"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  Some new illustrations\nhave been introduced, and four of the old drawings have been replaced by\nbetter ones, done from life by Mr.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 or