 55.)\n\nI may remark before proceeding that, under the present and next two classes\nof cases, the facts are so complex and the conclusions so doubtful, that\nany one who feels no especial interest in the subject had better pass them\nover.\n\nThe brilliant or conspicuous colours which characterise many birds in the\npresent class, can rarely or never be of service to them as a protection;\nso that they have probably been gained by the males through sexual\nselection, and then transferred to the females and the young.  It is,\nhowever, possible that the males may have selected the more attractive\nfemales; and if these transmitted their characters to their offspring of\nboth sexes, the same results would follow as from the selection of the more\nattractive males by the females.  But there is evidence that this\ncontingency has rarely, if ever, occurred in any of those groups of birds\nin which the sexes are generally alike; for, if even a few of the\nsuccessive variations had failed to be transmitted to both sexes, the\nfemales would have slightly exceeded the males in beauty.  Exactly the\nreverse occurs under nature; for, in almost every large group in which the\nsexes generally resemble each other, the males of some few species are in a\nslight degree more brightly coloured than the females.  It is again\npossible that the females may have selected the more beautiful males, these\nmales having reciprocally selected the more beautiful females; but it is\ndoubtful whether this double process of selection would be likely to occur,\nowing to the greater eagerness of one sex than the other, and whether it\nwould be more efficient than selection on one side alone.  It is,\ntherefore, the most probable view that sexual selection has acted, in the\npresent class, as far as ornamental characters are concerned, in accordance\nwith the general rule throughout the animal kingdom, that is, on the males;\nand that these have transmitted their gradually-acquired colours, either\nequally or almost equally, to their offspring of both sexes.\n\nAnother point is more doubtful, namely, whether the successive variations\nfirst appeared in the males after they had become nearly mature, or whilst quite\nyoung.  In either case sexual selection must have acted on the male when he\nhad to compete with rivals for the possession of the female; and in both\ncases the characters thus acquired have been transmitted to both sexes and\nall ages.  But these characters if acquired by the males when adult, may\nhave been transmitted at first to the adults alone, and at some subsequent\nperiod transferred to the young.  For it is known that, when the law of\ninheritance at corresponding ages fails, the offspring often inherit\ncharacters at an earlier age than that at which they first appeared in\ntheir parents.  (30.  'Variation of Animals and Plants under\nDomestication,' vol. ii. p. 79.)  Cases apparently of this kind have been\nobserved with birds in a state of nature.  For instance Mr. Blyth has seen\nspecimens of Lanius rufus and of Colymbus glacialis which had assumed\nwhilst young, in a quite anomalous manner, the adult plumage of their\nparents.  (31.  'Charlesworth's Magazine of Natural History,' vol. i. 1837,\npp. 305, 306.)  Again, the young of the common swan (Cygnus olor) do not\ncast off their dark feathers and become white until eighteen months or two\nyears old; but Dr. F. Forel has described the case of three vigorous young\nbirds, out of a brood of four, which were born pure white.  These young\nbirds were not albinos, as shewn by the colour of their beaks and legs,\nwhich nearly resembled the same parts in the adults.  (32.  'Bulletin de la\nSoc. Vaudoise des Sc. Nat.' vol. x. 1869, p. 132.  The young of the Polish\nswan, Cygnus immutabilis of Yarrell, are always white; but this species, as\nMr. Sclater informs me, is believed to be nothing more than a variety of\nthe domestic swan (Cygnus olor).)\n\nIt may be worth while to illustrate the above three modes by which, in the\npresent class, the two sexes and the young may have come to resemble each\nother, by the curious case of the genus Passer.  (33.  I am indebted to Mr.\nBlyth for information in regard to this genus.  The sparrow of Palestine\nbelongs to the sub-genus Petronia.)  In the house-sparrow (P. domesticus)\nthe male differs much from the female and from the young.  The young and\nthe females are alike, and resemble to a large extent both sexes and the\nyoung of the sparrow of Palestine (P. brachydactylus), as well as of some\nallied species.  We may therefore assume that the female and young of the\nhouse-sparrow approximately shew us the plumage of the progenitor of the\ngenus.  Now with the tree-sparrow (P. montanus) both sexes and the young\nclosely resemble the male of the house-sparrow; so that they have all been\nmodified in the same manner, and all depart from the typical colouring of\ntheir early progenitor.  This may have been effected by a male ancestor of\nthe tree-sparrow having varied, firstly, when nearly mature; or, secondly,\nwhilst quite young, and by having in either case transmitted his modified\nplumage to the females and the young; or, thirdly, he may have varied when\nadult and transmitted his plumage to both adult sexes, and, owing to the\nfailure of the law of inheritance at corresponding ages, at some subsequent\nperiod to his young.\n\nIt is impossible to decide which of these three modes has generally\nprevailed throughout the present class of cases.  That the males varied\nwhilst young, and transmitted their variations to their offspring of both\nsexes, is the most probable.  I may here add that I have, with little\nsuccess, endeavoured, by consulting various works, to decide how far the\nperiod of variation in birds has generally determined the transmission of\ncharacters to one sex or to both.  The two rules, often referred to\n(namely, that variations occurring late in life are transmitted to one and\nthe same sex, whilst those which occur early in life are transmitted to\nboth sexes), apparently hold good in the first (34.  For instance, the\nmales of Tanagra aestiva and Fringilla cyanea require three years, the male\nof Fringilla ciris four years, to complete their beautiful plumage.  (See\nAudubon, 'Ornith. Biography,' vol. i. pp. 233, 280, 378).  The Harlequin\nduck takes three years (ibid. vol. iii. p. 614).  The male of the Gold\npheasant, as I hear from Mr. Jenner Weir, can be distinguished from the\nfemale when about three months old, but he does not acquire his full\nsplendour until the end of the September in the following year.), second,\nand fourth classes of cases; but they fail in the third, often in the fifth\n(35.  Thus the Ibis tantalus and Grus americanus take four years, the\nFlamingo several years, and the Ardea ludovicana two years, before they\nacquire their perfect plumage.  See Audubon, ibid. vol. i. p. 221; vol.\niii. pp. 133, 139, 211.), and in the sixth small class.  They apply,\nhowever, as far as I can judge, to a considerable majority of the species;\nand we must not forget the striking generalisation by Dr. W. Marshall with\nrespect to the protuberances on the heads of birds.  Whether or not the two\nrules generally hold good, we may conclude from the facts given in the\neighth chapter, that the period of variation is one important element in\ndetermining the form of transmission.\n\nWith birds it is difficult to decide by what standard we ought to judge of\nthe earliness or lateness of the period of variation, whether by the age in\nreference to the duration of life, or to the power of reproduction, or to\nthe number of moults through which the species passes.  The moulting of\nbirds, even within the same family, sometimes differs much without any\nassignable cause.  Some birds moult so early, that nearly all the body\nfeathers are cast off before the first wing-feathers are fully grown; and\nwe cannot believe that this was the primordial state of things.  When the\nperiod of moulting has been accelerated, the age at which the colours of\nthe adult plumage are first developed will falsely appear to us to be\nearlier than it really is.  This may be illustrated by the practice\nfollowed by some bird-fanciers, who pull out a few feathers from the breast\nof nestling bullfinches, and from the head or neck of young gold-pheasants,\nin order to ascertain their sex; for in the males, these feathers are\nimmediately replaced by coloured ones.  (36.  Mr. Blyth, in Charlesworth's\n'Magazine of Natural History,' vol. i. 1837, p. 300.  Mr. Bartlett has\ninformed me in regard to gold pheasants.)  The actual duration of life is\nknown in but few birds, so that we can hardly judge by this standard.  And,\nwith reference to the period at which the power of reproduction is gained,\nit is a remarkable fact that various birds occasionally breed whilst\nretaining their immature plumage.  (37.  I have noticed the following cases\nin Audubon's 'Ornith. Biography.'  The redstart of America (Muscapica\nruticilla, vol. i. p. 203).  The Ibis tantalus takes four years to come to\nfull maturity, but sometimes breeds in the second year (vol. iii. p. 133).\nThe Grus americanus takes the same time, but breeds before acquiring its\nfull plumage (vol. iii. p. 211).  The adults of Ardea caerulea are blue,\nand the young white; and white, mottled, and mature blue birds may all be\nseen breeding together (vol. iv. p. 58):  but Mr. Blyth informs me that\ncertain herons apparently are dimorphic, for white and coloured individuals\nof the same age may be observed.  The Harlequin duck (Anas histrionica,\nLinn.) takes three years to acquire its full plumage, though many birds\nbreed in the second year (vol. iii. p. 614).  The White-headed Eagle (Falco\nleucocephalus, vol. iii. p. 210) is likewise known to breed in its immature\nstate.  Some species of Oriolus (according to Mr. Blyth and Mr. Swinhoe, in\n'Ibis,' July 1863, p. 68) likewise breed before they attain their full\nplumage.)\n\nThe fact of birds breeding in their immature plumage seems opposed to the\nbelief that sexual selection has played as important a part, as I believe\nit has, in giving ornamental colours, plumes, etc., to the males, and, by\nmeans of equal transmission, to the females of many species.  The objection\nwould be a valid one, if the younger and less ornamented males were as\nsuccessful in winning females and propagating their kind, as the older and\nmore beautiful males.  But we have no reason to suppose that this is the\ncase.  Audubon speaks of the breeding of the immature males of Ibis\ntantalus as a rare event, as does Mr. Swinhoe, in regard to the immature\nmales of Oriolus.  (38.  See footnote 37 above.)  If the young of any\nspecies in their immature plumage were more successful in winning partners\nthan the adults, the adult plumage would probably soon be lost, as the\nmales would prevail, which retained their immature dress for the longest\nperiod, and thus the character of the species would ultimately be modified.\n(39.  Other animals, belonging to quite distinct classes, are either\nhabitually or occasionally capable of breeding before they have fully\nacquired their adult characters.  This is the case with the young males of\nthe salmon.  Several amphibians have been known to breed whilst retaining\ntheir larval structure.  Fritz Mueller has shewn ('Facts and arguments for\nDarwin,' Eng. trans. 1869, p. 79) that the males of several amphipod\ncrustaceans become sexually mature whilst young; and I infer that this is a\ncase of premature breeding, because they have not as yet acquired their\nfully-developed claspers.  All such facts are highly interesting, as\nbearing on one means by which species may undergo great modifications of\ncharacter.)  If, on the other hand, the young never succeeded in obtaining\na female, the habit of early reproduction would perhaps be sooner or later\neliminated, from being superfluous and entailing waste of power.\n\nThe plumage of certain birds goes on increasing in beauty during many years\nafter they are fully mature; this is the case with the train of the\npeacock, with some of the birds of paradise, and with the crest and plumes\nof certain herons, for instance, the Ardea ludovicana.  (40.  Jerdon,\n'Birds of India,' vol. iii. p. 507, on the peacock.  Dr. Marshall thinks\nthat the older and more brilliant males of birds of paradise, have an\nadvantage over the younger males; see 'Archives Neerlandaises,' tom. vi.\n1871.--On Ardea, Audubon, ibid. vol. iii. p. 139.)  But it is doubtful\nwhether the continued development of such feathers is the result of the\nselection of successive beneficial variations (though this is the most\nprobable view with birds of paradise) or merely of continuous growth.  Most\nfishes continue increasing in size, as long as they are in good health and\nhave plenty of food; and a somewhat similar law may prevail with the plumes\nof birds.\n\nCLASS V.\n\nWHEN THE ADULTS OF BOTH SEXES HAVE A DISTINCT WINTER AND SUMMER PLUMAGE,\nWHETHER OR NOT THE MALE DIFFERS FROM THE FEMALE, THE YOUNG RESEMBLE THE\nADULTS OF BOTH SEXES IN THEIR WINTER DRESS, OR MUCH MORE RARELY IN THEIR\nSUMMER DRESS, OR THEY RESEMBLE THE FEMALES ALONE.  OR THE YOUNG MAY HAVE AN\nINTERMEDIATE CHARACTER; OR, AGAIN, THEY MAY DIFFER GREATLY FROM THE ADULTS\nIN BOTH THEIR SEASONAL PLUMAGES.\n\nThe cases in this class are singularly complex; nor is this surprising, as\nthey depend on inheritance, limited in a greater or less degree in three\ndifferent ways, namely, by sex, age, and the season of the year.  In some\ncases the individuals of the same species pass through at least five\ndistinct states of plumage.  With the species, in which the male differs\nfrom the female during the summer season alone, or, which is rarer, during\nboth seasons (41.  For illustrative cases, see vol. iv. of Macgillivray's\n'History of British Birds;' on Tringa, etc., pp. 229, 271; on the Machetes,\np. 172; on the Charadrius hiaticula, p. 118; on the Charadrius pluvialis,\np. 94.), the young generally resemble the females,--as with the so-called\ngoldfinch of North America, and apparently with the splendid Maluri of\nAustralia.  (42.  For the goldfinch of N. America, Fringilla tristis,\nLinn., see Audubon, 'Ornithological Biography,' vol. i. p. 172.  For the\nMaluri, Gould's 'Handbook of the Birds of Australia,' vol. i. p. 318.)\nWith those species, the sexes of which are alike during both the summer and\nwinter, the young may resemble the adults, firstly, in their winter dress;\nsecondly, and this is of much rarer occurrence, in their summer dress;\nthirdly, they may be intermediate between these two states; and, fourthly,\nthey may differ greatly from the adults at all seasons.  We have an\ninstance of the first of these four cases in one of the egrets of India\n(Buphus coromandus), in which the young and the adults of both sexes are\nwhite during the winter, the adults becoming golden-buff during the summer.\n\nWith the gaper (Anastomus oscitans) of India we have a similar case, but\nthe colours are reversed:  for the young and the adults of both sexes are\ngrey and black during the winter, the adults becoming white during the\nsummer.  (43.  I am indebted to Mr. Blyth for information as to the Buphus;\nsee also Jerdon, 'Birds of India,' vol. iii. p. 749.  On the Anastomus, see\nBlyth, in 'Ibis,' 1867, p. 173.)  As an instance of the second case, the\nyoung of the razor-bill (Alca torda, Linn.), in an early state of plumage,\nare coloured like the adults during the summer; and the young of the white-\ncrowned sparrow of North America (Fringilla leucophrys), as soon as\nfledged, have elegant white stripes on their heads, which are lost by the\nyoung and the old during the winter.  (44.  On the Alca, see Macgillivray,\n'Hist. Brit. Birds,' vol. v. p. 347.  On the Fringilla leucophrys, Audubon,\nibid. vol. ii. p. 89.  I shall have hereafter to refer to the young of\ncertain herons and egrets being white.)  With respect to the third case,\nnamely, that of the young having an intermediate character between the\nsummer and winter adult plumages, Yarrell (45.  'History of British Birds,'\nvol. i. 1839, p. 159.) insists that this occurs with many waders.  Lastly,\nin regard to the young differing greatly from both sexes in their adult\nsummer and winter plumages, this occurs with some herons and egrets of\nNorth America and India,--the young alone being white.\n\nI will make only a few remarks on these complicated cases.  When the young\nresemble the females in their summer dress, or the adults of both sexes in\ntheir winter dress, the cases differ from those given under Classes I. and\nIII. only in the characters originally acquired by the males during the\nbreeding-season, having been limited in their transmission to the\ncorresponding season.  When the adults have a distinct summer and winter\nplumage, and the young differ from both, the case is more difficult to\nunderstand.  We may admit as probable that the young have retained an\nancient state of plumage; we can account by sexual selection for the summer\nor nuptial plumage of the adults, but how are we to account for their\ndistinct winter plumage?  If we could admit that this plumage serves in all\ncases as a protection, its acquirement would be a simple affair; but there\nseems no good reason for this admission.  It may be suggested that the\nwidely different conditions of life during the winter and summer have acted\nin a direct manner on the plumage; this may have had some effect, but I\nhave not much confidence in so great a difference as we sometimes see\nbetween the two plumages, having been thus caused.  A more probable\nexplanation is, that an ancient style of plumage, partially modified\nthrough the transference of some characters from the summer plumage, has\nbeen retained by the adults during the winter.  Finally, all the cases in\nour present class apparently depend on characters acquired by the adult\nmales, having been variously limited in their transmission according to\nage, season, and sex; but it would not be worth while to attempt to follow\nout these complex relations.\n\nCLASS VI.\n\nTHE YOUNG IN THEIR FIRST PLUMAGE DIFFER FROM EACH OTHER ACCORDING TO SEX;\nTHE YOUNG MALES RESEMBLING MORE OR LESS CLOSELY THE ADULT MALES, AND THE\nYOUNG FEMALES MORE OR LESS CLOSELY THE ADULT FEMALES.\n\nThe cases in the present class, though occurring in various groups, are not\nnumerous; yet it seems the most natural thing that the young should at\nfirst somewhat resemble the adults of the same sex, and gradually become\nmore and more like them.  The adult male blackcap (Sylvia atricapilla) has\na black head, that of the female being reddish-brown; and I am informed by\nMr. Blyth, that the young of both sexes can be distinguished by this\ncharacter even as nestlings.  In the family of thrushes an unusual number\nof similar cases have been noticed; thus, the male blackbird (Turdus\nmerula) can be distinguished in the nest from the female.  The two sexes of\nthe mocking bird (Turdus polyglottus, Linn.) differ very little from each\nother, yet the males can easily be distinguished at a very early age from\nthe females by showing more pure white.  (46.  Audubon, 'Ornith.\nBiography,' vol. i. p. 113.)  The males of a forest-thrush and of a rock-\nthrush (Orocetes erythrogastra and Petrocincla cyanea) have much of their\nplumage of a fine blue, whilst the females are brown; and the nestling\nmales of both species have their main wing and tail-feathers edged with\nblue whilst those of the female are edged with brown.  (47.  Mr. C.A.\nWright, in 'Ibis,' vol. vi. 1864, p. 65.  Jerdon, 'Birds of India,' vol. i.\np. 515.  See also on the blackbird, Blyth in Charlesworth's 'Magazine of\nNatural History,' vol. i. 1837, p. 113.)  In the young blackbird the wing-\nfeathers assume their mature character and become black after the others;\non the other hand, in the two species just named the wing-feathers become\nblue before the others.  The most probable view with reference to the cases\nin the present class is that the males, differently from what occurs in\nClass I., have transmitted their colours to their male offspring at an\nearlier age than that at which they were first acquired; for, if the males\nhad varied whilst quite young, their characters would probably have been\ntransmitted to both sexes.  (48.  The following additional cases may be\nmentioned; the young males of Tanagra rubra can be distinguished from the\nyoung females (Audubon, 'Ornith. Biography,' vol. iv. p. 392), and so it is\nwithin the nestlings of a blue nuthatch, Dendrophila frontalis of India\n(Jerdon, 'Birds of India,' vol. i. p. 389).  Mr. Blyth also informs me that\nthe sexes of the stonechat, Saxicola rubicola, are distinguishable at a\nvery early age.  Mr. Salvin gives ('Proc. Zoolog. Soc.' 1870, p. 206) the\ncase of a humming-bird, like the following one of Eustephanus.)\n\nIn Aithurus polytmus, a humming-bird, the male is splendidly coloured black\nand green, and two of the tail-feathers are immensely lengthened; the\nfemale has an ordinary tail and inconspicuous colours; now the young males,\ninstead of resembling the adult female, in accordance with the common rule,\nbegin from the first to assume the colours proper to their sex, and their\ntail-feathers soon become elongated.  I owe this information to Mr. Gould,\nwho has given me the following more striking and as yet unpublished case.\nTwo humming-birds belonging to the genus Eustephanus, both beautifully\ncoloured, inhabit the small island of Juan Fernandez, and have always been\nranked as specifically distinct.  But it has lately been ascertained that\nthe one which is of a rich chestnut-brown colour with a golden-red head, is\nthe male, whilst the other which is elegantly variegated with green and\nwhite with a metallic green head is the female.  Now the young from the\nfirst somewhat resemble the adults of the corresponding sex, the\nresemblance gradually becoming more and more complete.\n\nIn considering this last case, if as before we take the plumage of the\nyoung as our guide, it would appear that both sexes have been rendered\nbeautiful independently; and not that one sex has partially transferred its\nbeauty to the other.  The male apparently has acquired his bright colours\nthrough sexual selection in the same manner as, for instance, the peacock\nor pheasant in our first class of cases; and the female in the same manner\nas the female Rhynchaea or Turnix in our second class of cases.  But there\nis much difficulty in understanding how this could have been effected at\nthe same time with the two sexes of the same species.  Mr. Salvin states,\nas we have seen in the eighth chapter, that with certain humming-birds the\nmales greatly exceed the females in number, whilst with other species\ninhabiting the same country the females greatly exceed the males.  If,\nthen, we might assume that during some former lengthened period the males\nof the Juan Fernandez species had greatly exceeded the females in number,\nbut that during another lengthened period the females had far exceeded the\nmales, we could understand how the males at one time, and the females at\nanother, might have been rendered beautiful by the selection of the\nbrighter coloured individuals of either sex; both sexes transmitting their\ncharacters to their young at a rather earlier age than usual.  Whether this\nis the true explanation I will not pretend to say; but the case is too\nremarkable to be passed over without notice.\n\nWe have now seen in all six classes, that an intimate relation exists\nbetween the plumage of the young and the adults, either of one sex or both.\nThese relations are fairly well explained on the principle that one sex--\nthis being in the great majority of cases the male--first acquired through\nvariation and sexual selection bright colours or other ornaments, and\ntransmitted them in various ways, in accordance with the recognised laws of\ninheritance.  Why variations have occurred at different periods of life,\neven sometimes with species of the same group, we do not know, but with\nrespect to the form of transmission, one important determining cause seems\nto be the age at which the variations first appear.\n\nFrom the principle of inheritance at corresponding ages, and from any\nvariations in colour which occurred in the males at an early age not being\nthen selected--on the contrary being often eliminated as dangerous--whilst\nsimilar variations occurring at or near the period of reproduction have\nbeen preserved, it follows that the plumage of the young will often have\nbeen left unmodified, or but little modified.  We thus get some insight\ninto the colouring of the progenitors of our existing species.  In a vast\nnumber of species in five out of our six classes of cases, the adults of\none sex or of both are bright coloured, at least during the breeding-\nseason, whilst the young are invariably less brightly coloured than the\nadults, or are quite dull coloured; for no instance is known, as far as I\ncan discover, of the young of dull-coloured species displaying bright\ncolours, or of the young of bright-coloured species being more brilliant\nthan their parents.  In the fourth class, however, in which the young and\nthe old resemble each other, there are many species (though by no means\nall), of which the young are bright-coloured, and as these form old groups,\nwe may infer that their early progenitors were likewise bright.  With this\nexception, if we look to the birds of the world, it appears that their\nbeauty has been much increased since that period, of which their immature\nplumage gives us a partial record.\n\nON THE COLOUR OF THE PLUMAGE IN RELATION TO PROTECTION.\n\nIt will have been seen that I cannot follow Mr. Wallace in the belief that\ndull colours, when confined to the females, have been in most cases\nspecially gained for the sake of protection.  There can, however, be no\ndoubt, as formerly remarked, that both sexes of many birds have had their\ncolours modified, so as to escape the notice of their enemies; or in some\ninstances, so as to approach their prey unobserved, just as owls have had\ntheir plumage rendered soft, that their flight may not be overheard.  Mr.\nWallace remarks (49.  'Westminster Review,' July 1867, p. 5.) that \"it is\nonly in the tropics, among forests which never lose their foliage, that we\nfind whole groups of birds, whose chief colour is green.\"  It will be\nadmitted by every one, who has ever tried, how difficult it is to\ndistinguish parrots in a leaf-covered tree.  Nevertheless, we must remember\nthat many parrots are ornamented with crimson, blue, and orange tints,\nwhich can hardly be protective.  Woodpeckers are eminently arboreal, but\nbesides green species, there are many black, and black-and-white kinds--all\nthe species being apparently exposed to nearly the same dangers.  It is\ntherefore probable that with tree-haunting birds, strongly-pronounced\ncolours have been acquired through sexual selection, but that a green tint\nhas been acquired oftener than any other, from the additional advantage of\nprotection.\n\nIn regard to birds which live on the ground, every one admits that they are\ncoloured so as to imitate the surrounding surface.  How difficult it is to\nsee a partridge, snipe, woodcock, certain plovers, larks, and night-jars\nwhen crouched on ground.  Animals inhabiting deserts offer the most\nstriking cases, for the bare surface affords no concealment, and nearly all\nthe smaller quadrupeds, reptiles, and birds depend for safety on their\ncolours.  Mr. Tristram has remarked in regard to the inhabitants of the\nSahara, that all are protected by their \"isabelline or sand-colour.\"  (50.\n'Ibis,' 1859, vol. i. p. 429, et seq.  Dr. Rohlfs, however, remarks to me\nin a letter that according to his experience of the Sahara, this statement\nis too strong.)  Calling to my recollection the desert-birds of South\nAmerica, as well as most of the ground-birds of Great Britain, it appeared\nto me that both sexes in such cases are generally coloured nearly alike.\nAccordingly, I applied to Mr. Tristram with respect to the birds of the\nSahara, and he has kindly given me the following information.  There are\ntwenty-six species belonging to fifteen genera, which manifestly have their\nplumage coloured in a protective manner; and this colouring is all the more\nstriking, as with most of these birds it differs from that of their\ncongeners.  Both sexes of thirteen out of the twenty-six species are\ncoloured in the same manner; but these belong to genera in which this rule\ncommonly prevails, so that they tell us nothing about the protective\ncolours being the same in both sexes of desert-birds.  Of the other\nthirteen species, three belong to genera in which the sexes usually differ\nfrom each other, yet here they have the sexes alike.  In the remaining ten\nspecies, the male differs from the female; but the difference is confined\nchiefly to the under surface of the plumage, which is concealed when the\nbird crouches on the ground; the head and back being of the same sand-\ncoloured hue in the two sexes.  So that in these ten species the upper\nsurfaces of both sexes have been acted on and rendered alike, through\nnatural selection, for the sake of protection; whilst the lower surfaces of\nthe males alone have been diversified, through sexual selection, for the\nsake of ornament.  Here, as both sexes are equally well protected, we\nclearly see that the females have not been prevented by natural selection\nfrom inheriting the colours of their male parents; so that we must look to\nthe law of sexually-limited transmission.\n\nIn all parts of the world both sexes of many soft-billed birds, especially\nthose which frequent reeds or sedges, are obscurely coloured.  No doubt if\ntheir colours had been brilliant, they would have been much more\nconspicuous to their enemies; but whether their dull tints have been\nspecially gained for the sake of protection seems, as far as I can judge,\nrather doubtful.  It is still more doubtful whether such dull tints can\nhave been gained for the sake of ornament.  We must, however, bear in mind\nthat male birds, though dull-coloured, often differ much from their females\n(as with the common sparrow), and this leads to the belief that such\ncolours have been gained through sexual selection, from being attractive.\nMany of the soft-billed birds are songsters; and a discussion in a former\nchapter should not be forgotten, in which it was shewn that the best\nsongsters are rarely ornamented with bright tints.  It would appear that\nfemale birds, as a general rule, have selected their mates either for their\nsweet voices or gay colours, but not for both charms combined.  Some\nspecies, which are manifestly coloured for the sake of protection, such as\nthe jack-snipe, woodcock, and night-jar, are likewise marked and shaded,\naccording to our standard of taste, with extreme elegance.  In such cases\nwe may conclude that both natural and sexual selection have acted\nconjointly for protection and ornament.  Whether any bird exists which does\nnot possess some special attraction, by which to charm the opposite sex,\nmay be doubted.  When both sexes are so obscurely coloured that it would be\nrash to assume the agency of sexual selection, and when no direct evidence\ncan be advanced shewing that such colours serve as a protection, it is best\nto own complete ignorance of the cause, or, which comes to nearly the same\nthing, to attribute the result to the direct action of the conditions of\nlife.\n\nBoth sexes of many birds are conspicuously, though not brilliantly\ncoloured, such as the numerous black, white, or piebald species; and these\ncolours are probably the result of sexual selection.  With the common\nblackbird, capercailzie, blackcock, black scoter-duck (Oidemia), and even\nwith one of the birds of paradise (Lophorina atra), the males alone are\nblack, whilst the females are brown or mottled; and there can hardly be a\ndoubt that blackness in these cases has been a sexually selected character.\nTherefore it is in some degree probable that the complete or partial\nblackness of both sexes in such birds as crows, certain cockatoos, storks,\nand swans, and many marine birds, is likewise the result of sexual\nselection, accompanied by equal transmission to both sexes; for blackness\ncan hardly serve in any case as a protection.  With several birds, in which\nthe male alone is black, and in others in which both sexes are black, the\nbeak or skin about the head is brightly coloured, and the contrast thus\nafforded adds much to their beauty; we see this in the bright yellow beak\nof the male blackbird, in the crimson skin over the eyes of the blackcock\nand capercailzie, in the brightly and variously coloured beak of the\nscoter-drake (Oidemia), in the red beak of the chough (Corvus graculus,\nLinn.), of the black swan, and the black stork.  This leads me to remark\nthat it is not incredible that toucans may owe the enormous size of their\nbeaks to sexual selection, for the sake of displaying the diversified and\nvivid stripes of colour, with which these organs are ornamented.  (51.  No\nsatisfactory explanation has ever been offered of the immense size, and\nstill less of the bright colours, of the toucan's beak.  Mr. Bates ('The\nNaturalist on the Amazons,' vol. ii. 1863, p. 341) states that they use\ntheir beaks for reaching fruit at the extreme tips of the branches; and\nlikewise, as stated by other authors, for extracting eggs and young birds\nfrom the nests of other birds.  But, as Mr. Bates admits, the beak \"can\nscarcely be considered a very perfectly-formed instrument for the end to\nwhich it is applied.\"  The great bulk of the beak, as shewn by its breadth,\ndepth, as well as length, is not intelligible on the view, that it serves\nmerely as an organ of prehension.  Mr. Belt believes ('The Naturalist in\nNicaragua,' p. 197) that the principal use of the beak is as a defence\nagainst enemies, especially to the female whilst nesting in a hole in a\ntree.)  The naked skin, also, at the base of the beak and round the eyes is\nlikewise often brilliantly coloured; and Mr. Gould, in speaking of one\nspecies (52.  Rhamphastos carinatus, Gould's 'Monograph of Ramphastidae.'),\nsays that the colours of the beak \"are doubtless in the finest and most\nbrilliant state during the time of pairing.\"  There is no greater\nimprobability that toucans should be encumbered with immense beaks, though\nrendered as light as possible by their cancellated structure, for the\ndisplay of fine colours (an object falsely appearing to us unimportant),\nthan that the male Argus pheasant and some other birds should be encumbered\nwith plumes so long as to impede their flight.\n\nIn the same manner, as the males alone of various species are black, the\nfemales being dull-coloured; so in a few cases the males alone are either\nwholly or partially white, as with the several bell-birds of South America\n(Chasmorhynchus), the Antarctic goose (Bernicla antarctica), the silver\npheasant, etc., whilst the females are brown or obscurely mottled.\nTherefore, on the same principle as before, it is probable that both sexes\nof many birds, such as white cockatoos, several egrets with their beautiful\nplumes, certain ibises, gulls, terns, etc., have acquired their more or\nless completely white plumage through sexual selection.  In some of these\ncases the plumage becomes white only at maturity.  This is the case with\ncertain gannets, tropic-birds, etc., and with the snow-goose (Anser\nhyperboreus).  As the latter breeds on the \"barren grounds,\" when not\ncovered with snow, and as it migrates southward during the winter, there is\nno reason to suppose that its snow-white adult plumage serves as a\nprotection.  In the Anastomus oscitans, we have still better evidence that\nthe white plumage is a nuptial character, for it is developed only during the\nsummer; the young in their immature state, and the adults in their winter\ndress, being grey and black.  With many kinds of gulls (Larus), the head\nand neck become pure white during the summer, being grey or mottled during\nthe winter and in the young state.  On the other hand, with the smaller\ngulls, or sea-mews (Gavia), and with some terns (Sterna), exactly the\nreverse occurs; for the heads of the young birds during the first year, and\nof the adults during the winter, are either pure white, or much paler\ncoloured than during the breeding-season.  These latter cases offer another\ninstance of the capricious manner in which sexual selection appears often\nto have acted.  (53.  On Larus, Gavia, and Sterna, see Macgillivray,\n'History of British Birds,' vol. v. pp. 515, 584, 626.  On the Anser\nhyperboreus, Audubon, 'Ornithological Biography,' vol. iv. p. 562.  On the\nAnastomus, Mr. Blyth, in 'Ibis,' 1867, p. 173.)\n\nThat aquatic birds have acquired a white plumage so much oftener than\nterrestrial birds, probably depends on their large size and strong powers\nof flight, so that they can easily defend themselves or escape from birds\nof prey, to which moreover they are not much exposed.  Consequently, sexual\nselection has not here been interfered with or guided for the sake of\nprotection.  No doubt with birds which roam over the open ocean, the males\nand females could find each other much more easily, when made conspicuous\neither by being perfectly white or intensely black; so that these colours\nmay possibly serve the same end as the call-notes of many land-birds.  (54.\nIt may be noticed that with vultures, which roam far and wide high in the\nair, like marine birds over the ocean, three or four species are almost\nwholly or largely white, and that many others are black.  So that here\nagain conspicuous colours may possibly aid the sexes in finding each other\nduring the breeding-season.)  A white or black bird when it discovers and\nflies down to a carcase floating on the sea or cast up on the beach, will\nbe seen from a great distance, and will guide other birds of the same and\nother species, to the prey; but as this would be a disadvantage to the\nfirst finders, the individuals which were the whitest or blackest would not\nthus procure more food than the less strongly coloured individuals.  Hence\nconspicuous colours cannot have been gradually acquired for this purpose\nthrough natural selection.\n\nAs sexual selection depends on so fluctuating an element as taste, we can\nunderstand how it is that, within the same group of birds having nearly the\nsame habits, there should exist white or nearly white, as well as black, or\nnearly black species,--for instance, both white and black cockatoos,\nstorks, ibises, swans, terns, and petrels.  Piebald birds likewise\nsometimes occur in the same groups together with black and white species;\nfor instance, the black-necked swan, certain terns, and the common magpie.\nThat a strong contrast in colour is agreeable to birds, we may conclude by\nlooking through any large collection, for the sexes often differ from each\nother in the male having the pale parts of a purer white, and the variously\ncoloured dark parts of still darker tints than the female.\n\nIt would even appear that mere novelty, or slight changes for the sake of\nchange, have sometimes acted on female birds as a charm, like changes of\nfashion with us.  Thus the males of some parrots can hardly be said to be\nmore beautiful than the females, at least according to our taste, but they\ndiffer in such points, as in having a rose-coloured collar instead of \"a\nbright emeraldine narrow green collar\"; or in the male having a black\ncollar instead of \"a yellow demi-collar in front,\" with a pale roseate\ninstead of a plum-blue head.  (55.  See Jerdon on the genus Palaeornis,\n'Birds of India,' vol. i. pp. 258-260.)  As so many male birds have\nelongated tail-feathers or elongated crests for their chief ornament, the\nshortened tail, formerly described in the male of a humming-bird, and the\nshortened crest of the male goosander, seem like one of the many changes of\nfashion which we admire in our own dresses.\n\nSome members of the heron family offer a still more curious case of novelty\nin colouring having, as it appears, been appreciated for the sake of\nnovelty.  The young of the Ardea asha are white, the adults being dark\nslate-coloured; and not only the young, but the adults in their winter\nplumage, of the allied Buphus coromandus are white, this colour changing\ninto a rich golden-buff during the breeding-season.  It is incredible that\nthe young of these two species, as well as of some other members of the\nsame family (56.  The young of Ardea rufescens and A. caerulea of the\nUnited States are likewise white, the adults being coloured in accordance\nwith their specific names.  Audubon ('Ornithological Biography,' vol. iii.\np. 416; vol. iv. p. 58) seems rather pleased at the thought that this\nremarkable change of plumage will greatly \"disconcert the systematists.\"),\nshould for any special purpose have been rendered pure white and thus made\nconspicuous to their enemies; or that the adults of one of these two\nspecies should have been specially rendered white during the winter in a\ncountry which is never covered with snow.  On the other hand we have good\nreason to believe that whiteness has been gained by many birds as a sexual\nornament.  We may therefore conclude that some early progenitor of the\nArdea asha and the Buphus acquired a white plumage for nuptial purposes,\nand transmitted this colour to their young; so that the young and the old\nbecame white like certain existing egrets; and that the whiteness was\nafterwards retained by the young, whilst it was exchanged by the adults for\nmore strongly-pronounced tints.  But if we could look still further back to\nthe still earlier progenitors of these two species, we should probably see\nthe adults dark-coloured.  I infer that this would be the case, from the\nanalogy of many other birds, which are dark whilst young, and when adult\nare white; and more especially from the case of the Ardea gularis, the\ncolours of which are the reverse of those of A. asha, for the young are\ndark-coloured and the adults white, the young having retained a former\nstate of plumage.  It appears therefore that, during a long line of\ndescent, the adult progenitors of the Ardea asha, the Buphus, and of some\nallies, have undergone the following changes of colour:  first, a dark\nshade; secondly, pure white; and thirdly, owing to another change of\nfashion (if I may so express myself), their present slaty, reddish, or\ngolden-buff tints.  These successive changes are intelligible only on the\nprinciple of novelty having been admired by birds for its own sake.\n\nSeveral writers have objected to the whole theory of sexual selection, by\nassuming that with animals and savages the taste of the female for certain\ncolours or other ornaments would not remain constant for many generations;\nthat first one colour and then another would be admired, and consequently\nthat no permanent effect could be produced.  We may admit that taste is\nfluctuating, but it is not quite arbitrary.  It depends much on habit, as\nwe see in mankind; and we may infer that this would hold good with birds\nand other animals.  Even in our own dress, the general character lasts\nlong, and the changes are to a certain extent graduated.  Abundant evidence\nwill be given in two places in a future chapter, that savages of many races\nhave admired for many generations the same cicatrices on the skin, the same\nhideously perforated lips, nostrils, or ears, distorted heads, etc.; and\nthese deformities present some analogy to the natural ornaments of various\nanimals.  Nevertheless, with savages such fashions do not endure for ever,\nas we may infer from the differences in this respect between allied tribes\non the same continent.  So again the raisers of fancy animals certainly\nhave admired for many generations and still admire the same breeds; they\nearnestly desire slight changes, which are considered as improvements, but\nany great or sudden change is looked at as the greatest blemish.  With\nbirds in a state of nature we have no reason to suppose that they would\nadmire an entirely new style of coloration, even if great and sudden\nvariations often occurred, which is far from being the case.  We know that\ndovecot pigeons do not willingly associate with the variously coloured\nfancy breeds; that albino birds do not commonly get partners in marriage;\nand that the black ravens of the Feroe Islands chase away their piebald\nbrethren.  But this dislike of a sudden change would not preclude their\nappreciating slight changes, any more than it does in the case of man.\nHence with respect to taste, which depends on many elements, but partly on\nhabit and partly on a love of novelty, there seems no improbability in\nanimals admiring for a very long period the same general style of\nornamentation or other attractions, and yet appreciating slight changes in\ncolours, form, or sound.\n\nSUMMARY OF THE FOUR CHAPTERS ON BIRDS.\n\nMost male birds are highly pugnacious during the breeding-season, and some\npossess weapons adapted for fighting with their rivals.  But the most\npugnacious and the best armed males rarely or never depend for success\nsolely on their power to drive away or kill their rivals, but have special\nmeans for charming the female.  With some it is the power of song, or of\ngiving forth strange cries, or instrumental music, and the males in\nconsequence differ from the females in their vocal organs, or in the\nstructure of certain feathers.  From the curiously diversified means for\nproducing various sounds, we gain a high idea of the importance of this\nmeans of courtship.  Many birds endeavour to charm the females by love-\ndances or antics, performed on the ground or in the air, and sometimes at\nprepared places.  But ornaments of many kinds, the most brilliant tints,\ncombs and wattles, beautiful plumes, elongated feathers, top-knots, and so\nforth, are by far the commonest means.  In some cases mere novelty appears\nto have acted as a charm.  The ornaments of the males must be highly\nimportant to them, for they have been acquired in not a few cases at the\ncost of increased danger from enemies, and even at some loss of power in\nfighting with their rivals.  The males of very many species do not assume\ntheir ornamental dress until they arrive at maturity, or they assume it\nonly during the breeding-season, or the tints then become more vivid.\nCertain ornamental appendages become enlarged, turgid, and brightly\ncoloured during the act of courtship.  The males display their charms with\nelaborate care and to the best effect; and this is done in the presence of\nthe females.  The courtship is sometimes a prolonged affair, and many males\nand females congregate at an appointed place.  To suppose that the females\ndo not appreciate the beauty of the males, is to admit that their splendid\ndecorations, all their pomp and display, are useless; and this is\nincredible.  Birds have fine powers of discrimination, and in some few\ninstances it can be shewn that they have a taste for the beautiful.  The\nfemales, moreover, are known occasionally to exhibit a marked preference or\nantipathy for certain individual males.\n\nIf it be admitted that the females prefer, or are unconsciously excited by\nthe more beautiful males, then the males would slowly but surely be\nrendered more and more attractive through sexual selection.  That it is\nthis sex which has been chiefly modified, we may infer from the fact that,\nin almost every genus where the sexes differ, the males differ much more\nfrom one another than do the females; this is well shewn in certain\nclosely-allied representative species, in which the females can hardly be\ndistinguished, whilst the males are quite distinct.  Birds in a state of\nnature offer individual differences which would amply suffice for the work\nof sexual selection; but we have seen that they occasionally present more\nstrongly marked variations which recur so frequently that they would\nimmediately be fixed, if they served to allure the female.  The laws of\nvariation must determine the nature of the initial changes, and will have\nlargely influenced the final result.  The gradations, which may be observed\nbetween the males of allied species, indicate the nature of the steps\nthrough which they have passed.  They explain also in the most interesting\nmanner how certain characters have originated, such as the indented ocelli\non the tail-feathers of the peacock, and the ball-and-socket ocelli on the\nwing-feathers of the Argus pheasant.  It is evident that the brilliant\ncolours, top-knots, fine plumes, etc., of many male birds cannot have been\nacquired as a protection; indeed, they sometimes lead to danger.  That they\nare not due to the direct and definite action of the conditions of life, we\nmay feel assured, because the females have been exposed to the same\nconditions, and yet often differ from the males to an extreme degree.\nAlthough it is probable that changed conditions acting during a lengthened\nperiod have in some cases produced a definite effect on both sexes, or\nsometimes on one sex alone, the more important result will have been an\nincreased tendency to vary or to present more strongly-marked individual\ndifferences; and such differences will have afforded an excellent ground-\nwork for the action of sexual selection.\n\nThe laws of inheritance, irrespectively of selection, appear to have\ndetermined whether the characters acquired by the males for the sake of\nornament, for producing various sounds, and for fighting together, have\nbeen transmitted to the males alone or to both sexes, either permanently,\nor periodically during certain seasons of the year.  Why various characters\nshould have been transmitted sometimes in one way and sometimes in another,\nis not in most cases known; but the period of variability seems often to\nhave been the determining cause.  When the two sexes have inherited all\ncharacters in common they necessarily resemble each other; but as the\nsuccessive variations may be differently transmitted, every possible\ngradation may be found, even within the same genus, from the closest\nsimilarity to the widest dissimilarity between the sexes.  With many\nclosely-allied species, following nearly the same habits of life, the males\nhave come to differ from each other chiefly through the action of sexual\nselection; whilst the females have come to differ chiefly from partaking\nmore or less of the characters thus acquired by the males.  The effects,\nmoreover, of the definite action of the conditions of life, will not have\nbeen masked in the females, as in the males, by the accumulation through\nsexual selection of strongly-pronounced colours and other ornaments.  The\nindividuals of both sexes, however affected, will have been kept at each\nsuccessive period nearly uniform by the free intercrossing of many\nindividuals.\n\nWith species, in which the sexes differ in colour, it is possible or\nprobable that some of the successive variations often tended to be\ntransmitted equally to both sexes; but that when this occurred the females\nwere prevented from acquiring the bright colours of the males, by the\ndestruction which they suffered during incubation.  There is no evidence\nthat it is possible by natural selection to convert one form of\ntransmission into another.  But there would not be the least difficulty in\nrendering a female dull-coloured, the male being still kept bright-\ncoloured, by the selection of successive variations, which were from the\nfirst limited in their transmission to the same sex.  Whether the females\nof many species have actually been thus modified, must at present remain\ndoubtful.  When, through the law of the equal transmission of characters to\nboth sexes, the females were rendered as conspicuously coloured as the\nmales, their instincts appear often to have been modified so that they were\nled to build domed or concealed nests.\n\nIn one small and curious class of cases the characters and habits of the\ntwo sexes have been completely transposed, for the females are larger,\nstronger, more vociferous and brighter coloured than the males.  They have,\nalso, become so quarrelsome that they often fight together for the\npossession of the males, like the males of other pugnacious species for the\npossession of the females.  If, as seems probable, such females habitually\ndrive away their rivals, and by the display of their bright colours or\nother charms endeavour to attract the males, we can understand how it is\nthat they have gradually been rendered, by sexual selection and sexually-\nlimited transmission, more beautiful than the males--the latter being left\nunmodified or only slightly modified.\n\nWhenever the law of inheritance at corresponding ages prevails but not that\nof sexually-limited transmission, then if the parents vary late in life--\nand we know that this constantly occurs with our poultry, and occasionally\nwith other birds--the young will be left unaffected, whilst the adults of\nboth sexes will be modified.  If both these laws of inheritance prevail and\neither sex varies late in life, that sex alone will be modified, the other\nsex and the young being unaffected.  When variations in brightness or in\nother conspicuous characters occur early in life, as no doubt often\nhappens, they will not be acted on through sexual selection until the\nperiod of reproduction arrives; consequently if dangerous to the young,\nthey will be eliminated through natural selection.  Thus we can understand\nhow it is that variations arising late in life have so often been preserved\nfor the ornamentation of the males; the females and the young being left\nalmost unaffected, and therefore like each other.  With species having a\ndistinct summer and winter plumage, the males of which either resemble or\ndiffer from the females during both seasons or during the summer alone, the\ndegrees and kinds of resemblance between the young and the old are\nexceedingly complex; and this complexity apparently depends on characters,\nfirst acquired by the males, being transmitted in various ways and degrees,\nas limited by age, sex, and season.\n\nAs the young of so many species have been but little modified in colour and\nin other ornaments, we are enabled to form some judgment with respect to\nthe plumage of their early progenitors; and we may infer that the beauty of\nour existing species, if we look to the whole class, has been largely\nincreased since that period, of which the immature plumage gives us an\nindirect record.  Many birds, especially those which live much on the\nground, have undoubtedly been obscurely coloured for the sake of\nprotection.  In some instances the upper exposed surface of the plumage has\nbeen thus coloured in both sexes, whilst the lower surface in the males\nalone has been variously ornamented through sexual selection.  Finally,\nfrom the facts given in these four chapters, we may conclude that weapons\nfor battle, organs for producing sound, ornaments of many kinds, bright and\nconspicuous colours, have generally been acquired by the males through\nvariation and sexual selection, and have been transmitted in various ways\naccording to the several laws of inheritance--the females and the young\nbeing left comparatively but little modified.  (57.  I am greatly indebted\nto the kindness of Mr. Sclater for having looked over these four chapters\non birds, and the two following ones on mammals.  In this way I have been\nsaved from making mistakes about the names of the species, and from stating\nanything as a fact which is known to this distinguished naturalist to be\nerroneous.  But, of course, he is not at all answerable for the accuracy of\nthe statements quoted by me from various authorities.)\n\n\nCHAPTER XVII.\n\nSECONDARY SEXUAL CHARACTERS OF MAMMALS.\n\nThe law of battle--Special weapons, confined to the males--Cause of absence\nof weapons in the female--Weapons common to both sexes, yet primarily\nacquired by the male--Other uses of such weapons--Their high importance--\nGreater size of the male--Means of defence--On the preference shown by\neither sex in the pairing of quadrupeds.\n\nWith mammals the male appears to win the female much more through the law\nof battle than through the display of his charms.  The most timid animals,\nnot provided with any special weapons for fighting, engage in desperate\nconflicts during the season of love.  Two male hares have been seen to\nfight together until one was killed; male moles often fight, and sometimes\nwith fatal results; male squirrels engage in frequent contests, \"and often\nwound each other severely\"; as do male beavers, so that \"hardly a skin is\nwithout scars.\"  (1.  See Waterton's account of two hares fighting,\n'Zoologist,' vol. i. 1843, p. 211.  On moles, Bell, 'Hist. of British\nQuadrupeds,' 1st ed., p. 100.  On squirrels, Audubon and Bachman,\nViviparous Quadrupeds of N. America, 1846, p. 269.  On beavers, Mr. A.H.\nGreen, in 'Journal of Linnean Society, Zoology,' vol. x. 1869, p. 362.)  I\nobserved the same fact with the hides of the guanacoes in Patagonia; and on\none occasion several were so absorbed in fighting that they fearlessly\nrushed close by me.  Livingstone speaks of the males of the many animals in\nSouthern Africa as almost invariably shewing the scars received in former\ncontests.\n\nThe law of battle prevails with aquatic as with terrestrial mammals.  It is\nnotorious how desperately male seals fight, both with their teeth and\nclaws, during the breeding-season; and their hides are likewise often\ncovered with scars.  Male sperm-whales are very jealous at this season; and\nin their battles \"they often lock their jaws together, and turn on their\nsides and twist about\"; so that their lower jaws often become distorted.\n(2.  On the battles of seals, see Capt. C. Abbott in 'Proc. Zool. Soc.'\n1868, p. 191; Mr. R. Brown, ibid. 1868, p. 436; also L. Lloyd, 'Game Birds\nof Sweden,' 1867, p. 412; also Pennant.  On the sperm-whale see Mr. J.H.\nThompson, in 'Proc. Zool. Soc.' 1867, p. 246.)\n\nAll male animals which are furnished with special weapons for fighting, are\nwell known to engage in fierce battles.  The courage and the desperate\nconflicts of stags have often been described; their skeletons have been\nfound in various parts of the world, with the horns inextricably locked\ntogether, shewing how miserably the victor and vanquished had perished.\n(3.  See Scrope ('Art of Deer-stalking,' p. 17) on the locking of the horns\nwith the Cervus elaphus.  Richardson, in 'Fauna Bor. Americana,' 1829, p.\n252, says that the wapiti, moose, and reindeer have been found thus locked\ntogether.  Sir A. Smith found at the Cape of Good Hope the skeletons of\ntwo gnus in the same condition.)  No animal in the world is so dangerous as\nan elephant in must.  Lord Tankerville has given me a graphic description\nof the battles between the wild bulls in Chillingham Park, the descendants,\ndegenerated in size but not in courage, of the gigantic Bos primigenius.\nIn 1861 several contended for mastery; and it was observed that two of the\nyounger bulls attacked in concert the old leader of the herd, overthrew and\ndisabled him, so that he was believed by the keepers to be lying mortally\nwounded in a neighbouring wood.  But a few days afterwards one of the young\nbulls approached the wood alone; and then the \"monarch of the chase,\" who\nhad been lashing himself up for vengeance, came out and, in a short time,\nkilled his antagonist.  He then quietly joined the herd, and long held\nundisputed sway.  Admiral Sir B.J. Sulivan informs me that, when he lived\nin the Falkland Islands, he imported a young English stallion, which\nfrequented the hills near Port William with eight mares.  On these hills\nthere were two wild stallions, each with a small troop of mares; \"and it is\ncertain that these stallions would never have approached each other without\nfighting.  Both had tried singly to fight the English horse and drive away\nhis mares, but had failed.  One day they came in TOGETHER and attacked him.\nThis was seen by the capitan who had charge of the horses, and who, on\nriding to the spot, found one of the two stallions engaged with the English\nhorse, whilst the other was driving away the mares, and had already\nseparated four from the rest.  The capitan settled the matter by driving\nthe whole party into the corral, for the wild stallions would not leave the\nmares.\"\n\nMale animals which are provided with efficient cutting or tearing teeth for\nthe ordinary purposes of life, such as the carnivora, insectivora, and\nrodents, are seldom furnished with weapons especially adapted for fighting\nwith their rivals.  The case is very different with the males of many other\nanimals.  We see this in the horns of stags and of certain kinds of\nantelopes in which the females are hornless.  With many animals the canine\nteeth in the upper or lower jaw, or in both, are much larger in the males\nthan in the females, or are absent in the latter, with the exception\nsometimes of a hidden rudiment.  Certain antelopes, the musk-deer, camel,\nhorse, boar, various apes, seals, and the walrus, offer instances.  In the\nfemales of the walrus the tusks are sometimes quite absent.  (4.  Mr.\nLamont ('Seasons with the Sea-Horses,' 1861, p. 143) says that a good tusk\nof the male walrus weighs 4 pounds, and is longer than that of the female,\nwhich weighs about 3 pounds.  The males are described as fighting\nferociously.  On the occasional absence of the tusks in the female, see Mr.\nR. Brown, 'Proceedings, Zoological Society,' 1868, p. 429.)  In the male\nelephant of India and in the male dugong (5.  Owen, 'Anatomy of\nVertebrates,' vol. iii. p. 283.) the upper incisors form offensive weapons.\nIn the male narwhal the left canine alone is developed into the well-known,\nspirally-twisted, so-called horn, which is sometimes from nine to ten feet\nin length.  It is believed that the males use these horns for fighting\ntogether; for \"an unbroken one can rarely be got, and occasionally one may\nbe found with the point of another jammed into the broken place.\"  (6.  Mr.\nR. Brown, in 'Proc. Zool. Soc.' 1869, p. 553.  See Prof. Turner, in\n'Journal of Anat. and Phys.' 1872, p. 76, on the homological nature of\nthese tusks.  Also Mr. J.W. Clarke on two tusks being developed in the\nmales, in 'Proceedings of the Zoological Society,' 1871, p. 42.)  The tooth\non the opposite side of the head in the male consists of a rudiment about\nten inches in length, which is embedded in the jaw; but sometimes, though\nrarely, both are equally developed on the two sides.  In the female both\nare always rudimentary.  The male cachalot has a larger head than that of\nthe female, and it no doubt aids him in his aquatic battles.  Lastly, the\nadult male ornithorhynchus is provided with a remarkable apparatus, namely\na spur on the foreleg, closely resembling the poison-fang of a venomous\nsnake; but according to Harting, the secretion from the gland is not\npoisonous; and on the leg of the female there is a hollow, apparently for\nthe reception of the spur.  (7.  Owen on the cachalot and Ornithorhynchus,\nibid. vol. iii. pp. 638, 641.  Harting is quoted by Dr. Zouteveen in the\nDutch translation of this work, vol. ii. p. 292.)\n\nWhen the males are provided with weapons which in the females are absent,\nthere can be hardly a doubt that these serve for fighting with other males;\nand that they were acquired through sexual selection, and were transmitted\nto the male sex alone.  It is not probable, at least in most cases, that\nthe females have been prevented from acquiring such weapons, on account of\ntheir being useless, superfluous, or in some way injurious.  On the\ncontrary, as they are often used by the males for various purposes, more\nespecially as a defence against their enemies, it is a surprising fact that\nthey are so poorly developed, or quite absent, in the females of so many\nanimals.  With female deer the development during each recurrent season of\ngreat branching horns, and with female elephants the development of immense\ntusks, would be a great waste of vital power, supposing that they were of\nno use to the females.  Consequently, they would have tended to be\neliminated in the female through natural selection; that is, if the\nsuccessive variations were limited in their transmission to the female sex,\nfor otherwise the weapons of the males would have been injuriously\naffected, and this would have been a greater evil.  On the whole, and from\nthe consideration of the following facts, it seems probable that when the\nvarious weapons differ in the two sexes, this has generally depended on the\nkind of transmission which has prevailed.\n\nAs the reindeer is the one species in the whole family of Deer, in which\nthe female is furnished with horns, though they are somewhat smaller,\nthinner, and less branched than in the male, it might naturally be thought\nthat, at least in this case, they must be of some special service to her.\nThe female retains her horns from the time when they are fully developed,\nnamely, in September, throughout the winter until April or May, when she\nbrings forth her young.  Mr. Crotch made particular enquiries for me in\nNorway, and it appears that the females at this season conceal themselves\nfor about a fortnight in order to bring forth their young, and then\nreappear, generally hornless.  In Nova Scotia, however, as I hear from Mr.\nH. Reeks, the female sometimes retains her horns longer.  The male on the\nother hand casts his horns much earlier, towards the end of November.  As\nboth sexes have the same requirements and follow the same habits of life,\nand as the male is destitute of horns during the winter, it is improbable\nthat they can be of any special service to the female during this season,\nwhich includes the larger part of the time during which she is horned.  Nor\nis it probable that she can have inherited horns from some ancient\nprogenitor of the family of deer, for, from the fact of the females of so\nmany species in all quarters of the globe not having horns, we may conclude\nthat this was the primordial character of the group.  (8.  On the structure\nand shedding of the horns of the reindeer, Hoffberg, 'Amoenitates Acad.'\nvol. iv. 1788, p. 149.  See Richardson, 'Fauna Bor. Americana,' p. 241, in\nregard to the American variety or species:  also Major W. Ross King, 'The\nSportsman in Canada,' 1866, p. 80.\n\nThe horns of the reindeer are developed at a most unusually early age; but\nwhat the cause of this may be is not known.  The effect has apparently been\nthe transference of the horns to both sexes.  We should bear in mind that\nhorns are always transmitted through the female, and that she has a latent\ncapacity for their development, as we see in old or diseased females.  (9.\nIsidore Geoffroy St.-Hilaire, 'Essais de Zoolog. Generale,' 1841, p. 513.\nOther masculine characters, besides the horns, are sometimes similarly\ntransferred to the female; thus Mr. Boner, in speaking of an old female\nchamois ('Chamois Hunting in the Mountains of Bavaria,' 1860, 2nd ed., p.\n363), says, \"not only was the head very male-looking, but along the back\nthere was a ridge of long hair, usually to be found only in bucks.\")\nMoreover the females of some other species of deer exhibit, either normally\nor occasionally, rudiments of horns; thus the female of Cervulus moschatus\nhas \"bristly tufts, ending in a knob, instead of a horn\"; and \"in most\nspecimens of the female wapiti (Cervus canadensis) there is a sharp bony\nprotuberance in the place of the horn.\"  (10.  On the Cervulus, Dr. Gray,\n'Catalogue of Mammalia in the British Museum,' part iii. p. 220.  On the\nCervus canadensis or wapiti, see Hon. J.D. Caton, 'Ottawa Academy of Nat.\nSciences,' May 1868, p. 9.)  From these several considerations we may\nconclude that the possession of fairly well-developed horns by the female\nreindeer, is due to the males having first acquired them as weapons for\nfighting with other males; and secondarily to their development from some\nunknown cause at an unusually early age in the males, and their consequent\ntransference to both sexes.\n\nTurning to the sheath-horned ruminants:  with antelopes a graduated series\ncan be formed, beginning with species, the females of which are completely\ndestitute of horns--passing on to those which have horns so small as to be\nalmost rudimentary (as with the Antilocapra americana, in which species\nthey are present in only one out of four or five females (11.  I am\nindebted to Dr. Canfield for this information; see also his paper in the\n'Proceedings of the Zoological Society,' 1866, p. 105.))--to those which\nhave fairly developed horns, but manifestly smaller and thinner than in the\nmale and sometimes of a different shape (12.  For instance the horns of the\nfemale Ant. euchore resemble those of a distinct species, viz. the Ant.\ndorcas var. Corine, see Desmarest, 'Mammalogie,' p. 455.),--and ending with\nthose in which both sexes have horns of equal size.  As with the reindeer,\nso with antelopes, there exists, as previously shewn, a relation between\nthe period of the development of the horns and their transmission to one or\nboth sexes; it is therefore probable that their presence or absence in the\nfemales of some species, and their more or less perfect condition in the\nfemales of other species, depends, not on their being of any special use,\nbut simply on inheritance.  It accords with this view that even in the same\nrestricted genus both sexes of some species, and the males alone of others,\nare thus provided.  It is also a remarkable fact that, although the females\nof Antilope bezoartica are normally destitute of horns, Mr. Blyth has seen\nno less than three females thus furnished; and there was no reason to\nsuppose that they were old or diseased.\n\nIn all the wild species of goats and sheep the horns are larger in the male\nthan in the female, and are sometimes quite absent in the latter.  (13.\nGray, 'Catalogue of Mammalia, the British Museum,' part iii. 1852, p. 160.)\nIn several domestic breeds of these two animals, the males alone are\nfurnished with horns; and in some breeds, for instance, in the sheep of\nNorth Wales, though both sexes are properly horned, the ewes are very\nliable to be hornless.  I have been informed by a trustworthy witness, who\npurposely inspected a flock of these same sheep during the lambing season,\nthat the horns at birth are generally more fully developed in the male than\nin the female.  Mr. J. Peel crossed his Lonk sheep, both sexes of which\nalways bear horns, with hornless Leicesters and hornless Shropshire Downs;\nand the result was that the male offspring had their horns considerably\nreduced, whilst the females were wholly destitute of them.  These several\nfacts indicate that, with sheep, the horns are a much less firmly fixed\ncharacter in the females than in the males; and this leads us to look at\nthe horns as properly of masculine origin.\n\nWith the adult musk-ox (Ovibos moschatus) the horns of the male are larger\nthan those of the female, and in the latter the bases do not touch.  (14.\nRichardson, 'Fauna Bor. Americana,' p. 278.)  In regard to ordinary cattle\nMr. Blyth remarks:  \"In most of the wild bovine animals the horns are both\nlonger and thicker in the bull than in the cow, and in the cow-banteng (Bos\nsondaicus) the horns are remarkably small, and inclined much backwards.  In\nthe domestic races of cattle, both of the humped and humpless types, the\nhorns are short and thick in the bull, longer and more slender in the cow\nand ox; and in the Indian buffalo, they are shorter and thicker in the\nbull, longer and more slender in the cow.  In the wild gaour (B. gaurus)\nthe horns are mostly both longer and thicker in the bull than in the cow.\"\n(15.  'Land and Water,' 1867, p. 346.)  Dr. Forsyth Major also informs me\nthat a fossil skull, believed to be that of the female Bos etruscus, has\nbeen found in Val d'Arno, which is wholly without horns.  In the Rhinoceros\nsimus, as I may add, the horns of the female are generally longer but less\npowerful than in the male; and in some other species of rhinoceros they are\nsaid to be shorter in the female.  (16.  Sir Andrew Smith, 'Zoology of S.\nAfrica,' pl. xix. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 624.)  From\nthese various facts we may infer as probable that horns of all kinds, even\nwhen they are equally developed in the two sexes, were primarily acquired\nby the male in order to conquer other males, and have been transferred more\nor less completely to the female.\n\nThe effects of castration deserve notice, as throwing light on this same\npoint.  Stags after the operation never renew their horns.  The male\nreindeer, however, must be excepted, as after castration he does renew\nthem.  This fact, as well as the possession of horns by both sexes, seems\nat first to prove that the horns in this species do not constitute a sexual\ncharacter (17.  This is the conclusion of Seidlitz, 'Die Darwinsche\nTheorie,' 1871, p. 47.); but as they are developed at a very early age,\nbefore the sexes differ in constitution, it is not surprising that they\nshould be unaffected by castration, even if they were aboriginally acquired\nby the male.  With sheep both sexes properly bear horns; and I am informed\nthat with Welch sheep the horns of the males are considerably reduced by\ncastration; but the degree depends much on the age at which the operation\nis performed, as is likewise the case with other animals.  Merino rams have\nlarge horns, whilst the ewes \"generally speaking are without horns\"; and in\nthis breed castration seems to produce a somewhat greater effect, so that\nif performed at an early age the horns \"remain almost undeveloped.\"  (18.\nI am much obliged to Prof. Victor Carus, for having made enquiries for me\nin Saxony on this subject.  H. von Nathusius ('Viehzucht,' 1872, p. 64)\nsays that the horns of sheep castrated at an early period, either\naltogether disappear or remain as mere rudiments; but I do not know whether\nhe refers to merinos or to ordinary breeds.)  On the Guinea coast there is\na breed in which the females never bear horns, and, as Mr. Winwood Reade\ninforms me, the rams after castration are quite destitute of them.  With\ncattle, the horns of the males are much altered by castration; for instead\nof being short and thick, they become longer than those of the cow, but\notherwise resemble them.  The Antilope bezoartica offers a somewhat\nanalogous case:  the males have long straight spiral horns, nearly parallel\nto each other, and directed backwards; the females occasionally bear horns,\nbut these when present are of a very different shape, for they are not\nspiral, and spreading widely, bend round with the points forwards.  Now it\n\nis a remarkable fact that, in the castrated male, as Mr. Blyth informs me,\nthe horns are of the same peculiar shape as in the female, but longer and\nthicker.  If we may judge from analogy, the female probably shews us, in\nthese two cases of cattle and the antelope, the former condition of the\nhorns in some early progenitor of each species.  But why castration should\nlead to the reappearance of an early condition of the horns cannot be\nexplained with any certainty.  Nevertheless, it seems probable, that in\nnearly the same manner as the constitutional disturbance in the offspring,\ncaused by a cross between two distinct species or races, often leads to the\nreappearance of long-lost characters (19.  I have given various experiments\nand other evidence proving that this is the case, in my 'Variation of\nAnimals and Plants under Domestication,' vol. ii. 1868, pp. 39-47.); so\nhere, the disturbance in the constitution of the individual, resulting from\ncastration, produces the same effect.\n\nThe tusks of the elephant, in the different species or races, differ\naccording to sex, nearly as do the horns of ruminants.  In India and\nMalacca the males alone are provided with well-developed tusks.  The\nelephant of Ceylon is considered by most naturalists as a distinct race,\nbut by some as a distinct species, and here \"not one in a hundred is found\nwith tusks, the few that possess them being exclusively males.\"  (20.  Sir\nJ. Emerson Tennent, 'Ceylon,' 1859, vol. ii. p. 274.  For Malacca, 'Journal\nof Indian Archipelago,' vol. iv. p. 357.)  The African elephant is\nundoubtedly distinct, and the female has large well-developed tusks, though\nnot so large as those of the male.\n\nThese differences in the tusks of the several races and species of\nelephants--the great variability of the horns of deer, as notably in the\nwild reindeer--the occasional presence of horns in the female Antilope\nBezoartica, and their frequent absence in the female of Antilocapra\namericana--the presence of two tusks in some few male narwhals--the\ncomplete absence of tusks in some female walruses--are all instances of the\nextreme variability of secondary sexual characters, and of their liability\nto differ in closely-allied forms.\n\nAlthough tusks and horns appear in all cases to have been primarily\ndeveloped as sexual weapons, they often serve other purposes.  The elephant\nuses his tusks in attacking the tiger; according to Bruce, he scores the\ntrunks of trees until they can be thrown down easily, and he likewise thus\nextracts the farinaceous cores of palms; in Africa he often uses one tusk,\nalways the same, to probe the ground and thus ascertain whether it will\nbear his weight.  The common bull defends the herd with his horns; and the\nelk in Sweden has been known, according to Lloyd, to strike a wolf dead\nwith a single blow of his great horns.  Many similar facts could be given.\nOne of the most curious secondary uses to which the horns of an animal may\nbe occasionally put is that observed by Captain Hutton (21.  'Calcutta\nJournal of Natural History,' vol. ii, 1843, p. 526.) with the wild goat\n(Capra aegagrus) of the Himalayas and, as it is also said with the ibex,\nnamely that when the male accidentally falls from a height he bends inwards\nhis head, and by alighting on his massive horns, breaks the shock.  The\nfemale cannot thus use her horns, which are smaller, but from her more\nquiet disposition she does not need this strange kind of shield so much.\n\nEach male animal uses his weapons in his own peculiar fashion.  The common\nram makes a charge and butts with such force with the bases of his horns,\nthat I have seen a powerful man knocked over like a child.  Goats and\ncertain species of sheep, for instance the Ovis cycloceros of Afghanistan\n(22.  Mr. Blyth, in 'Land and Water,' March, 1867, p. 134, on the authority\nof Capt. Hutton and others.  For the wild Pembrokeshire goats, see the\n'Field,' 1869, p. 150.), rear on their hind legs, and then not only butt,\nbut \"make a cut down and a jerk up, with the ribbed front of their\nscimitar-shaped horn, as with a sabre.  When the O. cycloceros attacked a\nlarge domestic ram, who was a noted bruiser, he conquered him by the sheer\nnovelty of his mode of fighting, always closing at once with his adversary,\nand catching him across the face and nose with a sharp drawing jerk of the\nhead, and then bounding out of the way before the blow could be returned.\"\nIn Pembrokeshire a male goat, the master of a flock which during several\ngenerations had run wild, was known to have killed several males in single\ncombat; this goat possessed enormous horns, measuring thirty-nine inches in\na straight line from tip to tip.  The common bull, as every one knows,\ngores and tosses his opponent; but the Italian buffalo is said never to use\nhis horns:  he gives a tremendous blow with his convex forehead, and then\ntramples on his fallen enemy with his knees--an instinct which the common\nbull does not possess.  (23.  M. E.M. Bailly, \"Sur l'usage des cornes,\"\netc., .Annal des Sciences Nat.' tom. ii. 1824, p. 369.)  Hence a dog who\npins a buffalo by the nose is immediately crushed.  We must, however,\nremember that the Italian buffalo has been long domesticated, and it is by\nno means certain that the wild parent-form had similar horns.  Mr. Bartlett\ninforms me that when a female Cape buffalo (Bubalus caffer) was turned into\nan enclosure with a bull of the same species, she attacked him, and he in\nreturn pushed her about with great violence.  But it was manifest to Mr.\nBartlett that, had not the bull shewn dignified forbearance, he could\neasily have killed her by a single lateral thrust with his immense horns.\nThe giraffe uses his short, hair-covered horns, which are rather longer in\nthe male than in the female, in a curious manner; for, with his long neck,\nhe swings his head to either side, almost upside down, with such force that\nI have seen a hard plank deeply indented by a single blow.\n\n[Fig. 63.  Oryx leucoryx, male (from the Knowsley Menagerie).]\n\nWith antelopes it is sometimes difficult to imagine how they can possibly\nuse their curiously-shaped horns; thus the springboc (Ant. euchore) has\nrather short upright horns, with the sharp points bent inwards almost at\nright angles, so as to face each other; Mr. Bartlett does not know how they\nare used, but suggests that they would inflict a fearful wound down each\nside of the face of an antagonist.  The slightly-curved horns of the Oryx\nleucoryx (Fig. 63) are directed backwards, and are of such length that\ntheir points reach beyond the middle of the back, over which they extend in\nalmost parallel lines.  Thus they seem singularly ill-fitted for fighting;\nbut Mr. Bartlett informs me that when two of these animals prepare for\nbattle, they kneel down, with their heads between their fore legs, and in\nthis attitude the horns stand nearly parallel and close to the ground, with\nthe points directed forwards and a little upwards.  The combatants then\ngradually approach each other, and each endeavours to get the upturned\npoints under the body of the other; if one succeeds in doing this, he\nsuddenly springs up, throwing up his head at the same time, and can thus\nwound or perhaps even transfix his antagonist.  Both animals always kneel\ndown, so as to guard as far as possible against this manoeuvre.  It has\nbeen recorded that one of these antelopes has used his horn with effect\neven against a lion; yet from being forced to place his head between the\nforelegs in order to bring the points of the horns forward, he would\ngenerally be under a great disadvantage when attacked by any other animal.\nIt is, therefore, not probable that the horns have been modified into their\npresent great length and peculiar position, as a protection against beasts\nof prey.  We can however see that, as soon as some ancient male progenitor\nof the Oryx acquired moderately long horns, directed a little backwards, he\nwould be compelled, in his battles with rival males, to bend his head\nsomewhat inwards or downwards, as is now done by certain stags; and it is\nnot improbable that he might have acquired the habit of at first\noccasionally and afterwards of regularly kneeling down.  In this case it is\nalmost certain that the males which possessed the longest horns would have\nhad a great advantage over others with shorter horns; and then the horns\nwould gradually have been rendered longer and longer, through sexual\nselection, until they acquired their present extraordinary length and\nposition.\n\nWith stags of many kinds the branches of the horns offer a curious case of\ndifficulty; for certainly a single straight point would inflict a much more\nserious wound than several diverging ones.  In Sir Philip Egerton's museum\nthere is a horn of the red-deer (Cervus elaphus), thirty inches in length,\nwith \"not fewer than fifteen snags or branches\"; and at Moritzburg there is\nstill preserved a pair of antlers of a red-deer, shot in 1699 by Frederick\nI., one of which bears the astonishing number of thirty-three branches and\nthe other twenty-seven, making altogether sixty branches.  Richardson\nfigures a pair of antlers of the wild reindeer with twenty-nine points.\n(24.  On the horns of red-deer, Owen, 'British Fossil Mammals,' 1846, p.\n478; Richardson on the horns of the reindeer, 'Fauna Bor. Americana,' 1829,\np. 240.  I am indebted to Prof. Victor Carus, for the Moritzburg case.)\nFrom the manner in which the horns are branched, and more especially from\ndeer being known occasionally to fight together by kicking with their fore-\nfeet (25.  Hon. J.D. Caton ('Ottawa Acad. of Nat. Science,' May 1868, p. 9)\nsays that the American deer fight with their fore-feet, after \"the question\nof superiority has been once settled and acknowledged in the herd.\"\nBailly, 'Sur l'Usage des cornes,' 'Annales des Sciences Nat.' tom. ii.\n1824, p. 371.), M. Bailly actually comes to the conclusion that their horns\nare more injurious than useful to them.  But this author overlooks the\npitched battles between rival males.  As I felt much perplexed about the\nuse or advantage of the branches, I applied to Mr. McNeill of Colonsay, who\nhas long and carefully observed the habits of red-deer, and he informs me\nthat he has never seen some of the branches brought into use, but that the\nbrow antlers, from inclining downwards, are a great protection to the\nforehead, and their points are likewise used in attack.  Sir Philip Egerton\nalso informs me both as to red-deer and fallow-deer that, in fighting, they\nsuddenly dash together, and getting their horns fixed against each other's\nbodies, a desperate struggle ensues.  When one is at last forced to yield\nand turn round, the victor endeavours to plunge his brow antlers into his\ndefeated foe.  It thus appears that the upper branches are used chiefly or\nexclusively for pushing and fencing.  Nevertheless in some species the\nupper branches are used as weapons of offence; when a man was attacked by a\nwapiti deer (Cervus canadensis) in Judge Caton's park in Ottawa, and\nseveral men tried to rescue him, the stag \"never raised his head from the\nground; in fact he kept his face almost flat on the ground, with his nose\nnearly between his fore feet, except when he rolled his head to one side to\ntake a new observation preparatory to a plunge.\"  In this position the ends\nof the horns were directed against his adversaries.  \"In rolling his head\nhe necessarily raised it somewhat, because his antlers were so long that he\ncould not roll his head without raising them on one side, while, on the\nother side they touched the ground.\"  The stag by this procedure gradually\ndrove the party of rescuers backwards to a distance of 150 or 200 feet; and\nthe attacked man was killed.  (26.  See a most interesting account in the\nAppendix to Hon. J.D. Caton's paper, as above quoted.)\n\n[Fig. 64.  Strepsiceros Kudu (from Sir Andrew Smith's 'Zoology of South\nAfrica.']\n\nAlthough the horns of stags are efficient weapons, there can, I think, be no\ndoubt that a single point would have been much more dangerous than a\nbranched antler; and Judge Caton, who has had large experience with deer,\nfully concurs in this conclusion.  Nor do the branching horns, though\nhighly important as a means of defence against rival stags, appear\nperfectly well adapted for this purpose, as they are liable to become\ninterlocked.  The suspicion has therefore crossed my mind that they may\nserve in part as ornaments.  That the branched antlers of stags as well as\nthe elegant lyrated horns of certain antelopes, with their graceful double\ncurvature (Fig. 64), are ornamental in our eyes, no one will dispute.  If,\nthen, the horns, like the splendid accoutrements of the knights of old, add\nto the noble appearance of stags and antelopes, they may have been modified\npartly for this purpose, though mainly for actual service in battle; but I\nhave no evidence in favour of this belief.\n\nAn interesting case has lately been published, from which it appears that\nthe horns of a deer in one district in the United States are now being\nmodified through sexual and natural selection.  A writer in an excellent\nAmerican Journal (27.  The 'American Naturalist,' Dec. 1869, p. 552.) says,\nthat he has hunted for the last twenty-one years in the Adirondacks, where\nthe Cervus virginianus abounds.  About fourteen years ago he first heard of\nSPIKE-HORN BUCKS.  These became from year to year more common; about five\nyears ago he shot one, and afterwards another, and now they are frequently\nkilled.  \"The spike-horn differs greatly from the common antler of the C.\nvirginianus.  It consists of a single spike, more slender than the antler,\nand scarcely half so long, projecting forward from the brow, and\nterminating in a very sharp point.  It gives a considerable advantage to\nits possessor over the common buck.  Besides enabling him to run more\nswiftly through the thick woods and underbrush (every hunter knows that\ndoes and yearling bucks run much more rapidly than the large bucks when\narmed with their cumbrous antlers), the spike-horn is a more effective\nweapon than the common antler.  With this advantage the spike-horn bucks\nare gaining upon the common bucks, and may, in time, entirely supersede\nthem in the Adirondacks.  Undoubtedly, the first spike-horn buck was merely\nan accidental freak of nature.  But his spike-horns gave him an advantage,\nand enabled him to propagate his peculiarity.  His descendants having a\nlike advantage, have propagated the peculiarity in a constantly increasing\nratio, till they are slowly crowding the antlered deer from the region they\ninhabit.\"  A critic has well objected to this account by asking, why, if\nthe simple horns are now so advantageous, were the branched antlers of the\nparent-form ever developed?  To this I can only answer by remarking, that a\nnew mode of attack with new weapons might be a great advantage, as shewn by\nthe case of the Ovis cycloceros, who thus conquered a domestic ram famous\nfor his fighting power.  Though the branched antlers of a stag are well\nadapted for fighting with his rivals, and though it might be an advantage\nto the prong-horned variety slowly to acquire long and branched horns, if\nhe had to fight only with others of the same kind, yet it by no means\nfollows that branched horns would be the best fitted for conquering a foe\ndifferently armed.  In the foregoing case of the Oryx leucoryx, it is\nalmost certain that the victory would rest with an antelope having short\nhorns, and who therefore did not need to kneel down, though an oryx might\nprofit by having still longer horns, if he fought only with his proper\nrivals.\n\nMale quadrupeds, which are furnished with tusks, use them in various ways,\nas in the case of horns.  The boar strikes laterally and upwards; the musk-\ndeer downwards with serious effect.  (28.  Pallas, 'Spicilegia Zoologica,'\nfasc. xiii. 1779, p. 18.)  The walrus, though having so short a neck and so\nunwieldy a body, \"can strike either upwards, or downwards, or sideways,\nwith equal dexterity.\"  (29.  Lamont, 'Seasons with the Sea-Horses,' 1861,\np. 141.)  I was informed by the late Dr. Falconer, that the Indian elephant\nfights in a different manner according to the position and curvature of his\ntusks.  When they are directed forwards and upwards he is able to fling a\ntiger to a great distance--it is said to even thirty feet; when they are\nshort and turned downwards he endeavours suddenly to pin the tiger to the\nground and, in consequence, is dangerous to the rider, who is liable to be\njerked off the howdah.  (30.  See also Corse ('Philosophical Transactions,'\n1799, p. 212) on the manner in which the short-tusked Mooknah variety\nattacks other elephants.)\n\nVery few male quadrupeds possess weapons of two distinct kinds specially\nadapted for fighting with rival males.  The male muntjac-deer (Cervulus),\nhowever, offers an exception, as he is provided with horns and exserted\ncanine teeth.  But we may infer from what follows that one form of weapon\nhas often been replaced in the course of ages by another.  With ruminants\nthe development of horns generally stands in an inverse relation with that\nof even moderately developed canine teeth.  Thus camels, guanacoes,\nchevrotains, and musk-deer, are hornless, and they have efficient canines;\nthese teeth being \"always of smaller size in the females than in the\nmales.\"  The Camelidae have, in addition to their true canines, a pair of\ncanine-shaped incisors in their upper jaws.  (31.  Owen, 'Anatomy of\nVertebrates,' vol. iii. p. 349.)  Male deer and antelopes, on the other\nhand, possess horns, and they rarely have canine teeth; and these, when\npresent, are always of small size, so that it is doubtful whether they are\nof any service in their battles.  In Antilope montana they exist only as\nrudiments in the young male, disappearing as he grows old; and they are\nabsent in the female at all ages; but the females of certain other\nantelopes and of certain deer have been known occasionally to exhibit\nrudiments of these teeth.  (32.  See Ruppell (in 'Proc. Zoolog. Soc.' Jan.\n12, 1836, p. 3) on the canines in deer and antelopes, with a note by Mr.\nMartin on a female American deer.  See also Falconer ('Palaeont. Memoirs\nand Notes,' vol. i. 1868, p. 576) on canines in an adult female deer.  In\nold males of the musk-deer the canines (Pallas, 'Spic. Zoolog.' fasc. xiii.\n1779, p. 18) sometimes grow to the length of three inches, whilst in old\nfemales a rudiment projects scarcely half an inch above the gums.)\nStallions have small canine teeth, which are either quite absent or\nrudimentary in the mare; but they do not appear to be used in fighting, for\nstallions bite with their incisors, and do not open their mouths wide like\ncamels and guanacoes.  Whenever the adult male possesses canines, now\ninefficient, whilst the female has either none or mere rudiments, we may\nconclude that the early male progenitor of the species was provided with\nefficient canines, which have been partially transferred to the females.\nThe reduction of these teeth in the males seems to have followed from some\nchange in their manner of fighting, often (but not in the horse) caused by\nthe development of new weapons.\n\nTusks and horns are manifestly of high importance to their possessors, for\ntheir development consumes much organised matter.  A single tusk of the\nAsiatic elephant--one of the extinct woolly species--and of the African\nelephant, have been known to weigh respectively 150, 160, and 180 pounds;\nand even greater weights have been given by some authors.  (33.  Emerson\nTennent, 'Ceylon,' 1859, vol. ii. p. 275; Owen, 'British Fossil Mammals,'\n1846, p. 245.)  With deer, in which the horns are periodically renewed, the\ndrain on the constitution must be greater; the horns, for instance, of the\nmoose weigh from fifty to sixty pounds, and those of the extinct Irish elk\nfrom sixty to seventy pounds--the skull of the latter weighing on an\naverage only five pounds and a quarter.  Although the horns are not\nperiodically renewed in sheep, yet their development, in the opinion of\nmany agriculturists, entails a sensible loss to the breeder.  Stags,\nmoreover, in escaping from beasts of prey are loaded with an additional\nweight for the race, and are greatly retarded in passing through a woody\ncountry.  The moose, for instance, with horns extending five and a half\nfeet from tip to tip, although so skilful in their use that he will not\ntouch or break a twig when walking quietly, cannot act so dexterously\nwhilst rushing away from a pack of wolves.  \"During his progress he holds\nhis nose up, so as to lay the horns horizontally back; and in this attitude\ncannot see the ground distinctly.\"  (34.  Richardson, 'Fauna Bor.\nAmericana,' on the moose, Alces palmata, pp. 236, 237; on the expanse of\nthe horns, 'Land and Water,' 1869, p. 143.  See also Owen, 'British Fossil\nMammals,' on the Irish elk, pp. 447, 455.)  The tips of the horns of the\ngreat Irish elk were actually eight feet apart!  Whilst the horns are\ncovered with velvet, which lasts with red-deer for about twelve weeks, they\nare extremely sensitive to a blow; so that in Germany the stags at this\ntime somewhat change their habits, and avoiding dense forests, frequent\nyoung woods and low thickets.  (35.  'Forest Creatures,' by C. Boner, 1861,\np. 60.)  These facts remind us that male birds have acquired ornamental\nplumes at the cost of retarded flight, and other ornaments at the cost of\nsome loss of power in their battles with rival males.\n\nWith mammals, when, as is often the case, the sexes differ in size, the\nmales are almost always larger and stronger.  I am informed by Mr. Gould\nthat this holds good in a marked manner with the marsupials of Australia,\nthe males of which appear to continue growing until an unusually late age.\nBut the most extraordinary case is that of one of the seals (Callorhinus\nursinus), a full-grown female weighing less than one-sixth of a full-grown\nmale.  (36.  See the very interesting paper by Mr. J.A. Allen in 'Bull.\nMus. Comp. Zoology of Cambridge, United States,' vol. ii. No. 1, p. 82.\nThe weights were ascertained by a careful observer, Capt. Bryant.  Dr. Gill\nin 'The American Naturalist,' January, 1871, Prof. Shaler on the relative\nsize of the sexes of whales, 'American Naturalist,' January, 1873.)  Dr.\nGill remarks that it is with the polygamous seals, the males of which are\nwell known to fight savagely together, that the sexes differ much in size;\nthe monogamous species differing but little.  Whales also afford evidence\nof the relation existing between the pugnacity of the males and their large\nsize compared with that of the female; the males of the right-whales do not\nfight together, and they are not larger, but rather smaller, than their\nfemales; on the other hand, male sperm-whales fight much together, and\ntheir bodies are \"often found scarred with the imprint of their rival's\nteeth,\" and they are double the size of the females.  The greater strength\nof the male, as Hunter long ago remarked (37.  'Animal Economy,' p. 45.),\nis invariably displayed in those parts of the body which are brought into\naction in fighting with rival males--for instance, in the massive neck of\nthe bull.  Male quadrupeds are also more courageous and pugnacious than the\nfemales.  There can be little doubt that these characters have been gained,\npartly through sexual selection, owing to a long series of victories, by\nthe stronger and more courageous males over the weaker, and partly through\nthe inherited effects of use.  It is probable that the successive\nvariations in strength, size, and courage, whether due to mere variability\nor to the effects of use, by the accumulation of which male quadrupeds have\nacquired these characteristic qualities, occurred rather late in life, and\nwere consequently to a large extent limited in their transmission to the\nsame sex.\n\nFrom these considerations I was anxious to obtain information as to the\nScotch deer-hound, the sexes of which differ more in size than those of any\nother breed (though blood-hounds differ considerably), or than in any wild\ncanine species known to me.  Accordingly, I applied to Mr. Cupples, well\nknown for his success with this breed, who has weighed and measured many of\nhis own dogs, and who has with great kindness collected for me the\nfollowing facts from various sources.  Fine male dogs, measured at the\nshoulder, range from 28 inches, which is low, to 33 or even 34 inches in\nheight; and in weight from 80 pounds, which is light, to 120 pounds, or\neven more.  The females range in height from 23 to 27, or even to 28\ninches; and in weight from 50 to 70, or even 80 pounds.  (38.  See also\nRichardson's 'Manual on the Dog,' p. 59.  Much valuable information on the\nScottish deer-hound is given by Mr. McNeill, who first called attention to\nthe inequality in size between the sexes, in Scrope's 'Art of Deer-\nStalking.'  I hope that Mr. Cupples will keep to his intention of\npublishing a full account and history of this famous breed.)  Mr. Cupples\nconcludes that from 95 to 100 pounds for the male, and 70 for the female,\nwould be a safe average; but there is reason to believe that formerly both\nsexes attained a greater weight.  Mr. Cupples has weighed puppies when a\nfortnight old; in one litter the average weight of four males exceeded that\nof two females by six and a half ounces; in another litter the average\nweight of four males exceeded that of one female by less than one ounce;\nthe same males when three weeks old, exceeded the female by seven and a\nhalf ounces, and at the age of six weeks by nearly fourteen ounces.  Mr.\nWright of Yeldersley House, in a letter to Mr. Cupples, says:  \"I have\ntaken notes on the sizes and weights of puppies of many litters, and as far\nas my experience goes, dog-puppies as a rule differ very little from\nbitches till they arrive at about five or six months old; and then the dogs\nbegin to increase, gaining upon the bitches both in weight and size.  At\nbirth, and for several weeks afterwards, a bitch-puppy will occasionally be\nlarger than any of the dogs, but they are invariably beaten by them later.\"\nMr. McNeill, of Colonsay, concludes that \"the males do not attain their\nfull growth till over two years old, though the females attain it sooner.\"\nAccording to Mr. Cupples' experience, male dogs go on growing in stature\ntill they are from twelve to eighteen months old, and in weight till from\neighteen to twenty-four months old; whilst the females cease increasing in\nstature at the age of from nine to fourteen or fifteen months, and in\nweight at the age of from twelve to fifteen months.  From these various\nstatements it is clear that the full difference in size between the male\nand female Scotch deer-hound is not acquired until rather late in life.\nThe males almost exclusively are used for coursing, for, as Mr. McNeill\ninforms me, the females have not sufficient strength and weight to pull\ndown a full-grown deer.  From the names used in old legends, it appears, as\nI hear from Mr. Cupples, that, at a very ancient period, the males were the\nmost celebrated, the females being mentioned only as the mothers of famous\ndogs.  Hence, during many generations, it is the male which has been\nchiefly tested for strength, size, speed, and courage, and the best will\nhave been bred from.  As, however, the males do not attain their full\ndimensions until rather late in life, they will have tended, in accordance\nwith the law often indicated, to transmit their characters to their male\noffspring alone; and thus the great inequality in size between the sexes of\nthe Scotch deer-hound may probably be accounted for.\n\n[Fig. 65.  Head of Common wild boar, in prime of life (from Brehm).]\n\nThe males of some few quadrupeds possess organs or parts developed solely\nas a means of defence against the attacks of other males.  Some kinds of\ndeer use, as we have seen, the upper branches of their horns chiefly or\nexclusively for defending themselves; and the Oryx antelope, as I am\ninformed by Mr. Bartlett, fences most skilfully with his long, gently\ncurved horns; but these are likewise used as organs of offence.  The same\nobserver remarks that rhinoceroses in fighting, parry each other's sidelong\nblows with their horns, which clatter loudly together, as do the tusks of\nboars.  Although wild boars fight desperately, they seldom, according to\nBrehm, receive fatal wounds, as the blows fall on each other's tusks, or on\nthe layer of gristly skin covering the shoulder, called by the German\nhunters, the shield; and here we have a part specially modified for\ndefence.  With boars in the prime of life (Fig. 65) the tusks in the lower\njaw are used for fighting, but they become in old age, as Brehm states, so\nmuch curved inwards and upwards over the snout that they can no longer be\nused in this way.  They may, however, still serve, and even more\neffectively, as a means of defence.  In compensation for the loss of the\nlower tusks as weapons of offence, those in the upper jaw, which always\nproject a little laterally, increase in old age so much in length and curve\nso much upwards that they can be used for attack.  Nevertheless, an old\nboar is not so dangerous to man as one at the age of six or seven years.\n(39.  Brehm, 'Thierleben,' B. ii. ss. 729-732.)\n\n[Fig. 66.  Skull of the Babirusa Pig (from Wallace's 'Malay Archipelago').]\n\nIn the full-grown male Babirusa pig of Celebes (Fig. 66), the lower tusks\nare formidable weapons, like those of the European boar in the prime of\nlife, whilst the upper tusks are so long and have their points so much\ncurled inwards, sometimes even touching the forehead, that they are utterly\nuseless as weapons of attack.  They more nearly resemble horns than teeth,\nand are so manifestly useless as teeth that the animal was formerly\nsupposed to rest his head by hooking them on to a branch!  Their convex\nsurfaces, however, if the head were held a little laterally, would serve as\nan excellent guard; and hence, perhaps, it is that in old animals they \"are\ngenerally broken off, as if by fighting.\"  (40.  See Mr. Wallace's\ninteresting account of this animal, 'The Malay Archipelago,' 1869, vol. i.\np. 435.)  Here, then, we have the curious case of the upper tusks of the\nBabirusa regularly assuming during the prime of life a structure which\napparently renders them fitted only for defence; whilst in the European\nboar the lower tusks assume in a less degree and only during old age nearly\nthe same form, and then serve in like manner solely for defence.\n\n[Fig. 67.  Head of female Aethiopian wart-hog, from 'Proc. Zool. Soc.' 1869,\nshewing the same characters as the male, though on a reduced scale.\nN.B. When the engraving was first made, I was under the impression that it\nrepresented the male.]\n\nIn the wart-hog (see Phacochoerus aethiopicus, Fig. 67) the tusks in the\nupper jaw of the male curve upwards during the prime of life, and from\nbeing pointed serve as formidable weapons.  The tusks in the lower jaw are\nsharper than those in the upper, but from their shortness it seems hardly\npossible that they can be used as weapons of attack.  They must, however,\ngreatly strengthen those in the upper jaw, from being ground so as to fit\nclosely against their bases.  Neither the upper nor the lower tusks appear\nto have been specially modified to act as guards, though no doubt they are\nto a certain extent used for this purpose.  But the wart-hog is not\ndestitute of other special means of protection, for it has, on each side of\nthe face, beneath the eyes, a rather stiff, yet flexible, cartilaginous,\noblong pad (Fig. 67), which projects two or three inches outwards; and it\nappeared to Mr. Bartlett and myself, when viewing the living animal, that\nthese pads, when struck from beneath by the tusks of an opponent, would be\nturned upwards, and would thus admirably protect the somewhat prominent\neyes.  I may add, on the authority of Mr. Bartlett, that these boars when\nfighting stand directly face to face.\n\nLastly, the African river-hog (Potomochoerus penicillatus) has a hard\ncartilaginous knob on each side of the face beneath the eyes, which answers\nto the flexible pad of the wart-hog; it has also two bony prominences on\nthe upper jaw above the nostrils.  A boar of this species in the Zoological\nGardens recently broke into the cage of the wart-hog.  They fought all\nnight long, and were found in the morning much exhausted, but not seriously\nwounded.  It is a significant fact, as shewing the purposes of the above-\ndescribed projections and excrescences, that these were covered with blood,\nand were scored and abraded in an extraordinary manner.\n\nAlthough the males of so many members of the pig family are provided with\nweapons, and as we have just seen with means of defence, these weapons seem\nto have been acquired within a rather late geological period.  Dr. Forsyth\nMajor specifies (41.  'Atti della Soc. Italiana di Sc. Nat.' 1873, vol. xv.\nfasc. iv.) several miocene species, in none of which do the tusks appear to\nhave been largely developed in the males; and Professor Rutimeyer was\nformerly struck with this same fact.\n\nThe mane of the lion forms a good defence against the attacks of rival\nlions, the one danger to which he is liable; for the males, as Sir A. Smith\ninforms me, engage in terrible battles, and a young lion dares not approach\nan old one.  In 1857 a tiger at Bromwich broke into the cage of a lion and\na fearful scene ensued:  \"the lion's mane saved his neck and head from\nbeing much injured, but the tiger at last succeeded in ripping up his\nbelly, and in a few minutes he was dead.\"  (42.  'The Times,' Nov. 10,\n1857.  In regard to the Canada lynx, see Audubon and Bachman, 'Quadrupeds\nof North America,' 1846, p. 139.)  The broad ruff round the throat and chin\nof the Canadian lynx (Felis canadensis) is much longer in the male than in\nthe female; but whether it serves as a defence I do not know.  Male seals\nare well known to fight desperately together, and the males of certain\nkinds (Otaria jubata) (43.  Dr. Murie, on Otaria, 'Proc. Zoolog. Soc.'\n1869, p. 109.  Mr. J.A. Allen, in the paper above quoted (p. 75), doubts\nwhether the hair, which is longer on the neck in the male than in the\nfemale, deserves to be called a mane.) have great manes, whilst the females\nhave small ones or none.  The male baboon of the Cape of Good Hope\n(Cynocephalus porcarius) has a much longer mane and larger canine teeth\nthan the female; and the mane probably serves as a protection, for, on\nasking the keepers in the Zoological Gardens, without giving them any clue\nto my object, whether any of the monkeys especially attacked each other by\nthe nape of the neck, I was answered that this was not the case, except\nwith the above baboon.  In the Hamadryas baboon, Ehrenberg compares the\nmane of the adult male to that of a young lion, whilst in the young of both\nsexes and in the female the mane is almost absent.\n\nIt appeared to me probable that the immense woolly mane of the male\nAmerican bison, which reaches almost to the ground, and is much more\ndeveloped in the males than in the females, served as a protection to them\nin their terrible battles; but an experienced hunter told Judge Caton that\nhe had never observed anything which favoured this belief.  The stallion\nhas a thicker and fuller mane than the mare; and I have made particular\ninquiries of two great trainers and breeders, who have had charge of many\nentire horses, and am assured that they \"invariably endeavour to seize one\nanother by the neck.\"  It does not, however, follow from the foregoing\nstatements, that when the hair on the neck serves as a defence, that it was\noriginally developed for this purpose, though this is probable in some\ncases, as in that of the lion.  I am informed by Mr. McNeill that the long\nhairs on the throat of the stag (Cervus elaphus) serve as a great\nprotection to him when hunted, for the dogs generally endeavour to seize\nhim by the throat; but it is not probable that these hairs were specially\ndeveloped for this purpose; otherwise the young and the females would have\nbeen equally protected.\n\nCHOICE IN PAIRING BY EITHER SEX OF QUADRUPEDS.\n\nBefore describing in the next chapter, the differences between the sexes in\nvoice, odours emitted, and ornaments, it will be convenient here to\nconsider whether the sexes exert any choice in their unions.  Does the\nfemale prefer any particular male, either before or after the males may\nhave fought together for supremacy; or does the male, when not a\npolygamist, select any particular female?  The general impression amongst\nbreeders seems to be that the male accepts any female; and this owing to\nhis eagerness, is, in most cases, probably the truth.  Whether the female\nas a general rule indifferently accepts any male is much more doubtful.  In\nthe fourteenth chapter, on Birds, a considerable body of direct and\nindirect evidence was advanced, shewing that the female selects her\npartner; and it would be a strange anomaly if female quadrupeds, which\nstand higher in the scale and have higher mental powers, did not generally,\nor at least often, exert some choice.  The female could in most cases\nescape, if wooed by a male that did not please or excite her; and when\npursued by several males, as commonly occurs, she would often have the\nopportunity, whilst they were fighting together, of escaping with some one\nmale, or at least of temporarily pairing with him.  This latter contingency\nhas often been observed in Scotland with female red-deer, as I am informed\nby Sir Philip Egerton and others.  (44. Mr. Boner, in his excellent\ndescription of the habits of the red-deer in Germany ('Forest Creatures,'\n1861, p. 81) says, \"while the stag is defending his rights against one\nintruder, another invades the sanctuary of his harem, and carries off\ntrophy after trophy.\"  Exactly the same thing occurs with seals; see Mr.\nJ.A. Allen, ibid. p. 100.)\n\nIt is scarcely possible that much should be known about female quadrupeds\nin a state of nature making any choice in their marriage unions.  The\nfollowing curious details on the courtship of one of the eared seals\n(Callorhinus ursinus) are given (45.  Mr. J.A. Allen in 'Bull. Mus. Comp.\nZoolog. of Cambridge, United States,' vol. ii. No. 1, p. 99.) on the\nauthority of Capt. Bryant, who had ample opportunities for observation.  He\nsays, \"Many of the females on their arrival at the island where they breed\nappear desirous of returning to some particular male, and frequently climb\nthe outlying rocks to overlook the rookeries, calling out and listening as\nif for a familiar voice.  Then changing to another place they do the same\nagain...As soon as a female reaches the shore, the nearest male goes down\nto meet her, making meanwhile a noise like the clucking of a hen to her\nchickens.  He bows to her and coaxes her until he gets between her and the\nwater so that she cannot escape him.  Then his manner changes, and with a\nharsh growl he drives her to a place in his harem.  This continues until\nthe lower row of harems is nearly full.  Then the males higher up select\nthe time when their more fortunate neighbours are off their guard to steal\ntheir wives.  This they do by taking them in their mouths and lifting them\nover the heads of the other females, and carefully placing them in their\nown harem, carrying them as cats do their kittens.  Those still higher up\npursue the same method until the whole space is occupied.  Frequently a\nstruggle ensues between two males for the possession of the same female,\nand both seizing her at once pull her in two or terribly lacerate her with\ntheir teeth.  When the space is all filled, the old male walks around\ncomplacently reviewing his family, scolding those who crowd or disturb the\nothers, and fiercely driving off all intruders.  This surveillance always\nkeeps him actively occupied.\"\n\nAs so little is known about the courtship of animals in a state of nature,\nI have endeavoured to discover how far our domesticated quadrupeds evince\nany choice in their unions.  Dogs offer the best opportunity for\nobservation, as they are carefully attended to and well understood.  Many\nbreeders have expressed a strong opinion on this head.  Thus, Mr. Mayhew\nremarks, \"The females are able to bestow their affections; and tender\nrecollections are as potent over them as they are known to be in other\ncases, where higher animals are concerned.  Bitches are not always prudent\nin their loves, but are apt to fling themselves away on curs of low degree.\nIf reared with a companion of vulgar appearance, there often springs up\nbetween the pair a devotion which no time can afterwards subdue.  The\npassion, for such it really is, becomes of a more than romantic endurance.\"\nMr. Mayhew, who attended chiefly to the smaller breeds, is convinced that\nthe females are strongly attracted by males of a large size.  (46.  'Dogs:\ntheir Management,' by E. Mayhew, M.R.C.V.S., 2nd ed., 1864, pp. 187-192.)\nThe well-known veterinary Blaine states (47.  Quoted by Alex. Walker, 'On\nIntermarriage,' 1838, p. 276; see also p. 244.) that his own female pug dog\nbecame so attached to a spaniel, and a female setter to a cur, that in\nneither case would they pair with a dog of their own breed until several\nweeks had elapsed.  Two similar and trustworthy accounts have been given me\nin regard to a female retriever and a spaniel, both of which became\nenamoured with terrier-dogs.\n\nMr. Cupples informs me that he can personally vouch for the accuracy of the\nfollowing more remarkable case, in which a valuable and wonderfully-\nintelligent female terrier loved a retriever belonging to a neighbour to\nsuch a degree, that she had often to be dragged away from him.  After their\npermanent separation, although repeatedly shewing milk in her teats, she\nwould never acknowledge the courtship of any other dog, and to the regret\nof her owner never bore puppies. Mr. Cupples also states, that in 1868, a\nfemale deerhound in his kennel thrice produced puppies, and on each\noccasion shewed a marked preference for one of the largest and handsomest,\nbut not the most eager, of four deerhounds living with her, all in the\nprime of life. Mr. Cupples has observed that the female generally favours a\ndog whom she has associated with and knows; her shyness and timidity at\nfirst incline her against a strange dog.  The male, on the contrary, seems\nrather inclined towards strange females.  It appears to be rare when the\nmale refuses any particular female, but Mr. Wright, of Yeldersley House, a\ngreat breeder of dogs, informs me that he has known some instances; he\ncites the case of one of his own deerhounds, who would not take any notice\nof a particular female mastiff, so that another deerhound had to be\nemployed.  It would be superfluous to give, as I could, other instances,\nand I will only add that Mr. Barr, who has carefully bred many bloodhounds,\nstates that in almost every instance particular individuals of opposite\nsexes shew a decided preference for each other.  Finally, Mr. Cupples,\nafter attending to this subject for another year, has written to me, \"I\nhave had full confirmation of my former statement, that dogs in breeding\nform decided preferences for each other, being often influenced by size,\nbright colour, and individual characters, as well as by the degree of their\nprevious familiarity.\"\n\nIn regard to horses, Mr. Blenkiron, the greatest breeder of race-horses in\nthe world, informs me that stallions are so frequently capricious in their\nchoice, rejecting one mare and without any apparent cause taking to\nanother, that various artifices have to be habitually used.  The famous\nMonarque, for instance, would never consciously look at the dam of\nGladiateur, and a trick had to be practised.  We can partly see the reason\nwhy valuable race-horse stallions, which are in such demand as to be\nexhausted, should be so particular in their choice.  Mr. Blenkiron has\nnever known a mare reject a horse; but this has occurred in Mr. Wright's\nstable, so that the mare had to be cheated.  Prosper Lucas (48.  'Traite de\nl'Hered. Nat.' tom. ii. 1850, p. 296.) quotes various statements from\nFrench authorities, and remarks, \"On voit des etalons qui s'eprennent d'une\njument, et negligent toutes les autres.\"  He gives, on the authority of\nBaelen, similar facts in regard to bulls; and Mr. H. Reeks assures me that\na famous short-horn bull belonging to his father \"invariably refused to be\nmatched with a black cow.\"  Hoffberg, in describing the domesticated\nreindeer of Lapland says, \"Foeminae majores et fortiores mares prae\ncaeteris admittunt, ad eos confugiunt, a junioribus agitatae, qui hos in\nfugam conjiciunt.\"  (49.  'Amoenitates Acad.' vol. iv. 1788, p. 160.)  A\nclergyman, who has bred many pigs, asserts that sows often reject one boar\nand immediately accept another.\n\nFrom these facts there can be no doubt that, with most of our domesticated\nquadrupeds, strong individual antipathies and preferences are frequently\nexhibited, and much more commonly by the female than by the male.  This\nbeing the case, it is improbable that the unions of quadrupeds in a state\nof nature should be left to mere chance.  It is much more probable that the\nfemales are allured or excited by particular males, who possess certain\ncharacters in a higher degree than other males; but what these characters\nare, we can seldom or never discover with certainty.\n\n\nCHAPTER XVIII.\n\nSECONDARY SEXUAL CHARACTERS OF MAMMALS--continued.\n\nVoice--Remarkable sexual peculiarities in seals--Odour--Development of the\nhair--Colour of the hair and skin--Anomalous case of the female being more\nornamented than the male--Colour and ornaments due to sexual selection--\nColour acquired for the sake of protection--Colour, though common to both\nsexes, often due to sexual selection--On the disappearance of spots and\nstripes in adult quadrupeds--On the colours and ornaments of the\nQuadrumana--Summary.\n\nQuadrupeds use their voices for various purposes, as a signal of danger, as\na call from one member of a troop to another, or from the mother to her\nlost offspring, or from the latter for protection to their mother; but such\nuses need not here be considered.  We are concerned only with the\ndifference between the voices of the sexes, for instance between that of\nthe lion and lioness, or of the bull and cow.  Almost all male animals use\ntheir voices much more during the rutting-season than at any other time;\nand some, as the giraffe and porcupine (1.  Owen, 'Anatomy of Vertebrates,'\nvol. iii. p. 585.), are said to be completely mute excepting at this\nseason.  As the throats (i.e. the larynx and thyroid bodies (2.  Ibid. p.\n595.)) of stags periodically become enlarged at the beginning of the\nbreeding-season, it might be thought that their powerful voices must be\nsomehow of high importance to them; but this is very doubtful.  From\ninformation given to me by two experienced observers, Mr. McNeill and Sir\nP. Egerton, it seems that young stags under three years old do not roar or\nbellow; and that the old ones begin bellowing at the commencement of the\nbreeding-season, at first only occasionally and moderately, whilst they\nrestlessly wander about in search of the females.  Their battles are\nprefaced by loud and prolonged bellowing, but during the actual conflict\nthey are silent.  Animals of all kinds which habitually use their voices\nutter various noises under any strong emotion, as when enraged and\npreparing to fight; but this may merely be the result of nervous\nexcitement, which leads to the spasmodic contraction of almost all the\nmuscles of the body, as when a man grinds his teeth and clenches his fists\nin rage or agony.  No doubt stags challenge each other to mortal combat by\nbellowing; but those with the more powerful voices, unless at the same time\nthe stronger, better-armed, and more courageous, would not gain any\nadvantage over their rivals.\n\nIt is possible that the roaring of the lion may be of some service to him\nby striking terror into his adversary; for when enraged he likewise erects\nhis mane and thus instinctively tries to make himself appear as terrible as\npossible.  But it can hardly be supposed that the bellowing of the stag,\neven if it be of service to him in this way, can have been important enough\nto have led to the periodical enlargement of the throat.  Some writers\nsuggest that the bellowing serves as a call to the female; but the\nexperienced observers above quoted inform me that female deer do not search\nfor the male, though the males search eagerly for the females, as indeed\nmight be expected from what we know of the habits of other male quadrupeds.\nThe voice of the female, on the other hand, quickly brings to her one or\nmore stags (3.  See, for instance, Major W. Ross King ('The Sportsman in\nCanada,' 1866, pp. 53, 131) on the habits of the moose and wild reindeer.),\nas is well known to the hunters who in wild countries imitate her cry.  If\nwe could believe that the male had the power to excite or allure the female\nby his voice, the periodical enlargement of his vocal organs would be\nintelligible on the principle of sexual selection, together with\ninheritance limited to the same sex and season; but we have no evidence in\nfavour of this view.  As the case stands, the loud voice of the stag during\nthe breeding-season does not seem to be of any special service to him,\neither during his courtship or battles, or in any other way.  But may we\nnot believe that the frequent use of the voice, under the strong excitement\nof love, jealousy, and rage, continued during many generations, may at last\nhave produced an inherited effect on the vocal organs of the stag, as well\nas of other male animals?  This appears to me, in our present state of\nknowledge, the most probable view.\n\nThe voice of the adult male gorilla is tremendous, and he is furnished with\na laryngeal sack, as is the adult male orang.  (4.  Owen 'Anatomy of\nVertebrates,' vol. iii. p. 600.)  The gibbons rank among the noisiest of\nmonkeys, and the Sumatra species (Hylobates syndactylus) is also furnished\nwith an air sack; but Mr. Blyth, who has had opportunities for observation,\ndoes not believe that the male is noisier than the female.  Hence, these\nlatter monkeys probably use their voices as a mutual call; and this is\ncertainly the case with some quadrupeds, for instance the beaver.  (5.  Mr.\nGreen, in 'Journal of Linnean Society,' vol. x. 'Zoology,' 1869, note 362.)\nAnother gibbon, the H. agilis, is remarkable, from having the power of\ngiving a complete and correct octave of musical notes (6.  C.L. Martin,\n'General Introduction to the Natural History of Mamm. Animals,' 1841, p.\n431.), which we may reasonably suspect serves as a sexual charm; but I\nshall have to recur to this subject in the next chapter.  The vocal organs\nof the American Mycetes caraya are one-third larger in the male than in the\nfemale, and are wonderfully powerful.  These monkeys in warm weather make\nthe forests resound at morning and evening with their overwhelming voices.\nThe males begin the dreadful concert, and often continue it during many\nhours, the females sometimes joining in with their less powerful voices.\nAn excellent observer, Rengger (7.  'Naturgeschichte der Saeugethiere von\nParaguay,' 1830, ss. 15, 21.), could not perceive that they were excited to\nbegin by any special cause; he thinks that, like many birds, they delight\nin their own music, and try to excel each other.  Whether most of the\nforegoing monkeys have acquired their powerful voices in order to beat\ntheir rivals and charm the females--or whether the vocal organs have been\nstrengthened and enlarged through the inherited effects of long-continued\nuse without any particular good being thus gained--I will not pretend to\nsay; but the former view, at least in the case of the Hylobates agilis,\nseems the most probable.\n\nI may here mention two very curious sexual peculiarities occurring in\nseals, because they have been supposed by some writers to affect the voice.\nThe nose of the male sea-elephant (Macrorhinus proboscideus) becomes\ngreatly elongated during the breeding-season, and can then be erected.  In\nthis state it is sometimes a foot in length.  The female is not thus\nprovided at any period of life.  The male makes a wild, hoarse, gurgling\nnoise, which is audible at a great distance and is believed to be\nstrengthened by the proboscis; the voice of the female being different.\nLesson compares the erection of the proboscis, with the swelling of the\nwattles of male gallinaceous birds whilst courting the females.  In another\nallied kind of seal, the bladder-nose (Cystophora cristata), the head is\ncovered by a great hood or bladder.  This is supported by the septum of the\nnose, which is produced far backwards and rises into an internal crest\nseven inches in height.  The hood is clothed with short hair, and is\nmuscular; can be inflated until it more than equals the whole head in size!\nThe males when rutting, fight furiously on the ice, and their roaring \"is\nsaid to be sometimes so loud as to be heard four miles off.\"  When attacked\nthey likewise roar or bellow; and whenever irritated the bladder is\ninflated and quivers.  Some naturalists believe that the voice is thus\nstrengthened, but various other uses have been assigned to this\nextraordinary structure.  Mr. R. Brown thinks that it serves as a\nprotection against accidents of all kinds; but this is not probable, for,\nas I am assured by Mr. Lamont who killed 600 of these animals, the hood is\nrudimentary in the females, and it is not developed in the males during\nyouth.  (8.  On the sea-elephant, see an article by Lesson, in 'Dict.\nClass. Hist. Nat.' tom. xiii. p. 418.  For the Cystophora, or Stemmatopus,\nsee Dr. Dekay, 'Annals of Lyceum of Nat. Hist.' New York, vol. i. 1824, p.\n94.  Pennant has also collected information from the sealers on this\nanimal.  The fullest account is given by Mr. Brown, in 'Proc. Zoolog. Soc.'\n1868, p. 435.)\n\nODOUR.\n\nWith some animals, as with the notorious skunk of America, the overwhelming\nodour which they emit appears to serve exclusively as a defence.  With\nshrew-mice (Sorex) both sexes possess abdominal scent-glands, and there can\nbe little doubt, from the rejection of their bodies by birds and beasts of\nprey, that the odour is protective; nevertheless, the glands become\nenlarged in the males during the breeding-season.  In many other quadrupeds\nthe glands are of the same size in both sexes (9.  As with the castoreum of\nthe beaver, see Mr. L.H. Morgan's most interesting work, 'The American\nBeaver,' 1868, p. 300.  Pallas ('Spic. Zoolog.' fasc. viii. 1779, p. 23)\nhas well discussed the odoriferous glands of mammals.  Owen ('Anat. of\nVertebrates,' vol. iii. p. 634) also gives an account of these glands,\nincluding those of the elephant, and (p. 763) those of shrew-mice.  On\nbats, Mr. Dobson in 'Proceedings of the Zoological Society' 1873, p. 241.),\nbut their uses are not known.  In other species the glands are confined to\nthe males, or are more developed than in the females; and they almost\nalways become more active during the rutting-season.  At this period the\nglands on the sides of the face of the male elephant enlarge, and emit a\nsecretion having a strong musky odour.  The males, and rarely the females,\nof many kinds of bats have glands and protrudable sacks situated in various\nparts; and it is believed that these are odoriferous.\n\nThe rank effluvium of the male goat is well known, and that of certain male\ndeer is wonderfully strong and persistent.  On the banks of the Plata I\nperceived the air tainted with the odour of the male Cervus campestris, at\nhalf a mile to leeward of a herd; and a silk handkerchief, in which I\ncarried home a skin, though often used and washed, retained, when first\nunfolded, traces of the odour for one year and seven months.  This animal\ndoes not emit its strong odour until more than a year old, and if castrated\nwhilst young never emits it.  (10.  Rengger, 'Naturgeschichte der\nSaeugethiere von Paraguay,' 1830, s. 355.  This observer also gives some\ncurious particulars in regard to the odour.)  Besides the general odour,\npermeating the whole body of certain ruminants (for instance, Bos\nmoschatus) in the breeding-season, many deer, antelopes, sheep, and goats\npossess odoriferous glands in various situations, more especially on their\nfaces.  The so-called tear-sacks, or suborbital pits, come under this head.\nThese glands secrete a semi-fluid fetid matter which is sometimes so\ncopious as to stain the whole face, as I have myself seen in an antelope.\nThey are \"usually larger in the male than in the female, and their\ndevelopment is checked by castration.\"  (11.  Owen, 'Anatomy of\nVertebrates,' vol. iii. p. 632.  See also Dr. Murie's observations on those\nglands in the 'Proc. Zoolog. Soc.' 1870, p. 340.  Desmarest, 'On the\nAntilope subgutturosa, 'Mammalogie,' 1820, p. 455.)  According to Desmarest\nthey are altogether absent in the female of Antilope subgutturosa.  Hence,\nthere can be no doubt that they stand in close relation with the\nreproductive functions.  They are also sometimes present, and sometimes\nabsent, in nearly allied forms.  In the adult male musk-deer (Moschus\nmoschiferus), a naked space round the tail is bedewed with an odoriferous\nfluid, whilst in the adult female, and in the male until two years old,\nthis space is covered with hair and is not odoriferous.  The proper musk-\nsack of this deer is from its position necessarily confined to the male,\nand forms an additional scent-organ.  It is a singular fact that the matter\nsecreted by this latter gland, does not, according to Pallas, change in\nconsistence, or increase in quantity, during the rutting-season;\nnevertheless this naturalist admits that its presence is in some way\nconnected with the act of reproduction.  He gives, however, only a\nconjectural and unsatisfactory explanation of its use.  (12.  Pallas,\n'Spicilegia Zoolog.' fasc. xiii. 1799, p. 24; Desmoulins, 'Dict. Class.\nd'Hist. Nat.' tom. iii. p. 586.)\n\nIn most cases, when only the male emits a strong odour during the breeding-\nseason, it probably serves to excite or allure the female.  We must not\njudge on this head by our own taste, for it is well known that rats are\nenticed by certain essential oils, and cats by valerian, substances far\nfrom agreeable to us; and that dogs, though they will not eat carrion,\nsniff and roll on it.  From the reasons given when discussing the voice of\nthe stag, we may reject the idea that the odour serves to bring the females\nfrom a distance to the males.  Active and long-continued use cannot here\nhave come into play, as in the case of the vocal organs.  The odour emitted\nmust be of considerable importance to the male, inasmuch as large and\ncomplex glands, furnished with muscles for everting the sack, and for\nclosing or opening the orifice, have in some cases been developed.  The\ndevelopment of these organs is intelligible through sexual selection, if\nthe most odoriferous males are the most successful in winning the females,\nand in leaving offspring to inherit their gradually perfected glands and\nodours.\n\nDEVELOPMENT OF THE HAIR.\n\nWe have seen that male quadrupeds often have the hair on their necks and\nshoulders much more developed than the females; and many additional\ninstances could be given.  This sometimes serves as a defence to the male\nduring his battles; but whether the hair in most cases has been specially\ndeveloped for this purpose, is very doubtful.  We may feel almost certain\nthat this is not the case, when only a thin and narrow crest runs along the\nback; for a crest of this kind would afford scarcely any protection, and\nthe ridge of the back is not a place likely to be injured; nevertheless\nsuch crests are sometimes confined to the males, or are much more developed\nin them than in the females.  Two antelopes, the Tragelaphus scriptus (13.\nDr. Gray, 'Gleanings from the Menagerie at Knowsley,' pl. 28.) (Fig. 70)\nand Portax picta may be given as instances.  When stags, and the males of\nthe wild goat, are enraged or terrified, these crests stand erect (14.\nJudge Caton on the Wapiti, 'Transact. Ottawa Acad. Nat. Sciences,' 1868,\npp. 36, 40; Blyth, 'Land and Water,' on Capra aegagrus 1867, p. 37.); but\nit cannot be supposed that they have been developed merely for the sake of\nexciting fear in their enemies.  One of the above-named antelopes, the\nPortax picta, has a large well-defined brush of black hair on the throat,\nand this is much larger in the male than in the female.  In the Ammotragus\ntragelaphus of North Africa, a member of the sheep-family, the fore-legs\nare almost concealed by an extraordinary growth of hair, which depends from\nthe neck and upper halves of the legs; but Mr. Bartlett does not believe\nthat this mantle is of the least use to the male, in whom it is much more\ndeveloped than in the female.\n\n[Fig. 68.  Pithecia satanas, male (from Brehm).]\n\nMale quadrupeds of many kinds differ from the females in having more hair,\nor hair of a different character, on certain parts of their faces.  Thus\nthe bull alone has curled hair on the forehead.  (15.  Hunter's 'Essays and\nObservations,' edited by Owen, 1861. vol. i. p. 236.)  In three closely-\nallied sub-genera of the goat family, only the males possess beards,\nsometimes of large size; in two other sub-genera both sexes have a beard,\nbut it disappears in some of the domestic breeds of the common goat; and\nneither sex of the Hemitragus has a beard.  In the ibex the beard is not\ndeveloped during the summer, and is so small at other times that it may be\ncalled rudimentary.  (16.  See Dr. Gray's 'Catalogue of Mammalia in the\nBritish Museum,' part iii. 1852, p. 144.)  With some monkeys the beard is\nconfined to the male, as in the orang; or is much larger in the male than\nin the female, as in the Mycetes caraya and Pithecia satanas (Fig. 68).  So\nit is with the whiskers of some species of Macacus (17.  Rengger,\n'Saeugethiere,' etc., s. 14; Desmarest, 'Mammalogie,' p. 86.), and, as we\nhave seen, with the manes of some species of baboons.  But with most kinds\nof monkeys the various tufts of hair about the face and head are alike in\nboth sexes.\n\nThe males of various members of the ox family (Bovidae), and of certain\nantelopes, are furnished with a dewlap, or great fold of skin on the neck,\nwhich is much less developed in the female.\n\nNow, what must we conclude with respect to such sexual differences as\nthese?  No one will pretend that the beards of certain male goats, or the\ndewlaps of the bull, or the crests of hair along the backs of certain male\nantelopes, are of any use to them in their ordinary habits.  It is possible\nthat the immense beard of the male Pithecia, and the large beard of the\nmale orang, may protect their throats when fighting; for the keepers in the\nZoological Gardens inform me that many monkeys attack each other by the\nthroat; but it is not probable that the beard has been developed for a\ndistinct purpose from that served by the whiskers, moustache, and other\ntufts of hair on the face; and no one will suppose that these are useful as\na protection.  Must we attribute all these appendages of hair or skin to\nmere purposeless variability in the male?  It cannot be denied that this is\npossible; for in many domesticated quadrupeds, certain characters,\napparently not derived through reversion from any wild parent form, are\nconfined to the males, or are more developed in them than in the females--\nfor instance, the hump on the male zebu-cattle of India, the tail of fat-\ntailed rams, the arched outline of the forehead in the males of several\nbreeds of sheep, and lastly, the mane, the long hairs on the hind legs, and\nthe dewlap of the male of the Berbura goat.  (18.  See the chapters on\nthese several animals in vol. i. of my 'Variation of Animals under\nDomestication;' also vol. ii. p. 73; also chap. xx. on the practice of\nselection by semi-civilised people.  For the Berbura goat, see Dr. Gray,\n'Catalogue,' ibid. p. 157.)  The mane, which occurs only in the rams of an\nAfrican breed of sheep, is a true secondary sexual character, for, as I\nhear from Mr. Winwood Reade, it is not developed if the animal be\ncastrated.  Although we ought to be extremely cautious, as shewn in my work\non 'Variation under Domestication,' in concluding that any character, even\nwith animals kept by semi-civilised people, has not been subjected to\nselection by man, and thus augmented, yet in the cases just specified this\nis improbable; more especially as the characters are confined to the males,\nor are more strongly developed in them than in the females.  If it were\npositively known that the above African ram is a descendant of the same\nprimitive stock as the other breeds of sheep, and if the Berbura male-goat\nwith his mane, dewlap, etc., is descended from the same stock as other\ngoats, then, assuming that selection has not been applied to these\ncharacters, they must be due to simple variability, together with sexually-\nlimited inheritance.\n\nHence it appears reasonable to extend this same view to all analogous cases\nwith animals in a state of nature.  Nevertheless I cannot persuade myself\nthat it generally holds good, as in the case of the extraordinary\ndevelopment of hair on the throat and fore-legs of the male Ammotragus, or\nin that of the immense beard of the male Pithecia.  Such study as I have\nbeen able to give to nature makes me believe that parts or organs which are\nhighly developed, were acquired at some period for a special purpose.  With\nthose antelopes in which the adult male is more strongly-coloured than the\nfemale, and with those monkeys in which the hair on the face is elegantly\narranged and coloured in a diversified manner, it seems probable that the\ncrests and tufts of hair were gained as ornaments; and this I know is the\nopinion of some naturalists.  If this be correct, there can be little doubt\nthat they were gained or at least modified through sexual selection; but\nhow far the same view may be extended to other mammals is doubtful.\n\nCOLOUR OF THE HAIR AND OF THE NAKED SKIN.\n\nI will first give briefly all the cases known to me of male quadrupeds\ndiffering in colour from the females.  With Marsupials, as I am informed by\nMr. Gould, the sexes rarely differ in this respect; but the great red\nkangaroo offers a striking exception, \"delicate blue being the prevailing\ntint in those parts of the female which in the male are red.\"  (19.\nOsphranter rufus, Gould, 'Mammals of Australia,' 1863, vol. ii.  On the\nDidelphis, Desmarest, 'Mammalogie,' p. 256.)  In the Didelphis opossum of\nCayenne the female is said to be a little more red than the male.  Of the\nRodents, Dr. Gray remarks:  \"African squirrels, especially those found in\nthe tropical regions, have the fur much brighter and more vivid at some\nseasons of the year than at others, and the fur of the male is generally\nbrighter than that of the female.\"  (20.  'Annals and Magazine of Natural\nHistory,' Nov. 1867, p. 325.  On the Mus minutus, Desmarest, 'Mammalogie,'\np. 304.)  Dr. Gray informs me that he specified the African squirrels,\nbecause, from their unusually bright colours, they best exhibit this\ndifference.  The female of the Mus minutus of Russia is of a paler and\ndirtier tint than the male.  In a large number of bats the fur of the male\nis lighter than in the female.  (21.  J.A. Allen, in 'Bulletin of Mus.\nComp. Zoolog. of Cambridge, United States,' 1869, p. 207.  Mr. Dobson on\nsexual characters in the Chiroptera, 'Proceedings of the Zoological\nSociety,' 1873, p. 241.  Dr. Gray on Sloths, ibid. 1871, p. 436.)  Mr.\nDobson also remarks, with respect to these animals:  \"Differences,\ndepending partly or entirely on the possession by the male of fur of a much\nmore brilliant hue, or distinguished by different markings or by the\ngreater length of certain portions, are met only, to any appreciable\nextent, in the frugivorous bats in which the sense of sight is well\ndeveloped.\"  This last remark deserves attention, as bearing on the\nquestion whether bright colours are serviceable to male animals from being\nornamental.  In one genus of sloths, it is now established, as Dr. Gray\nstates, \"that the males are ornamented differently from the females--that\nis to say, that they have a patch of soft short hair between the shoulders,\nwhich is generally of a more or less orange colour, and in one species pure\nwhite.  The females, on the contrary, are destitute of this mark.\"\n\nThe terrestrial Carnivora and Insectivora rarely exhibit sexual differences\nof any kind, including colour.  The ocelot (Felis pardalis), however, is\nexceptional, for the colours of the female, compared with those of the\nmale, are \"moins apparentes, le fauve, etant plus terne, le blanc moins\npur, les raies ayant moins de largeur et les taches moins de diametre.\"\n(22.  Desmarest, 'Mammalogie,' 1820, p. 220.  On Felis mitis, Rengger,\nibid. s. 194.)  The sexes of the allied Felis mitis also differ, but in a\nless degree; the general hues of the female being rather paler than in the\nmale, with the spots less black.  The marine Carnivora or seals, on the\nother hand, sometimes differ considerably in colour, and they present, as\nwe have already seen, other remarkable sexual differences.  Thus the male\nof the Otaria nigrescens of the southern hemisphere is of a rich brown\nshade above; whilst the female, who acquires her adult tints earlier in\nlife than the male, is dark-grey above, the young of both sexes being of a\ndeep chocolate colour.  The male of the northern Phoca groenlandica is\ntawny grey, with a curious saddle-shaped dark mark on the back; the female\nis much smaller, and has a very different appearance, being \"dull white or\nyellowish straw-colour, with a tawny hue on the back\"; the young at first\nare pure white, and can \"hardly be distinguished among the icy hummocks and\nsnow, their colour thus acting as a protection.\"  (23.  Dr. Murie on the\nOtaria, 'Proceedings Zoological Society,' 1869, p. 108.  Mr. R. Brown on\nthe P. groenlandica, ibid. 1868, p. 417.  See also on the colours of seals,\nDesmarest, ibid. pp. 243, 249.)\n\nWith Ruminants sexual differences of colour occur more commonly than in any\nother order.  A difference of this kind is general in the Strepsicerene\nantelopes; thus the male nilghau (Portax picta) is bluish-grey and much\ndarker than the female, with the square white patch on the throat, the\nwhite marks on the fetlocks, and the black spots on the ears all much more\ndistinct.  We have seen that in this species the crests and tufts of hair\nare likewise more developed in the male than in the hornless female.  I am\ninformed by Mr. Blyth that the male, without shedding his hair,\nperiodically becomes darker during the breeding-season.  Young males cannot\nbe distinguished from young females until about twelve months old; and if\nthe male is emasculated before this period, he never, according to the same\nauthority, changes colour.  The importance of this latter fact, as evidence\nthat the colouring of the Portax is of sexual origin, becomes obvious, when\nwe hear (24.  Judge Caton, in 'Transactions of the Ottawa Academy of\nNatural Sciences,' 1868, p. 4.) that neither the red summer-coat nor the\nblue winter-coat of the Virginian deer is at all affected by emasculation.\nWith most or all of the highly-ornamented species of Tragelaphus the males\nare darker than the hornless females, and their crests of hair are more\nfully developed.  In the male of that magnificent antelope, the Derbyan\neland, the body is redder, the whole neck much blacker, and the white band\nwhich separates these colours broader than in the female.  In the Cape\neland, also, the male is slightly darker than the female.  (25.  Dr. Gray,\n'Cat. of Mamm. in Brit. Mus.' part iii. 1852, pp. 134-142; also Dr. Gray,\n'Gleanings from the Menagerie of Knowsley,' in which there is a splendid\ndrawing of the Oreas derbianus:  see the text on Tragelaphus.  For the Cape\neland (Oreas canna), see Andrew Smith, 'Zoology of S. Africa,' pl. 41 and\n42.  There are also many of these Antelopes in the Zoological Gardens.)\n\nIn the Indian black-buck (A. bezoartica), which belongs to another tribe of\nantelopes, the male is very dark, almost black; whilst the hornless female\nis fawn-coloured.  We meet in this species, as Mr. Blyth informs me, with\nan exactly similar series of facts, as in the Portax picta, namely, in the\nmale periodically changing colour during the breeding-season, in the\neffects of emasculation on this change, and in the young of both sexes\nbeing indistinguishable from each other.  In the Antilope niger the male is\nblack, the female, as well as the young of both sexes, being brown; in A.\nsing-sing the male is much brighter coloured than the hornless female, and\nhis chest and belly are blacker; in the male A. caama, the marks and lines\nwhich occur on various parts of the body are black, instead of brown as in\nthe female; in the brindled gnu (A. gorgon) \"the colours of the male are\nnearly the same as those of the female, only deeper and of a brighter hue.\"\n(26.  On the Ant. niger, see 'Proc. Zool. Soc.' 1850, p. 133.  With respect\nto an allied species, in which there is an equal sexual difference in\ncolour, see Sir S. Baker, 'The Albert Nyanza,' 1866, vol. ii. p. 627.  For\nthe A. sing-sing, Gray, 'Cat. B. Mus.' p. 100.  Desmarest, 'Mammalogie,' p.\n468, on the A. caama.  Andrew Smith, 'Zoology of S. Africa,' on the Gnu.)\nOther analogous cases could be added.\n\nThe Banteng bull (Bos sondaicus) of the Malayan Archipelago is almost\nblack, with white legs and buttocks; the cow is of a bright dun, as are the\nyoung males until about the age of three years, when they rapidly change\ncolour.  The emasculated bull reverts to the colour of the female.  The\nfemale Kemas goat is paler, and both it and the female Capra aegagrus are\nsaid to be more uniformly tinted than their males.  Deer rarely present any\nsexual differences in colour.  Judge Caton, however, informs me that in the\nmales of the wapiti deer (Cervus canadensis) the neck, belly, and legs are\nmuch darker than in the female; but during the winter the darker tints\ngradually fade away and disappear.  I may here mention that Judge Caton has\nin his park three races of the Virginian deer, which differ slightly in\ncolour, but the differences are almost exclusively confined to the blue\nwinter or breeding-coat; so that this case may be compared with those given\nin a previous chapter of closely-allied or representative species of birds,\nwhich differ from each other only in their breeding plumage.  (27.  'Ottawa\nAcademy of Sciences,' May 21, 1868, pp. 3, 5.)  The females of Cervus\npaludosus of S. America, as well as the young of both sexes, do not possess\nthe black stripes on the nose and the blackish-brown line on the breast,\nwhich are characteristic of the adult males.  (28.  S. Muller, on the\nBanteng, 'Zoog. Indischen Archipel.' 1839-1844, tab. 35; see also Raffles,\nas quoted by Mr. Blyth, in 'Land and Water,' 1867, p. 476.  On goats, Dr.\nGray, 'Catalogue of the British Museum,' p. 146; Desmarest, 'Mammalogie,'\np. 482.  On the Cervus paludosus, Rengger, ibid. s. 345.)  Lastly, as I am\ninformed by Mr. Blyth, the mature male of the beautifully coloured and\nspotted axis deer is considerably darker than the female:  and this hue the\ncastrated male never acquires.\n\nThe last Order which we need consider is that of the Primates.  The male of\nthe Lemur macaco is generally coal-black, whilst the female is brown.  (29.\nSclater, 'Proc. Zool. Soc.' 1866, p. i.  The same fact has also been fully\nascertained by MM. Pollen and van Dam.  See, also, Dr. Gray in 'Annals and\nMagazine of Natural History,' May 1871, p. 340.)  Of the Quadrumana of the\nNew World, the females and young of Mycetes caraya are greyish-yellow and\nlike each other; in the second year the young male becomes reddish-brown;\nin the third, black, excepting the stomach, which, however, becomes quite\nblack in the fourth or fifth year.  There is also a strongly-marked\ndifference in colour between the sexes of Mycetes seniculus and Cebus\ncapucinus; the young of the former, and I believe of the latter species,\nresembling the females.  With Pithecia leucocephala the young likewise\nresemble the females, which are brownish-black above and light rusty-red\nbeneath, the adult males being black.  The ruff of hair round the face of\nAteles marginatus is tinted yellow in the male and white in the female.\nTurning to the Old World, the males of Hylobates hoolock are always black,\nwith the exception of a white band over the brows; the females vary from\nwhity-brown to a dark tint mixed with black, but are never wholly black.\n(30.  On Mycetes, Rengger, ibid. s. 14; and Brehm, 'Thierleben,' B. i. s.\n96, 107.  On Ateles Desmarest, 'Mammalogie,' p. 75.  On Hylobates, Blyth,\n'Land and Water,' 1867, p. 135.  On the Semnopithecus, S. Muller, 'Zoog.\nIndischen Archipel.' tab. x.)  In the beautiful Cercopithecus diana, the\nhead of the adult male is of an intense black, whilst that of the female is\ndark grey; in the former the fur between the thighs is of an elegant fawn-\ncolour, in the latter it is paler.  In the beautiful and curious moustache\nmonkey (Cercopithecus cephus) the only difference between the sexes is that\nthe tail of the male is chestnut and that of the female grey; but Mr.\nBartlett informs me that all the hues become more pronounced in the male\nwhen adult, whilst in the female they remain as they were during youth.\nAccording to the coloured figures given by Solomon Muller, the male of\nSemnopithecus chrysomelas is nearly black, the female being pale brown.  In\nthe Cercopithecus cynosurus and griseo-viridis one part of the body, which\nis confined to the male sex, is of the most brilliant blue or green, and\ncontrasts strikingly with the naked skin on the hinder part of the body,\nwhich is vivid red.\n\n[Fig. 69.  Head of male Mandrill (from Gervais, 'Hist. Nat. des\nMammiferes').]\n\nLastly, in the baboon family, the adult male of Cynocephalus hamadryas\ndiffers from the female not only by his immense mane, but slightly in the\ncolour of the hair and of the naked callosities.  In the drill (C.\nleucophaeus) the females and young are much paler-coloured, with less\ngreen, than the adult males.  No other member in the whole class of mammals\nis coloured in so extraordinary a manner as the adult male mandrill (C.\nmormon).  The face at this age becomes of a fine blue, with the ridge and\ntip of the nose of the most brilliant red.  According to some authors, the\nface is also marked with whitish stripes, and is shaded in parts with\nblack, but the colours appear to be variable.  On the forehead there is a\ncrest of hair, and on the chin a yellow beard.  \"Toutes les parties\nsuperieures de leurs cuisses et le grand espace nu de leurs fesses sont\negalement colores du rouge le plus vif, avec un melange de bleu qui ne\nmanque reellement pas d'elegance.\"  (31.  Gervais, 'Hist. Nat. des\nMammiferes,' 1854, p. 103.  Figures are given of the skull of the male.\nAlso Desmarest, 'Mammalogie,' p. 70.  Geoffroy St.-Hilaire and F. Cuvier,\n'Hist. Nat. des Mammiferes,' 1824, tom. i.)  When the animal is excited all\nthe naked parts become much more vividly tinted.  Several authors have used\nthe strongest expressions in describing these resplendent colours, which\nthey compare with those of the most brilliant birds.  Another remarkable\npeculiarity is that when the great canine teeth are fully developed,\nimmense protuberances of bone are formed on each cheek, which are deeply\nfurrowed longitudinally, and the naked skin over them is brilliantly-\ncoloured, as just-described.  (Fig. 69.)  In the adult females and in the\nyoung of both sexes these protuberances are scarcely perceptible; and the\nnaked parts are much less bright coloured, the face being almost black,\ntinged with blue.  In the adult female, however, the nose at certain\nregular intervals of time becomes tinted with red.\n\nIn all the cases hitherto given the male is more strongly or brighter\ncoloured than the female, and differs from the young of both sexes.  But as\nwith some few birds it is the female which is brighter coloured than the\nmale, so with the Rhesus monkey (Macacus rhesus), the female has a large\nsurface of naked skin round the tail, of a brilliant carmine red, which, as\nI was assured by the keepers in the Zoological Gardens, periodically\nbecomes even yet more vivid, and her face also is pale red.  On the other\nhand, in the adult male and in the young of both sexes (as I saw in the\nGardens), neither the naked skin at the posterior end of the body, nor the\nface, shew a trace of red.  It appears, however, from some published\naccounts, that the male does occasionally, or during certain seasons,\nexhibit some traces of the red.  Although he is thus less ornamented than\nthe female, yet in the larger size of his body, larger canine teeth, more\ndeveloped whiskers, more prominent superciliary ridges, he follows the\ncommon rule of the male excelling the female.\n\nI have now given all the cases known to me of a difference in colour\nbetween the sexes of mammals.  Some of these may be the result of\nvariations confined to one sex and transmitted to the same sex, without any\ngood being gained, and therefore without the aid of selection.  We have\ninstances of this with our domesticated animals, as in the males of certain\ncats being rusty-red, whilst the females are tortoise-shell coloured.\nAnalogous cases occur in nature:  Mr. Bartlett has seen many black\nvarieties of the jaguar, leopard, vulpine phalanger, and wombat; and he is\ncertain that all, or nearly all these animals, were males.  On the other\nhand, with wolves, foxes, and apparently American squirrels, both sexes are\noccasionally born black.  Hence it is quite possible that with some mammals\na difference in colour between the sexes, especially when this is\ncongenital, may simply be the result, without the aid of selection, of the\noccurrence of one or more variations, which from the first were sexually\nlimited in their transmission.  Nevertheless it is improbable that the\ndiversified, vivid, and contrasted colours of certain quadrupeds, for\ninstance, of the above monkeys and antelopes, can thus be accounted for.\nWe should bear in mind that these colours do not appear in the male at\nbirth, but only at or near maturity; and that unlike ordinary variations,\nthey are lost if the male be emasculated.  It is on the whole probable that\nthe strongly-marked colours and other ornamental characters of male\nquadrupeds are beneficial to them in their rivalry with other males, and\nhave consequently been acquired through sexual selection.  This view is\nstrengthened by the differences in colour between the sexes occurring\nalmost exclusively, as may be collected from the previous details, in those\ngroups and sub-groups of mammals which present other and strongly-marked\nsecondary sexual characters; these being likewise due to sexual selection.\n\nQuadrupeds manifestly take notice of colour.  Sir S. Baker repeatedly\nobserved that the African elephant and rhinoceros attacked white or grey\nhorses with special fury.  I have elsewhere shewn (32.  The 'Variation of\nAnimals and Plants under Domestication,' 1868, vol. ii. pp. 102, 103.) that\nhalf-wild horses apparently prefer to pair with those of the same colour,\nand that herds of fallow-deer of different colours, though living together,\nhave long kept distinct.  It is a more significant fact that a female zebra\nwould not admit the addresses of a male ass until he was painted so as to\nresemble a zebra, and then, as John Hunter remarks, \"she received him very\nreadily.  In this curious fact, we have instinct excited by mere colour,\nwhich had so strong an effect as to get the better of everything else.  But\nthe male did not require this, the female being an animal somewhat similar\nto himself, was sufficient to rouse him.\"  (33.  'Essays and Observations,'\nby J. Hunter, edited by Owen, 1861, vol. i. p. 194.)\n\nIn an earlier chapter we have seen that the mental powers of the higher\nanimals do not differ in kind, though greatly in degree, from the\ncorresponding powers of man, especially of the lower and barbarous races;\nand it would appear that even their taste for the beautiful is not widely\ndifferent from that of the Quadrumana.  As the negro of Africa raises the\nflesh on his face into parallel ridges \"or cicatrices, high above the\nnatural surface, which unsightly deformities are considered great personal\nattractions\" (34.  Sir S. Baker, 'The Nile Tributaries of Abyssinia,'\n1867.);--as negroes and savages in many parts of the world paint their\nfaces with red, blue, white, or black bars,--so the male mandrill of Africa\nappears to have acquired his deeply-furrowed and gaudily-coloured face from\nhaving been thus rendered attractive to the female.  No doubt it is to us a\nmost grotesque notion that the posterior end of the body should be coloured\nfor the sake of ornament even more brilliantly than the face; but this is\nnot more strange than that the tails of many birds should be especially\ndecorated.\n\nWith mammals we do not at present possess any evidence that the males take\npains to display their charms before the female; and the elaborate manner\nin which this is performed by male birds and other animals is the strongest\nargument in favour of the belief that the females admire, or are excited\nby, the ornaments and colours displayed before them.  There is, however, a\nstriking parallelism between mammals and birds in all their secondary\nsexual characters, namely in their weapons for fighting with rival males,\nin their ornamental appendages, and in their colours.  In both classes,\nwhen the male differs from the female, the young of both sexes almost\nalways resemble each other, and in a large majority of cases resemble the\nadult female.  In both classes the male assumes the characters proper to\nhis sex shortly before the age of reproduction; and if emasculated at an\nearly period, loses them.  In both classes the change of colour is\nsometimes seasonal, and the tints of the naked parts sometimes become more\nvivid during the act of courtship.  In both classes the male is almost\nalways more vividly or strongly coloured than the female, and is ornamented\nwith larger crests of hair or feathers, or other such appendages.  In a few\nexceptional cases the female in both classes is more highly ornamented than\nthe male.  With many mammals, and at least in the case of one bird, the\nmale is more odoriferous than the female.  In both classes the voice of the\nmale is more powerful than that of the female.  Considering this\nparallelism, there can be little doubt that the same cause, whatever it may\nbe, has acted on mammals and birds; and the result, as far as ornamental\ncharacters are concerned, may be attributed, as it appears to me, to the\nlong-continued preference of the individuals of one sex for certain\nindividuals of the opposite sex, combined with their success in leaving a\nlarger number of offspring to inherit their superior attractions.\n\nEQUAL TRANSMISSION OF ORNAMENTAL CHARACTERS TO BOTH SEXES.\n\nWith many birds, ornaments, which analogy leads us to believe were\nprimarily acquired by the males, have been transmitted equally, or almost\nequally, to both sexes; and we may now enquire how far this view applies to\nmammals.  With a considerable number of species, especially of the smaller\nkinds, both sexes have been coloured, independently of sexual selection,\nfor the sake of protection; but not, as far as I can judge, in so many\ncases, nor in so striking a manner, as in most of the lower classes.\nAudubon remarks that he often mistook the musk-rat (35.  Fiber zibethicus,\nAudubon and Bachman, 'The Quadrupeds of North America,' 1846, p. 109.),\nwhilst sitting on the banks of a muddy stream, for a clod of earth, so\ncomplete was the resemblance.  The hare on her form is a familiar instance\nof concealment through colour; yet this principle partly fails in a\nclosely-allied species, the rabbit, for when running to its burrow, it is\nmade conspicuous to the sportsman, and no doubt to all beasts of prey, by\nits upturned white tail.  No one doubts that the quadrupeds inhabiting\nsnow-clad regions have been rendered white to protect them from their\nenemies, or to favour their stealing on their prey.  In regions where snow\nnever lies for long, a white coat would be injurious; consequently, species\nof this colour are extremely rare in the hotter parts of the world.  It\ndeserves notice that many quadrupeds inhabiting moderately cold regions,\nalthough they do not assume a white winter dress, become paler during this\nseason; and this apparently is the direct result of the conditions to which\nthey have long been exposed.  Pallas (36.  'Novae species Quadrupedum e\nGlirium ordine,' 1778, p. 7.  What I have called the roe is the Capreolus\nsibiricus subecaudatus of Pallas.) states that in Siberia a change of this\nnature occurs with the wolf, two species of Mustela, the domestic horse,\nthe Equus hemionus, the domestic cow, two species of antelopes, the musk-\ndeer, the roe, elk, and reindeer.  The roe, for instance, has a red summer\nand a greyish-white winter coat; and the latter may perhaps serve as a\nprotection to the animal whilst wandering through the leafless thickets,\nsprinkled with snow and hoar-frost.  If the above-named animals were\ngradually to extend their range into regions perpetually covered with snow,\ntheir pale winter-coats would probably be rendered through natural\nselection, whiter and whiter, until they became as white as snow.\n\nMr. Reeks has given me a curious instance of an animal profiting by being\npeculiarly coloured.  He raised from fifty to sixty white and brown piebald\nrabbits in a large walled orchard; and he had at the same time some\nsimilarly coloured cats in his house.  Such cats, as I have often noticed,\nare very conspicuous during day; but as they used to lie in watch during\nthe dusk at the mouths of the burrows, the rabbits apparently did not\ndistinguish them from their parti-coloured brethren.  The result was that,\nwithin eighteen months, every one of these parti-coloured rabbits was\ndestroyed; and there was evidence that this was effected by the cats.\nColour seems to be advantageous to another animal, the skunk, in a manner\nof which we have had many instances in other classes.  No animal will\nvoluntarily attack one of these creatures on account of the dreadful odour\nwhich it emits when irritated; but during the dusk it would not easily be\nrecognised and might be attacked by a beast of prey.  Hence it is, as Mr.\nBelt believes (37.  'The Naturalist in Nicaragua,' p. 249.), that the skunk\nis provided with a great white bushy tail, which serves as a conspicuous\nwarning.\n\n[Fig. 70.  Tragelaphus scriptus, male (from the Knowsley Menagerie).\n\nFig. 71.  Damalis pygarga, male (from the Knowsley Menagerie).]\n\nAlthough we must admit that many quadrupeds have received their present\ntints either as a protection, or as an aid in procuring prey, yet with a\nhost of species, the colours are far too conspicuous and too singularly\narranged to allow us to suppose that they serve for these purposes.  We may\ntake as an illustration certain antelopes; when we see the square white\npatch on the throat, the white marks on the fetlocks, and the round black\nspots on the ears, all more distinct in the male of the Portax picta, than\nin the female;--when we see that the colours are more vivid, that the\nnarrow white lines on the flank and the broad white bar on the shoulder are\nmore distinct in the male Oreas derbyanus than in the female;--when we see\na similar difference between the sexes of the curiously-ornamented\nTragelaphus scriptus (Fig. 70),--we cannot believe that differences of this\nkind are of any service to either sex in their daily habits of life.  It\nseems a much more probable conclusion that the various marks were first\nacquired by the males and their colours intensified through sexual\nselection, and then partially transferred to the females.  If this view be\nadmitted, there can be little doubt that the equally singular colours and\nmarks of many other antelopes, though common to both sexes, have been\ngained and transmitted in a like manner.  Both sexes, for instance, of the\nkoodoo (Strepsiceros kudu) (Fig. 64) have narrow white vertical lines on\ntheir hind flanks, and an elegant angular white mark on their foreheads.\nBoth sexes in the genus Damalis are very oddly coloured; in D. pygarga the\nback and neck are purplish-red, shading on the flanks into black; and these\ncolours are abruptly separated from the white belly and from a large white\nspace on the buttocks; the head is still more oddly coloured, a large\noblong white mask, narrowly-edged with black, covers the face up to the\neyes (Fig. 71); there are three white stripes on the forehead, and the ears\nare marked with white.  The fawns of this species are of a uniform pale\nyellowish-brown.  In Damalis albifrons the colouring of the head differs\nfrom that in the last species in a single white stripe replacing the three\nstripes, and in the ears being almost wholly white.  (38.  See the fine\nplates in A. Smith's 'Zoology of South Africa,' and Dr. Gray's 'Gleanings\nfrom the Menagerie of Knowsley.')  After having studied to the best of my\nability the sexual differences of animals belonging to all classes, I\ncannot avoid the conclusion that the curiously-arranged colours of many\nantelopes, though common to both sexes, are the result of sexual selection\nprimarily applied to the male.\n\nThe same conclusion may perhaps be extended to the tiger, one of the most\nbeautiful animals in the world, the sexes of which cannot be distinguished\nby colour, even by the dealers in wild beasts.  Mr. Wallace believes (39.\n'Westminster Review,' July 1, 1867, p. 5.) that the striped coat of the\ntiger \"so assimilates with the vertical stems of the bamboo, as to assist\ngreatly in concealing him from his approaching prey.\"  But this view does\nnot appear to me satisfactory.  We have some slight evidence that his\nbeauty may be due to sexual selection, for in two species of Felis the\nanalogous marks and colours are rather brighter in the male than in the\nfemale.  The zebra is conspicuously striped, and stripes cannot afford any\nprotection in the open plains of South Africa.  Burchell (40.  'Travels in\nSouth Africa,' 1824, vol. ii. p. 315.) in describing a herd says, \"their\nsleek ribs glistened in the sun, and the brightness and regularity of their\nstriped coats presented a picture of extraordinary beauty, in which\nprobably they are not surpassed by any other quadruped.\"  But as throughout\nthe whole group of the Equidae the sexes are identical in colour, we have\nhere no evidence of sexual selection.  Nevertheless he who attributes the\nwhite and dark vertical stripes on the flanks of various antelopes to this\nprocess, will probably extend the same view to the Royal Tiger and\nbeautiful Zebra.\n\nWe have seen in a former chapter that when young animals belonging to any\nclass follow nearly the same habits of life as their parents, and yet are\ncoloured in a different manner, it may be inferred that they have retained\nthe colouring of some ancient and extinct progenitor.  In the family of\npigs, and in the tapirs, the young are marked with longitudinal stripes,\nand thus differ from all the existing adult species in these two groups.\nWith many kinds of deer the young are marked with elegant white spots, of\nwhich their parents exhibit not a trace.  A graduated series can be\nfollowed from the axis deer, both sexes of which at all ages and during all\nseasons are beautifully spotted (the male being rather more strongly\ncoloured than the female), to species in which neither the old nor the\nyoung are spotted.  I will specify some of the steps in this series.  The\nMantchurian deer (Cervus mantchuricus) is spotted during the whole year,\nbut, as I have seen in the Zoological Gardens, the spots are much plainer\nduring the summer, when the general colour of the coat is lighter, than\nduring the winter, when the general colour is darker and the horns are\nfully developed.  In the hog-deer (Hyelaphus porcinus) the spots are\nextremely conspicuous during the summer when the coat is reddish-brown, but\nquite disappear during the winter when the coat is brown.  (41.  Dr. Gray,\n'Gleanings from the Menagerie of Knowsley,' p. 64.  Mr. Blyth, in speaking\n('Land and Water,' 1869, p. 42) of the hog-deer of Ceylon, says it is more\nbrightly spotted with white than the common hog-deer, at the season when it\nrenews its horns.)  In both these species the young are spotted.  In the\nVirginian deer the young are likewise spotted, and about five per cent. of\nthe adult animals living in Judge Caton's park, as I am informed by him,\ntemporarily exhibit at the period when the red summer coat is being\nreplaced by the bluish winter coat, a row of spots on each flank, which are\nalways the same in number, though very variable in distinctness.  From this\ncondition there is but a very small step to the complete absence of spots\nin the adults at all seasons; and, lastly, to their absence at all ages and\nseasons, as occurs with certain species.  From the existence of this\nperfect series, and more especially from the fawns of so many species being\nspotted, we may conclude that the now living members of the deer family are\nthe descendants of some ancient species which, like the axis deer, was\nspotted at all ages and seasons.  A still more ancient progenitor probably\nsomewhat resembled the Hyomoschus aquaticus--for this animal is spotted,\nand the hornless males have large exserted canine teeth, of which some few\ntrue deer still retain rudiments.  Hyomoschus, also, offers one of those\ninteresting cases of a form linking together two groups, for it is\nintermediate in certain osteological characters between the pachyderms and\nruminants, which were formerly thought to be quite distinct.  (42.\nFalconer and Cautley, 'Proc. Geolog. Soc.' 1843; and Falconer's 'Pal.\nMemoirs,' vol. i. p. 196.)\n\nA curious difficulty here arises.  If we admit that coloured spots and\nstripes were first acquired as ornaments, how comes it that so many\nexisting deer, the descendants of an aboriginally spotted animal, and all\nthe species of pigs and tapirs, the descendants of an aboriginally striped\nanimal, have lost in their adult state their former ornaments?  I cannot\nsatisfactorily answer this question.  We may feel almost sure that the\nspots and stripes disappeared at or near maturity in the progenitors of our\nexisting species, so that they were still retained by the young; and, owing\nto the law of inheritance at corresponding ages, were transmitted to the\nyoung of all succeeding generations.  It may have been a great advantage to\nthe lion and puma, from the open nature of their usual haunts, to have lost\ntheir stripes, and to have been thus rendered less conspicuous to their\nprey; and if the successive variations, by which this end was gained,\noccurred rather late in life, the young would have retained their stripes,\nas is now the case.  As to deer, pigs, and tapirs, Fritz Mueller has\nsuggested to me that these animals, by the removal of their spots or\nstripes through natural selection, would have been less easily seen by\ntheir enemies; and that they would have especially required this\nprotection, as soon as the carnivora increased in size and number during\nthe tertiary periods.  This may be the true explanation, but it is rather\nstrange that the young should not have been thus protected, and still more\nso that the adults of some species should have retained their spots, either\npartially or completely, during part of the year.  We know that, when the\ndomestic ass varies and becomes reddish-brown, grey, or black, the stripes\non the shoulders and even on the spine frequently disappear, though we\ncannot explain the cause.  Very few horses, except dun-coloured kinds, have\nstripes on any part of their bodies, yet we have good reason to believe\nthat the aboriginal horse was striped on the legs and spine, and probably\non the shoulders.  (43.  The 'Variation of Animals and Plants under\nDomestication,' 1868, vol. i. pp. 61-64.)  Hence the disappearance of the\nspots and stripes in our adult existing deer, pigs, and tapirs, may be due\nto a change in the general colour of their coats; but whether this change\nwas effected through sexual or natural selection, or was due to the direct\naction of the conditions of life, or to some other unknown cause, it is\nimpossible to decide.  An observation made by Mr. Sclater well illustrates\nour ignorance of the laws which regulate the appearance and disappearance\nof stripes; the species of Asinus which inhabit the Asiatic continent are\ndestitute of stripes, not having even the cross shoulder-stripe, whilst\nthose which inhabit Africa are conspicuously striped, with the partial\nexception of A. taeniopus, which has only the cross shoulder-stripe and\ngenerally some faint bars on the legs; and this species inhabits the almost\nintermediate region of Upper Egypt and Abyssinia.  (44.  'Proc. Zool. Soc.'\n1862, p. 164.  See, also, Dr. Hartmann, 'Ann. d. Landw.' Bd. xliii. s.\n222.)\n\nQUADRUMANA.\n\n[Fig. 72.  Head of Semnopithecus rubicundus.  This and the following\nfigures (from Prof. Gervais) are given to shew the odd arrangement and\ndevelopment of the hair on the head.\n\nFig. 73.  Head of Semnopithecus comatus.\n\nFig. 74.  Head of Cebus capucinus.\n\nFig. 75.  Head of Ateles marginatus.\n\nFig. 76.  Head of Cebus vellerosus.]\n\nBefore we conclude, it will be well to add a few remarks on the ornaments\nof monkeys.  In most of the species the sexes resemble each other in\ncolour, but in some, as we have seen, the males differ from the females,\nespecially in the colour of the naked parts of the skin, in the development\nof the beard, whiskers, and mane.  Many species are coloured either in so\nextraordinary or so beautiful a manner, and are furnished with such curious\nand elegant crests of hair, that we can hardly avoid looking at these\ncharacters as having been gained for the sake of ornament.  The\naccompanying figures (Figs. 72 to 76) serve to shew the arrangement of the\nhair on the face and head in several species.  It is scarcely conceivable\nthat these crests of hair, and the strongly contrasted colours of the fur\nand skin, can be the result of mere variability without the aid of\nselection; and it is inconceivable that they can be of use in any ordinary\nway to these animals.  If so, they have probably been gained through sexual\nselection, though transmitted equally, or almost equally, to both sexes.\nWith many of the Quadrumana, we have additional evidence of the action of\nsexual selection in the greater size and strength of the males, and in the\ngreater development of their canine teeth, in comparison with the females.\n\n[Fig. 77.  Cercopithecus petaurista (from Brehm).]\n\nA few instances will suffice of the strange manner in which both sexes of\nsome species are coloured, and of the beauty of others.  The face of the\nCercopithecus petaurista (Fig. 77) is black, the whiskers and beard being\nwhite, with a defined, round, white spot on the nose, covered with short\nwhite hair, which gives to the animal an almost ludicrous aspect.  The\nSemnopithecus frontatus likewise has a blackish face with a long black\nbeard, and a large naked spot on the forehead of a bluish-white colour.\nThe face of Macacus lasiotus is dirty flesh-coloured, with a defined red\nspot on each cheek.  The appearance of Cercocebus aethiops is grotesque,\nwith its black face, white whiskers and collar, chestnut head, and a large\nnaked white spot over each eyelid.  In very many species, the beard,\nwhiskers, and crests of hair round the face are of a different colour from\nthe rest of the head, and when different, are always of a lighter tint (45.\nI observed this fact in the Zoological Gardens; and many cases may be seen\nin the coloured plates in Geoffroy St.-Hilaire and F. Cuvier, 'Histoire\nNat. des Mammiferes,' tom. i. 1824.), being often pure white, sometimes\nbright yellow, or reddish.  The whole face of the South American Brachyurus\ncalvus is of a \"glowing scarlet hue\"; but this colour does not appear until\nthe animal is nearly mature.  (46.  Bates, 'The Naturalist on the Amazons,'\n1863, vol. ii. p. 310.)  The naked skin of the face differs wonderfully in\ncolour in the various species.  It is often brown or flesh-colour, with\nparts perfectly white, and often as black as that of the most sooty negro.\nIn the Brachyurus the scarlet tint is brighter than that of the most\nblushing Caucasian damsel.  It is sometimes more distinctly orange than in\nany Mongolian, and in several species it is blue, passing into violet or\ngrey.  In all the species known to Mr. Bartlett, in which the adults of\nboth sexes have strongly-coloured faces, the colours are dull or absent\nduring early youth.  This likewise holds good with the mandrill and Rhesus,\nin which the face and the posterior parts of the body are brilliantly\ncoloured in one sex alone.  In these latter cases we have reason to believe\nthat the colours were acquired through sexual selection; and we are\nnaturally led to extend the same view to the foregoing species, though both\nsexes when adult have their faces coloured in the same manner.\n\n[Fig. 78.  Cercopithecus diana (from Brehm).]\n\nAlthough many kinds of monkeys are far from beautiful according to our\ntaste, other species are universally admired for their elegant appearance\nand bright colours.  The Semnopithecus nemaeus, though peculiarly coloured,\nis described as extremely pretty; the orange-tinted face is surrounded by\nlong whiskers of glossy whiteness, with a line of chestnut-red over the\neyebrows; the fur on the back is of a delicate grey, with a square patch on\nthe loins, the tail and the fore-arms being of a pure white; a gorget of\nchestnut surmounts the chest; the thighs are black, with the legs chestnut-\nred.  I will mention only two other monkeys for their beauty; and I have\nselected these as presenting slight sexual differences in colour, which\nrenders it in some degree probable that both sexes owe their elegant\nappearance to sexual selection.  In the moustache-monkey (Cercopithecus\ncephus) the general colour of the fur is mottled-greenish with the throat\nwhite; in the male the end of the tail is chestnut, but the face is the\nmost ornamented part, the skin being chiefly bluish-grey, shading into a\nblackish tint beneath the eyes, with the upper lip of a delicate blue,\nclothed on the lower edge with a thin black moustache; the whiskers are\norange-coloured, with the upper part black, forming a band which extends\nbackwards to the ears, the latter being clothed with whitish hairs.  In the\nZoological Society's Gardens I have often overheard visitors admiring the\nbeauty of another monkey, deservedly called Cercopithecus diana (Fig. 78);\nthe general colour of the fur is grey; the chest and inner surface of the\nforelegs are white; a large triangular defined space on the hinder part of\nthe back is rich chestnut; in the male the inner sides of the thighs and\nthe abdomen are delicate fawn-coloured, and the top of the head is black;\nthe face and ears are intensely black, contrasting finely with a white\ntransverse crest over the eyebrows and a long white peaked beard, of which\nthe basal portion is black.  (47.  I have seen most of the above monkeys in\nthe Zoological Society's Gardens.  The description of the Semnopithecus\nnemaeus is taken from Mr. W.C. Martin's 'Natural History of Mammalia,'\n1841, p. 460; see also pp. 475, 523.)\n\nIn these and many other monkeys, the beauty and singular arrangement of\ntheir colours, and still more the diversified and elegant arrangement of\nthe crests and tufts of hair on their heads, force the conviction on my\nmind that these characters have been acquired through sexual selection\nexclusively as ornaments.\n\nSUMMARY.\n\nThe law of battle for the possession of the female appears to prevail\nthroughout the whole great class of mammals.  Most naturalists will admit\nthat the greater size, strength, courage, and pugnacity of the male, his\nspecial weapons of offence, as well as his special means of defence, have\nbeen acquired or modified through that form of selection which I have\ncalled sexual.  This does not depend on any superiority in the general\nstruggle for life, but on certain individuals of one sex, generally the\nmale, being successful in conquering other males, and leaving a larger\nnumber of offspring to inherit their superiority than do the less\nsuccessful males.\n\nThere is another and more peaceful kind of contest, in which the males\nendeavour to excite or allure the females by various charms.  This is\nprobably carried on in some cases by the powerful odours emitted by the\nmales during the breeding-season; the odoriferous glands having been\nacquired through sexual selection.  Whether the same view can be extended\nto the voice is doubtful, for the vocal organs of the males must have been\nstrengthened by use during maturity, under the powerful excitements of\nlove, jealousy or rage, and will consequently have been transmitted to the\nsame sex.  Various crests, tufts, and mantles of hair, which are either\nconfined to the male, or are more developed in this sex than in the female,\nseem in most cases to be merely ornamental, though they sometimes serve as\na defence against rival males.  There is even reason to suspect that the\nbranching horns of stags, and the elegant horns of certain antelopes,\nthough properly serving as weapons of offence or defence, have been partly\nmodified for ornament.\n\nWhen the male differs in colour from the female, he generally exhibits\ndarker and more strongly-contrasted tints.  We do not in this class meet\nwith the splendid red, blue, yellow, and green tints, so common with male\nbirds and many other animals.  The naked parts, however, of certain\nQuadrumana must be excepted; for such parts, often oddly situated, are\nbrilliantly coloured in some species.  The colours of the male in other\ncases may be due to simple variation, without the aid of selection.  But\nwhen the colours are diversified and strongly pronounced, when they are not\ndeveloped until near maturity, and when they are lost after emasculation,\nwe can hardly avoid the conclusion that they have been acquired through\nsexual selection for the sake of ornament, and have been transmitted\nexclusively, or almost exclusively, to the same sex.  When both sexes are\ncoloured in the same manner, and the colours are conspicuous or curiously\narranged, without being of the least apparent use as a protection, and\nespecially when they are associated with various other ornamental\nappendages, we are led by analogy to the same conclusion, namely, that they\nhave been acquired through sexual selection, although transmitted to both\nsexes.  That conspicuous and diversified colours, whether confined to the\nmales or common to both sexes, are as a general rule associated in the same\ngroups and sub-groups with other secondary sexual characters serving for\nwar or for ornament, will be found to hold good, if we look back to the\nvarious cases given in this and the last chapter.\n\nThe law of the equal transmission of characters to both sexes, as far as\ncolour and other ornaments are concerned, has prevailed far more\nextensively with mammals than with birds; but weapons, such as horns and\ntusks, have often been transmitted either exclusively or much more\nperfectly to the males than to the females.  This is surprising, for, as\nthe males generally use their weapons for defence against enemies of all\nkinds, their weapons would have been of service to the females.  As far as\nwe can see, their absence in this sex can be accounted for only by the form\nof inheritance which has prevailed.  Finally, with quadrupeds the contest\nbetween the individuals of the same sex, whether peaceful or bloody, has,\nwith the rarest exceptions, been confined to the males; so that the latter\nhave been modified through sexual selection, far more commonly than the\nfemales, either for fighting with each other or for alluring the opposite\nsex.\n\n\nPART III.\n\nSEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION.\n\n\nCHAPTER XIX.\n\nSECONDARY SEXUAL CHARACTERS OF MAN.\n\nDifferences between man and woman--Causes of such differences and of\ncertain characters common to both sexes--Law of battle--Differences in\nmental powers, and voice--On the influence of beauty in determining the\nmarriages of mankind--Attention paid by savages to ornaments--Their ideas\nof beauty in woman--The tendency to exaggerate each natural peculiarity.\n\nWith mankind the differences between the sexes are greater than in most of\nthe Quadrumana, but not so great as in some, for instance, the mandrill.\nMan on an average is considerably taller, heavier, and stronger than woman,\nwith squarer shoulders and more plainly-pronounced muscles.  Owing to the\nrelation which exists between muscular development and the projection of\nthe brows (1.  Schaaffhausen, translation in 'Anthropological Review,' Oct.\n1868, pp. 419, 420, 427.), the superciliary ridge is generally more marked\nin man than in woman.  His body, and especially his face, is more hairy,\nand his voice has a different and more powerful tone.  In certain races the\nwomen are said to differ slightly in tint from the men.  For instance,\nSchweinfurth, in speaking of a negress belonging to the Monbuttoos, who\ninhabit the interior of Africa a few degrees north of the equator, says,\n\"Like all her race, she had a skin several shades lighter than her\nhusband's, being something of the colour of half-roasted coffee.\" (2.  'The\nHeart of Africa,' English transl. 1873, vol i. p. 544.)  As the women\nlabour in the fields and are quite unclothed, it is not likely that they\ndiffer in colour from the men owing to less exposure to the weather.\nEuropean women are perhaps the brighter coloured of the two sexes, as may\nbe seen when both have been equally exposed.\n\nMan is more courageous, pugnacious and energetic than woman, and has a more\ninventive genius.  His brain is absolutely larger, but whether or not\nproportionately to his larger body, has not, I believe, been fully\nascertained.  In woman the face is rounder; the jaws and the base of the\nskull smaller; the outlines of the body rounder, in parts more prominent;\nand her pelvis is broader than in man (3.  Ecker, translation, in\n'Anthropological Review,' Oct. 1868, pp. 351-356.  The comparison of the\nform of the skull in men and women has been followed out with much care by\nWelcker.); but this latter character may perhaps be considered rather as a\nprimary than a secondary sexual character.  She comes to maturity at an\nearlier age than man.\n\nAs with animals of all classes, so with man, the distinctive characters of\nthe male sex are not fully developed until he is nearly mature; and if\nemasculated they never appear.  The beard, for instance, is a secondary\n\nsexual character, and male children are beardless, though at an early age\nthey have abundant hair on the head.  It is probably due to the rather late\nappearance in life of the successive variations whereby man has acquired\nhis masculine characters, that they are transmitted to the male sex alone.\nMale and female children resemble each other closely, like the young of so\nmany other animals in which the adult sexes differ widely; they likewise\nresemble the mature female much more closely than the mature male.  The\nfemale, however, ultimately assumes certain distinctive characters, and in\nthe formation of her skull, is said to be intermediate between the child\nand the man.  (4.  Ecker and Welcker, ibid. pp. 352, 355; Vogt, 'Lectures\non Man,' Eng. translat. p. 81.)  Again, as the young of closely allied\nthough distinct species do not differ nearly so much from each other as do\nthe adults, so it is with the children of the different races of man.  Some\nhave even maintained that race-differences cannot be detected in the\ninfantile skull.  (5.  Schaaffhausen, 'Anthropolog. Review,' ibid. p. 429.)\nIn regard to colour, the new-born negro child is reddish nut-brown, which\nsoon becomes slaty-grey; the black colour being fully developed within a\nyear in the Soudan, but not until three years in Egypt.  The eyes of the\nnegro are at first blue, and the hair chestnut-brown rather than black,\nbeing curled only at the ends.  The children of the Australians immediately\nafter birth are yellowish-brown, and become dark at a later age.  Those of\nthe Guaranys of Paraguay are whitish-yellow, but they acquire in the course\nof a few weeks the yellowish-brown tint of their parents.  Similar\nobservations have been made in other parts of America.  (6.  Pruner-Bey, on\nnegro infants as quoted by Vogt, 'Lectures on Man,' Eng. translat. 1864, p.\n189:  for further facts on negro infants, as quoted from Winterbottom and\nCamper, see Lawrence, 'Lectures on Physiology,' etc. 1822, p. 451.  For the\ninfants of the Guaranys, see Rengger, 'Saeugethiere,' etc. s. 3.  See also\nGodron, 'De l'Espece,' tom. ii. 1859, p. 253.  For the Australians, Waitz,\n'Introduction to Anthropology,' Eng. translat. 1863, p. 99.)\n\nI have specified the foregoing differences between the male and female sex\nin mankind, because they are curiously like those of the Quadrumana.  With\nthese animals the female is mature at an earlier age than the male; at\nleast this is certainly the case in Cebus azarae.  (7.  Rengger,\n'Saeugethiere,' etc., 1830, s. 49.)  The males of most species are larger\nand stronger than the females, of which fact the gorilla affords a well-\nknown instance.  Even in so trifling a character as the greater prominence\nof the superciliary ridge, the males of certain monkeys differ from the\nfemales (8.  As in Macacus cynomolgus (Desmarest, 'Mammalogie,' p. 65), and\nin Hylobates agilis (Geoffroy St.-Hilaire and F. Cuvier, 'Histoire Nat. des\nMammiferes,' 1824, tom. i. p. 2).), and agree in this respect with mankind.\nIn the gorilla and certain other monkeys, the cranium of the adult male\npresents a strongly-marked sagittal crest, which is absent in the female;\nand Ecker found a trace of a similar difference between the two sexes in\nthe Australians.  (9.  'Anthropological Review,' Oct. 1868, p. 353.)  With\nmonkeys when there is any difference in the voice, that of the male is the\nmore powerful.  We have seen that certain male monkeys have a well-\ndeveloped beard, which is quite deficient, or much less developed in the\nfemale.  No instance is known of the beard, whiskers, or moustache being\nlarger in the female than in the male monkey.  Even in the colour of the\nbeard there is a curious parallelism between man and the Quadrumana, for\nwith man when the beard differs in colour from the hair of the head, as is\ncommonly the case, it is, I believe, almost always of a lighter tint, being\noften reddish.  I have repeatedly observed this fact in England; but two\ngentlemen have lately written to me, saying that they form an exception to\nthe rule.  One of these gentlemen accounts for the fact by the wide\ndifference in colour of the hair on the paternal and maternal sides of his\nfamily.  Both had been long aware of this peculiarity (one of them having\noften been accused of dyeing his beard), and had been thus led to observe\nother men, and were convinced that the exceptions were very rare.  Dr.\nHooker attended to this little point for me in Russia, and found no\nexception to the rule.  In Calcutta, Mr. J. Scott, of the Botanic Gardens,\nwas so kind as to observe the many races of men to be seen there, as well\nas in some other parts of India, namely, two races of Sikhim, the Bhoteas,\nHindoos, Burmese, and Chinese, most of which races have very little hair on\nthe face; and he always found that when there was any difference in colour\nbetween the hair of the head and the beard, the latter was invariably\nlighter.  Now with monkeys, as has already been stated, the beard\nfrequently differs strikingly in colour from the hair of the head, and in\nsuch cases it is always of a lighter hue, being often pure white, sometimes\nyellow or reddish.  (10.  Mr. Blyth informs me that he has only seen one\ninstance of the beard, whiskers, etc., in a monkey becoming white with old\nage, as is so commonly the case with us.  This, however, occurred in an\naged Macacus cynomolgus, kept in confinement whose moustaches were\n\"remarkably long and human-like.\"  Altogether this old monkey presented a\nludicrous resemblance to one of the reigning monarchs of Europe, after whom\nhe was universally nick-named.  In certain races of man the hair on the\nhead hardly ever becomes grey; thus Mr. D. Forbes has never, as he informs\nme, seen an instance with the Aymaras and Quichuas of South America.)\n\nIn regard to the general hairiness of the body, the women in all races are\nless hairy than the men; and in some few Quadrumana the under side of the\nbody of the female is less hairy than that of the male.  (11.  This is the\ncase with the females of several species of Hylobates; see Geoffroy St.-\nHilaire and F. Cuvier, 'Hist. Nat. des Mamm.' tom. i.  See also, on H. lar,\n'Penny Cyclopedia,' vol. ii. pp. 149, 150.)  Lastly, male monkeys, like\nmen, are bolder and fiercer than the females.  They lead the troop, and\nwhen there is danger, come to the front.  We thus see how close is the\nparallelism between the sexual differences of man and the Quadrumana.  With\nsome few species, however, as with certain baboons, the orang and the\ngorilla, there is a considerably greater difference between the sexes, as\nin the size of the canine teeth, in the development and colour of the hair,\nand especially in the colour of the naked parts of the skin, than in\nmankind.\n\nAll the secondary sexual characters of man are highly variable, even within\nthe limits of the same race; and they differ much in the several races.\nThese two rules hold good generally throughout the animal kingdom.  In the\nexcellent observations made on board the Novara (12.  The results were\ndeduced by Dr. Weisbach from the measurements made by Drs. K. Scherzer and\nSchwarz, see 'Reise der Novara:  Anthropolog. Theil,' 1867, ss. 216, 231,\n234, 236, 239, 269.), the male Australians were found to exceed the females\nby only 65 millim. in height, whilst with the Javans the average excess was\n218 millim.; so that in this latter race the difference in height between\nthe sexes is more than thrice as great as with the Australians.  Numerous\nmeasurements were carefully made of the stature, the circumference of the\nneck and chest, the length of the back-bone and of the arms, in various\nraces; and nearly all these measurements shew that the males differ much\nmore from one another than do the females.  This fact indicates that, as\nfar as these characters are concerned, it is the male which has been\nchiefly modified, since the several races diverged from their common stock.\n\nThe development of the beard and the hairiness of the body differ\nremarkably in the men of distinct races, and even in different tribes or\nfamilies of the same race.  We Europeans see this amongst ourselves.  In\nthe Island of St. Kilda, according to Martin (13.  'Voyage to St. Kilda'\n(3rd ed. 1753), p. 37.), the men do not acquire beards until the age of\nthirty or upwards, and even then the beards are very thin.  On the\nEuropaeo-Asiatic continent, beards prevail until we pass beyond India;\nthough with the natives of Ceylon they are often absent, as was noticed in\nancient times by Diodorus.  (14.  Sir J.E. Tennent, 'Ceylon,' vol. ii.\n1859, p. 107.)  Eastward of India beards disappear, as with the Siamese,\nMalays, Kalmucks, Chinese, and Japanese; nevertheless, the Ainos (15.\nQuatrefages, 'Revue des Cours Scientifiques,' Aug. 29, 1868, p. 630; Vogt,\n'Lectures on Man,' Eng. trans. p. 127.), who inhabit the northernmost\nislands of the Japan Archipelago, are the hairiest men in the world.  With\nnegroes the beard is scanty or wanting, and they rarely have whiskers; in\nboth sexes the body is frequently almost destitute of fine down.  (16.  On\nthe beards of negroes, Vogt, 'Lectures,' etc. p. 127; Waitz, 'Introduct. to\nAnthropology,' Engl. translat. 1863, vol. i. p. 96.  It is remarkable that\nin the United States ('Investigations in Military and Anthropological\nStatistics of American Soldiers,' 1869, p. 569) the pure negroes and their\ncrossed offspring seem to have bodies almost as hairy as Europeans.)  On\nthe other hand, the Papuans of the Malay Archipelago, who are nearly as\nblack as negroes, possess well-developed beards.  (17.  Wallace, 'The Malay\nArch.' vol. ii. 1869, p. 178.)  In the Pacific Ocean the inhabitants of the\nFiji Archipelago have large bushy beards, whilst those of the not distant\narchipelagoes of Tonga and Samoa are beardless; but these men belong to\ndistinct races.  In the Ellice group all the inhabitants belong to the same\nrace; yet on one island alone, namely Nunemaya, \"the men have splendid\nbeards\"; whilst on the other islands \"they have, as a rule, a dozen\nstraggling hairs for a beard.\"  (18.  Dr. J. Barnard Davis on Oceanic\nRaces, in 'Anthropological Review,' April 1870, pp. 185, 191.)\n\nThroughout the great American continent the men may be said to be\nbeardless; but in almost all the tribes a few short hairs are apt to appear\non the face, especially in old age.  With the tribes of North America,\nCatlin estimates that eighteen out of twenty men are completely destitute\nby nature of a beard; but occasionally there may be seen a man, who has\nneglected to pluck out the hairs at puberty, with a soft beard an inch or\ntwo in length.  The Guaranys of Paraguay differ from all the surrounding\ntribes in having a small beard, and even some hair on the body, but no\nwhiskers.  (19.  Catlin, 'North American Indians,' 3rd. ed. 1842, vol. ii.\np. 227.  On the Guaranys, see Azara, 'Voyages dans l'Amerique Merid.' tom.\nii. 1809, p. 85; also Rengger, 'Saeugethiere von Paraguay,' s. 3.)  I am\ninformed by Mr. D. Forbes, who particularly attended to this point, that\nthe Aymaras and Quichuas of the Cordillera are remarkably hairless, yet in\nold age a few straggling hairs occasionally appear on the chin.  The men of\nthese two tribes have very little hair on the various parts of the body\nwhere hair grows abundantly in Europeans, and the women have none on the\ncorresponding parts.  The hair on the head, however, attains an\nextraordinary length in both sexes, often reaching almost to the ground;\nand this is likewise the case with some of the N. American tribes.  In the\namount of hair, and in the general shape of the body, the sexes of the\nAmerican aborigines do not differ so much from each other, as in most other\nraces.  (20.  Prof. and Mrs. Agassiz ('Journey in Brazil,' p. 530) remark\nthat the sexes of the American Indians differ less than those of the\nnegroes and of the higher races.  See also Rengger, ibid. p. 3, on the\nGuaranys.)  This fact is analogous with what occurs with some closely\nallied monkeys; thus the sexes of the chimpanzee are not as different as\nthose of the orang or gorilla.  (21.  Rutimeyer, 'Die Grenzen der\nThierwelt; eine Betrachtung zu Darwin's Lehre,' 1868, s. 54.)\n\nIn the previous chapters we have seen that with mammals, birds, fishes,\ninsects, etc., many characters, which there is every reason to believe were\nprimarily gained through sexual selection by one sex, have been transferred\nto the other.  As this same form of transmission has apparently prevailed\nmuch with mankind, it will save useless repetition if we discuss the origin\nof characters peculiar to the male sex together with certain other\ncharacters common to both sexes.\n\nLAW OF BATTLE.\n\nWith savages, for instance, the Australians, the women are the constant\ncause of war both between members of the same tribe and between distinct\ntribes.  So no doubt it was in ancient times; \"nam fuit ante Helenam mulier\nteterrima belli causa.\"  With some of the North American Indians, the\ncontest is reduced to a system.  That excellent observer, Hearne (22.  'A\nJourney from Prince of Wales Fort,' 8vo. ed. Dublin, 1796, p. 104.  Sir J.\nLubbock ('Origin of Civilisation,' 1870, p. 69) gives other and similar\ncases in North America.  For the Guanas of South America see Azara,\n'Voyages,' etc. tom. ii. p. 94.), says:--\"It has ever been the custom among\nthese people for the men to wrestle for any woman to whom they are\nattached; and, of course, the strongest party always carries off the prize.\nA weak man, unless he be a good hunter, and well-beloved, is seldom\npermitted to keep a wife that a stronger man thinks worth his notice.  This\ncustom prevails throughout all the tribes, and causes a great spirit of\nemulation among their youth, who are upon all occasions, from their\nchildhood, trying their strength and skill in wrestling.\"  With the Guanas\nof South America, Azara states that the men rarely marry till twenty years\nold or more, as before that age they cannot conquer their rivals.\n\nOther similar facts could be given; but even if we had no evidence on this\nhead, we might feel almost sure, from the analogy of the higher Quadrumana\n(23.  On the fighting of the male gorillas, see Dr. Savage, in 'Boston\nJournal of Natural History,' vol. v. 1847, p. 423.  On Presbytis entellus,\nsee the 'Indian Field,' 1859, p. 146.), that the law of battle had\nprevailed with man during the early stages of his development.  The\noccasional appearance at the present day of canine teeth which project\nabove the others, with traces of a diastema or open space for the reception\nof the opposite canines, is in all probability a case of reversion to a\nformer state, when the progenitors of man were provided with these weapons,\nlike so many existing male Quadrumana.  It was remarked in a former chapter\nthat as man gradually became erect, and continually used his hands and arms\nfor fighting with sticks and stones, as well as for the other purposes of\nlife, he would have used his jaws and teeth less and less.  The jaws,\ntogether with their muscles, would then have been reduced through disuse,\nas would the teeth through the not well understood principles of\ncorrelation and economy of growth; for we everywhere see that parts, which\nare no longer of service, are reduced in size.  By such steps the original\ninequality between the jaws and teeth in the two sexes of mankind would\nultimately have been obliterated.  The case is almost parallel with that of\nmany male Ruminants, in which the canine teeth have been reduced to mere\nrudiments, or have disappeared, apparently in consequence of the\ndevelopment of horns.  As the prodigious difference between the skulls of\nthe two sexes in the orang and gorilla stands in close relation with the\ndevelopment of the immense canine teeth in the males, we may infer that the\nreduction of the jaws and teeth in the early male progenitors of man must\nhave led to a most striking and favourable change in his appearance.\n\nThere can be little doubt that the greater size and strength of man, in\ncomparison with woman, together with his broader shoulders, more developed\nmuscles, rugged outline of body, his greater courage and pugnacity, are all\ndue in chief part to inheritance from his half-human male ancestors.  These\ncharacters would, however, have been preserved or even augmented during the\nlong ages of man's savagery, by the success of the strongest and boldest\nmen, both in the general struggle for life and in their contests for wives;\na success which would have ensured their leaving a more numerous progeny\nthan their less favoured brethren.  It is not probable that the greater\nstrength of man was primarily acquired through the inherited effects of his\nhaving worked harder than woman for his own subsistence and that of his\nfamily; for the women in all barbarous nations are compelled to work at\nleast as hard as the men.  With civilised people the arbitrament of battle\nfor the possession of the women has long ceased; on the other hand, the\nmen, as a general rule, have to work harder than the women for their joint\nsubsistence, and thus their greater strength will have been kept up.\n\nDIFFERENCE IN THE MENTAL POWERS OF THE TWO SEXES.\n\nWith respect to differences of this nature between man and woman, it is\nprobable that sexual selection has played a highly important part.  I am\naware that some writers doubt whether there is any such inherent\ndifference; but this is at least probable from the analogy of the lower\nanimals which present other secondary sexual characters.  No one disputes\nthat the bull differs in disposition from the cow, the wild-boar from the\nsow, the stallion from the mare, and, as is well known to the keepers of\nmenageries, the males of the larger apes from the females.  Woman seems to\ndiffer from man in mental disposition, chiefly in her greater tenderness\nand less selfishness; and this holds good even with savages, as shewn by a\nwell-known passage in Mungo Park's Travels, and by statements made by many\nother travellers.  Woman, owing to her maternal instincts, displays these\nqualities towards her infants in an eminent degree; therefore it is likely\nthat she would often extend them towards her fellow-creatures.  Man is the\nrival of other men; he delights in competition, and this leads to ambition\nwhich passes too easily into selfishness.  These latter qualities seem to\nbe his natural and unfortunate birthright.  It is generally admitted that\nwith woman the powers of intuition, of rapid perception, and perhaps of\nimitation, are more strongly marked than in man; but some, at least, of\nthese faculties are characteristic of the lower races, and therefore of a\npast and lower state of civilisation.\n\nThe chief distinction in the intellectual powers of the two sexes is shewn\nby man's attaining to a higher eminence, in whatever he takes up, than can\nwoman--whether requiring deep thought, reason, or imagination, or merely\nthe use of the senses and hands.  If two lists were made of the most\neminent men and women in poetry, painting, sculpture, music (inclusive both\nof composition and performance), history, science, and philosophy, with\nhalf-a-dozen names under each subject, the two lists would not bear\ncomparison.  We may also infer, from the law of the deviation from\naverages, so well illustrated by Mr. Galton, in his work on 'Hereditary\nGenius,' that if men are capable of a decided pre-eminence over women in\nmany subjects, the average of mental power in man must be above that of\nwoman.\n\nAmongst the half-human progenitors of man, and amongst savages, there have\nbeen struggles between the males during many generations for the possession\nof the females.  But mere bodily strength and size would do little for\nvictory, unless associated with courage, perseverance, and determined\nenergy.  With social animals, the young males have to pass through many a\ncontest before they win a female, and the older males have to retain their\nfemales by renewed battles.  They have, also, in the case of mankind, to\ndefend their females, as well as their young, from enemies of all kinds,\nand to hunt for their joint subsistence.  But to avoid enemies or to attack\nthem with success, to capture wild animals, and to fashion weapons,\nrequires the aid of the higher mental faculties, namely, observation,\nreason, invention, or imagination.  These various faculties will thus have\nbeen continually put to the test and selected during manhood; they will,\nmoreover, have been strengthened by use during this same period of life.\nConsequently in accordance with the principle often alluded to, we might\nexpect that they would at least tend to be transmitted chiefly to the male\noffspring at the corresponding period of manhood.\n\nNow, when two men are put into competition, or a man with a woman, both\npossessed of every mental quality in equal perfection, save that one has\nhigher energy, perseverance, and courage, the latter will generally become\nmore eminent in every pursuit, and will gain the ascendancy.  (24.  J.\nStuart Mill remarks ('The Subjection of Women,' 1869, p. 122), \"The things\nin which man most excels woman are those which require most plodding, and\nlong hammering at single thoughts.\"  What is this but energy and\nperseverance?)  He may be said to possess genius--for genius has been\ndeclared by a great authority to be patience; and patience, in this sense,\nmeans unflinching, undaunted perseverance.  But this view of genius is\nperhaps deficient; for without the higher powers of the imagination and\nreason, no eminent success can be gained in many subjects.  These latter\nfaculties, as well as the former, will have been developed in man, partly\nthrough sexual selection,--that is, through the contest of rival males, and\npartly through natural selection, that is, from success in the general\nstruggle for life; and as in both cases the struggle will have been during\nmaturity, the characters gained will have been transmitted more fully to\nthe male than to the female offspring.  It accords in a striking manner\nwith this view of the modification and re-inforcement of many of our mental\nfaculties by sexual selection, that, firstly, they notoriously undergo a\nconsiderable change at puberty (25.  Maudsley, 'Mind and Body,' p. 31.),\nand, secondly, that eunuchs remain throughout life inferior in these same\nqualities.  Thus, man has ultimately become superior to woman.  It is,\nindeed, fortunate that the law of the equal transmission of characters to\nboth sexes prevails with mammals; otherwise, it is probable that man would\nhave become as superior in mental endowment to woman, as the peacock is in\nornamental plumage to the peahen.\n\nIt must be borne in mind that the tendency in characters acquired by either\nsex late in life, to be transmitted to the same sex at the same age, and of\nearly acquired characters to be transmitted to both sexes, are rules which,\nthough general, do not always hold.  If they always held good, we might\nconclude (but I here exceed my proper bounds) that the inherited effects of\nthe early education of boys and girls would be transmitted equally to both\nsexes; so that the present inequality in mental power between the sexes\nwould not be effaced by a similar course of early training; nor can it have\nbeen caused by their dissimilar early training.  In order that woman should\nreach the same standard as man, she ought, when nearly adult, to be trained\nto energy and perseverance, and to have her reason and imagination\nexercised to the highest point; and then she would probably transmit these\nqualities chiefly to her adult daughters.  All women, however, could not be\nthus raised, unless during many generations those who excelled in the above\nrobust virtues were married, and produced offspring in larger numbers than\nother women.  As before remarked of bodily strength, although men do not\nnow fight for their wives, and this form of selection has passed away, yet\nduring manhood, they generally undergo a severe struggle in order to\nmaintain themselves and their families; and this will tend to keep up or\neven increase their mental powers, and, as a consequence, the present\ninequality between the sexes.  (26.  An observation by Vogt bears on this\nsubject:  he says, \"It is a remarkable circumstance, that the difference\nbetween the sexes, as regards the cranial cavity, increases with the\ndevelopment of the race, so that the male European excels much more the\nfemale, than the negro the negress.  Welcker confirms this statement of\nHuschke from his measurements of negro and German skulls.\"  But Vogt admits\n('Lectures on Man,' Eng. translat. 1864, p. 81) that more observations are\nrequisite on this point.\n\nVOICE AND MUSICAL POWERS.\n\nIn some species of Quadrumana there is a great difference between the adult\nsexes, in the power of their voices and in the development of the vocal\norgans; and man appears to have inherited this difference from his early\nprogenitors.  His vocal cords are about one-third longer than in woman, or\nthan in boys; and emasculation produces the same effect on him as on the\nlower animals, for it \"arrests that prominent growth of the thyroid, etc.,\nwhich accompanies the elongation of the cords.\"  (27.  Owen, 'Anatomy of\nVertebrates,' vol. iii. p. 603.)  With respect to the cause of this\ndifference between the sexes, I have nothing to add to the remarks in the\nlast chapter on the probable effects of the long-continued use of the vocal\norgans by the male under the excitement of love, rage and jealousy.\nAccording to Sir Duncan Gibb (28.  'Journal of the Anthropological\nSociety,' April 1869, p. lvii. and lxvi.), the voice and the form of the\nlarynx differ in the different races of mankind; but with the Tartars,\nChinese, etc., the voice of the male is said not to differ so much from\nthat of the female, as in most other races.\n\nThe capacity and love for singing or music, though not a sexual character\nin man, must not here be passed over.  Although the sounds emitted by\nanimals of all kinds serve many purposes, a strong case can be made out,\nthat the vocal organs were primarily used and perfected in relation to the\npropagation of the species.  Insects and some few spiders are the lowest\nanimals which voluntarily produce any sound; and this is generally effected\nby the aid of beautifully constructed stridulating organs, which are often\nconfined to the males.  The sounds thus produced consist, I believe in all\ncases, of the same note, repeated rhythmically (29.  Dr. Scudder, 'Notes on\nStridulation,' in 'Proc. Boston Soc. of Nat. Hist.' vol. xi. April 1868.);\nand this is sometimes pleasing even to the ears of man.  The chief and, in\nsome cases, exclusive purpose appears to be either to call or charm the\nopposite sex.\n\nThe sounds produced by fishes are said in some cases to be made only by the\nmales during the breeding-season.  All the air-breathing Vertebrata\nnecessarily possess an apparatus for inhaling and expelling air, with a\npipe capable of being closed at one end.  Hence when the primeval members\nof this class were strongly excited and their muscles violently contracted,\npurposeless sounds would almost certainly have been produced; and these, if\nthey proved in any way serviceable, might readily have been modified or\nintensified by the preservation of properly adapted variations.  The lowest\nVertebrates which breathe air are Amphibians; and of these, frogs and toads\npossess vocal organs, which are incessantly used during the breeding-\nseason, and which are often more highly developed in the male than in the\nfemale.  The male alone of the tortoise utters a noise, and this only\nduring the season of love.  Male alligators roar or bellow during the same\nseason.  Every one knows how much birds use their vocal organs as a means\nof courtship; and some species likewise perform what may be called\ninstrumental music.\n\nIn the class of Mammals, with which we are here more particularly\nconcerned, the males of almost all the species use their voices during the\nbreeding-season much more than at any other time; and some are absolutely\nmute excepting at this season.  With other species both sexes, or only the\nfemales, use their voices as a love-call.  Considering these facts, and\nthat the vocal organs of some quadrupeds are much more largely developed in\nthe male than in the female, either permanently or temporarily during the\nbreeding-season; and considering that in most of the lower classes the\nsounds produced by the males, serve not only to call but to excite or\nallure the female, it is a surprising fact that we have not as yet any good\nevidence that these organs are used by male mammals to charm the females.\nThe American Mycetes caraya perhaps forms an exception, as does the\nHylobates agilis, an ape allied to man.  This gibbon has an extremely loud\nbut musical voice.  Mr. Waterhouse states (30.  Given in W.C.L. Martin's\n'General Introduction to Natural History of Mamm. Animals,' 1841, p. 432;\nOwen, 'Anatomy of Vertebrates,' vol. iii, p. 600.), \"It appeared to me that\nin ascending and descending the scale, the intervals were always exactly\nhalf-tones; and I am sure that the highest note was the exact octave to the\nlowest.  The quality of the notes is very musical; and I do not doubt that\na good violinist would be able to give a correct idea of the gibbon's\ncomposition, excepting as regards its loudness.\"  Mr. Waterhouse then gives\nthe notes.  Professor Owen, who is a musician, confirms the foregoing\nstatement, and remarks, though erroneously, that this gibbon \"alone of\nbrute mammals may be said to sing.\"  It appears to be much excited after\nits performance.  Unfortunately, its habits have never been closely\nobserved in a state of nature; but from the analogy of other animals, it is\nprobable that it uses its musical powers more especially during the season\nof courtship.\n\nThis gibbon is not the only species in the genus which sings, for my son,\nFrancis Darwin, attentively listened in the Zoological Gardens to H.\nleuciscus whilst singing a cadence of three notes, in true musical\nintervals and with a clear musical tone.  It is a more surprising fact that\ncertain rodents utter musical sounds.  Singing mice have often been\nmentioned and exhibited, but imposture has commonly been suspected.  We\nhave, however, at last a clear account by a well-known observer, the Rev.\nS. Lockwood (31.  The 'American Naturalist,' 1871, p. 761.), of the musical\npowers of an American species, the Hesperomys cognatus, belonging to a\ngenus distinct from that of the English mouse.  This little animal was kept\nin confinement, and the performance was repeatedly heard.  In one of the\ntwo chief songs, \"the last bar would frequently be prolonged to two or\nthree; and she would sometimes change from C sharp and D, to C natural and\nD, then warble on these two notes awhile, and wind up with a quick chirp on\nC sharp and D.  The distinctness between the semitones was very marked, and\neasily appreciable to a good ear.\"  Mr. Lockwood gives both songs in\nmusical notation; and adds that though this little mouse \"had no ear for\ntime, yet she would keep to the key of B (two flats) and strictly in a\nmajor key.\"...\"Her soft clear voice falls an octave with all the precision\npossible; then at the wind up, it rises again into a very quick trill on C\nsharp and D.\"\n\nA critic has asked how the ears of man, and he ought to have added of other\nanimals, could have been adapted by selection so as to distinguish musical\nnotes.  But this question shews some confusion on the subject; a noise is\nthe sensation resulting from the co-existence of several aerial \"simple\nvibrations\" of various periods, each of which intermits so frequently that\nits separate existence cannot be perceived.  It is only in the want of\ncontinuity of such vibrations, and in their want of harmony inter se, that\na noise differs from a musical note.  Thus an ear to be capable of\ndiscriminating noises--and the high importance of this power to all animals\nis admitted by every one--must be sensitive to musical notes.  We have\nevidence of this capacity even low down in the animal scale:  thus\nCrustaceans are provided with auditory hairs of different lengths, which\nhave been seen to vibrate when the proper musical notes are struck.  (32.\nHelmholtz, 'Theorie Phys. de la Musique,' 1868, p. 187.)  As stated in a\nprevious chapter, similar observations have been made on the hairs of the\nantennae of gnats.  It has been positively asserted by good observers that\nspiders are attracted by music.  It is also well known that some dogs howl\nwhen hearing particular tones.  (33.  Several accounts have been published\nto this effect.  Mr. Peach writes to me that an old dog of his howls when B\nflat is sounded on the flute, and to no other note.  I may add another\ninstance of a dog always whining, when one note on a concertina, which was\nout of tune, was played.)  Seals apparently appreciate music, and their\nfondness for it \"was well known to the ancients, and is often taken\nadvantage of by the hunters at the present day.\"  (34.  Mr. R. Brown, in\n'Proc. Zool. Soc.' 1868, p. 410.)\n\nTherefore, as far as the mere perception of musical notes is concerned,\nthere seems no special difficulty in the case of man or of any other\nanimal.  Helmholtz has explained on physiological principles why concords\nare agreeable, and discords disagreeable to the human ear; but we are\nlittle concerned with these, as music in harmony is a late invention.  We\nare more concerned with melody, and here again, according to Helmholtz, it\nis intelligible why the notes of our musical scale are used.  The ear\nanalyses all sounds into their component \"simple vibrations,\" although we\nare not conscious of this analysis.  In a musical note the lowest in pitch\nof these is generally predominant, and the others which are less marked are\nthe octave, the twelfth, the second octave, etc., all harmonies of the\nfundamental predominant note; any two notes of our scale have many of these\nharmonic over-tones in common.  It seems pretty clear then, that if an\nanimal always wished to sing precisely the same song, he would guide\nhimself by sounding those notes in succession, which possess many over-\ntones in common--that is, he would choose for his song, notes which belong\nto our musical scale.\n\nBut if it be further asked why musical tones in a certain order and rhythm\ngive man and other animals pleasure, we can no more give the reason than\nfor the pleasantness of certain tastes and smells.  That they do give\npleasure of some kind to animals, we may infer from their being produced\nduring the season of courtship by many insects, spiders, fishes,\namphibians, and birds; for unless the females were able to appreciate such\nsounds and were excited or charmed by them, the persevering efforts of the\nmales, and the complex structures often possessed by them alone, would be\nuseless; and this it is impossible to believe.\n\nHuman song is generally admitted to be the basis or origin of instrumental\nmusic.  As neither the enjoyment nor the capacity of producing musical\nnotes are faculties of the least use to man in reference to his daily\nhabits of life, they must be ranked amongst the most mysterious with which\nhe is endowed.  They are present, though in a very rude condition, in men\nof all races, even the most savage; but so different is the taste of the\nseveral races, that our music gives no pleasure to savages, and their music\nis to us in most cases hideous and unmeaning.  Dr. Seemann, in some\ninteresting remarks on this subject (35.  'Journal of Anthropological\nSociety,' Oct. 1870, p. clv.  See also the several later chapters in Sir\nJohn Lubbock's 'Prehistoric Times,' 2nd ed. 1869, which contain an\nadmirable account of the habits of savages.), \"doubts whether even amongst\nthe nations of Western Europe, intimately connected as they are by close\nand frequent intercourse, the music of the one is interpreted in the same\nsense by the others.  By travelling eastwards we find that there is\ncertainly a different language of music.  Songs of joy and dance-\naccompaniments are no longer, as with us, in the major keys, but always in\nthe minor.\"  Whether or not the half-human progenitors of man possessed,\nlike the singing gibbons, the capacity of producing, and therefore no doubt\nof appreciating, musical notes, we know that man possessed these faculties\nat a very remote period.  M. Lartet has described two flutes made out of\nthe bones and horns of the reindeer, found in caves together with flint\ntools and the remains of extinct animals.  The arts of singing and of\ndancing are also very ancient, and are now practised by all or nearly all\nthe lowest races of man.  Poetry, which may be considered as the offspring\nof song, is likewise so ancient, that many persons have felt astonished\nthat it should have arisen during the earliest ages of which we have any\nrecord.\n\nWe see that the musical faculties, which are not wholly deficient in any\nrace, are capable of prompt and high development, for Hottentots and\nNegroes have become excellent musicians, although in their native countries\nthey rarely practise anything that we should consider music.  Schweinfurth,\nhowever, was pleased with some of the simple melodies which he heard in the\ninterior of Africa.  But there is nothing anomalous in the musical\nfaculties lying dormant in man:  some species of birds which never\nnaturally sing, can without much difficulty be taught to do so; thus a\nhouse-sparrow has learnt the song of a linnet.  As these two species are\nclosely allied, and belong to the order of Insessores, which includes\nnearly all the singing-birds in the world, it is possible that a progenitor\nof the sparrow may have been a songster.  It is more remarkable that\nparrots, belonging to a group distinct from the Insessores, and having\ndifferently constructed vocal organs, can be taught not only to speak, but\nto pipe or whistle tunes invented by man, so that they must have some\nmusical capacity.  Nevertheless it would be very rash to assume that\nparrots are descended from some ancient form which was a songster.  Many\ncases could be advanced of organs and instincts originally adapted for one\npurpose, having been utilised for some distinct purpose.  (36.  Since this\nchapter was printed, I have seen a valuable article by Mr. Chauncey Wright\n('North American Review,' Oct. 1870, page 293), who, in discussing the\nabove subject, remarks, \"There are many consequences of the ultimate laws\nor uniformities of nature, through which the acquisition of one useful\npower will bring with it many resulting advantages as well as limiting\ndisadvantages, actual or possible, which the principle of utility may not\nhave comprehended in its action.\"  As I have attempted to shew in an early\nchapter of this work, this principle has an important bearing on the\nacquisition by man of some of his mental characteristics.)  Hence the\ncapacity for high musical development which the savage races of man\npossess, may be due either to the practice by our semi-human progenitors of\nsome rude form of music, or simply to their having acquired the proper\nvocal organs for a different purpose.  But in this latter case we must\nassume, as in the above instance of parrots, and as seems to occur with\nmany animals, that they already possessed some sense of melody.\n\nMusic arouses in us various emotions, but not the more terrible ones of\nhorror, fear, rage, etc.  It awakens the gentler feelings of tenderness and\nlove, which readily pass into devotion.  In the Chinese annals it is said,\n\"Music hath the power of making heaven descend upon earth.\"  It likewise\nstirs up in us the sense of triumph and the glorious ardour for war.  These\npowerful and mingled feelings may well give rise to the sense of sublimity.\nWe can concentrate, as Dr. Seemann observes, greater intensity of feeling\nin a single musical note than in pages of writing.  It is probable that\nnearly the same emotions, but much weaker and far less complex, are felt by\nbirds when the male pours forth his full volume of song, in rivalry with\nother males, to captivate the female.  Love is still the commonest theme of\nour songs.  As Herbert Spencer remarks, \"music arouses dormant sentiments\nof which we had not conceived the possibility, and do not know the meaning;\nor, as Richter says, tells us of things we have not seen and shall not\nsee.\"  Conversely, when vivid emotions are felt and expressed by the\norator, or even in common speech, musical cadences and rhythm are\ninstinctively used.  The negro in Africa when excited often bursts forth in\nsong; \"another will reply in song, whilst the company, as if touched by a\nmusical wave, murmur a chorus in perfect unison.\"  (37.  Winwood Reade,\n'The Martyrdom of Man,' 1872, p. 441, and 'African Sketch Book,' 1873, vol.\nii. p. 313.)  Even monkeys express strong feelings in different tones--\nanger and impatience by low,--fear and pain by high notes.  (38.  Rengger,\n'Saeugethiere von Paraguay,' s. 49.)  The sensations and ideas thus excited\nin us by music, or expressed by the cadences of oratory, appear from their\nvagueness, yet depth, like mental reversions to the emotions and thoughts\nof a long-past age.\n\nAll these facts with respect to music and impassioned speech become\nintelligible to a certain extent, if we may assume that musical tones and\nrhythm were used by our half-human ancestors, during the season of\ncourtship, when animals of all kinds are excited not only by love, but by\nthe strong passions of jealousy, rivalry, and triumph.  From the deeply-\nlaid principle of inherited associations, musical tones in this case would\nbe likely to call up vaguely and indefinitely the strong emotions of a\nlong-past age.  As we have every reason to suppose that articulate speech\nis one of the latest, as it certainly is the highest, of the arts acquired\nby man, and as the instinctive power of producing musical notes and rhythms\nis developed low down in the animal series, it would be altogether opposed\nto the principle of evolution, if we were to admit that man's musical\ncapacity has been developed from the tones used in impassioned speech.  We\nmust suppose that the rhythms and cadences of oratory are derived from\npreviously developed musical powers.  (39.  See the very interesting\ndiscussion on the 'Origin and Function of Music,' by Mr. Herbert Spencer,\nin his collected 'Essays,' 1858, p. 359.  Mr. Spencer comes to an exactly\nopposite conclusion to that at which I have arrived.  He concludes, as did\nDiderot formerly, that the cadences used in emotional speech afford the\nfoundation from which music has been developed; whilst I conclude that\nmusical notes and rhythm were first acquired by the male or female\nprogenitors of mankind for the sake of charming the opposite sex.  Thus\nmusical tones became firmly associated with some of the strongest passions\nan animal is capable of feeling, and are consequently used instinctively,\nor through association when strong emotions are expressed in speech.  Mr.\nSpencer does not offer any satisfactory explanation, nor can I, why high or\ndeep notes should be expressive, both with man and the lower animals, of\ncertain emotions.  Mr. Spencer gives also an interesting discussion on the\nrelations between poetry, recitative and song.)  We can thus understand how\nit is that music, dancing, song, and poetry are such very ancient arts.  We\nmay go even further than this, and, as remarked in a former chapter,\nbelieve that musical sounds afforded one of the bases for the development\nof language.  (40.  I find in Lord Monboddo's 'Origin of Language,' vol. i.\n1774, p. 469, that Dr. Blacklock likewise thought \"that the first language\namong men was music, and that before our ideas were expressed by articulate\nsounds, they were communicated by tones varied according to different\ndegrees of gravity and acuteness.\")\n\nAs the males of several quadrumanous animals have their vocal organs much\nmore developed than in the females, and as a gibbon, one of the\nanthropomorphous apes, pours forth a whole octave of musical notes and may\nbe said to sing, it appears probable that the progenitors of man, either\nthe males or females or both sexes, before acquiring the power of\nexpressing their mutual love in articulate language, endeavoured to charm\neach other with musical notes and rhythm.  So little is known about the use\nof the voice by the Quadrumana during the season of love, that we have no\nmeans of judging whether the habit of singing was first acquired by our\nmale or female ancestors.  Women are generally thought to possess sweeter\nvoices than men, and as far as this serves as any guide, we may infer that\nthey first acquired musical powers in order to attract the other sex.  (41.\nSee an interesting discussion on this subject by Haeckel, 'Generelle\nMorphologie,' B. ii. 1866, s. 246.)  But if so, this must have occurred\nlong ago, before our ancestors had become sufficiently human to treat and\nvalue their women merely as useful slaves.  The impassioned orator, bard,\nor musician, when with his varied tones and cadences he excites the\nstrongest emotions in his hearers, little suspects that he uses the same\nmeans by which his half-human ancestors long ago aroused each other's\nardent passions, during their courtship and rivalry.\n\nTHE INFLUENCE OF BEAUTY IN DETERMINING THE MARRIAGES OF MANKIND.\n\nIn civilised life man is largely, but by no means exclusively, influenced\nin the choice of his wife by external appearance; but we are chiefly\nconcerned with primeval times, and our only means of forming a judgment on\nthis subject is to study the habits of existing semi-civilised and savage\nnations.  If it can be shewn that the men of different races prefer women\nhaving various characteristics, or conversely with the women, we have then\nto enquire whether such choice, continued during many generations, would\nproduce any sensible effect on the race, either on one sex or both\naccording to the form of inheritance which has prevailed.\n\nIt will be well first to shew in some detail that savages pay the greatest\nattention to their personal appearance.  (42.  A full and excellent account\nof the manner in which savages in all parts of the world ornament\nthemselves, is given by the Italian traveller, Professor Mantegazza, 'Rio\nde la Plata, Viaggi e Studi,' 1867, pp. 525-545; all the following\nstatements, when other references are not given, are taken from this work.\nSee, also, Waitz, 'Introduction to Anthropology,' Eng. translat. vol. i.\n1863, p. 275, et passim.  Lawrence also gives very full details in his\n'Lectures on Physiology,' 1822.  Since this chapter was written Sir J.\nLubbock has published his 'Origin of Civilisation,' 1870, in which there is\nan interesting chapter on the present subject, and from which (pp. 42, 48)\nI have taken some facts about savages dyeing their teeth and hair, and\npiercing their teeth.)  That they have a passion for ornament is notorious;\nand an English philosopher goes so far as to maintain, that clothes were\nfirst made for ornament and not for warmth.  As Professor Waitz remarks,\n\"however poor and miserable man is, he finds a pleasure in adorning\nhimself.\"  The extravagance of the naked Indians of South America in\ndecorating themselves is shewn \"by a man of large stature gaining with\ndifficulty enough by the labour of a fortnight to procure in exchange the\nchica necessary to paint himself red.\"  (43.  Humboldt, 'Personal\nNarrative,' Eng. translat. vol. iv. p. 515; on the imagination shewn in\npainting the body, p. 522; on modifying the form of the calf of the leg, p.\n466.)  The ancient barbarians of Europe during the Reindeer period brought\nto their caves any brilliant or singular objects which they happened to\nfind.  Savages at the present day everywhere deck themselves with plumes,\nnecklaces, armlets, ear-rings, etc.  They paint themselves in the most\ndiversified manner.  \"If painted nations,\" as Humboldt observes, \"had been\nexamined with the same attention as clothed nations, it would have been\nperceived that the most fertile imagination and the most mutable caprice\nhave created the fashions of painting, as well as those of garments.\"\n\nIn one part of Africa the eyelids are coloured black; in another the nails\nare coloured yellow or purple.  In many places the hair is dyed of various\ntints.  In different countries the teeth are stained black, red, blue,\netc., and in the Malay Archipelago it is thought shameful to have white\nteeth \"like those of a dog.\"  Not one great country can be named, from the\npolar regions in the north to New Zealand in the south, in which the\naborigines do not tattoo themselves.  This practice was followed by the\nJews of old, and by the ancient Britons.  In Africa some of the natives\ntattoo themselves, but it is a much more common practice to raise\nprotuberances by rubbing salt into incisions made in various parts of the\nbody; and these are considered by the inhabitants of Kordofan and Darfur\n\"to be great personal attractions.\"  In the Arab countries no beauty can be\nperfect until the cheeks \"or temples have been gashed.\"  (44.  'The Nile\nTributaries,' 1867; 'The Albert N'yanza,' 1866, vol. i. p. 218.)  In South\nAmerica, as Humboldt remarks, \"a mother would be accused of culpable\nindifference towards her children, if she did not employ artificial means\nto shape the calf of the leg after the fashion of the country.\"  In the Old\nand New Worlds the shape of the skull was formerly modified during infancy\nin the most extraordinary manner, as is still the case in many places, and\nsuch deformities are considered ornamental.  For instance, the savages of\nColombia (45.  Quoted by Prichard, 'Physical History of Mankind,' 4th ed.\nvol. i. 1851, p. 321.) deem a much flattened head \"an essential point of\nbeauty.\"\n\nThe hair is treated with especial care in various countries; it is allowed\nto grow to full length, so as to reach to the ground, or is combed into \"a\ncompact frizzled mop, which is the Papuan's pride and glory.\"  (46.  On the\nPapuans, Wallace, 'The Malay Archipelago,' vol. ii. p. 445.  On the\ncoiffure of the Africans, Sir S. Baker, 'The Albert N'yanza,' vol. i. p.\n210.)  In northern Africa \"a man requires a period of from eight to ten\nyears to perfect his coiffure.\"  With other nations the head is shaved, and\nin parts of South America and Africa even the eyebrows and eyelashes are\neradicated.  The natives of the Upper Nile knock out the four front teeth,\nsaying that they do not wish to resemble brutes.  Further south, the\nBatokas knock out only the two upper incisors, which, as Livingstone (47.\n'Travels,' p. 533.) remarks, gives the face a hideous appearance, owing to\nthe prominence of the lower jaw; but these people think the presence of the\nincisors most unsightly, and on beholding some Europeans, cried out, \"Look\nat the great teeth!\"  The chief Sebituani tried in vain to alter this\nfashion.  In various parts of Africa and in the Malay Archipelago the\nnatives file the incisors into points like those of a saw, or pierce them\nwith holes, into which they insert studs.\n\nAs the face with us is chiefly admired for its beauty, so with savages it\nis the chief seat of mutilation.  In all quarters of the world the septum,\nand more rarely the wings of the nose are pierced; rings, sticks, feathers,\nand other ornaments being inserted into the holes.  The ears are everywhere\npierced and similarly ornamented, and with the Botocudos and Lenguas of\nSouth America the hole is gradually so much enlarged that the lower edge\ntouches the shoulder.  In North and South America and in Africa either the\nupper or lower lip is pierced; and with the Botocudos the hole in the lower\nlip is so large that a disc of wood, four inches in diameter, is placed in\nit.  Mantegazza gives a curious account of the shame felt by a South\nAmerican native, and of the ridicule which he excited, when he sold his\ntembeta,--the large coloured piece of wood which is passed through the\nhole.  In Central Africa the women perforate the lower lip and wear a\ncrystal, which, from the movement of the tongue, has \"a wriggling motion,\nindescribably ludicrous during conversation.\"  The wife of the chief of\nLatooka told Sir S. Baker (49.  'The Albert N'yanza,' 1866, vol. i. p.\n217.) that Lady Baker \"would be much improved if she would extract her four\nfront teeth from the lower jaw, and wear the long pointed polished crystal\nin her under lip.\"  Further south with the Makalolo, the upper lip is\nperforated, and a large metal and bamboo ring, called a pelele, is worn in\nthe hole.  \"This caused the lip in one case to project two inches beyond\nthe tip of the nose; and when the lady smiled, the contraction of the\nmuscles elevated it over the eyes.  'Why do the women wear these things?'\nthe venerable chief, Chinsurdi, was asked.  Evidently surprised at such a\nstupid question, he replied, 'For beauty!  They are the only beautiful\nthings women have; men have beards, women have none.  What kind of a person\nwould she be without the pelele?  She would not be a woman at all with a\nmouth like a man, but no beard.'\"  (49.  Livingstone, 'British\nAssociation,' 1860; report given in the 'Athenaeum,' July 7, 1860, p. 29.)\n\nHardly any part of the body, which can be unnaturally modified, has\nescaped.  The amount of suffering thus caused must have been extreme, for\nmany of the operations require several years for their completion, so that\nthe idea of their necessity must be imperative.  The motives are various;\nthe men paint their bodies to make themselves appear terrible in battle;\ncertain mutilations are connected with religious rites, or they mark the\nage of puberty, or the rank of the man, or they serve to distinguish the\ntribes.  Amongst savages the same fashions prevail for long periods (50.\nSir S. Baker (ibid. vol. i. p. 210) speaking of the natives of Central\nAfrica says, \"every tribe has a distinct and unchanging fashion for\ndressing the hair.\"  See Agassiz ('Journey in Brazil,' 1868, p. 318) on\ninvariability of the tattooing of Amazonian Indians.), and thus\nmutilations, from whatever cause first made, soon come to be valued as\ndistinctive marks.  But self-adornment, vanity, and the admiration of\nothers, seem to be the commonest motives.  In regard to tattooing, I was\ntold by the missionaries in New Zealand that when they tried to persuade\nsome girls to give up the practice, they answered, \"We must just have a few\nlines on our lips; else when we grow old we shall be so very ugly.\"  With\nthe men of New Zealand, a most capable judge (51.  Rev. R. Taylor, 'New\nZealand and its Inhabitants,' 1855, p. 152.) says, \"to have fine tattooed\nfaces was the great ambition of the young, both to render themselves\nattractive to the ladies, and conspicuous in war.\"  A star tattooed on the\nforehead and a spot on the chin are thought by the women in one part of\nAfrica to be irresistible attractions.  (52.  Mantegazza, 'Viaggi e Studi,'\np. 542.)  In most, but not all parts of the world, the men are more\nornamented than the women, and often in a different manner; sometimes,\nthough rarely, the women are hardly at all ornamented.  As the women are\nmade by savages to perform the greatest share of the work, and as they are\nnot allowed to eat the best kinds of food, so it accords with the\ncharacteristic selfishness of man that they should not be allowed to\nobtain, or use the finest ornaments.  Lastly, it is a remarkable fact, as\nproved by the foregoing quotations, that the same fashions in modifying the\nshape of the head, in ornamenting the hair, in painting, tattooing, in\nperforating the nose, lips, or ears, in removing or filing the teeth, etc.,\nnow prevail, and have long prevailed, in the most distant quarters of the\nworld.  It is extremely improbable that these practices, followed by so\nmany distinct nations, should be due to tradition from any common source.\nThey indicate the close similarity of the mind of man, to whatever race he\nmay belong, just as do the almost universal habits of dancing,\nmasquerading, and making rude pictures.\n\nHaving made these preliminary remarks on the admiration felt by savages for\nvarious ornaments, and for deformities most unsightly in our eyes, let us\nsee how far the men are attracted by the appearance of their women, and\nwhat are their ideas of beauty.  I have heard it maintained that savages\nare quite indifferent about the beauty of their women, valuing them solely\nas slaves; it may therefore be well to observe that this conclusion does\nnot at all agree with the care which the women take in ornamenting\nthemselves, or with their vanity.  Burchell (53.  'Travels in South\nAfrica,' 1824, vol. i. p. 414.) gives an amusing account of a Bush-woman\nwho used as much grease, red ochre, and shining powder \"as would have\nruined any but a very rich husband.\"  She displayed also \"much vanity and\ntoo evident a consciousness of her superiority.\"  Mr. Winwood Reade informs\nme that the negroes of the West Coast often discuss the beauty of their\nwomen.  Some competent observers have attributed the fearfully common\npractice of infanticide partly to the desire felt by the women to retain\ntheir good looks.  (54.  See, for references, Gerland, 'Ueber das\nAussterben der Naturvoelker,' 1868, ss. 51, 53, 55; also Azara, 'Voyages,'\netc., tom. ii. p. 116.)  In several regions the women wear charms and use\nlove-philters to gain the affections of the men; and Mr. Brown enumerates\nfour plants used for this purpose by the women of North-Western America.\n(55.  On the vegetable productions used by the North-Western American\nIndians, see 'Pharmaceutical Journal,' vol. x.)\n\nHearne (56.  'A Journey from Prince of Wales Fort,' 8vo. ed. 1796, p. 89.),\nan excellent observer, who lived many years with the American Indians,\nsays, in speaking of the women, \"Ask a Northern Indian what is beauty, and\nhe will answer, a broad flat face, small eyes, high cheek-bones, three or\nfour broad black lines across each cheek, a low forehead, a large broad\nchin, a clumsy hook nose, a tawny hide, and breasts hanging down to the\nbelt.\"  Pallas, who visited the northern parts of the Chinese empire, says,\n\"those women are preferred who have the Mandschu form; that is to say, a\nbroad face, high cheek-bones, very broad noses, and enormous ears\"(57.\nQuoted by Prichard, 'Physical History of Mankind,' 3rd ed. vol. iv. 1844,\np. 519; Vogt, 'Lectures on Man,' Eng. translat. p. 129.  On the opinion of\nthe Chinese on the Cingalese, E. Tennent, 'Ceylon,' 1859, vol. ii. p.\n107.); and Vogt remarks that the obliquity of the eye, which is proper to\nthe Chinese and Japanese, is exaggerated in their pictures for the purpose,\nas it \"seems, of exhibiting its beauty, as contrasted with the eye of the\nred-haired barbarians.\"  It is well known, as Huc repeatedly remarks, that\nthe Chinese of the interior think Europeans hideous, with their white skins\nand prominent noses.  The nose is far from being too prominent, according\nto our ideas, in the natives of Ceylon; yet \"the Chinese in the seventh\ncentury, accustomed to the flat features of the Mongol races, were\nsurprised at the prominent noses of the Cingalese; and Thsang described\nthem as having 'the beak of a bird, with the body of a man.'\"\n\nFinlayson, after minutely describing the people of Cochin China, says that\ntheir rounded heads and faces are their chief characteristics; and, he\nadds, \"the roundness of the whole countenance is more striking in the\nwomen, who are reckoned beautiful in proportion as they display this form\nof face.\"  The Siamese have small noses with divergent nostrils, a wide\nmouth, rather thick lips, a remarkably large face, with very high and broad\ncheek-bones.  It is, therefore, not wonderful that \"beauty, according to\nour notion, is a stranger to them.  Yet they consider their own females to\nbe much more beautiful than those of Europe.\"  (58.  Prichard, as taken\nfrom Crawfurd and Finlayson, 'Phys. Hist. of Mankind,' vol. iv. pp. 534,\n535.)\n\nIt is well known that with many Hottentot women the posterior part of the\nbody projects in a wonderful manner; they are steatopygous; and Sir Andrew\nSmith is certain that this peculiarity is greatly admired by the men.  (59.\nIdem illustrissimus viator dixit mihi praecinctorium vel tabulam foeminae,\nquod nobis teterrimum est, quondam permagno aestimari ab hominibus in hac\ngente.  Nunc res mutata est, et censent talem conformationem minime\noptandam esse.)  He once saw a woman who was considered a beauty, and she\nwas so immensely developed behind, that when seated on level ground she\ncould not rise, and had to push herself along until she came to a slope.\nSome of the women in various negro tribes have the same peculiarity; and,\naccording to Burton, the Somal men are said to choose their wives by\nranging them in a line, and by picking her out who projects farthest a\ntergo.  Nothing can be more hateful to a negro than the opposite form.\"\n(60.  The 'Anthropological Review,' November 1864, p. 237.  For additional\nreferences, see Waitz, 'Introduction to Anthropology,' Eng. translat.,\n1863, vol. i. p. 105.)\n\nWith respect to colour, the negroes rallied Mungo Park on the whiteness of\nhis skin and the prominence of his nose, both of which they considered as\n\"unsightly and unnatural conformations.\"  He in return praised the glossy\njet of their skins and the lovely depression of their noses; this they said\nwas \"honeymouth,\" nevertheless they gave him food.  The African Moors,\nalso, \"knitted their brows and seemed to shudder\" at the whiteness of his\nskin.  On the eastern coast, the negro boys when they saw Burton, cried\nout, \"Look at the white man; does he not look like a white ape?\"  On the\nwestern coast, as Mr. Winwood Reade informs me, the negroes admire a very\nblack skin more than one of a lighter tint.  But their horror of whiteness\nmay be attributed, according to this same traveller, partly to the belief\nheld by most negroes that demons and spirits are white, and partly to their\nthinking it a sign of ill-health.\n\nThe Banyai of the more southern part of the continent are negroes, but \"a\ngreat many of them are of a light coffee-and-milk colour, and, indeed, this\ncolour is considered handsome throughout the whole country\"; so that here\nwe have a different standard of taste.  With the Kaffirs, who differ much\nfrom negroes, \"the skin, except among the tribes near Delagoa Bay, is not\nusually black, the prevailing colour being a mixture of black and red, the\nmost common shade being chocolate.  Dark complexions, as being most common,\nare naturally held in the highest esteem.  To be told that he is light-\ncoloured, or like a white man, would be deemed a very poor compliment by a\nKaffir.  I have heard of one unfortunate man who was so very fair that no\ngirl would marry him.\"  One of the titles of the Zulu king is, \"You who are\nblack.\"  (61.  Mungo Park's 'Travels in Africa,' 4to. 1816, pp. 53, 131.\nBurton's statement is quoted by Schaaffhausen, 'Archiv. fur Anthropologie,'\n1866, s. 163.  On the Banyai, Livingstone, 'Travels,' p. 64.  On the\nKaffirs, the Rev. J. Shooter, 'The Kafirs of Natal and the Zulu Country,'\n1857, p. 1.)  Mr. Galton, in speaking to me about the natives of S. Africa,\nremarked that their ideas of beauty seem very different from ours; for in\none tribe two slim, slight, and pretty girls were not admired by the\nnatives.\n\nTurning to other quarters of the world; in Java, a yellow, not a white\ngirl, is considered, according to Madame Pfeiffer, a beauty.  A man of\nCochin China \"spoke with contempt of the wife of the English Ambassador,\nthat she had white teeth like a dog, and a rosy colour like that of potato-\nflowers.\"  We have seen that the Chinese dislike our white skin, and that\nthe N. Americans admire \"a tawny hide.\"  In S. America, the Yuracaras, who\ninhabit the wooded, damp slopes of the eastern Cordillera, are remarkably\npale-coloured, as their name in their own language expresses; nevertheless\nthey consider European women as very inferior to their own.  (62.  For the\nJavans and Cochin-Chinese, see Waitz, 'Introduct. to Anthropology,' Eng.\ntranslat. vol. i. p. 305.  On the Yuracaras, A. d'Orbigny, as quoted in\nPrichard, 'Physical History of Mankind,' vol. v. 3rd ed. p. 476.)\n\nIn several of the tribes of North America the hair on the head grows to a\nwonderful length; and Catlin gives a curious proof how much this is\nesteemed, for the chief of the Crows was elected to this office from having\nthe longest hair of any man in the tribe, namely ten feet and seven inches.\nThe Aymaras and Quichuas of S. America, likewise have very long hair; and\nthis, as Mr. D. Forbes informs me, is so much valued as a beauty, that\ncutting it off was the severest punishment which he could inflict on them.\nIn both the Northern and Southern halves of the continent the natives\nsometimes increase the apparent length of their hair by weaving into it\nfibrous substances.  Although the hair on the head is thus cherished, that\non the face is considered by the North American Indians \"as very vulgar,\"\nand every hair is carefully eradicated.  This practice prevails throughout\nthe American continent from Vancouver's Island in the north to Tierra del\nFuego in the south.  When York Minster, a Fuegian on board the \"Beagle,\"\nwas taken back to his country, the natives told him be ought to pull out\nthe few short hairs on his face.  They also threatened a young missionary,\nwho was left for a time with them, to strip him naked, and pluck the hair\nfrom his face and body, yet he was far from being a hairy man.  This\nfashion is carried so far that the Indians of Paraguay eradicate their\neyebrows and eyelashes, saying that they do not wish to be like horses.\n(63.  'North American Indians,' by G. Catlin, 3rd ed., 1842, vol. i. p. 49;\nvol. ii, p. 227.  On the natives of Vancouver's Island, see Sproat, 'Scenes\nand Studies of Savage Life,' 1868, p. 25.  On the Indians of Paraguay,\nAzara, 'Voyages,' tom. ii. p. 105.)\n\nIt is remarkable that throughout the world the races which are almost\ncompletely destitute of a beard dislike hairs on the face and body, and\ntake pains to eradicate them.  The Kalmucks are beardless, and they are\nwell known, like the Americans, to pluck out all straggling hairs; and so\nit is with the Polynesians, some of the Malays, and the Siamese.  Mr.\nVeitch states that the Japanese ladies \"all objected to our whiskers,\nconsidering them very ugly, and told us to cut them off, and be like\nJapanese men.\"  The New Zealanders have short, curled beards; yet they\nformerly plucked out the hairs on the face.  They had a saying that \"there\nis no woman for a hairy man;\" but it would appear that the fashion has\nchanged in New Zealand, perhaps owing to the presence of Europeans, and I\nam assured that beards are now admired by the Maories.  (64.  On the\nSiamese, Prichard, ibid. vol. iv. p. 533.  On the Japanese, Veitch in\n'Gardeners' Chronicle,' 1860, p. 1104.  On the New Zealanders, Mantegazza,\n'Viaggi e Studi,' 1867, p. 526.  For the other nations mentioned, see\nreferences in Lawrence, 'Lectures on Physiology,' etc., 1822, p. 272.)\n\nOn the other hand, bearded races admire and greatly value their beards;\namong the Anglo-Saxons every part of the body had a recognised value; \"the\nloss of the beard being estimated at twenty shillings, while the breaking\nof a thigh was fixed at only twelve.\"  (65.  Lubbock, 'Origin of\nCivilisation,' 1870, p. 321.)  In the East men swear solemnly by their\nbeards.  We have seen that Chinsurdi, the chief of the Makalolo in Africa,\nthought that beards were a great ornament.  In the Pacific the Fijian's\nbeard is \"profuse and bushy, and is his greatest pride\"; whilst the\ninhabitants of the adjacent archipelagoes of Tonga and Samoa are\n\"beardless, and abhor a rough chin.\"  In one island alone of the Ellice\ngroup \"the men are heavily bearded, and not a little proud thereof.\"  (66.\nDr. Barnard Davis quotes Mr. Prichard and others for these facts in regard\nto the Polynesians, in 'Anthropolog. Review,' April 1870, pp. 185, 191.)\n\nWe thus see how widely the different races of man differ in their taste for\nthe beautiful.  In every nation sufficiently advanced to have made effigies\nof their gods or of their deified rulers, the sculptors no doubt have\nendeavoured to express their highest ideal of beauty and grandeur.  (67.\nCh. Comte has remarks to this effect in his 'Traite de Legislation,' 3rd\ned. 1837, p. 136.)  Under this point of view it is well to compare in our\nmind the Jupiter or Apollo of the Greeks with the Egyptian or Assyrian\nstatues; and these with the hideous bas-reliefs on the ruined buildings of\nCentral America.\n\nI have met with very few statements opposed to this conclusion.  Mr.\nWinwood Reade, however, who has had ample opportunities for observation,\nnot only with the negroes of the West Coast of Africa, but with those of\nthe interior who have never associated with Europeans, is convinced that\ntheir ideas of beauty are ON THE WHOLE the same as ours; and Dr. Rohlfs\nwrites to me to the same effect with respect to Bornu and the countries\ninhabited by the Pullo tribes.  Mr. Reade found that he agreed with the\nnegroes in their estimation of the beauty of the native girls; and that\ntheir appreciation of the beauty of European women corresponded with ours.\nThey admire long hair, and use artificial means to make it appear abundant;\nthey admire also a beard, though themselves very scantily provided.  Mr.\nReade feels doubtful what kind of nose is most appreciated; a girl has been\nheard to say, \"I do not want to marry him, he has got no nose\"; and this\nshews that a very flat nose is not admired.  We should, however, bear in\nmind that the depressed, broad noses and projecting jaws of the negroes of\nthe West Coast are exceptional types with the inhabitants of Africa.\nNotwithstanding the foregoing statements, Mr. Reade admits that negroes \"do\nnot like the colour of our skin; they look on blue eyes with aversion, and\nthey think our noses too long and our lips too thin.\"  He does not think it\nprobable that negroes would ever prefer the most beautiful European woman,\non the mere grounds of physical admiration, to a good-looking negress.\n(68.  The 'African Sketch Book,' vol. ii. 1873, pp. 253, 394, 521.  The\nFuegians, as I have been informed by a missionary who long resided with\nthem, consider European women as extremely beautiful; but from what we have\nseen of the judgment of the other aborigines of America, I cannot but think\nthat this must be a mistake, unless indeed the statement refers to the few\nFuegians who have lived for some time with Europeans, and who must consider\nus as superior beings.  I should add that a most experienced observer,\nCapt. Burton, believes that a woman whom we consider beautiful is admired\nthroughout the world.  'Anthropological Review,' March, 1864, p. 245.)\n\nThe general truth of the principle, long ago insisted on by Humboldt (69.\n'Personal Narrative,' Eng. translat. vol. iv. p. 518, and elsewhere.\nMantegazza, in his 'Viaggi e Studi,' strongly insists on this same\nprinciple.), that man admires and often tries to exaggerate whatever\ncharacters nature may have given him, is shewn in many ways.  The practice\nof beardless races extirpating every trace of a beard, and often all the\nhairs on the body affords one illustration.  The skull has been greatly\nmodified during ancient and modern times by many nations; and there can be\nlittle doubt that this has been practised, especially in N. and S. America,\nin order to exaggerate some natural and admired peculiarity.  Many American\nIndians are known to admire a head so extremely flattened as to appear to\nus idiotic.  The natives on the north-western coast compress the head into\na pointed cone; and it is their constant practice to gather the hair into a\nknot on the top of the head, for the sake, as Dr. Wilson remarks, \"of\nincreasing the apparent elevation of the favourite conoid form.\"  The\ninhabitants of Arakhan admire a broad, smooth forehead, and in order to\nproduce it, they fasten a plate of lead on the heads of the new-born\nchildren.  On the other hand, \"a broad, well-rounded occiput is considered\na great beauty\" by the natives of the Fiji Islands.  (70.  On the skulls of\nthe American tribes, see Nott and Gliddon, 'Types of Mankind,' 1854, p.\n440; Prichard, 'Physical History of Mankind,' vol. i. 3rd ed. p. 321; on\nthe natives of Arakhan, ibid. vol. iv. p. 537.  Wilson, 'Physical\nEthnology,' Smithsonian Institution, 1863, p. 288; on the Fijians, p. 290.\nSir J. Lubbock ('Prehistoric Times,' 2nd ed. 1869, p. 506) gives an\nexcellent resume on this subject.)\n\nAs with the skull, so with the nose; the ancient Huns during the age of\nAttila were accustomed to flatten the noses of their infants with bandages,\n\"for the sake of exaggerating a natural conformation.\"  With the Tahitians,\nto be called LONG-NOSE is considered as an insult, and they compress the\nnoses and foreheads of their children for the sake of beauty.  The same\nholds with the Malays of Sumatra, the Hottentots, certain Negroes, and the\nnatives of Brazil.  (71.  On the Huns, Godron, 'De l'Espece,' tom. ii.\n1859, p. 300.  On the Tahitians, Waitz, 'Anthropology,' Eng. translat. vol.\ni. p. 305.  Marsden, quoted by Prichard, 'Phys. Hist. of Mankind,' 3rd\nedit. vol. v. p. 67.  Lawrence, 'Lectures on Physiology,' p. 337.)  The\nChinese have by nature unusually small feet (72.  This fact was ascertained\nin the 'Reise der Novara:  Anthropolog. Theil.' Dr. Weisbach, 1867, s.\n265.); and it is well known that the women of the upper classes distort\ntheir feet to make them still smaller.  Lastly, Humboldt thinks that the\nAmerican Indians prefer colouring their bodies with red paint in order to\nexaggerate their natural tint; and until recently European women added to\ntheir naturally bright colours by rouge and white cosmetics; but it may be\ndoubted whether barbarous nations have generally had any such intention in\npainting themselves.\n\nIn the fashions of our own dress we see exactly the same principle and the\nsame desire to carry every point to an extreme; we exhibit, also, the same\nspirit of emulation.  But the fashions of savages are far more permanent\nthan ours; and whenever their bodies are artificially modified, this is\nnecessarily the case.  The Arab women of the Upper Nile occupy about three\ndays in dressing their hair; they never imitate other tribes, \"but simply\nvie with each other in the superlativeness of their own style.\"  Dr.\nWilson, in speaking of the compressed skulls of various American races,\nadds, \"such usages are among the least eradicable, and long survive the\nshock of revolutions that change dynasties and efface more important\nnational peculiarities.\"  (73.  'Smithsonian Institution,' 1863, p. 289.\nOn the fashions of Arab women, Sir S. Baker, 'The Nile Tributaries,' 1867,\np. 121.)  The same principle comes into play in the art of breeding; and we\ncan thus understand, as I have elsewhere explained (74.  The 'Variation of\nAnimals and Plants under Domestication,' vol. i. p. 214; vol. ii. p. 240.),\nthe wonderful development of the many races of animals and plants, which\nhave been kept merely for ornament.  Fanciers always wish each character to\nbe somewhat increased; they do not admire a medium standard; they certainly\ndo not desire any great and abrupt change in the character of their breeds;\nthey admire solely what they are accustomed to, but they ardently desire to\nsee each characteristic feature a little more developed.\n\nThe senses of man and of the lower animals seem to be so constituted that\nbrilliant colours and certain forms, as well as harmonious and rhythmical\nsounds, give pleasure and are called beautiful; but why this should be so\nwe know not.  It is certainly not true that there is in the mind of man any\nuniversal standard of beauty with respect to the human body.  It is,\nhowever, possible that certain tastes may in the course of time become\ninherited, though there is no evidence in favour of this belief:  and if\nso, each race would possess its own innate ideal standard of beauty.  It\nhas been argued (75.  Schaaffhausen, 'Archiv. fuer Anthropologie,' 1866, s.\n164.) that ugliness consists in an approach to the structure of the lower\nanimals, and no doubt this is partly true with the more civilised nations,\nin which intellect is highly appreciated; but this explanation will hardly\napply to all forms of ugliness.  The men of each race prefer what they are\naccustomed to; they cannot endure any great change; but they like variety,\nand admire each characteristic carried to a moderate extreme.  (76.  Mr.\nBain has collected ('Mental and Moral Science,' 1868, pp. 304-314) about a\ndozen more or less different theories of the idea of beauty; but none is\nquite the same as that here given.)  Men accustomed to a nearly oval face,\nto straight and regular features, and to bright colours, admire, as we\nEuropeans know, these points when strongly developed.  On the other hand,\nmen accustomed to a broad face, with high cheek-bones, a depressed nose,\nand a black skin, admire these peculiarities when strongly marked.  No\ndoubt characters of all kinds may be too much developed for beauty.  Hence\na perfect beauty, which implies many characters modified in a particular\nmanner, will be in every race a prodigy.  As the great anatomist Bichat\nlong ago said, if every one were cast in the same mould, there would be no\nsuch thing as beauty.  If all our women were to become as beautiful as the\nVenus de' Medici, we should for a time be charmed; but we should soon wish\nfor variety; and as soon as we had obtained variety, we should wish to see\ncertain characters a little exaggerated beyond the then existing common\nstandard.\n\n\nCHAPTER XX.\n\nSECONDARY SEXUAL CHARACTERS OF MAN--continued.\n\nOn the effects of the continued selection of women according to a different\nstandard of beauty in each race--On the causes which interfere with sexual\nselection in civilised and savage nations--Conditions favourable to sexual\nselection during primeval times--On the manner of action of sexual\nselection with mankind--On the women in savage tribes having some power to\nchoose their husbands--Absence of hair on the body, and development of the\nbeard--Colour of the skin--Summary.\n\nWe have seen in the last chapter that with all barbarous races ornaments,\ndress, and external appearance are highly valued; and that the men judge of\nthe beauty of their women by widely different standards.  We must next\ninquire whether this preference and the consequent selection during many\ngenerations of those women, which appear to the men of each race the most\nattractive, has altered the character either of the females alone, or of\nboth sexes.  With mammals the general rule appears to be that characters of\nall kinds are inherited equally by the males and females; we might\ntherefore expect that with mankind any characters gained by the females or\nby the males through sexual selection would commonly be transferred to the\noffspring of both sexes.  If any change has thus been effected, it is\nalmost certain that the different races would be differently modified, as\neach has its own standard of beauty.\n\nWith mankind, especially with savages, many causes interfere with the\naction of sexual selection as far as the bodily frame is concerned.\nCivilised men are largely attracted by the mental charms of women, by their\nwealth, and especially by their social position; for men rarely marry into\na much lower rank.  The men who succeed in obtaining the more beautiful\nwomen will not have a better chance of leaving a long line of descendants\nthan other men with plainer wives, save the few who bequeath their fortunes\naccording to primogeniture.  With respect to the opposite form of\nselection, namely, of the more attractive men by the women, although in\ncivilised nations women have free or almost free choice, which is not the\ncase with barbarous races, yet their choice is largely influenced by the\nsocial position and wealth of the men; and the success of the latter in\nlife depends much on their intellectual powers and energy, or on the fruits\nof these same powers in their forefathers.  No excuse is needed for\ntreating this subject in some detail; for, as the German philosopher\nSchopenhauer remarks, \"the final aim of all love intrigues, be they comic\nor tragic, is really of more importance than all other ends in human life.\nWhat it all turns upon is nothing less than the composition of the next\ngeneration...It is not the weal or woe of any one individual, but that of\nthe human race to come, which is here at stake.\"  (1.  'Schopenhauer and\nDarwinism,' in 'Journal of Anthropology,' Jan. 1871, p. 323.\n\nThere is, however, reason to believe that in certain civilised and semi-\ncivilised nations sexual selection has effected something in modifying the\nbodily frame of some of the members.  Many persons are convinced, as it\nappears to me with justice, that our aristocracy, including under this term\nall wealthy families in which primogeniture has long prevailed, from having\nchosen during many generations from all classes the more beautiful women as\ntheir wives, have become handsomer, according to the European standard,\nthan the middle classes; yet the middle classes are placed under equally\nfavourable conditions of life for the perfect development of the body.\nCook remarks that the superiority in personal appearance \"which is\nobservable in the erees or nobles in all the other islands (of the Pacific)\nis found in the Sandwich Islands\"; but this may be chiefly due to their\nbetter food and manner of life.\n\nThe old traveller Chardin, in describing the Persians, says their \"blood is\nnow highly refined by frequent intermixtures with the Georgians and\nCircassians, two nations which surpass all the world in personal beauty.\nThere is hardly a man of rank in Persia who is not born of a Georgian or\nCircassian mother.\"  He adds that they inherit their beauty, \"not from\ntheir ancestors, for without the above mixture, the men of rank in Persia,\nwho are descendants of the Tartars, would be extremely ugly.\"  (2.  These\nquotations are taken from Lawrence ('Lectures on Physiology,' etc., 1822,\np. 393), who attributes the beauty of the upper classes in England to the\nmen having long selected the more beautiful women.)  Here is a more curious\ncase; the priestesses who attended the temple of Venus Erycina at San-\nGiuliano in Sicily, were selected for their beauty out of the whole of\nGreece; they were not vestal virgins, and Quatrefages (3.  'Anthropologie,'\n'Revue des Cours Scientifiques,' Oct. 1868, p. 721.), who states the\nforegoing fact, says that the women of San-Giuliano are now famous as the\nmost beautiful in the island, and are sought by artists as models.  But it\nis obvious that the evidence in all the above cases is doubtful.\n\nThe following case, though relating to savages, is well worth giving for\nits curiosity.  Mr. Winwood Reade informs me that the Jollofs, a tribe of\nnegroes on the west coast of Africa, \"are remarkable for their uniformly\nfine appearance.\"  A friend of his asked one of these men, \"How is it that\nevery one whom I meet is so fine looking, not only your men but your\nwomen?\"  The Jollof answered, \"It is very easily explained:  it has always\nbeen our custom to pick out our worst-looking slaves and to sell them.\"  It\nneed hardly be added that with all savages, female slaves serve as\nconcubines.  That this negro should have attributed, whether rightly or\nwrongly, the fine appearance of his tribe to the long-continued elimination\nof the ugly women is not so surprising as it may at first appear; for I\nhave elsewhere shewn (4.  'Variation of Animals and Plants under\nDomestication,' vol. i. p. 207.) that negroes fully appreciate the\nimportance of selection in the breeding of their domestic animals, and I\ncould give from Mr. Reade additional evidence on this head.\n\nTHE CAUSES WHICH PREVENT OR CHECK THE ACTION OF SEXUAL SELECTION WITH\nSAVAGES.\n\nThe chief causes are, first, so-called communal marriages or promiscuous\nintercourse; secondly, the consequences of female infanticide; thirdly,\nearly betrothals; and lastly, the low estimation in which women are held,\nas mere slaves.  These four points must be considered in some detail.\n\nIt is obvious that as long as the pairing of man, or of any other animal,\nis left to mere chance, with no choice exerted by either sex, there can be\nno sexual selection; and no effect will be produced on the offspring by\ncertain individuals having had an advantage over others in their courtship.\nNow it is asserted that there exist at the present day tribes which\npractise what Sir J. Lubbock by courtesy calls communal marriages; that is,\nall the men and women in the tribe are husbands and wives to one another.\nThe licentiousness of many savages is no doubt astonishing, but it seems to\nme that more evidence is requisite, before we fully admit that their\nintercourse is in any case promiscuous.  Nevertheless all those who have\nmost closely studied the subject (5.  Sir J. Lubbock, 'The Origin of\nCivilisation,' 1870, chap. iii. especially pp. 60-67.  Mr. M'Lennan, in his\nextremely valuable work on 'Primitive Marriage,' 1865, p. 163, speaks of\nthe union of the sexes \"in the earliest times as loose, transitory, and in\nsome degree promiscuous.\"  Mr. M'Lennan and Sir J. Lubbock have collected\nmuch evidence on the extreme licentiousness of savages at the present time.\nMr. L.H. Morgan, in his interesting memoir of the classificatory system of\nrelationship.  ('Proceedings of the American Academy of Sciences,' vol.\nvii. Feb. 1868, p. 475), concludes that polygamy and all forms of marriage\nduring primeval times were essentially unknown.  It appears also, from Sir\nJ. Lubbock's work, that Bachofen likewise believes that communal\nintercourse originally prevailed.), and whose judgment is worth much more\nthan mine, believe that communal marriage (this expression being variously\nguarded) was the original and universal form throughout the world,\nincluding therein the intermarriage of brothers and sisters.  The late Sir\nA. Smith, who had travelled widely in S. Africa, and knew much about the\nhabits of savages there and elsewhere, expressed to me the strongest\nopinion that no race exists in which woman is considered as the property of\nthe community.  I believe that his judgment was largely determined by what\nis implied by the term marriage.  Throughout the following discussion I use\nthe term in the same sense as when naturalists speak of animals as\nmonogamous, meaning thereby that the male is accepted by or chooses a\nsingle female, and lives with her either during the breeding-season or for\nthe whole year, keeping possession of her by the law of might; or, as when\nthey speak of a polygamous species, meaning that the male lives with\nseveral females.  This kind of marriage is all that concerns us here, as it\nsuffices for the work of sexual selection.  But I know that some of the\nwriters above referred to imply by the term marriage a recognised right\nprotected by the tribe.\n\nThe indirect evidence in favour of the belief of the former prevalence of\ncommunal marriages is strong, and rests chiefly on the terms of\nrelationship which are employed between the members of the same tribe,\nimplying a connection with the tribe, and not with either parent.  But the\nsubject is too large and complex for even an abstract to be here given, and\nI will confine myself to a few remarks.  It is evident in the case of such\nmarriages, or where the marriage tie is very loose, that the relationship\nof the child to its father cannot be known.  But it seems almost incredible\nthat the relationship of the child to its mother should ever be completely\nignored, especially as the women in most savage tribes nurse their infants\nfor a long time.  Accordingly, in many cases the lines of descent are\ntraced through the mother alone, to the exclusion of the father.  But in\nother cases the terms employed express a connection with the tribe alone,\nto the exclusion even of the mother.  It seems possible that the connection\nbetween the related members of the same barbarous tribe, exposed to all\nsorts of danger, might be so much more important, owing to the need of\nmutual protection and aid, than that between the mother and her child, as\nto lead to the sole use of terms expressive of the former relationships;\nbut Mr. Morgan is convinced that this view is by no means sufficient.\n\nThe terms of relationship used in different parts of the world may be\ndivided, according to the author just quoted, into two great classes, the\nclassificatory and descriptive, the latter being employed by us.  It is the\nclassificatory system which so strongly leads to the belief that communal\nand other extremely loose forms of marriage were originally universal.  But\nas far as I can see, there is no necessity on this ground for believing in\nabsolutely promiscuous intercourse; and I am glad to find that this is Sir\nJ. Lubbock's view.  Men and women, like many of the lower animals, might\nformerly have entered into strict though temporary unions for each birth,\nand in this case nearly as much confusion would have arisen in the terms of\nrelationship as in the case of promiscuous intercourse.  As far as sexual\nselection is concerned, all that is required is that choice should be\nexerted before the parents unite, and it signifies little whether the\nunions last for life or only for a season.\n\nBesides the evidence derived from the terms of relationship, other lines of\nreasoning indicate the former wide prevalence of communal marriage.  Sir J.\nLubbock accounts for the strange and widely-extended habit of exogamy--that\nis, the men of one tribe taking wives from a distinct tribe,--by communism\nhaving been the original form of intercourse; so that a man never obtained\na wife for himself unless he captured her from a neighbouring and hostile\ntribe, and then she would naturally have become his sole and valuable\nproperty.  Thus the practice of capturing wives might have arisen; and from\nthe honour so gained it might ultimately have become the universal habit.\nAccording to Sir J. Lubbock (6.  'Address to British Association On the\nSocial and Religious Condition of the Lower Races of Man,' 1870, p. 20.),\nwe can also thus understand \"the necessity of expiation for marriage as an\ninfringement of tribal rites, since according to old ideas, a man had no\nright to appropriate to himself that which belonged to the whole tribe.\"\nSir J. Lubbock further gives a curious body of facts shewing that in old\ntimes high honour was bestowed on women who were utterly licentious; and\nthis, as he explains, is intelligible, if we admit that promiscuous\nintercourse was the aboriginal, and therefore long revered custom of the\ntribe.  (7.  'Origin of Civilisation,' 1870, p. 86.  In the several works\nabove quoted, there will be found copious evidence on relationship through\nthe females alone, or with the tribe alone.)\n\nAlthough the manner of development of the marriage tie is an obscure\nsubject, as we may infer from the divergent opinions on several points\nbetween the three authors who have studied it most closely, namely, Mr.\nMorgan, Mr. M'Lennan, and Sir J. Lubbock, yet from the foregoing and\nseveral other lines of evidence it seems probable (8.  Mr. C. Staniland\nWake argues strongly ('Anthropologia,' March, 1874, p. 197) against the\nviews held by these three writers on the former prevalence of almost\npromiscuous intercourse; and he thinks that the classificatory system of\nrelationship can be otherwise explained.) that the habit of marriage, in\nany strict sense of the word, has been gradually developed; and that almost\npromiscuous or very loose intercourse was once extremely common throughout\nthe world.  Nevertheless, from the strength of the feeling of jealousy all\nthrough the animal kingdom, as well as from the analogy of the lower\nanimals, more particularly of those which come nearest to man, I cannot\nbelieve that absolutely promiscuous intercourse prevailed in times past,\nshortly before man attained to his present rank in the zoological scale.\nMan, as I have attempted to shew, is certainly descended from some ape-like\ncreature.  With the existing Quadrumana, as far as their habits are known,\nthe males of some species are monogamous, but live during only a part of\nthe year with the females:  of this the orang seems to afford an instance.\nSeveral kinds, for example some of the Indian and American monkeys, are\nstrictly monogamous, and associate all the year round with their wives.\nOthers are polygamous, for example the gorilla and several American\nspecies, and each family lives separate.  Even when this occurs, the\nfamilies inhabiting the same district are probably somewhat social; the\nchimpanzee, for instance, is occasionally met with in large bands.  Again,\nother species are polygamous, but several males, each with his own females,\nlive associated in a body, as with several species of baboons.  (9.  Brehm\n('Thierleben,' B. i. p. 77) says Cynocephalus hamadryas lives in great\ntroops containing twice as many adult females as adult males.  See Rengger\non American polygamous species, and Owen ('Anatomy of Vertebrates,' vol.\niii. p. 746) on American monogamous species.  Other references might be\nadded.)  We may indeed conclude from what we know of the jealousy of all\nmale quadrupeds, armed, as many of them are, with special weapons for\nbattling with their rivals, that promiscuous intercourse in a state of\nnature is extremely improbable.  The pairing may not last for life, but\nonly for each birth; yet if the males which are the strongest and best able\nto defend or otherwise assist their females and young, were to select the\nmore attractive females, this would suffice for sexual selection.\n\nTherefore, looking far enough back in the stream of time, and judging from\nthe social habits of man as he now exists, the most probable view is that\nhe aboriginally lived in small communities, each with a single wife, or if\npowerful with several, whom he jealously guarded against all other men.  Or\nhe may not have been a social animal, and yet have lived with several\nwives, like the gorilla; for all the natives \"agree that but one adult male\nis seen in a band; when the young male grows up, a contest takes place for\nmastery, and the strongest, by killing and driving out the others,\nestablishes himself as the head of the community.\"  (10.  Dr. Savage, in\n'Boston Journal of Natural History,' vol. v. 1845-47, p. 423.)  The younger\nmales, being thus expelled and wandering about, would, when at last\nsuccessful in finding a partner, prevent too close interbreeding within the\nlimits of the same family.\n\nAlthough savages are now extremely licentious, and although communal\nmarriages may formerly have largely prevailed, yet many tribes practise\nsome form of marriage, but of a far more lax nature than that of civilised\nnations.  Polygamy, as just stated, is almost universally followed by the\nleading men in every tribe.  Nevertheless there are tribes, standing almost\nat the bottom of the scale, which are strictly monogamous.  This is the\ncase with the Veddahs of Ceylon:  they have a saying, according to Sir J.\nLubbock (11.  'Prehistoric Times,' 1869, p. 424.), \"that death alone can\nseparate husband and wife.\"  An intelligent Kandyan chief, of course a\npolygamist, \"was perfectly scandalised at the utter barbarism of living\nwith only one wife, and never parting until separated by death.\"  It was,\nhe said, \"just like the Wanderoo monkeys.\"  Whether savages who now enter\ninto some form of marriage, either polygamous or monogamous, have retained\nthis habit from primeval times, or whether they have returned to some form\nof marriage, after passing through a stage of promiscuous intercourse, I\nwill not pretend to conjecture.\n\nINFANTICIDE.\n\nThis practice is now very common throughout the world, and there is reason\nto believe that it prevailed much more extensively during former times.\n(12.  Mr. M'Lennan, 'Primitive Marriage,' 1865.  See especially on exogamy\nand infanticide, pp. 130, 138, 165.)  Barbarians find it difficult to\nsupport themselves and their children, and it is a simple plan to kill\ntheir infants.  In South America some tribes, according to Azara, formerly\ndestroyed so many infants of both sexes that they were on the point of\nextinction.  In the Polynesian Islands women have been known to kill from\nfour or five, to even ten of their children; and Ellis could not find a\nsingle woman who had not killed at least one.  In a village on the eastern\nfrontier of India Colonel MacCulloch found not a single female child.\nWherever infanticide (13.  Dr. Gerland ('Ueber das Aussterben der\nNaturvoelker,' 1868) has collected much information on infanticide, see\nespecially ss. 27, 51, 54.  Azara ('Voyages,' etc., tom. ii. pp. 94, 116)\nenters in detail on the motives.  See also M'Lennan (ibid. p. 139) for\ncases in India.  In the former reprints of the 2nd edition of this book an\nincorrect quotation from Sir G. Grey was unfortunately given in the above\npassage and has now been removed from the text.) prevails the struggle for\nexistence will be in so far less severe, and all the members of the tribe\nwill have an almost equally good chance of rearing their few surviving\nchildren.  In most cases a larger number of female than of male infants are\ndestroyed, for it is obvious that the latter are of more value to the\ntribe, as they will, when grown up, aid in defending it, and can support\nthemselves.  But the trouble experienced by the women in rearing children,\ntheir consequent loss of beauty, the higher estimation set on them when\nfew, and their happier fate, are assigned by the women themselves, and by\nvarious observers, as additional motives for infanticide.\n\nWhen, owing to female infanticide, the women of a tribe were few, the habit\nof capturing wives from neighbouring tribes would naturally arise.  Sir J.\nLubbock, however, as we have seen, attributes the practice in chief part to\nthe former existence of communal marriage, and to the men having\nconsequently captured women from other tribes to hold as their sole\nproperty.  Additional causes might be assigned, such as the communities\nbeing very small, in which case, marriageable women would often be\ndeficient.  That the habit was most extensively practised during former\ntimes, even by the ancestors of civilised nations, is clearly shewn by the\npreservation of many curious customs and ceremonies, of which Mr. M'Lennan\nhas given an interesting account.  In our own marriages the \"best man\"\nseems originally to have been the chief abettor of the bridegroom in the\nact of capture.  Now as long as men habitually procured their wives through\nviolence and craft, they would have been glad to seize on any woman, and\nwould not have selected the more attractive ones.  But as soon as the\npractice of procuring wives from a distinct tribe was effected through\nbarter, as now occurs in many places, the more attractive women would\ngenerally have been purchased.  The incessant crossing, however, between\ntribe and tribe, which necessarily follows from any form of this habit,\nwould tend to keep all the people inhabiting the same country nearly\nuniform in character; and this would interfere with the power of sexual\nselection in differentiating the tribes.\n\nThe scarcity of women, consequent on female infanticide, leads, also, to\nanother practice, that of polyandry, still common in several parts of the\nworld, and which formerly, as Mr. M'Lennan believes, prevailed almost\nuniversally:  but this latter conclusion is doubted by Mr. Morgan and Sir\nJ. Lubbock.  (14.  'Primitive Marriage,' p. 208; Sir J. Lubbock, 'Origin of\nCivilisation,' p. 100.  See also Mr. Morgan, loc. cit., on the former\nprevalence of polyandry.)  Whenever two or more men are compelled to marry\none woman, it is certain that all the women of the tribe will get married,\nand there will be no selection by the men of the more attractive women.\nBut under these circumstances the women no doubt will have the power of\nchoice, and will prefer the more attractive men.  Azara, for instance,\ndescribes how carefully a Guana woman bargains for all sorts of privileges,\nbefore accepting some one or more husbands; and the men in consequence take\nunusual care of their personal appearance.  So amongst the Todas of India,\nwho practise polyandry, the girls can accept or refuse any man.  (15.\nAzara, 'Voyages,' etc., tom. ii. pp. 92-95; Colonel Marshall, 'Amongst the\nTodas,' p. 212.)  A very ugly man in these cases would perhaps altogether\nfail in getting a wife, or get one later in life; but the handsomer men,\nalthough more successful in obtaining wives, would not, as far as we can\nsee, leave more offspring to inherit their beauty than the less handsome\nhusbands of the same women.\n\nEARLY BETROTHALS AND SLAVERY OF WOMEN.\n\nWith many savages it is the custom to betroth the females whilst mere\ninfants; and this would effectually prevent preference being exerted on\neither side according to personal appearance.  But it would not prevent the\nmore attractive women from being afterwards stolen or taken by force from\ntheir husbands by the more powerful men; and this often happens in\nAustralia, America, and elsewhere.  The same consequences with reference to\nsexual selection would to a certain extent follow, when women are valued\nalmost solely as slaves or beasts of burden, as is the case with many\nsavages.  The men, however, at all times would prefer the handsomest slaves\naccording to their standard of beauty.\n\nWe thus see that several customs prevail with savages which must greatly\ninterfere with, or completely stop, the action of sexual selection.  On the\nother hand, the conditions of life to which savages are exposed, and some\nof their habits, are favourable to natural selection; and this comes into\nplay at the same time with sexual selection.  Savages are known to suffer\nseverely from recurrent famines; they do not increase their food by\nartificial means; they rarely refrain from marriage (16.  Burchell says\n('Travels in S. Africa,' vol. ii. 1824, p. 58), that among the wild nations\nof Southern Africa, neither men nor women ever pass their lives in a state\nof celibacy.  Azara ('Voyages dans l'Amerique Merid.' tom. ii. 1809, p. 21)\nmakes precisely the same remark in regard to the wild Indians of South\nAmerica.), and generally marry whilst young.  Consequently they must be\nsubjected to occasional hard struggles for existence, and the favoured\nindividuals will alone survive.\n\nAt a very early period, before man attained to his present rank in the\nscale, many of his conditions would be different from what now obtains\namongst savages.  Judging from the analogy of the lower animals, he would\nthen either live with a single female, or be a polygamist.  The most\npowerful and able males would succeed best in obtaining attractive females.\nThey would also succeed best in the general struggle for life, and in\ndefending their females, as well as their offspring, from enemies of all\nkinds.  At this early period the ancestors of man would not be sufficiently\nadvanced in intellect to look forward to distant contingencies; they would\nnot foresee that the rearing of all their children, especially their female\nchildren, would make the struggle for life severer for the tribe.  They\nwould be governed more by their instincts and less by their reason than are\nsavages at the present day.  They would not at that period have partially\nlost one of the strongest of all instincts, common to all the lower\nanimals, namely the love of their young offspring; and consequently they\nwould not have practised female infanticide.  Women would not have been\nthus rendered scarce, and polyandry would not have been practised; for\nhardly any other cause, except the scarcity of women seems sufficient to\nbreak down the natural and widely prevalent feeling of jealousy, and the\ndesire of each male to possess a female for himself.  Polyandry would be a\nnatural stepping-stone to communal marriages or almost promiscuous\nintercourse; though the best authorities believe that this latter habit\npreceded polyandry.  During primordial times there would be no early\nbetrothals, for this implies foresight.  Nor would women be valued merely\nas useful slaves or beasts of burthen.  Both sexes, if the females as well\nas the males were permitted to exert any choice, would choose their\npartners not for mental charms, or property, or social position, but almost\nsolely from external appearance.  All the adults would marry or pair, and\nall the offspring, as far as that was possible, would be reared; so that\nthe struggle for existence would be periodically excessively severe.  Thus\nduring these times all the conditions for sexual selection would have been\nmore favourable than at a later period, when man had advanced in his\nintellectual powers but had retrograded in his instincts.  Therefore,\nwhatever influence sexual selection may have had in producing the\ndifferences between the races of man, and between man and the higher\nQuadrumana, this influence would have been more powerful at a remote period\nthan at the present day, though probably not yet wholly lost.\n\nTHE MANNER OF ACTION OF SEXUAL SELECTION WITH MANKIND.\n\nWith primeval man under the favourable conditions just stated, and with\nthose savages who at the present time enter into any marriage tie, sexual\nselection has probably acted in the following manner, subject to greater or\nless interference from female infanticide, early betrothals, etc.  The\nstrongest and most vigorous men--those who could best defend and hunt for\ntheir families, who were provided with the best weapons and possessed the\nmost property, such as a large number of dogs or other animals,--would\nsucceed in rearing a greater average number of offspring than the weaker\nand poorer members of the same tribes.  There can, also, be no doubt that\nsuch men would generally be able to select the more attractive women.  At\npresent the chiefs of nearly every tribe throughout the world succeed in\nobtaining more than one wife.  I hear from Mr. Mantell that, until\nrecently, almost every girl in New Zealand who was pretty, or promised to\nbe pretty, was tapu to some chief.  With the Kafirs, as Mr. C. Hamilton\nstates (17.  'Anthropological Review,' Jan. 1870, p. xvi.), \"the chiefs\ngenerally have the pick of the women for many miles round, and are most\npersevering in establishing or confirming their privilege.\"  We have seen\nthat each race has its own style of beauty, and we know that it is natural\nto man to admire each characteristic point in his domestic animals, dress,\nornaments, and personal appearance, when carried a little beyond the\naverage.  If then the several foregoing propositions be admitted, and I\ncannot see that they are doubtful, it would be an inexplicable circumstance\nif the selection of the more attractive women by the more powerful men of\neach tribe, who would rear on an average a greater number of children, did\nnot after the lapse of many generations somewhat modify the character of\nthe tribe.\n\nWhen a foreign breed of our domestic animals is introduced into a new\ncountry, or when a native breed is long and carefully attended to, either\nfor use or ornament, it is found after several generations to have\nundergone a greater or less amount of change whenever the means of\ncomparison exist.  This follows from unconscious selection during a long\nseries of generations--that is, the preservation of the most approved\nindividuals--without any wish or expectation of such a result on the part\nof the breeder.  So again, if during many years two careful breeders rear\nanimals of the same family, and do not compare them together or with a\ncommon standard, the animals are found to have become, to the surprise of\ntheir owners, slightly different.  (18.  The 'Variation of Animals and\nPlants under Domestication,' vol. ii. pp. 210-217.)  Each breeder has\nimpressed, as von Nathusius well expresses it, the character of his own\nmind--his own taste and judgment--on his animals.  What reason, then, can\nbe assigned why similar results should not follow from the long-continued\nselection of the most admired women by those men of each tribe who were\nable to rear the greatest number of children?  This would be unconscious\nselection, for an effect would be produced, independently of any wish or\nexpectation on the part of the men who preferred certain women to others.\n\nLet us suppose the members of a tribe, practising some form of marriage, to\nspread over an unoccupied continent, they would soon split up into distinct\nhordes, separated from each other by various barriers, and still more\neffectually by the incessant wars between all barbarous nations.  The\nhordes would thus be exposed to slightly different conditions and habits of\nlife, and would sooner or later come to differ in some small degree.  As\nsoon as this occurred, each isolated tribe would form for itself a slightly\ndifferent standard of beauty (19.  An ingenious writer argues, from a\ncomparison of the pictures of Raphael, Rubens, and modern French artists,\nthat the idea of beauty is not absolutely the same even throughout Europe:\nsee the 'Lives of Haydn and Mozart,' by Bombet (otherwise M. Beyle),\nEnglish translation, p. 278.); and then unconscious selection would come\ninto action through the more powerful and leading men preferring certain\nwomen to others.  Thus the differences between the tribes, at first very\nslight, would gradually and inevitably be more or less increased.\n\nWith animals in a state of nature, many characters proper to the males,\nsuch as size, strength, special weapons, courage and pugnacity, have been\nacquired through the law of battle.  The semi-human progenitors of man,\nlike their allies the Quadrumana, will almost certainly have been thus\nmodified; and, as savages still fight for the possession of their women, a\nsimilar process of selection has probably gone on in a greater or less\ndegree to the present day.  Other characters proper to the males of the\nlower animals, such as bright colours and various ornaments, have been\nacquired by the more attractive males having been preferred by the females.\nThere are, however, exceptional cases in which the males are the selectors,\ninstead of having been the selected.  We recognise such cases by the\nfemales being more highly ornamented than the males,--their ornamental\ncharacters having been transmitted exclusively or chiefly to their female\noffspring.  One such case has been described in the order to which man\nbelongs, that of the Rhesus monkey.\n\nMan is more powerful in body and mind than woman, and in the savage state\nhe keeps her in a far more abject state of bondage than does the male of\nany other animal; therefore it is not surprising that he should have gained\nthe power of selection.  Women are everywhere conscious of the value of\ntheir own beauty; and when they have the means, they take more delight in\ndecorating themselves with all sorts of ornaments than do men.  They borrow\nthe plumes of male birds, with which nature has decked this sex, in order\nto charm the females.  As women have long been selected for beauty, it is\nnot surprising that some of their successive variations should have been\ntransmitted exclusively to the same sex; consequently that they should have\ntransmitted beauty in a somewhat higher degree to their female than to\ntheir male offspring, and thus have become more beautiful, according to\ngeneral opinion, than men.  Women, however, certainly transmit most of\ntheir characters, including some beauty, to their offspring of both sexes;\nso that the continued preference by the men of each race for the more\nattractive women, according to their standard of taste, will have tended to\nmodify in the same manner all the individuals of both sexes belonging to\nthe race.\n\nWith respect to the other form of sexual selection (which with the lower\nanimals is much the more common), namely, when the females are the\nselectors, and accept only those males which excite or charm them most, we\nhave reason to believe that it formerly acted on our progenitors.  Man in\nall probability owes his beard, and perhaps some other characters, to\ninheritance from an ancient progenitor who thus gained his ornaments.  But\nthis form of selection may have occasionally acted during later times; for\nin utterly barbarous tribes the women have more power in choosing,\nrejecting, and tempting their lovers, or of afterwards changing their\nhusbands, than might have been expected.  As this is a point of some\nimportance, I will give in detail such evidence as I have been able to\ncollect.\n\nHearne describes how a woman in one of the tribes of Arctic America\nrepeatedly ran away from her husband and joined her lover; and with the\nCharruas of S. America, according to Azara, divorce is quite optional.\nAmongst the Abipones, a man on choosing a wife bargains with the parents\nabout the price.  But \"it frequently happens that the girl rescinds what\nhas been agreed upon between the parents and the bridegroom, obstinately\nrejecting the very mention of marriage.\"  She often runs away, hides\nherself, and thus eludes the bridegroom.  Captain Musters who lived with\nthe Patagonians, says that their marriages are always settled by\ninclination; \"if the parents make a match contrary to the daughter's will,\nshe refuses and is never compelled to comply.\"  In Tierra del Fuego a young\nman first obtains the consent of the parents by doing them some service,\nand then he attempts to carry off the girl; \"but if she is unwilling, she\nhides herself in the woods until her admirer is heartily tired of looking\nfor her, and gives up the pursuit; but this seldom happens.\"  In the Fiji\nIslands the man seizes on the woman whom he wishes for his wife by actual\nor pretended force; but \"on reaching the home of her abductor, should she\nnot approve of the match, she runs to some one who can protect her; if,\nhowever, she is satisfied, the matter is settled forthwith.\"  With the\nKalmucks there is a regular race between the bride and bridegroom, the\nformer having a fair start; and Clarke \"was assured that no instance occurs\nof a girl being caught, unless she has a partiality to the pursuer.\"\nAmongst the wild tribes of the Malay Archipelago there is also a racing\nmatch; and it appears from M. Bourien's account, as Sir J. Lubbock remarks,\nthat \"the race, 'is not to the swift, nor the battle to the strong,' but to\nthe young man who has the good fortune to please his intended bride.\"  A\nsimilar custom, with the same result, prevails with the Koraks of North-\nEastern Asia.\n\nTurning to Africa:  the Kafirs buy their wives, and girls are severely\nbeaten by their fathers if they will not accept a chosen husband; but it is\nmanifest from many facts given by the Rev. Mr. Shooter, that they have\nconsiderable power of choice.  Thus very ugly, though rich men, have been\nknown to fail in getting wives.  The girls, before consenting to be\nbetrothed, compel the men to shew themselves off first in front and then\nbehind, and \"exhibit their paces.\"  They have been known to propose to a\nman, and they not rarely run away with a favoured lover.  So again, Mr.\nLeslie, who was intimately acquainted with the Kafirs, says, \"it is a\nmistake to imagine that a girl is sold by her father in the same manner,\nand with the same authority, with which he would dispose of a cow.\"\nAmongst the degraded Bushmen of S. Africa, \"when a girl has grown up to\nwomanhood without having been betrothed, which, however, does not often\nhappen, her lover must gain her approbation, as well as that of the\nparents.\"  (20.  Azara, 'Voyages,' etc., tom. ii. p. 23.  Dobrizhoffer, 'An\nAccount of the Abipones,' vol. ii. 1822, p. 207.  Capt. Musters, in 'Proc.\nR. Geograph. Soc.' vol. xv. p. 47.  Williams on the Fiji Islanders, as\nquoted by Lubbock, 'Origin of Civilisation,' 1870, p. 79.  On the Fuegians,\nKing and Fitzroy, 'Voyages of the \"Adventure\" and \"Beagle,\"' vol. ii. 1839,\np. 182.  On the Kalmucks, quoted by M'Lennan, 'Primitive Marriage,' 1865,\np. 32.  On the Malays, Lubbock, ibid. p. 76.  The Rev. J. Shooter, 'On the\nKafirs of Natal,' 1857, pp. 52-60.  Mr. D. Leslie, 'Kafir Character and\nCustoms,' 1871, p. 4.  On the Bush-men, Burchell, 'Travels in S. Africa,'\nii. 1824, p. 59.  On the Koraks by McKennan, as quoted by Mr. Wake, in\n'Anthropologia,' Oct. 1873, p. 75.)  Mr. Winwood Reade made inquiries for\nme with respect to the negroes of Western Africa, and he informs me that\n\"the women, at least among the more intelligent Pagan tribes, have no\ndifficulty in getting the husbands whom they may desire, although it is\nconsidered unwomanly to ask a man to marry them.  They are quite capable of\nfalling in love, and of forming tender, passionate, and faithful\nattachments.\"  Additional cases could be given.\n\nWe thus see that with savages the women are not in quite so abject a state\nin relation to marriage as has often been supposed.  They can tempt the men\nwhom they prefer, and can sometimes reject those whom they dislike, either\nbefore or after marriage.  Preference on the part of the women, steadily\nacting in any one direction, would ultimately affect the character of the\ntribe; for the women would generally choose not merely the handsomest men,\naccording to their standard of taste, but those who were at the same time\nbest able to defend and support them.  Such well-endowed pairs would\ncommonly rear a larger number of offspring than the less favoured.  The\nsame result would obviously follow in a still more marked manner if there\nwas selection on both sides; that is, if the more attractive, and at the\nsame time more powerful men were to prefer, and were preferred by, the more\nattractive women.  And this double form of selection seems actually to have\noccurred, especially during the earlier periods of our long history.\n\nWe will now examine a little more closely some of the characters which\ndistinguish the several races of man from one another and from the lower\nanimals, namely, the greater or less deficiency of hair on the body, and\nthe colour of the skin.  We need say nothing about the great diversity in\nthe shape of the features and of the skull between the different races, as\nwe have seen in the last chapter how different is the standard of beauty in\nthese respects.  These characters will therefore probably have been acted\non through sexual selection; but we have no means of judging whether they\nhave been acted on chiefly from the male or female side.  The musical\nfaculties of man have likewise been already discussed.\n\nABSENCE OF HAIR ON THE BODY, AND ITS DEVELOPMENT ON THE FACE AND HEAD.\n\nFrom the presence of the woolly hair or lanugo on the human foetus, and of\nrudimentary hairs scattered over the body during maturity, we may infer\nthat man is descended from some animal which was born hairy and remained so\nduring life.  The loss of hair is an inconvenience and probably an injury\nto man, even in a hot climate, for he is thus exposed to the scorching of\nthe sun, and to sudden chills, especially during wet weather.  As Mr.\nWallace remarks, the natives in all countries are glad to protect their\nnaked backs and shoulders with some slight covering.  No one supposes that\nthe nakedness of the skin is any direct advantage to man; his body\ntherefore cannot have been divested of hair through natural selection.\n(21.  'Contributions to the Theory of Natural Selection,' 1870, p. 346.\nMr. Wallace believes (p. 350) \"that some intelligent power has guided or\ndetermined the development of man\"; and he considers the hairless condition\nof the skin as coming under this head.  The Rev. T.R. Stebbing, in\ncommenting on this view ('Transactions of Devonshire Association for\nScience,' 1870) remarks, that had Mr. Wallace \"employed his usual ingenuity\non the question of man's hairless skin, he might have seen the possibility\nof its selection through its superior beauty or the health attaching to\nsuperior cleanliness.\")  Nor, as shewn in a former chapter, have we any\nevidence that this can be due to the direct action of climate, or that it\nis the result of correlated development.\n\nThe absence of hair on the body is to a certain extent a secondary sexual\ncharacter; for in all parts of the world women are less hairy than men.\nTherefore we may reasonably suspect that this character has been gained\nthrough sexual selection.  We know that the faces of several species of\nmonkeys, and large surfaces at the posterior end of the body of other\nspecies, have been denuded of hair; and this we may safely attribute to\nsexual selection, for these surfaces are not only vividly coloured, but\nsometimes, as with the male mandrill and female rhesus, much more vividly\nin the one sex than in the other, especially during the breeding-season.  I\nam informed by Mr. Bartlett that, as these animals gradually reach\nmaturity, the naked surfaces grow larger compared with the size of their\nbodies.  The hair, however, appears to have been removed, not for the sake\nof nudity, but that the colour of the skin may be more fully displayed.  So\nagain with many birds, it appears as if the head and neck had been divested\nof feathers through sexual selection, to exhibit the brightly-coloured\nskin.\n\nAs the body in woman is less hairy than in man, and as this character is\ncommon to all races, we may conclude that it was our female semi-human\nancestors who were first divested of hair, and that this occurred at an\nextremely remote period before the several races had diverged from a common\nstock.  Whilst our female ancestors were gradually acquiring this new\ncharacter of nudity, they must have transmitted it almost equally to their\noffspring of both sexes whilst young; so that its transmission, as with the\nornaments of many mammals and birds, has not been limited either by sex or\nage.  There is nothing surprising in a partial loss of hair having been\nesteemed as an ornament by our ape-like progenitors, for we have seen that\ninnumerable strange characters have been thus esteemed by animals of all\nkinds, and have consequently been gained through sexual selection.  Nor is\nit surprising that a slightly injurious character should have been thus\nacquired; for we know that this is the case with the plumes of certain\nbirds, and with the horns of certain stags.\n\nThe females of some of the anthropoid apes, as stated in a former chapter,\nare somewhat less hairy on the under surface than the males; and here we\nhave what might have afforded a commencement for the process of denudation.\nWith respect to the completion of the process through sexual selection, it\nis well to bear in mind the New Zealand proverb, \"There is no woman for a\nhairy man.\"  All who have seen photographs of the Siamese hairy family will\nadmit how ludicrously hideous is the opposite extreme of excessive\nhairiness.  And the king of Siam had to bribe a man to marry the first\nhairy woman in the family; and she transmitted this character to her young\noffspring of both sexes.  (22.  The 'Variation of Animals and Plants under\nDomestication,' vol. ii. 1868, p. 237.)\n\nSome races are much more hairy than others, especially the males; but it\nmust not be assumed that the more hairy races, such as the European, have\nretained their primordial condition more completely than the naked races,\nsuch as the Kalmucks or Americans.  It is more probable that the hairiness\nof the former is due to partial reversion; for characters which have been\nat some former period long inherited are always apt to return.  We have\nseen that idiots are often very hairy, and they are apt to revert in other\ncharacters to a lower animal type.  It does not appear that a cold climate\nhas been influential in leading to this kind of reversion; excepting\nperhaps with the negroes, who have been reared during several generations\nin the United States (23.  'Investigations into Military and\nAnthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p.\n568:--Observations were carefully made on the hairiness of 2129 black and\ncoloured soldiers, whilst they were bathing; and by looking to the\npublished table, \"it is manifest at a glance that there is but little, if\nany, difference between the white and the black races in this respect.\"  It\nis, however, certain that negroes in their native and much hotter land of\nAfrica, have remarkably smooth bodies.  It should be particularly observed,\nthat both pure blacks and mulattoes were included in the above enumeration;\nand this is an unfortunate circumstance, as in accordance with a principle,\nthe truth of which I have elsewhere proved, crossed races of man would be\neminently liable to revert to the primordial hairy character of their early\nape-like progenitors.), and possibly with the Ainos, who inhabit the\nnorthern islands of the Japan archipelago.  But the laws of inheritance are\nso complex that we can seldom understand their action.  If the greater\nhairiness of certain races be the result of reversion, unchecked by any\nform of selection, its extreme variability, even within the limits of the\nsame race, ceases to be remarkable.  (24.  Hardly any view advanced in this\nwork has met with so much disfavour (see for instance, Sprengel, 'Die\nFortschritte des Darwinismus,' 1874, p. 80) as the above explanation of the\nloss of hair in mankind through sexual selection; but none of the opposed\narguments seem to me of much weight, in comparison with the facts shewing\nthat the nudity of the skin is to a certain extent a secondary sexual\ncharacter in man and in some of the Quadrumana.)\n\nWith respect to the beard in man, if we turn to our best guide, the\nQuadrumana, we find beards equally developed in both sexes of many species,\nbut in some, either confined to the males, or more developed in them than\nin the females.  From this fact and from the curious arrangement, as well\nas the bright colours of the hair about the heads of many monkeys, it is\nhighly probable, as before explained, that the males first acquired their\nbeards through sexual selection as an ornament, transmitting them in most\ncases, equally or nearly so, to their offspring of both sexes.  We know\nfrom Eschricht (25.  'Ueber die Richtung der Haare am Menschlichen Koerper,'\nin Mueller's 'Archiv. fuer Anat. und Phys.' 1837, s. 40.) that with mankind\nthe female as well as the male foetus is furnished with much hair on the\nface, especially round the mouth; and this indicates that we are descended\nfrom progenitors of whom both sexes were bearded.  It appears therefore at\nfirst sight probable that man has retained his beard from a very early\nperiod, whilst woman lost her beard at the same time that her body became\nalmost completely divested of hair.  Even the colour of our beards seems to\nhave been inherited from an ape-like progenitor; for when there is any\ndifference in tint between the hair of the head and the beard, the latter\nis lighter coloured in all monkeys and in man.  In those Quadrumana in\nwhich the male has a larger beard than that of the female, it is fully\ndeveloped only at maturity, just as with mankind; and it is possible that\nonly the later stages of development have been retained by man.  In\nopposition to this view of the retention of the beard from an early period\nis the fact of its great variability in different races, and even within\nthe same race; for this indicates reversion,--long lost characters being\nvery apt to vary on re-appearance.\n\nNor must we overlook the part which sexual selection may have played in\nlater times; for we know that with savages the men of the beardless races\ntake infinite pains in eradicating every hair from their faces as something\nodious, whilst the men of the bearded races feel the greatest pride in\ntheir beards.  The women, no doubt, participate in these feelings, and if\nso sexual selection can hardly have failed to have effected something in\nthe course of later times.  It is also possible that the long-continued\nhabit of eradicating the hair may have produced an inherited effect.  Dr.\nBrown-Sequard has shewn that if certain animals are operated on in a\nparticular manner, their offspring are affected.  Further evidence could be\ngiven of the inheritance of the effects of mutilations; but a fact lately\nascertained by Mr. Salvin (26.  On the tail-feathers of Motmots,\n'Proceedings of the Zoological Society,' 1873, p. 429.) has a more direct\nbearing on the present question; for he has shewn that the motmots, which\nare known habitually to bite off the barbs of the two central tail-\nfeathers, have the barbs of these feathers naturally somewhat reduced.\n(27.  Mr. Sproat has suggested ('Scenes and Studies of Savage Life,' 1868,\np. 25) this same view.  Some distinguished ethnologists, amongst others M.\nGosse of Geneva, believe that artificial modifications of the skull tend to\nbe inherited.)  Nevertheless, with mankind the habit of eradicating the\nbeard and the hairs on the body would probably not have arisen until these\nhad already become by some means reduced.\n\nIt is difficult to form any judgment as to how the hair on the head became\ndeveloped to its present great length in many races.  Eschricht (28.\n'Ueber die Richtung,' ibid. s. 40.) states that in the human foetus the\nhair on the face during the fifth month is longer than that on the head;\nand this indicates that our semi-human progenitors were not furnished with\nlong tresses, which must therefore have been a late acquisition.  This is\nlikewise indicated by the extraordinary difference in the length of the\nhair in the different races; in the negro the hair forms a mere curly mat;\nwith us it is of great length, and with the American natives it not rarely\nreaches to the ground.  Some species of Semnopithecus have their heads\ncovered with moderately long hair, and this probably serves as an ornament\nand was acquired through sexual selection.  The same view may perhaps be\nextended to mankind, for we know that long tresses are now and were\nformerly much admired, as may be observed in the works of almost every\npoet; St. Paul says, \"if a woman have long hair, it is a glory to her;\" and\nwe have seen that in North America a chief was elected solely from the\nlength of his hair.\n\nCOLOUR OF THE SKIN.\n\nThe best kind of evidence that in man the colour of the skin has been\nmodified through sexual selection is scanty; for in most races the sexes do\nnot differ in this respect, and only slightly, as we have seen, in others.\nWe know, however, from the many facts already given that the colour of the\nskin is regarded by the men of all races as a highly important element in\ntheir beauty; so that it is a character which would be likely to have been\nmodified through selection, as has occurred in innumerable instances with\nthe lower animals.  It seems at first sight a monstrous supposition that\nthe jet-blackness of the negro should have been gained through sexual\nselection; but this view is supported by various analogies, and we know\nthat negroes admire their own colour.  With mammals, when the sexes differ\nin colour, the male is often black or much darker than the female; and it\ndepends merely on the form of inheritance whether this or any other tint is\ntransmitted to both sexes or to one alone.  The resemblance to a negro in\nminiature of Pithecia satanas with his jet black skin, white rolling\neyeballs, and hair parted on the top of the head, is almost ludicrous.\n\nThe colour of the face differs much more widely in the various kinds of\nmonkeys than it does in the races of man; and we have some reason to\nbelieve that the red, blue, orange, almost white and black tints of their\nskin, even when common to both sexes, as well as the bright colours of\ntheir fur, and the ornamental tufts about the head, have all been acquired\nthrough sexual selection.  As the order of development during growth,\ngenerally indicates the order in which the characters of a species have\nbeen developed and modified during previous generations; and as the newly-\nborn infants of the various races of man do not differ nearly as much in\ncolour as do the adults, although their bodies are as completely destitute\nof hair, we have some slight evidence that the tints of the different races\nwere acquired at a period subsequent to the removal of the hair, which must\nhave occurred at a very early period in the history of man.\n\nSUMMARY.\n\nWe may conclude that the greater size, strength, courage, pugnacity, and\nenergy of man, in comparison with woman, were acquired during primeval\ntimes, and have subsequently been augmented, chiefly through the contests\nof rival males for the possession of the females.  The greater intellectual\nvigour and power of invention in man is probably due to natural selection,\ncombined with the inherited effects of habit, for the most able men will\nhave succeeded best in defending and providing for themselves and for their\nwives and offspring.  As far as the extreme intricacy of the subject\npermits us to judge, it appears that our male ape-like progenitors acquired\ntheir beards as an ornament to charm or excite the opposite sex, and\ntransmitted them only to their male offspring.  The females apparently\nfirst had their bodies denuded of hair, also as a sexual ornament; but they\ntransmitted this character almost equally to both sexes.  It is not\nimprobable that the females were modified in other respects for the same\npurpose and by the same means; so that women have acquired sweeter voices\nand become more beautiful than men.\n\nIt deserves attention that with mankind the conditions were in many\nrespects much more favourable for sexual selection, during a very early\nperiod, when man had only just attained to the rank of manhood, than during\nlater times.  For he would then, as we may safely conclude, have been\nguided more by his instinctive passions, and less by foresight or reason.\nHe would have jealously guarded his wife or wives.  He would not have\npractised infanticide; nor valued his wives merely as useful slaves; nor\nhave been betrothed to them during infancy.  Hence we may infer that the\nraces of men were differentiated, as far as sexual selection is concerned,\nin chief part at a very remote epoch; and this conclusion throws light on\nthe remarkable fact that at the most ancient period, of which we have not\nas yet any record, the races of man had already come to differ nearly or\nquite as much as they do at the present day.\n\nThe views here advanced, on the part which sexual selection has played in\nthe history of man, want scientific precision.  He who does not admit this\nagency in the case of the lower animals, will disregard all that I have\nwritten in the later chapters on man.  We cannot positively say that this\ncharacter, but not that, has been thus modified; it has, however, been\nshewn that the races of man differ from each other and from their nearest\nallies, in certain characters which are of no service to them in their\ndaily habits of life, and which it is extremely probable would have been\nmodified through sexual selection.  We have seen that with the lowest\nsavages the people of each tribe admire their own characteristic\nqualities,--the shape of the head and face, the squareness of the cheek-\nbones, the prominence or depression of the nose, the colour of the skin,\nthe length of the hair on the head, the absence of hair on the face and\nbody, or the presence of a great beard, and so forth.  Hence these and\nother such points could hardly fail to be slowly and gradually exaggerated,\nfrom the more powerful and able men in each tribe, who would succeed in\nrearing the largest number of offspring, having selected during many\ngenerations for their wives the most strongly characterised and therefore\nmost attractive women.  For my own part I conclude that of all the causes\nwhich have led to the differences in external appearance between the races\nof man, and to a certain extent between man and the lower animals, sexual\nselection has been the most efficient.\n\n\nCHAPTER XXI.\n\nGENERAL SUMMARY AND CONCLUSION.\n\nMain conclusion that man is descended from some lower form--Manner of\ndevelopment--Genealogy of man--Intellectual and moral faculties--Sexual\nSelection--Concluding remarks.\n\nA brief summary will be sufficient to recall to the reader's mind the more\nsalient points in this work.  Many of the views which have been advanced\nare highly speculative, and some no doubt will prove erroneous; but I have\nin every case given the reasons which have led me to one view rather than\nto another.  It seemed worth while to try how far the principle of\nevolution would throw light on some of the more complex problems in the\nnatural history of man.  False facts are highly injurious to the progress\nof science, for they often endure long; but false views, if supported by\nsome evidence, do little harm, for every one takes a salutary pleasure in\nproving their falseness:  and when this is done, one path towards error is\nclosed and the road to truth is often at the same time opened.\n\nThe main conclusion here arrived at, and now held by many naturalists who\nare well competent to form a sound judgment, is that man is descended from\nsome less highly organised form.  The grounds upon which this conclusion\nrests will never be shaken, for the close similarity between man and the\nlower animals in embryonic development, as well as in innumerable points of\nstructure and constitution, both of high and of the most trifling\nimportance,--the rudiments which he retains, and the abnormal reversions to\nwhich he is occasionally liable,--are facts which cannot be disputed.  They\nhave long been known, but until recently they told us nothing with respect\nto the origin of man.  Now when viewed by the light of our knowledge of the\nwhole organic world, their meaning is unmistakable.  The great principle of\nevolution stands up clear and firm, when these groups or facts are\nconsidered in connection with others, such as the mutual affinities of the\nmembers of the same group, their geographical distribution in past and\npresent times, and their geological succession.  It is incredible that all\nthese facts should speak falsely.  He who is not content to look, like a\nsavage, at the phenomena of nature as disconnected, cannot any longer\nbelieve that man is the work of a separate act of creation.  He will be\nforced to admit that the close resemblance of the embryo of man to that,\nfor instance, of a dog--the construction of his skull, limbs and whole\nframe on the same plan with that of other mammals, independently of the\nuses to which the parts may be put--the occasional re-appearance of various\nstructures, for instance of several muscles, which man does not normally\npossess, but which are common to the Quadrumana--and a crowd of analogous\nfacts--all point in the plainest manner to the conclusion that man is the\nco-descendant with other mammals of a common progenitor.\n\nWe have seen that man incessantly presents individual differences in all\nparts of his body and in his mental faculties.  These differences or\nvariations seem to be induced by the same general causes, and to obey the\nsame laws as with the lower animals.  In both cases similar laws of\ninheritance prevail.  Man tends to increase at a greater rate than his\nmeans of subsistence; consequently he is occasionally subjected to a severe\nstruggle for existence, and natural selection will have effected whatever\nlies within its scope.  A succession of strongly-marked variations of a\nsimilar nature is by no means requisite; slight fluctuating differences in\nthe individual suffice for the work of natural selection; not that we have\nany reason to suppose that in the same species, all parts of the\norganisation tend to vary to the same degree.  We may feel assured that the\ninherited effects of the long-continued use or disuse of parts will have\ndone much in the same direction with natural selection.  Modifications\nformerly of importance, though no longer of any special use, are long-\ninherited.  When one part is modified, other parts change through the\nprinciple of correlation, of which we have instances in many curious cases\nof correlated monstrosities.  Something may be attributed to the direct and\ndefinite action of the surrounding conditions of life, such as abundant\nfood, heat or moisture; and lastly, many characters of slight physiological\nimportance, some indeed of considerable importance, have been gained\nthrough sexual selection.\n\nNo doubt man, as well as every other animal, presents structures, which\nseem to our limited knowledge, not to be now of any service to him, nor to\nhave been so formerly, either for the general conditions of life, or in the\nrelations of one sex to the other.  Such structures cannot be accounted for\nby any form of selection, or by the inherited effects of the use and disuse\nof parts.  We know, however, that many strange and strongly-marked\npeculiarities of structure occasionally appear in our domesticated\nproductions, and if their unknown causes were to act more uniformly, they\nwould probably become common to all the individuals of the species.  We may\nhope hereafter to understand something about the causes of such occasional\nmodifications, especially through the study of monstrosities:  hence the\nlabours of experimentalists, such as those of M. Camille Dareste, are full\nof promise for the future.  In general we can only say that the cause of\neach slight variation and of each monstrosity lies much more in the\nconstitution of the organism, than in the nature of the surrounding\nconditions; though new and changed conditions certainly play an important\npart in exciting organic changes of many kinds.\n\nThrough the means just specified, aided perhaps by others as yet\nundiscovered, man has been raised to his present state.  But since he\nattained to the rank of manhood, he has diverged into distinct races, or as\nthey may be more fitly called, sub-species.  Some of these, such as the\nNegro and European, are so distinct that, if specimens had been brought to\na naturalist without any further information, they would undoubtedly have\nbeen considered by him as good and true species.  Nevertheless all the\nraces agree in so many unimportant details of structure and in so many\nmental peculiarities that these can be accounted for only by inheritance\nfrom a common progenitor; and a progenitor thus characterised would\nprobably deserve to rank as man.\n\nIt must not be supposed that the divergence of each race from the other\nraces, and of all from a common stock, can be traced back to any one pair\nof progenitors.  On the contrary, at every stage in the process of\nmodification, all the individuals which were in any way better fitted for\ntheir conditions of life, though in different degrees, would have survived\nin greater numbers than the less well-fitted.  The process would have been\nlike that followed by man, when he does not intentionally select particular\nindividuals, but breeds from all the superior individuals, and neglects the\ninferior.  He thus slowly but surely modifies his stock, and unconsciously\nforms a new strain.  So with respect to modifications acquired\nindependently of selection, and due to variations arising from the nature\nof the organism and the action of the surrounding conditions, or from\nchanged habits of life, no single pair will have been modified much more\nthan the other pairs inhabiting the same country, for all will have been\ncontinually blended through free intercrossing.\n\nBy considering the embryological structure of man,--the homologies which he\npresents with the lower animals,--the rudiments which he retains,--and the\nreversions to which he is liable, we can partly recall in imagination the\nformer condition of our early progenitors; and can approximately place them\nin their proper place in the zoological series.  We thus learn that man is\ndescended from a hairy, tailed quadruped, probably arboreal in its habits,\nand an inhabitant of the Old World.  This creature, if its whole structure\nhad been examined by a naturalist, would have been classed amongst the\nQuadrumana, as surely as the still more ancient progenitor of the Old and\nNew World monkeys.  The Quadrumana and all the higher mammals are probably\nderived from an ancient marsupial animal, and this through a long line of\ndiversified forms, from some amphibian-like creature, and this again from\nsome fish-like animal.  In the dim obscurity of the past we can see that\nthe early progenitor of all the Vertebrata must have been an aquatic\nanimal, provided with branchiae, with the two sexes united in the same\nindividual, and with the most important organs of the body (such as the\nbrain and heart) imperfectly or not at all developed.  This animal seems to\nhave been more like the larvae of the existing marine Ascidians than any\nother known form.\n\nThe high standard of our intellectual powers and moral disposition is the\ngreatest difficulty which presents itself, after we have been driven to\nthis conclusion on the origin of man.  But every one who admits the\nprinciple of evolution, must see that the mental powers of the higher\nanimals, which are the same in kind with those of man, though so different\nin degree, are capable of advancement.  Thus the interval between the\nmental powers of one of the higher apes and of a fish, or between those of\nan ant and scale-insect, is immense; yet their development does not offer\nany special difficulty; for with our domesticated animals, the mental\nfaculties are certainly variable, and the variations are inherited.  No one\ndoubts that they are of the utmost importance to animals in a state of\nnature.  Therefore the conditions are favourable for their development\nthrough natural selection.  The same conclusion may be extended to man; the\nintellect must have been all-important to him, even at a very remote\nperiod, as enabling him to invent and use language, to make weapons, tools,\ntraps, etc., whereby with the aid of his social habits, he long ago became\nthe most dominant of all living creatures.\n\nA great stride in the development of the intellect will have followed, as\nsoon as the half-art and half-instinct of language came into use; for the\ncontinued use of language will have reacted on the brain and produced an\ninherited effect; and this again will have reacted on the improvement of\nlanguage.  As Mr. Chauncey Wright (1.  'On the Limits of Natural\nSelection,' in the 'North American Review,' Oct. 1870, p. 295.) has well\nremarked, the largeness of the brain in man relatively to his body,\ncompared with the lower animals, may be attributed in chief part to the\nearly use of some simple form of language,--that wonderful engine which\naffixes signs to all sorts of objects and qualities, and excites trains of\nthought which would never arise from the mere impression of the senses, or\nif they did arise could not be followed out.  The higher intellectual\npowers of man, such as those of ratiocination, abstraction, self-\nconsciousness, etc., probably follow from the continued improvement and\nexercise of the other mental faculties.\n\nThe development of the moral qualities is a more interesting problem.  The\nfoundation lies in the social instincts, including under this term the\nfamily ties.  These instincts are highly complex, and in the case of the\nlower animals give special tendencies towards certain definite actions; but\nthe more important elements are love, and the distinct emotion of sympathy.\nAnimals endowed with the social instincts take pleasure in one another's\ncompany, warn one another of danger, defend and aid one another in many\nways.  These instincts do not extend to all the individuals of the species,\nbut only to those of the same community.  As they are highly beneficial to\nthe species, they have in all probability been acquired through natural\nselection.\n\nA moral being is one who is capable of reflecting on his past actions and\ntheir motives--of approving of some and disapproving of others; and the\nfact that man is the one being who certainly deserves this designation, is\nthe greatest of all distinctions between him and the lower animals.  But in\nthe fourth chapter I have endeavoured to shew that the moral sense follows,\nfirstly, from the enduring and ever-present nature of the social instincts;\nsecondly, from man's appreciation of the approbation and disapprobation of\nhis fellows; and thirdly, from the high activity of his mental faculties,\nwith past impressions extremely vivid; and in these latter respects he\ndiffers from the lower animals.  Owing to this condition of mind, man\ncannot avoid looking both backwards and forwards, and comparing past\nimpressions.  Hence after some temporary desire or passion has mastered his\nsocial instincts, he reflects and compares the now weakened impression of\nsuch past impulses with the ever-present social instincts; and he then\nfeels that sense of dissatisfaction which all unsatisfied instincts leave\nbehind them, he therefore resolves to act differently for the future,--and\nthis is conscience.  Any instinct, permanently stronger or more enduring\nthan another, gives rise to a feeling which we express by saying that it\nought to be obeyed.  A pointer dog, if able to reflect on his past conduct,\nwould say to himself, I ought (as indeed we say of him) to have pointed at\nthat hare and not have yielded to the passing temptation of hunting it.\n\nSocial animals are impelled partly by a wish to aid the members of their\ncommunity in a general manner, but more commonly to perform certain\ndefinite actions.  Man is impelled by the same general wish to aid his\nfellows; but has few or no special instincts.  He differs also from the\nlower animals in the power of expressing his desires by words, which thus\nbecome a guide to the aid required and bestowed.  The motive to give aid is\nlikewise much modified in man:  it no longer consists solely of a blind\ninstinctive impulse, but is much influenced by the praise or blame of his\nfellows.  The appreciation and the bestowal of praise and blame both rest\non sympathy; and this emotion, as we have seen, is one of the most\nimportant elements of the social instincts.  Sympathy, though gained as an\ninstinct, is also much strengthened by exercise or habit.  As all men\ndesire their own happiness, praise or blame is bestowed on actions and\nmotives, according as they lead to this end; and as happiness is an\nessential part of the general good, the greatest-happinesss principle\nindirectly serves as a nearly safe standard of right and wrong.  As the\nreasoning powers advance and experience is gained, the remoter effects of\ncertain lines of conduct on the character of the individual, and on the\ngeneral good, are perceived; and then the self-regarding virtues come\nwithin the scope of public opinion, and receive praise, and their opposites\nblame.  But with the less civilised nations reason often errs, and many bad\ncustoms and base superstitions come within the same scope, and are then\nesteemed as high virtues, and their breach as heavy crimes.\n\nThe moral faculties are generally and justly esteemed as of higher value\nthan the intellectual powers.  But we should bear in mind that the activity\nof the mind in vividly recalling past impressions is one of the fundamental\nthough secondary bases of conscience.  This affords the strongest argument\nfor educating and stimulating in all possible ways the intellectual\nfaculties of every human being.  No doubt a man with a torpid mind, if his\nsocial affections and sympathies are well developed, will be led to good\nactions, and may have a fairly sensitive conscience.  But whatever renders\nthe imagination more vivid and strengthens the habit of recalling and\ncomparing past impressions, will make the conscience more sensitive, and\nmay even somewhat compensate for weak social affections and sympathies.\n\nThe moral nature of man has reached its present standard, partly through\nthe advancement of his reasoning powers and consequently of a just public\nopinion, but especially from his sympathies having been rendered more\ntender and widely diffused through the effects of habit, example,\ninstruction, and reflection.  It is not improbable that after long practice\nvirtuous tendencies may be inherited.  With the more civilised races, the\nconviction of the existence of an all-seeing Deity has had a potent\ninfluence on the advance of morality.  Ultimately man does not accept the\npraise or blame of his fellows as his sole guide, though few escape this\ninfluence, but his habitual convictions, controlled by reason, afford him\nthe safest rule.  His conscience then becomes the supreme judge and\nmonitor.  Nevertheless the first foundation or origin of the moral sense\nlies in the social instincts, including sympathy; and these instincts no\ndoubt were primarily gained, as in the case of the lower animals, through\nnatural selection.\n\nThe belief in God has often been advanced as not only the greatest, but the\nmost complete of all the distinctions between man and the lower animals.\nIt is however impossible, as we have seen, to maintain that this belief is\ninnate or instinctive in man.  On the other hand a belief in all-pervading\nspiritual agencies seems to be universal; and apparently follows from a\nconsiderable advance in man's reason, and from a still greater advance in\nhis faculties of imagination, curiosity and wonder.  I am aware that the\nassumed instinctive belief in God has been used by many persons as an\nargument for His existence.  But this is a rash argument, as we should thus\nbe compelled to believe in the existence of many cruel and malignant\nspirits, only a little more powerful than man; for the belief in them is\nfar more general than in a beneficent Deity.  The idea of a universal and\nbeneficent Creator does not seem to arise in the mind of man, until he has\nbeen elevated by long-continued culture.\n\nHe who believes in the advancement of man from some low organised form,\nwill naturally ask how does this bear on the belief in the immortality of\nthe soul.  The barbarous races of man, as Sir J. Lubbock has shewn, possess\nno clear belief of this kind; but arguments derived from the primeval\nbeliefs of savages are, as we have just seen, of little or no avail.  Few\npersons feel any anxiety from the impossibility of determining at what\nprecise period in the development of the individual, from the first trace\nof a minute germinal vesicle, man becomes an immortal being; and there is\nno greater cause for anxiety because the period cannot possibly be\ndetermined in the gradually ascending organic scale.  (2.  The Rev. J.A.\nPicton gives a discussion to this effect in his 'New Theories and the Old\nFaith,' 1870.)\n\nI am aware that the conclusions arrived at in this work will be denounced\nby some as highly irreligious; but he who denounces them is bound to shew\nwhy it is more irreligious to explain the origin of man as a distinct\nspecies by descent from some lower form, through the laws of variation and\nnatural selection, than to explain the birth of the individual through the\nlaws of ordinary reproduction.  The birth both of the species and of the\nindividual are equally parts of that grand sequence of events, which our\nminds refuse to accept as the result of blind chance.  The understanding\nrevolts at such a conclusion, whether or not we are able to believe that\nevery slight variation of structure,--the union of each pair in marriage,\nthe dissemination of each seed,--and other such events, have all been\nordained for some special purpose.\n\nSexual selection has been treated at great length in this work; for, as I\nhave attempted to shew, it has played an important part in the history of\nthe organic world.  I am aware that much remains doubtful, but I have\nendeavoured to give a fair view of the whole case.  In the lower divisions\nof the animal kingdom, sexual selection seems to have done nothing:  such\nanimals are often affixed for life to the same spot, or have the sexes\ncombined in the same individual, or what is still more important, their\nperceptive and intellectual faculties are not sufficiently advanced to\nallow of the feelings of love and jealousy, or of the exertion of choice.\nWhen, however, we come to the Arthropoda and Vertebrata, even to the lowest\nclasses in these two great Sub-Kingdoms, sexual selection has effected\nmuch.\n\nIn the several great classes of the animal kingdom,--in mammals, birds,\nreptiles, fishes, insects, and even crustaceans,--the differences between\nthe sexes follow nearly the same rules.  The males are almost always the\nwooers; and they alone are armed with special weapons for fighting with\ntheir rivals.  They are generally stronger and larger than the females, and\nare endowed with the requisite qualities of courage and pugnacity.  They\nare provided, either exclusively or in a much higher degree than the\nfemales, with organs for vocal or instrumental music, and with odoriferous\nglands.  They are ornamented with infinitely diversified appendages, and\nwith the most brilliant or conspicuous colours, often arranged in elegant\npatterns, whilst the females are unadorned.  When the sexes differ in more\nimportant structures, it is the male which is provided with special sense-\norgans for discovering the female, with locomotive organs for reaching her,\nand often with prehensile organs for holding her.  These various structures\nfor charming or securing the female are often developed in the male during\nonly part of the year, namely the breeding-season.  They have in many cases\nbeen more or less transferred to the females; and in the latter case they\noften appear in her as mere rudiments.  They are lost or never gained by\nthe males after emasculation.  Generally they are not developed in the male\nduring early youth, but appear a short time before the age for\nreproduction.  Hence in most cases the young of both sexes resemble each\nother; and the female somewhat resembles her young offspring throughout\nlife.  In almost every great class a few anomalous cases occur, where there\nhas been an almost complete transposition of the characters proper to the\ntwo sexes; the females assuming characters which properly belong to the\nmales.  This surprising uniformity in the laws regulating the differences\nbetween the sexes in so many and such widely separated classes, is\nintelligible if we admit the action of one common cause, namely sexual\nselection.\n\nSexual selection depends on the success of certain individuals over others\nof the same sex, in relation to the propagation of the species; whilst\nnatural selection depends on the success of both sexes, at all ages, in\nrelation to the general conditions of life.  The sexual struggle is of two\nkinds; in the one it is between individuals of the same sex, generally the\nmales, in order to drive away or kill their rivals, the females remaining\npassive; whilst in the other, the struggle is likewise between the\nindividuals of the same sex, in order to excite or charm those of the\nopposite sex, generally the females, which no longer remain passive, but\nselect the more agreeable partners.  This latter kind of selection is\nclosely analogous to that which man unintentionally, yet effectually,\nbrings to bear on his domesticated productions, when he preserves during a\nlong period the most pleasing or useful individuals, without any wish to\nmodify the breed.\n\nThe laws of inheritance determine whether characters gained through sexual\nselection by either sex shall be transmitted to the same sex, or to both;\nas well as the age at which they shall be developed.  It appears that\nvariations arising late in life are commonly transmitted to one and the\nsame sex.  Variability is the necessary basis for the action of selection,\nand is wholly independent of it.  It follows from this, that variations of\nthe same general nature have often been taken advantage of and accumulated\nthrough sexual selection in relation to the propagation of the species, as\nwell as through natural selection in relation to the general purposes of\nlife.  Hence secondary sexual characters, when equally transmitted to both\nsexes can be distinguished from ordinary specific characters only by the\nlight of analogy.  The modifications acquired through sexual selection are\noften so strongly pronounced that the two sexes have frequently been ranked\nas distinct species, or even as distinct genera.  Such strongly-marked\ndifferences must be in some manner highly important; and we know that they\nhave been acquired in some instances at the cost not only of inconvenience,\nbut of exposure to actual danger.\n\nThe belief in the power of sexual selection rests chiefly on the following\nconsiderations.  Certain characters are confined to one sex; and this alone\nrenders it probable that in most cases they are connected with the act of\nreproduction.  In innumerable instances these characters are fully\ndeveloped only at maturity, and often during only a part of the year, which\nis always the breeding-season.  The males (passing over a few exceptional\ncases) are the more active in courtship; they are the better armed, and are\nrendered the more attractive in various ways.  It is to be especially\nobserved that the males display their attractions with elaborate care in\nthe presence of the females; and that they rarely or never display them\nexcepting during the season of love.  It is incredible that all this should\nbe purposeless.  Lastly we have distinct evidence with some quadrupeds and\nbirds, that the individuals of one sex are capable of feeling a strong\nantipathy or preference for certain individuals of the other sex.\n\nBearing in mind these facts, and the marked results of man's unconscious\nselection, when applied to domesticated animals and cultivated plants, it\nseems to me almost certain that if the individuals of one sex were during a\nlong series of generations to prefer pairing with certain individuals of\nthe other sex, characterised in some peculiar manner, the offspring would\nslowly but surely become modified in this same manner.  I have not\nattempted to conceal that, excepting when the males are more numerous than\nthe females, or when polygamy prevails, it is doubtful how the more\nattractive males succeed in leaving a large number of offspring to inherit\ntheir superiority in ornaments or other charms than the less attractive\nmales; but I have shewn that this would probably follow from the females,--\nespecially the more vigorous ones, which would be the first to breed,--\npreferring not only the more attractive but at the same time the more\nvigorous and victorious males.\n\nAlthough we have some positive evidence that birds appreciate bright and\nbeautiful objects, as with the bower-birds of Australia, and although they\ncertainly appreciate the power of song, yet I fully admit that it is\nastonishing that the females of many birds and some mammals should be\nendowed with sufficient taste to appreciate ornaments, which we have reason\nto attribute to sexual selection; and this is even more astonishing in the\ncase of reptiles, fish, and insects.  But we really know little about the\nminds of the lower animals.  It cannot be supposed, for instance, that male\nbirds of paradise or peacocks should take such pains in erecting,\nspreading, and vibrating their beautiful plumes before the females for no\npurpose.  We should remember the fact given on excellent authority in a\nformer chapter, that several peahens, when debarred from an admired male,\nremained widows during a whole season rather than pair with another bird.\n\nNevertheless I know of no fact in natural history more wonderful than that\nthe female Argus pheasant should appreciate the exquisite shading of the\nball-and-socket ornaments and the elegant patterns on the wing-feather of\nthe male.  He who thinks that the male was created as he now exists must\nadmit that the great plumes, which prevent the wings from being used for\nflight, and which are displayed during courtship and at no other time in a\nmanner quite peculiar to this one species, were given to him as an\nornament.  If so, he must likewise admit that the female was created and\nendowed with the capacity of appreciating such ornaments.  I differ only in\nthe conviction that the male Argus pheasant acquired his beauty gradually,\nthrough the preference of the females during many generations for the more\nhighly ornamented males; the aesthetic capacity of the females having been\nadvanced through exercise or habit, just as our own taste is gradually\nimproved.  In the male through the fortunate chance of a few feathers being\nleft unchanged, we can distinctly trace how simple spots with a little\nfulvous shading on one side may have been developed by small steps into the\nwonderful ball-and-socket ornaments; and it is probable that they were\nactually thus developed.\n\nEveryone who admits the principle of evolution, and yet feels great\ndifficulty in admitting that female mammals, birds, reptiles, and fish,\ncould have acquired the high taste implied by the beauty of the males, and\nwhich generally coincides with our own standard, should reflect that the\nnerve-cells of the brain in the highest as well as in the lowest members of\nthe Vertebrate series, are derived from those of the common progenitor of\nthis great Kingdom.  For we can thus see how it has come to pass that\ncertain mental faculties, in various and widely distinct groups of animals,\nhave been developed in nearly the same manner and to nearly the same\ndegree.\n\nThe reader who has taken the trouble to go through the several chapters\ndevoted to sexual selection, will be able to judge how far the conclusions\nat which I have arrived are supported by sufficient evidence.  If he\naccepts these conclusions he may, I think, safely extend them to mankind;\nbut it would be superfluous here to repeat what I have so lately said on\nthe manner in which sexual selection apparently has acted on man, both on\nthe male and female side, causing the two sexes to differ in body and mind,\nand the several races to differ from each other in various characters, as\nwell as from their ancient and lowly-organised progenitors.\n\nHe who admits the principle of sexual selection will be led to the\nremarkable conclusion that the nervous system not only regulates most of\nthe existing functions of the body, but has indirectly influenced the\nprogressive development of various bodily structures and of certain mental\nqualities.  Courage, pugnacity, perseverance, strength and size of body,\nweapons of all kinds, musical organs, both vocal and instrumental, bright\ncolours and ornamental appendages, have all been indirectly gained by the\none sex or the other, through the exertion of choice, the influence of love\nand jealousy, and the appreciation of the beautiful in sound, colour or\nform; and these powers of the mind manifestly depend on the development of\nthe brain.\n\nMan scans with scrupulous care the character and pedigree of his horses,\ncattle, and dogs before he matches them; but when he comes to his own\nmarriage he rarely, or never, takes any such care.  He is impelled by\nnearly the same motives as the lower animals, when they are left to their\nown free choice, though he is in so far superior to them that he highly\nvalues mental charms and virtues.  On the other hand he is strongly\nattracted by mere wealth or rank.  Yet he might by selection do something\nnot only for the bodily constitution and frame of his offspring, but for\ntheir intellectual and moral qualities.  Both sexes ought to refrain from\nmarriage if they are in any marked degree inferior in body or mind; but\nsuch hopes are Utopian and will never be even partially realised until the\nlaws of inheritance are thoroughly known.  Everyone does good service, who\naids towards this end.  When the principles of breeding and inheritance are\nbetter understood, we shall not hear ignorant members of our legislature\nrejecting with scorn a plan for ascertaining whether or not consanguineous\nmarriages are injurious to man.\n\nThe advancement of the welfare of mankind is a most intricate problem:  all\nought to refrain from marriage who cannot avoid abject poverty for their\nchildren; for poverty is not only a great evil, but tends to its own\nincrease by leading to recklessness in marriage.  On the other hand, as Mr.\nGalton has remarked, if the prudent avoid marriage, whilst the reckless\nmarry, the inferior members tend to supplant the better members of society.\nMan, like every other animal, has no doubt advanced to his present high\ncondition through a struggle for existence consequent on his rapid\nmultiplication; and if he is to advance still higher, it is to be feared\nthat he must remain subject to a severe struggle.  Otherwise he would sink\ninto indolence, and the more gifted men would not be more successful in the\nbattle of life than the less gifted.  Hence our natural rate of increase,\nthough leading to many and obvious evils, must not be greatly diminished by\nany means.  There should be open competition for all men; and the most able\nshould not be prevented by laws or customs from succeeding best and rearing\nthe largest number of offspring.  Important as the struggle for existence\nhas been and even still is, yet as far as the highest part of man's nature\nis concerned there are other agencies more important.  For the moral\nqualities are advanced, either directly or indirectly, much more through\nthe effects of habit, the reasoning powers, instruction, religion, etc.,\nthan through natural selection; though to this latter agency may be safely\nattributed the social instincts, which afforded the basis for the\ndevelopment of the moral sense.\n\nThe main conclusion arrived at in this work, namely, that man is descended\nfrom some lowly organised form, will, I regret to think, be highly\ndistasteful to many.  But there can hardly be a doubt that we are descended\nfrom barbarians.  The astonishment which I felt on first seeing a party of\nFuegians on a wild and broken shore will never be forgotten by me, for the\nreflection at once rushed into my mind--such were our ancestors.  These men\nwere absolutely naked and bedaubed with paint, their long hair was tangled,\ntheir mouths frothed with excitement, and their expression was wild,\nstartled, and distrustful.  They possessed hardly any arts, and like wild\nanimals lived on what they could catch; they had no government, and were\nmerciless to every one not of their own small tribe.  He who has seen a\nsavage in his native land will not feel much shame, if forced to\nacknowledge that the blood of some more humble creature flows in his veins.\nFor my own part I would as soon be descended from that heroic little\nmonkey, who braved his dreaded enemy in order to save the life of his\nkeeper, or from that old baboon, who descending from the mountains, carried\naway in triumph his young comrade from a crowd of astonished dogs--as from\na savage who delights to torture his enemies, offers up bloody sacrifices,\npractices infanticide without remorse, treats his wives like slaves, knows\nno decency, and is haunted by the grossest superstitions.\n\nMan may be excused for feeling some pride at having risen, though not\nthrough his own exertions, to the very summit of the organic scale; and the\nfact of his having thus risen, instead of having been aboriginally placed\nthere, may give him hope for a still higher destiny in the distant future.\nBut we are not here concerned with hopes or fears, only with the truth as\nfar as our reason permits us to discover it; and I have given the evidence\nto the best of my ability.  We must, however, acknowledge, as it seems to\nme, that man with all his noble qualities, with sympathy which feels for\nthe most debased, with benevolence which extends not only to other men but\nto the humblest living creature, with his god-like intellect which has\npenetrated into the movements and constitution of the solar system--with\nall these exalted powers--Man still bears in his bodily frame the indelible\nstamp of his lowly origin.\n\n\nSUPPLEMENTAL NOTE.\n\nON SEXUAL SELECTION IN RELATION TO MONKEYS.\n\nReprinted from NATURE, November 2, 1876, p. 18.\n\nIn the discussion on Sexual Selection in my 'Descent of Man,' no case\ninterested and perplexed me so much as the brightly-coloured hinder ends\nand adjoining parts of certain monkeys.  As these parts are more brightly\ncoloured in one sex than the other, and as they become more brilliant\nduring the season of love, I concluded that the colours had been gained as\na sexual attraction.  I was well aware that I thus laid myself open to\nridicule; though in fact it is not more surprising that a monkey should\ndisplay his bright-red hinder end than that a peacock should display his\nmagnificent tail.  I had, however, at that time no evidence of monkeys\nexhibiting this part of their bodies during their courtship; and such\ndisplay in the case of birds affords the best evidence that the ornaments\nof the males are of service to them by attracting or exciting the females.\nI have lately read an article by Joh. von Fischer, of Gotha, published in\n'Der Zoologische Garten,' April 1876, on the expression of monkeys under\nvarious emotions, which is well worthy of study by any one interested in\nthe subject, and which shews that the author is a careful and acute\nobserver.  In this article there is an account of the behaviour of a young\nmale mandrill when he first beheld himself in a looking-glass, and it is\nadded, that after a time he turned round and presented his red hinder end\nto the glass.  Accordingly I wrote to Herr J. von Fischer to ask what he\nsupposed was the meaning of this strange action, and he has sent me two\nlong letters full of new and curious details, which will, I hope, be\nhereafter published.  He says that he was himself at first perplexed by the\nabove action, and was thus led carefully to observe several individuals of\nvarious other species of monkeys, which he has long kept in his house.  He\nfinds that not only the mandrill (Cynocephalus mormon) but the drill (C.\nleucophaeus) and three other kinds of baboons (C. hamadryas, sphinx, and\nbabouin), also Cynopithecus niger, and Macacus rhesus and nemestrinus, turn\nthis part of their bodies, which in all these species is more or less\nbrightly coloured, to him when they are pleased, and to other persons as a\nsort of greeting.  He took pains to cure a Macacus rhesus, which he had\nkept for five years, of this indecorous habit, and at last succeeded.\nThese monkeys are particularly apt to act in this manner, grinning at the\nsame time, when first introduced to a new monkey, but often also to their\nold monkey friends; and after this mutual display they begin to play\ntogether.  The young mandrill ceased spontaneously after a time to act in\nthis manner towards his master, von Fischer, but continued to do so towards\npersons who were strangers and to new monkeys.  A young Cynopithecus niger\nnever acted, excepting on one occasion, in this way towards his master, but\nfrequently towards strangers, and continues to do so up to the present\ntime.  From these facts Von Fischer concludes that the monkeys which\nbehaved in this manner before a looking-glass (viz., the mandrill, drill,\nCynopithecus niger, Macacus rhesus and nemestrinus) acted as if their\nreflection were a new acquaintance.  The mandrill and drill, which have\ntheir hinder ends especially ornamented, display it even whilst quite\nyoung, more frequently and more ostentatiously than do the other kinds.\nNext in order comes Cynocephalus hamadryas, whilst the other species act in\nthis manner seldomer.  The individuals, however, of the same species vary\nin this respect, and some which were very shy never displayed their hinder\nends.  It deserves especial attention that Von Fischer has never seen any\nspecies purposely exhibit the hinder part of its body, if not at all\ncoloured.  This remark applies to many individuals of Macacus cynomolgus\nand Cercocebus radiatus (which is closely allied to M. rhesus), to three\nspecies of Cercopithecus and several American monkeys.  The habit of\nturning the hinder ends as a greeting to an old friend or new acquaintance,\nwhich seems to us so odd, is not really more so than the habits of many\nsavages, for instance that of rubbing their bellies with their hands, or\nrubbing noses together.  The habit with the mandrill and drill seems to be\ninstinctive or inherited, as it was followed by very young animals; but it\nis modified or guided, like so many other instincts, by observation, for\nVon Fischer says that they take pains to make their display fully; and if\nmade before two observers, they turn to him who seems to pay the most\nattention.\n\nWith respect to the origin of the habit, Von Fischer remarks that his\nmonkeys like to have their naked hinder ends patted or stroked, and that\nthey then grunt with pleasure.  They often also turn this part of their\nbodies to other monkeys to have bits of dirt picked off, and so no doubt it\nwould be with respect to thorns.  But the habit with adult animals is\nconnected to a certain extent with sexual feelings, for Von Fischer watched\nthrough a glass door a female Cynopithecus niger, and she during several\ndays, \"umdrehte und dem Maennchen mit gurgelnden Toenen die stark geroethete\nSitzflache zeigte, was ich frueher nie an diesem Thier bemerkt hatte.  Beim\nAnblick dieses Gegenstandes erregte sich das Maennchen sichtlich, denn es\npolterte heftig an den Staeben, ebenfalls gurgelnde Laute ausstossend.\"  As\nall the monkeys which have the hinder parts of their bodies more or less\nbrightly coloured live, according to Von Fischer, in open rocky places, he\nthinks that these colours serve to render one sex conspicuous at a distance\nto the other; but, as monkeys are such gregarious animals, I should have\nthought that there was no need for the sexes to recognise each other at a\ndistance.  It seems to me more probable that the bright colours, whether on\nthe face or hinder end, or, as in the mandrill, on both, serve as a sexual\nornament and attraction.  Anyhow, as we now know that monkeys have the\nhabit of turning their hinder ends towards other monkeys, it ceases to be\nat all surprising that it should have been this part of their bodies which\nhas been more or less decorated.  The fact that it is only the monkeys thus\ncharacterised which, as far as at present known, act in this manner as a\ngreeting towards other monkeys renders it doubtful whether the habit was\nfirst acquired from some independent cause, and that afterwards the parts\nin question were coloured as a sexual ornament; or whether the colouring\nand the habit of turning round were first acquired through variation and\nsexual selection, and that afterwards the habit was retained as a sign of\npleasure or as a greeting, through the principle of inherited association.\nThis principle apparently comes into play on many occasions:  thus it is\ngenerally admitted that the songs of birds serve mainly as an attraction\nduring the season of love, and that the leks, or great congregations of the\nblack-grouse, are connected with their courtship; but the habit of singing\nhas been retained by some birds when they feel happy, for instance by the\ncommon robin, and the habit of congregating has been retained by the black-\ngrouse during other seasons of the year.\n\nI beg leave to refer to one other point in relation to sexual selection.\nIt has been objected that this form of selection, as far as the ornaments\nof the males are concerned, implies that all females within the same\ndistrict must possess and exercise exactly the same taste.  It should,\nhowever, be observed, in the first place, that although the range of\nvariation of a species may be very large, it is by no means indefinite.  I\nhave elsewhere given a good instance of this fact in the pigeon, of which\nthere are at least a hundred varieties differing widely in their colours,\nand at least a score of varieties of the fowl differing in the same kind of\nway; but the range of colour in these two species is extremely distinct.\nTherefore the females of natural species cannot have an unlimited scope for\ntheir taste.  In the second place, I presume that no supporter of the\nprinciple of sexual selection believes that the females select particular\npoints of beauty in the males; they are merely excited or attracted in a\ngreater degree by one male than by another, and this seems often to depend,\nespecially with birds, on brilliant colouring.  Even man, excepting perhaps\nan artist, does not analyse the slight differences in the features of the\nwoman whom he may admire, on which her beauty depends.  The male mandrill\nhas not only the hinder end of his body, but his face gorgeously coloured\nand marked with oblique ridges, a yellow beard, and other ornaments.  We\nmay infer from what we see of the variation of animals under domestication,\nthat the above several ornaments of the mandrill were gradually acquired by\none individual varying a little in one way, and another individual in\nanother way.  The males which were the handsomest or the most attractive in\nany manner to the females would pair oftenest, and would leave rather more\noffspring than other males.  The offspring of the former, although\nvariously intercrossed, would either inherit the peculiarities of their\nfathers or transmit an increased tendency to vary in the same manner.\nConsequently the whole body of males inhabiting the same country would tend\nfrom the effects of constant intercrossing to become modified almost\nuniformly, but sometimes a little more in one character and sometimes in\nanother, though at an extremely slow rate; all ultimately being thus\nrendered more attractive to the females.  The process is like that which I\nhave called unconscious selection by man, and of which I have given several\ninstances.  In one country the inhabitants value a fleet or light dog or\nhorse, and in another country a heavier and more powerful one; in neither\ncountry is there any selection of individual animals with lighter or\nstronger bodies and limbs; nevertheless after a considerable lapse of time\nthe individuals are found to have been modified in the desired manner\nalmost uniformly, though differently in each country.  In two absolutely\ndistinct countries inhabited by the same species, the individuals of which\ncan never during long ages have intermigrated and intercrossed, and where,\nmoreover, the variations will probably not have been identically the same,\nsexual selection might cause the males to differ.  Nor does the belief\nappear to me altogether fanciful that two sets of females, surrounded by a\nvery different environment, would be apt to acquire somewhat different\ntastes with respect to form, sound, or colour.  However this may be, I have\ngiven in my 'Descent of Man' instances of closely-allied birds inhabiting\ndistinct countries, of which the young and the females cannot be\ndistinguished, whilst the adult males differ considerably, and this may be\nattributed with much probability to the action of sexual selection."