THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 LOS ANGELES
 
 CHARLES DARWIN AND 
 THE ORIGIN OF SPECIES 
 
 ADDRESSES, ETC., IN AMERICA AND ENGLAND 
 IN THE YEAR OF THE TWO ANNIVERSARIES 
 
 BY 
 
 EDWARD BAGNALL POULTON, D.Sc.,M.A. 
 
 HON. LL.D. PRINCETON, F.R.S., V-P.L.S., F.Z.S., F.G.S., F.E.S. 
 
 HOPE PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF OXFORD 
 
 FELLOW OF JESUS COLLEGE, OXFORD 
 
 MEMB. HON. SOC. ENT. BELG. ; SOC. HON. REAL SOC. ESPAN. HIST. NAT. 
 CORRESP. MEMB. ACAD. SCI., NEW YORK, AND SOC. NAT. HIST. BOSTON 
 
 AUTHOR OF 'ESSAYS ON EVOLUTION', ETC. 
 
 PUBLISHED NOV. S4 t 1909, BEING THE FIFTIETH ANNIVERSARY 
 OF THE PUBLICATION OF 'THE ORIGIN OF SPECIES' 
 
 LONGMANS, GREEN, AND CO. 
 
 39 PATERNOSTER ROW, LONDON 
 NEW YORK, BOMBAY, AND CALCUTTA 
 1909

 
 Dl'omai . 
 Hisf. D/V. 
 
 QK 
 
 TO 
 
 ALFRED RUSSEL WALLACE 
 
 WHO GAVP: TO HIS BOOK ON NATURAL SELECTION 
 
 THE TITLE ' DARWINISM ', THIS COLLECTION 
 
 OF ADDRESSES ON DARWIN AND THE 
 
 ' ORIGIN ' IS AFFECTIONATELY 
 
 DEDICATED
 
 PREFACE 
 
 DURING the fourteen months preceding the date 
 on which this volume is issued I have devoted all 
 available time to work connected with the three 
 inspiring anniversaries of July 1, 1908, Feb. 12, 
 1909, and Nov. 24, 1909. With all diffidence I 
 have chosen the date which closes this period of 
 work, as the day of publication. It may help in 
 some small degree to keep in remembrance the 
 birthday of a mighty epoch in the history of 
 thought. 
 
 The first Section of this book attempts to give 
 a brief account of the history which led up to and 
 followed the publication of the theory of Natural 
 Selection and the Origin of Species. Darwin's 
 sure scientific insight, and his views on evolution 
 by mutation, briefly treated in this Section, 
 receive further consideration in Appendices A 
 and B. The confusion of thought threatened by 
 the unintentional but most unfortunate mis- 
 representation of de Vries's term, * fluctuating 
 variability,' is pointed out in a footnote and 
 further considered in Appendix D. I have given 
 at the end of this Appendix a very brief account 
 of certain phases of thought, during the past
 
 vi PREFACE 
 
 half century, on the variations forming the 
 material out of which the steps of evolutionary 
 progress have been supposed to be built. 
 
 The influence of Darwin's personality upon the 
 intellectual revolution of the past fifty years is 
 considered in the second Section. The wide- 
 spread misunderstanding of the changes which 
 Darwin describes in his own mind, and the 
 consequent injustice to scientific men generally, 
 and especially to Darwin himself, not only form 
 the subject of argument and protest in this 
 Section, but also occupy nearly all the brief third 
 Section, part of the seventh, and the whole of 
 Appendix C. 
 
 The unfortunate misinterpretations referred to 
 above require, for their complete and final refuta- 
 tion, the collection from Darwin's correspondence 
 of a large number of passages bearing upon 
 health. These, placed together, may convey to 
 the hasty reader an entirely wrong impression of 
 Darwin's heroic spirit, and I therefore trust 
 that the words on p. 216 will be remembered 
 whenever such passages may be read. 
 
 In the fourth Section the relationship of Darwin 
 to the two ancient English Universities, and 
 especially to his own University of Cambridge, is 
 very briefly considered. 
 
 The fifth Section is concerned with one of the 
 first and still perhaps the most striking of the
 
 PREFACE vii 
 
 interpretations that have sprung from the theory 
 of Natural Selection. The subject, * the Value of 
 Colour in the Struggle for Life,' is treated histori- 
 cally. Darwin's own hypotheses and discoveries 
 in this line, and his keen interest in the 
 hypotheses and discoveries of others are especially 
 considered here and also in part of the seventh 
 Section. 
 
 The sixth Section deals with Mimicry, the 
 most arresting of all the uses which colour may 
 subserve in the struggle for existence. It is 
 maintained that this complicated subject is best 
 approached by the study of North American 
 examples, and attention is directed to the number 
 of inspiring problems which await a thorough and 
 systematic attack by American naturalists. 
 
 Darwin's hitherto unpublished letters to Mr. 
 Roland Trimen, F.R.S., form the subject of the 
 seventh Section. An interesting account of 
 Mr. Trimen's first meeting with the illustrious 
 naturalist fifty years ago is also included. In 
 addition to the eighteen letters in Section VII, 
 four written by Darwin to other correspondents 
 are published in this volume one in Section I, 
 two in Section V, and one in Section VI. I 
 desire to thank my friends for generously 
 lending me these twenty-two deeply interesting 
 letters, and Mr. Francis Darwin for kindly 
 permitting their publication.
 
 viii PREFACE 
 
 The occasions on which the addresses here 
 printed were delivered are described in an 
 introductory note at the beginning of each 
 Section. Three out of the seven Sections of 
 this volume, viz. I, IV, and V, have already 
 appeared; four are now published for the first 
 time. 
 
 I have especial reasons for being grateful to my 
 American friends for permission to reprint the 
 address contained in the first Section. The Publi- 
 cation Committee of the American Association 
 for the Advancement of Science did me the 
 honour of choosing the title of my address as 
 the title of the complete work Fifty Years of 
 Darwinism, containing the eleven centennial 
 addresses, in honour of Charles Darwin, delivered 
 on Jan. 1, 1909. The publishers who owned the 
 copyright were very doubtful about the success of 
 the work unnecessarily as it happened, for I 
 understand that a second edition is already being 
 prepared. In spite of considerations which 
 seemed at the time to be weighty, both Com- 
 mittee and Publishers at once granted me the 
 most free and cordial permission to reprint the 
 address in the present work. 
 
 The Syndics of the Cambridge University Press 
 generously allowed the publication, on Nov. 24, of 
 Section V, which had appeared as Essay XV of 
 Darwin and Modern Science only eight months
 
 PREFACE ix 
 
 earlier, the Preface being dated March 20, 1909. 
 I also desire to acknowledge the kind permission 
 to publish Section IV from Darwin Celebration, 
 Cambridge, June, 1909. Speeches delivered at the 
 Banquet held on June 23rd, printed for private cir- 
 culation by Sir George Darwin and Mr. Francis 
 Darwin. 
 
 In these later years the multitudes seem, for 
 the moment at least, to recognize a prophet in 
 every reed shaken with the wind. It would be 
 interesting to know the number of forgotten 
 works, of works soon to be forgotten, of works 
 dead before they were born, which have been 
 proclaimed as * the most important contribu- 
 tion to biological thought since the appearance 
 of the Origin of Species'. I would that the 
 multitudes were not mere followers of the fleeting 
 scientific fashions of a day, but that they were 
 right in their intuitions : I would that Newtons 
 and Darwins might arise in every generation. 
 I cannot admit that the inability to see them 
 on every side is merely the natural consequence 
 of a cynical and pessimistic spirit. I am fully 
 aware of the intellectual rigidity that is so prone 
 to develop with the passing years ; but to know 
 the danger is in some measure to be armed against 
 it. I have steadily endeavoured to keep my 
 mind elastic and flexible ; and, in my own special
 
 x PREFACE 
 
 line of work, have again and again abandoned 
 the most dearly loved hypothesis when a new 
 interpretation was seen to be more consistent with 
 an ever-growing store of facts. And I submit 
 that it is even more difficult to keep an open 
 mind in the pursuit of a special line of research 
 than in the consideration of the broadest and 
 most far-reaching problems which confront the 
 human intellect. 
 
 Although the splendidly thorough work of the 
 present day must rightly compel the warmest 
 admiration, there are valid reasons why we should 
 direct a searching and critical gaze upon the pro- 
 clamation of each enthusiastic specialist that the 
 foundations of organic evolution are wholly sur- 
 rounded by the boundaries of his own field of 
 inquiry. Organic evolution, to be understood, 
 must be studied not in the light of one special 
 line of work, but of all. This was the great secret 
 of Darwin's unique power in dealing with it. He 
 could see the subject from all sides. And an 
 ample measure of Darwin's strength was possessed 
 by his great comrades of half a century ago. How 
 we long for a little of the sure insight and com- 
 prehensive vision of Asa Gray as we read the 
 address of his distinguished living representative, 
 Professor J. M. Coulter, who considers that an 
 adaptive response to environment is destructive 
 of Natural Selection, and finds it hard to imagine
 
 PREFACE xi 
 
 how Darwinism can account for the valuable 
 mechanical functions of lifeless structures. 1 And 
 even more arresting is the contrast between 
 Darwin's outlook on the world of life and that 
 of the eminent Dutch botanist who raised fresh 
 strains, or perhaps sorted over again old mixtures 
 of Evening Primroses, and straightway said to his 
 friends : * Go to, let us build us an exalted 
 theory of evolution based on the conception of 
 an inborn transforming force violently discharged 
 at regular intervals by every species of times past, 
 present, and to come.' And the historic fate of 
 the too-ambitious builders of Babel is already 
 evident ; for, when Professor de Vries, Professor 
 Bateson, and Mr. R C. Punnett begin to talk of 
 variability in its commonest form, their language 
 is confounded, 'that they may not understand 
 one another's speech.' - And when we remember 
 that the two last-named authorities are the recog- 
 nized English exponents of the views of the first- 
 named, it will be realized that the confusion 
 which has resulted from the misunderstanding of 
 the words 'acquired character' and the word 
 ' Mimicry ' is as nothing to the confusion worse 
 confounded which is even now upon us. The 
 misunderstanding of de Vries by his exponents 
 does however help us to solve one mystery, the 
 
 1 Fifty Years of Darwinism, New York (1909), 61-5. See also 
 the Quarterly Review (July, 1909), 7. 
 
 2 See 49, and Appendix D, 258.
 
 xii PREFACE 
 
 extraordinary and, as many naturalists think, 
 the unwarrantable exaggeration of the importance 
 of the Dutch botanist's contributions to evolution. 
 Omne ignotum pro magnifico. If de Vries had 
 indeed proved, as his exponents assert, that the 
 * individual differences ' in which Darwin saw the 
 steps of evolutionary progress the 'individual 
 differences ' whose behaviour in heredity is the life- 
 work of Francis Galton that these are in fact non- 
 transmissible to offspring, then surely the great- 
 ness of him who demonstrated such a discovery to 
 the world might be justly measured by the depth 
 of the error into which his predecessors had fallen. 
 I need hardly say that de Vries makes no such 
 claim, but, on the contrary, shows us again and 
 again that hereditary transmission to offspring is 
 essential to his conception of 'fluctuating varia- 
 bility'. 
 
 For de Vries's laborious and original investiga- 
 tions every one must feel the warmest admiration. 
 He and his friend Professor Hubrecht have 
 always been most anxious to emphasize their 
 conclusion that the MutationstJieorie is Darwinian, 
 and they are equally anxious to disown and dis- 
 credit any attempts to use it as a weapon against 
 Darwin. They have even fallen into the error of 
 maintaining that Darwin anticipated de Vries in 
 holding the main conclusion of the Mutationstheorie 
 the origin of species by the selection of large
 
 PKEFACE xiii 
 
 single variations. 1 It is with great reluctance that 
 I have protested against the unduly important posi- 
 tion which, as I believe, is assigned to de Vries's 
 work and conclusions in the history of evolution. 
 
 The Darwinian of the present day holds an inter- 
 mediate position between the followers of Buffon 
 and Lamarck, and the Mutationists, with whom 
 the Mendelians are somewhat unnecessarily allied. 
 The disciple of the two first-named naturalists, 
 in these days calling himself an oecologist, main- 
 tains that organisms are the product of their 
 environment : the Mutationist holds that organ- 
 isms are subject to inborn transformation, and 
 that environment selects the fittest from among 
 a crowd of finished products. The Darwinian 
 believes that the finished product or species is 
 gradually built up by the environmental selection 
 of minute increments, holding that, among inborn 
 variations of all degrees of magnitude, the small 
 and not the large become the steps by which 
 evolution proceeds. He attempts to avoid, as 
 Darwin did, on the one hand the error of as- 
 cribing the species-forming forces wholly to 
 a creative environment, and, on the other, the 
 perhaps more dangerous error of ascribing them 
 wholly to creative internal tendencies. 
 
 1 Both professors of course admit that Darwin also believed in 
 an evolution founded on the selection of ' individual differences '.
 
 xiv PKEFACE 
 
 The failure of the earlier attacks on the Origin 
 has been referred to in many pages of this book ; 
 but my chief object throughout has been to speak 
 of Darwinism and of Darwin himself. Hence 
 Mendelism, entirely unknown to the illustrious 
 naturalist, is on this occasion barely mentioned. 1 
 The conception of evolution by mutation, on the 
 other hand, is shown to have been from the first 
 entirely familiar to Darwin, and entirely rejected 
 by him. In the Quarterly Review 2 for July. 1909, 
 I have * endeavoured to set forth necessarily 
 with brevity the chief results of those modern 
 investigations which, after fifty years, are now 
 believed to be charged with menace for the 
 Darwin-Wallace hypothesis ' ; and I will con- 
 clude by quoting the final words of the article : 
 ' The inspiration of these investigations has at- 
 tracted a numerous band of enthusiastic and 
 devoted labourers, who have achieved and are 
 achieving results of the highest interest and im- 
 portance. No one of these, it is here maintained, 
 can be reasonably held to make good the claims 
 of the modern opponent of natural selection and 
 evolution as conceived by Darwin. The only 
 fundamental changes in the doctrine given to us 
 
 1 See however the close of Appendix D Attention is directed 
 in Section VI to certain North American butterflies which appear 
 to afford a peculiarly favourable opportunity of testing the 
 working of Mendel's law under natural conditions. 
 
 2 ' The Centenary of Darwin : Darwin and his Modern Critics,' 
 1-38.
 
 PREFACE xv 
 
 in 1858 and 1859 are those brought about by the 
 researches and the thoughts of Weismann ; and 
 these have given to the great theory which will 
 ever be associated with the names of the two 
 illustrious English naturalists a position far higher 
 than that ever assigned to it by Darwin himself.' 
 
 EDWARD B. POULTON. 
 
 OXFORD, 
 Nov. 24, 1909.
 
 CONTENTS 
 
 PAGE 
 
 I. FIFTY YEARS OF DARWINISM (Baltimore, Jan. 1, 
 
 1909) . . V . . . . . 1 
 
 II. THE PERSONALITY OF CHARLES DARWIN (Balti- 
 more, Jan. 1, 1909) 57 
 
 III. THE DARWIN CENTENARY AT OXFORD (Feb. 12, 
 
 1909) 78 
 
 IV. CHARLES DARWIN AND THE UNIVERSITY OF CAM- 
 
 BRIDGE (Cambridge, June 23, 1909) . . 84 
 
 V. THE VALUE OF COLOUR IN THE STRUGGLE FOR LIFE 92 
 
 VI. MIMICRY IN THE BUTTERFLIES OF NORTH AMERICA 
 
 (Baltimore, Dec. 31, 1908) . . . .144 
 
 VII. LETTERS FROM CHARLES DARWIN TO KOLAND 
 
 TRIMEN (1863-71) . . .. ' . .213 
 
 APPENDIX A. CHARLES DARWIN AND THE HYPO- 
 THESIS OF MULTIPLE ORIGINS . . .247 
 
 APPENDIX B. DARWIN AND EVOLUTION BY MU- 
 TATION . . . . . * . . 254 
 
 APPENDIX C. FURTHER PROOF THAT SCIENTIFIC 
 
 WORK WAS NECESSARY FOR DARWIN . . 256 
 
 APPENDIX D. DE VRIES'S 'FLUCTUATIONS' HERE- 
 DITARY ACCORDING TO DE VfilES, NON-TRANS- 
 MISSIBLE ACCORDING TO BATESON AND 
 PUNNETT 258 
 
 INDEX , 281
 
 I 
 
 FIFTY YEARS OF DARWINISM 
 
 One of the centennial addresses in honour of Charles 
 Darwin, read before the American Association for the 
 Advancement of Science, Baltimore, Friday, January 1, 
 1909. Eevised and extended. 
 
 ON this historic occasion it is of special interest 
 to reflect for a few moments on the part played 
 by the New World in the origin and growth of 
 the great intellectual force which dominates the 
 past half-century. The central doctrine of evolu- 
 tion, quite apart from any explanation of it, was 
 first forced upon Darwin's mind by his South 
 American observations during the voyage of the 
 Beagle ; and we may be sure that his experience 
 in this same country, teeming with innumerable 
 and varied forms of life, confirmed and deepened 
 his convictions as to the importance of adaptation 
 and thus prepared the way for Natural Selection. 
 Wallace, too, at first travelled in South America, 
 and only later in the parts of the Old World 
 tropics which stand next to South America in 
 richness. 
 
 Asa Gray in the New World represents 
 Sir Joseph Hooker in the Old, as regards the 
 help given to Darwin before the appearance of 
 B
 
 2 FIFTY YEAKS OF DARWINISM 
 
 the Origin ; and in strenuous and most efficient 
 defence after its appearance, Chauncey Wright 
 similarly represents Henry Fawcett. Fritz 
 Miiller not only actively defended Darwin, but 
 continually assisted him by the most admirable 
 and original observations carried out at his 
 Brazilian home. Turning to those who in some 
 important respects differed from Darwin, I do 
 not think a finer example of chivalrous con- 
 troversy can be found than that carried on 
 between him and Hyatt. The immense growth 
 of evolutionary teaching, in which John Fiske 
 played so important a part, although associated 
 with the name of Herbert Spencer, must not be 
 neglected on an occasion devoted to the memory 
 of Darwin. 
 
 Outside the conflict which raged round the 
 Origin, we find Dana the only naturalist who 
 at first supported Darwin in his views on the 
 persistence of ocean basins and continental areas, 
 and Alexander Agassiz, for many years the 
 principal defender of the Darwinian theory of 
 coral islands and atolls. 
 
 American Palaeontology, famed throughout the 
 world, has exercised a profound influence on 
 the growth and direction of evolutionary thought. 
 The scale and perfection of its splendid fossil 
 records have attracted the services of a large band 
 of the most eminent and successful labourers, of 
 whom I can only mention the leaders : Leidy, 
 Cope, Marsh, Osborn, and Scott, in the Verte-
 
 AMERICA AND EVOLUTION 3 
 
 brata ; Hall, Hyatt, and Walcott in the Inverte- 
 brata. The study of American Palaeontology 
 was at first believed to support a Neo-Lamarckian 
 view of evolution, but this, as well as the hypo- 
 thesis of polyphyletic or multiple origins (see 
 Appendix A, p. 247), was undermined by the 
 teachings of Weismann. Difficulties for which 
 the Lamarckian theory had been invoked were 
 met by the hypothesis of Organic Selection, sug- 
 gested by Baldwin and Osborn, and in England 
 by Lloyd Morgan. Weismann's contention that 
 inherent characters are alone transmissible by 
 heredity has also received strong support from 
 the immense body of Cytological, Mendelian, and 
 Mutationist work to which other addresses to be 
 delivered to-day will bear eloquent testimony. 1 
 Finally, the flourishing school of American Psy- 
 chology, under the leadership of William James 
 and James Mark Baldwin, accepts, and in accept- 
 ing helps to confirm, the theory of Natural 
 Selection. 
 
 ERASMUS DARWIN AND LAMARCK 
 
 Professor Henry F. Osborn, in his interesting 
 work, From the Greeks to Darwin, concludes that 
 Lamarck was unaware of Erasmus Darwin's Zoo- 
 nomia, and that the parallelism of thought is 
 a coincidence. 2 The following passage from 
 
 1 The addresses referred to are published in Fifty Years of 
 Darwinism, New York, Henry Holt and Company, 1909. 
 
 2 From the Greeks to Darwin, New York, 1894, 152-5. Professor 
 Osborn shows on p. 145 that Erasmus Darwin made use of the term 
 
 B 2
 
 4 FIFTY YEARS OF DARWINISM 
 
 a letter 1 written to Huxley, probably in 1859, 
 and published since the appearance of Professor 
 Osborn's book, indicates that Charles Darwin 
 suspected the French naturalist of borrowing 
 from his grandfather : 
 
 ' The history of error is quite unimportant, but it is curious 
 to observe how exactly and accurately my grandfather (in 
 Zoonomia, vol. L, p. 504, ] 794) gives Lamarck's theory. I 
 will quote one sentence. Speaking of birds' beaks, he says : 
 "All which seem to have been gradually produced during 
 many generations by the perpetual endeavour of the creatures 
 to supply the want of food, and to have been delivered to 
 their posterity with constant improvement of them for the 
 purposes required." Lamarck published Hist. Zoolog. in 1 809. 
 The Zoonomia was translated into many languages.' 
 
 A careful comparison of the French transla- 
 tion of the Zoonomia with Lamarck's PliilosopTiie 
 Zoologique and with a preliminary statement of 
 his views published in 1802, would probably 
 decide this interesting question. 
 
 THE INFLUENCE OF LYELL UPON CHARLES 
 DARWIN 
 
 The limits of space compel me to pass by the 
 youth of Charles Darwin, with the influence of 
 school, Edinburgh and Cambridge, including his 
 intimacy with Henslow a friendship leading to 
 the voyage in the Beagle. We must also pass 
 by his earliest convictions on evolution, the 
 
 ' acquired ' in the sense of ' acquired characters ' ; ' changement 
 acquis ' is the form employed many years later by Lamarck. 
 
 1 More Letters of Charles Darwin. Edited by Francis Darwin and 
 A. C. Seward, London, 1903, i. 125. Hereafter quoted as More 
 Letters.
 
 DARWIN'S DEBT TO LYELL 5 
 
 first note-book begun in 1837, the reading of 
 Malthus and discovery of Natural Selection in 
 October, 1838, the imperfect sketch of 1842, the 
 completed sketch of 1844. 
 
 It is necessary, however, to pause for a brief 
 consideration of the influence of Sir Charles Lyell. 
 Although the writings of the illustrious geologist 
 have always been looked upon as among the 
 chief of the forces brought to bear upon the mind 
 of Darwin, evidence derived from the later 
 volumes of correspondence justifies the belief 
 that the effect was even greater and more signi- 
 ficant than has been supposed. 
 
 Huxley has maintained with great force that 
 the way was paved for Darwin by Ly ell's Principles 
 of Geology far more thoroughly than by any other 
 work. 
 
 ' . . . consistent uniformitarianism postulates evolution 
 as much in the organic as in the inorganic world. The 
 origin of a new species by other than natural agencies would 
 be a vastly greater " catastrophe " than any of those which 
 Lyell successfully eliminated from sober geological specula- 
 tion.' 1 
 
 When the first volume of the Principles appeared 
 in 1830, Darwin was advised by Henslow to 
 obtain and study it, ' but on no account to accept 
 the views therein advocated.' Darwin took the 
 volume with him on the voyage, and a study of 
 the very first place at which the Beagle touched, 
 
 1 Life and Letters of Charles Dani'in, edited by Francis Darwin, 
 London, 1887, ii. 190. Hereafter quoted as Life and Letters.
 
 6 FIFTY YEAES OF DARWINISM 
 
 St. Jago, one of the Cape de Verde Islands, 
 showed him the infinite superiority of Lyell's 
 teachings. 1 
 
 He wrote in 1876 : ' The science of Geology is 
 enormously indebted to Lyell more so, as I 
 believe, than to any other man who ever lived.' 2 
 An even more remarkable tribute to his old 
 teacher is paid by Darwin in the following words 
 written to L. Horner, August 29, 1844 : 
 
 ' I have lately been reading with care A. d'Orbigny's work 
 on South America, and I cannot say how forcibly impressed 
 I am with the infinite superiority of the Lyellian school of 
 Geology over the continental. I always feel as if my books 
 came half out of Lyell's brain, and that I never acknowledge 
 this sufficiently ; nor do I know how I can without saying 
 so in so many words for I have always thought that the 
 great merit of the Principles was that it altered the whole 
 tone of one's mind, and therefore that, when seeing a thing 
 never seen by Lyell, one yet saw it partially through his 
 eyes it would have been in some respects better if I had 
 done this less . . . .' 3 
 
 This letter was written not two months after 
 the date which marks the completion of the 
 finished sketch of 1844. On July 5, Darwin 
 wrote the letter to his wife begging her, in the 
 event of his death, to arrange for the publication 
 of the account he had just prepared. At this 
 psychological moment in his career he wrote of 
 the influence received from Lyell, and we are 
 naturally led to observe how essentially Lyellian 
 
 1 Life and Letters, i. 62, 72, 73. 2 1. c., 72. 
 
 8 More Lttters, it. 117.
 
 LYELL'S DEBT TO DARWIN 7 
 
 are the three lines of argument two based on 
 geographical distribution, one on the relation 
 between the living and the dead which first 
 led Darwin toward a belief in evolution. The 
 thoughts which shook the world arose in a mind 
 whose whole tone had been altered by Lyell's 
 teachings. Inasmuch as the founder of modern 
 geology received his first inspiration from 
 Buckland, Oxford may claim some share in 
 moulding the mind of Darwin. 1 
 
 It is deeply interesting to set beside the 
 evidence of Darwin's debt to Lyell the words in 
 which Lyell gives us some conception of what 
 Darwin's friendship even in its early days 
 meant for him. Not long after Darwin's mar- 
 riage (Jan. 29, 1839), when he and his wife 
 were contemplating leaving London for the 
 country, Lyell wrote : 
 
 ' I cannot tell you how often since your long illness I 
 have missed the friendly intercourse which we had so 
 frequently before, and on which I built more than ever after 
 your marriage. It will not happen easily that twice in 
 one's life, even in the large world of London, a congenial 
 soul so occupied with precisely the same pursuits and with 
 an independence enabling him to pursue them will fall so 
 nearly in my way, and to have had it snatched from me 
 with the prospect of your residence somewhat far off is 
 a privation I feel to be a very great one.' 2 
 
 1 See also pp. 86, 87. 
 
 2 July?, 1841?. More Letters, i. 31. Darwin left London for 
 Down on Sept. 14, 1842.
 
 8 FIFTY YEARS OF DARWINISM 
 
 ' COMING EVENTS CAST THEIR SHADOWS 
 BEFORE ' 
 
 The characteristic feature in which Natural 
 Selection differs from every other attempt to 
 solve the problem of evolution is the account 
 taken of the struggle for existence, and the role 
 assigned to it. Professor Osborn l refers to the 
 keen appreciation of this struggle in Tennyson's 
 noble poem, In Memoriam, the dedication of which 
 is dated 1849, ten years before the Origin. The 
 poet is disquieted by : 
 
 ' Nature red in tooth and claw 
 
 With ravine, ' 
 
 and by 
 
 ' . . . finding that of fifty seeds 
 She often brings but one to bear.' 
 
 It is interesting to note that the obvious under- 
 statement of this last passage is corrected in the 
 author's notes published by his son a few years 
 ago. In these we find 'for fifty, read myriad'. 
 The poignant sense of the waste of individual 
 lives is brought into close relation in the poem 
 with the destruction of the type or species : 
 
 'So careful of the type she seems, 
 So careless of the single life ; ' 
 
 ' " So careful of the type ? " but no, 
 From scarped cliff and quarried stone 
 She cries " A thousand types are gone : 
 
 I care for nothing, all shall go ".' 
 
 1 From the Greeks to Darwin, New York, 1894, 141.
 
 TENNYSON AND THE 'ORIGIN' 9 
 
 In tliis association between the struggle for 
 existence waged by individuals and the extinction 
 and succession of species we seem to approach 
 the central idea of Darwin and Wallace. A few 
 years before Tennyson's death I asked Dr. Grove, 
 of Newport, in the Isle of Wight, if he would 
 point out the parallelism, so far as it existed, to his 
 illustrious patient, hoping that some light might 
 be thrown on the source of the inspiration. Nor 
 was I disappointed. 'Stay,' said the aged poet 
 when Dr. Grove had spoken, ' In Memoriam was 
 published long before the Origin of Species.' l Oh ! 
 then you are the man,' replied the doctor. * Yes, 
 I am the man.' There was silence for a time ; 
 then Tennyson said : 'I don't want you to go 
 away with a wrong impression. The fact is that 
 long before Darwin's work appeared these ideas 
 were known and talked about.' From this deeply 
 interesting conversation I think it is probable 
 that, perhaps through mutual friends, some echo 
 of Darwin's researches and thoughts had reached 
 the great author of In Memoriam. 1 
 
 The light which has been recently thrown 2 
 upon Philip Gosse's remarkable book, Omphalos, 
 indicates that its appearance in 1858 was 
 connected with the thoughts that were to arouse 
 
 1 In a valuable letter on Darwin and Tennyson in The Spectator 
 for Aug. 7, 1909 (pp. 197, 198), the Eev. F. St. John Thackeray 
 points out that the poet was from his youth deeply interested in 
 evolution, and that in 1837 he studied Lyell's Principles. It is 
 shown above, however, that the appreciation of the struggle for 
 existence is an essentially Darwinian idea. 
 
 1 In Father and Son, London, 1907.
 
 10 FIFTY YEAES OF DAKWINISM 
 
 the world in the following year. The author of 
 Omphalos was a keen and enthusiastic naturalist 
 held fast in the grip of the narrowest of religious 
 creeds. We learn with great interest that he 
 and others were by LyelTs advice prepared 
 beforehand for the central thoughts of the Origin. 
 To the new teaching all the naturalist side of his 
 nature responded, but from it the religious side 
 recoiled. Religion conquered in the strife, but 
 the naturalist found comfort in the perfectly 
 logical conclusion that : 
 
 ' any breach in the circular course of nature could be con- 
 ceived only on the supposition that the object created bore 
 false witness to past processes, which had never taken place.' * 
 
 Thus the divergence between the literal inter- 
 pretation of Scripture and the conclusions of both 
 geologist and evolutionist were for this remarkable 
 man reconciled by the conviction : 
 
 ' that there had been no gradual modification of the 
 surface of the earth, or slow development of organic forms, 
 but that when the catastrophic act of creation took place, 
 the world presented, instantly, the structural appearance of 
 a planet on which life had long existed.' 2 
 
 Philip Gosse could not but believe that the 
 thoughts which had brought so much comfort 
 to himself would prove a blessing to others also. 
 He offered Omphalos 'with a glowing gesture, 
 to atheists and Christians alike. . . . But, 
 alas ! atheists and Christians alike looked at it and 
 laughed, and threw it away'. 3 Charles Kingsley 
 
 1 1. c., 120, 121. 2 1. c., 120. * 1. c., 122.
 
 THE CREATION OF FALSE WITNESS 11 
 
 expressed the objection felt by the Christian when 
 he wrote that he could not ' believe that God had 
 written on the rocks one enormous and super- 
 fluous lie'. 1 
 
 About twenty years ago I was present when 
 precisely the same conclusion was advanced by 
 a high dignitary of the English Church. He 
 argued that even if the history of the Universe 
 were carried back to a single element such as 
 hydrogen, the human mind would remain unsatis- 
 fied and would inquire whence the hydrogen came, 
 and that any and every underlying form of mat- 
 ter must leave the inexorable question ' whence ? ' 
 still unanswered. Therefore if in the end the 
 question must be given up, we may as well, 
 he argued, admit the mystery of creation in the 
 later stages as in the earlier. Thus he arrived at 
 the belief in a world formed instantaneously, 
 ready-made and complete, with its fossils, marks 
 of denudation, and evidences of evolution a going 
 concern. Aubrey Moore, the clergyman who 
 more than any other man was responsible for 
 breaking down the antagonism towards evolution 
 then widely felt in the English Church, replied 
 very much as Kingsley had done, that he was 
 unwilling to believe that the Creator had de- 
 liberately cheated the intellectual powers He had 
 
 1 Ibid. It is possible that Darwin was referring to Omphalos 
 when he wrote, Sept. 2, 1859, to Lyell, ' our posterity will marvel 
 as much about the current belief as we do about fossil shells 
 having been thought to have been created as we now see them.' 
 Life and Letters, ii. 1 65.
 
 12 FIFTY YEARS OF DARWINISM 
 
 made. I may add that, inasmuch as science con- 
 sists in the attempt to carry down causation as 
 far as possible, it is above all the scientific side of 
 the human intellect that is outraged no weaker 
 term can be used by this more modern develop- 
 ment of the argument of Omphalos. 
 
 THE PUBLICATION OF THE DARWIN-WALLACE 
 ESSAY 
 
 In May, 1856, Darwin, urged by Lyell, began to 
 prepare for publication. He had determined to 
 present his conclusions in a volume, for he was 
 unwilling to place any responsibility for his 
 opinions on the Council of a Scientific Society. 
 On this point, he was, as he told Sir Joseph 
 Hooker, in the only fit state for asking advice, 
 namely, with his mind firmly made up : ' then 
 . . . good advice was very comfortable, and it was 
 easy to reject bad advice.' l The work was con- 
 tinued steadily until June 18, 1858, when Wal- 
 lace's letter and essay arrived from Ternate. As 
 a result of the anniversary held in London on 
 July 1, 1908, new light has been thrown upon 
 the circumstances under which the joint essay 
 was published fifty years before. 
 
 In consequence of the death of the eminent 
 botanist, Robert Brown, Vice-President and Ex- 
 President of the Linnean Society, the last meeting 
 of the summer session, called for June 17, was 
 adjourned. The bye-laws required that the 
 
 1 Life and Letters, ii. 70. See also 68, 69, 71.
 
 THE EVENTS OF JULY 1, 1858 13 
 
 vacancy on the Council should be filled up within 
 three months, and a special meeting was called 
 for July 1 for this purpose. Darwin received 
 Wallace's essay on June 18, too late for the 
 summer meetings of the Society, but in good 
 time for Lyell and Hooker to present it to the 
 special meeting. Hence, as Sir Joseph Hooker 
 said on July 1, 1908, the death of Robert Brown 
 caused the theory of Natural Selection to be 
 ' given to the world at least four months earlier 
 than would otherwise have been the case'. Sir 
 Joseph Hooker also informed us that from 
 June 18, up to the evening of July 1, when 
 he met Sir Charles Lyell at the Society, all the 
 intercourse with Darwin and with each other was 
 conducted by letter, and that no fourth person 
 was admitted into their confidence. The joint 
 essay was read by the Secretary of the Society. 
 Darwin was not present, but both Lyell and 
 Hooker * said a few words to emphasise the 
 importance of the subject V Among those who 
 were present were Oliver, Fitton, Carpenter, 
 Henfrey, Burchell, and Bentham, 2 who was elected 
 
 1 Darwin-Wallace Celebration of the Linnean Society of London 
 (1908), 14, 15. 
 
 2 July 1, 1858, was an important date in the life of the great 
 
 He " 
 
 botanist George Bentham. He had himself prepared for that very 
 meeting a long paper illustrating what he believed to be the 
 fixity of species. ' Most fortunately my paper had to give way to 
 
 mine for reconsideration ; I began to entertain doubts on the 
 subject, and on the appearance of the " Origin of Species ", I was 
 forced, however reluctantly, to give up my long-cherished con- 
 victions, the results of much labour and study, and I cancelled all 
 that part of my paper which urged original fixity.' Life and 
 Letters, ii. 294. See also the Quarterly Review (July, 1909), 6.
 
 14 FIFTY YEARS OF DARWINISM 
 
 on the Council and nominated as Vice-President 
 in place of Robert Brown. 
 
 I cannot resist the temptation to reprint from 
 the memorial volume issued by the Linnean 
 Society of London some passages in the address 
 which A. R. Wallace felt constrained to deliver 
 on July 1, 1908, protesting against the too great 
 credit which he believed had been assigned to 
 himself. After describing Darwin's discovery of 
 Natural Selection and the twenty years devoted 
 to confirmation and patient research, Wallace 
 continued : 
 
 ' How different from this long study and preparation 
 this philosophic caution this determination not to make 
 known his fruitful conception till he could back it up by 
 overwhelming proofs was my own conduct. The idea 
 came to me, as it had come to Darwin, in a sudden flash of 
 insight : it was thought out in a few hours was written 
 down with such a sketch of its various applications and 
 developments as occurred to me at the moment, then 
 copied on thin letter-paper and sent off to Darwin all with- 
 in one week. I was then (as often since) the " young man 
 in a hurry " : he, the painstaking and patient student, seek- 
 ing ever the full demonstration of the truth that he had 
 discovered, rather than to achieve immediate personal 
 fame. 
 
 ' Such being the actual facts of the case, I should have 
 had no cause for complaint if the respective shares of 
 Darwin and myself in regard to the elucidation of nature's 
 method of organic development had been thenceforth 
 estimated as being, roughly, proportional to the time we had 
 each bestowed upon it when it was thus first given to 
 the world that is to say, as 20 years is to one week. 
 For, he had already made it his own. If the persuasion of 
 his friends had prevailed with him, and he had published
 
 WALLACE'S WORDS ON JULY 1, 1908 15 
 
 his theory, after 10 years' 15 years' or even 18 years' 
 elaboration of it I should have had no part in it what- 
 ever, and he would have been at once recognised, and 
 should be ever recognised, as the sole and undisputed dis- 
 coverer and patient investigator of the great law of " Natural 
 Selection " in all its far-reaching consequences. 
 
 'It was really a singular piece of good luck that gave 
 me any share whatever in the discovery ... it was only 
 Darwin's extreme desire to perfect his work that allowed me 
 to come in, as a very bad second, in the truly Olympian race in 
 which all philosophical biologists, from Buffon and Erasmus 
 Darwin to Kichard Owen and Kobert Chambers, were more 
 or less actively engaged.' l 
 
 ECHOES OF THE STORM 
 
 It is impossible to do more than refer briefly 
 to the storm of opposition with which the Origin 
 was at first received. The reviewer in the 
 Athenaeum for Nov. 19, 1859, left the author 
 ' to the mercies of the Divinity Hall, the Col- 
 lege, the Lecture Room, and the Museum '. 2 
 Dr. Whewell for some years refused to allow 
 a copy of the Origin to be placed in the library 
 of Trinity College, Cambridge. 3 My predecessor, 
 Professor J. 0. Westwood, proposed to the last 
 Oxford University Commission the permanent 
 endowment of a lecturer to combat the errors 
 of Darwinism. ' Lyell had difficulty in prevent- 
 ing [Sir William] Dawson reviewing the Origin 
 on hearsay, without having looked at it. No 
 spirit of fairness can be expected from so biassed 
 
 1 Darwin-Wallace Celebration of the Linnean Society of London 
 (1908), 6, 7. 
 
 2 Life and Letters, ii. 228 . 8 Ibid., 261 n.
 
 16 FIFTY YEARS OF DARWINISM 
 
 a judge.' * And even when naturalists began to 
 be shaken by the force of Darwin's reasoning, 
 they were often afraid to own it. Thus Darwin 
 wrote to H. Fawcett, on Sept. 18, 1861 : 
 
 'Many are so fearful of speaking out. A German 
 naturalist came here the other day; and he tells me that 
 there are many in Germany on our side, but that all seem 
 fearful of speaking out, and waiting for some one to speak, 
 and then many will follow. The naturalists seem as timid 
 as young ladies should be, about their scientific reputation.' 2 
 
 Among the commonest criticisms in the early 
 days, and one that Darwin felt acutely, 3 was the 
 assertion that he had deserted the true method of 
 scientific investigation. One of the best exam- 
 ples of this is to be found in the letter of Darwin's 
 old teacher in geology, Adam Sedgwick : 
 
 ' You have deserted after a start in that tram-road of all 
 solid physical truth the true method of induction, and 
 started us in machinery as wild, I think, as Bishop Wilkins's 
 locomotive that was to sail with us to the moon.' * 
 
 This ill-aimed criticism was soon set to rest by 
 Henry Fawcett's article in Macmillan's Magazine 
 
 1 From a letter written by Darwin to Hooker, Nov. 4, 1862. 
 More Letters, i. 468. 
 
 2 More Letters, i. 196. 
 
 8 See Darwin's letter to Henslow, May 8, 1860. More Letters, i. 
 149, 150. 
 
 * Life and Letters, ii. 248. Sedgwick's letter is dated Dec. 24, 
 1859, but the editors of More Letters (i. 150 n.) express the opinion 
 that it must have been written in November at latest. See also 
 the Quarterly Review for July, I860. Sedgwick's review in the 
 Spectator, Mar. 24, 1860, contains the following passage : 
 '. . . I cannot conclude without expressing my detestation of the 
 theory, because of its unflinching materialism ; because it has 
 deserted the inductive track, the only track that leads to physical 
 truth ; because it utterly repudiates final causes, and thereby 
 indicates a demoralised understanding on the part of its advocates. 1 
 Quoted in Life and Letters, ii. 298.
 
 SUPPOKT BY MILL AND FAWCETT 17 
 
 in 1860, and by a paper read before the British 
 Association by the same author in 1861. Refer- 
 ring to this defence Fawcett wrote to Darwin, 
 July 16, 1861 : 
 
 ' I was particularly anxious to point out that the method 
 of investigation pursued was in every respect philosophically 
 correct. I was spending an evening last week with my 
 friend Mr. John Stuart Mill, and I am sure you will be 
 pleased to hear from such an authority that he considers 
 that your reasoning throughout is in the most exact accord- 
 ance with the strict principles of logic. He also says the 
 method of investigation you have followed is the only one 
 proper to such a subject. 
 
 ' It is easy for an antagonistic reviewer, when he finds it 
 difficult to answer your arguments, to attempt to dispose of 
 the whole matter by uttering some such commonplace as 
 " This is not a Baconian induction". . . . 
 
 ' As far as I am personally concerned, I am sure I ought 
 to be grateful to you, for since my accident nothing has 
 given me so much pleasure as the perusal of your book. 
 Such studies are now a great resource to me.' l 
 
 To this Darwin replied : 
 
 'You could not possibly have told me anything which 
 would have given me more satisfaction than what you say 
 about Mr. Mill's opinion. Until your review appeared I 
 began to think that perhaps I did not understand at all how 
 to reason scientifically.' 2 
 
 In the general truth of his theory Darwin felt 
 an entire confidence born of the long years of 
 pondering over difficulties throughout the whole 
 realm of natural history. And it was the con- 
 sciousness that a secure and undisturbed belief 
 lay behind the fair and cautious statements of the 
 
 1 More Letters, i. 189, 190. a Ibid., 189. 
 
 C
 
 18 FIFTY YEAES OF DARWINISM 
 
 Origin that was so intensely irritating to men 
 whose antagonism was based on religious con- 
 viction. Thus in Sedgwick's letter, from which 
 I have already quoted, we read : 
 
 ' Lastly, then, I greatly dislike the concluding chapter 
 not as a summary, for in that light it appears good but 
 I dislike it from the tone of triumphant confidence in which 
 you appeal to the rising generation . . . and prophecy of 
 things not yet in the womb of time, nor (if we are to trust 
 the accumulated experience of human sense and the 
 inferences of its logic) ever likely to be found anywhere but 
 in the fertile womb of man's imagination.' 1 
 
 THE MATURITY OF THE ORIGIN CONTRASTED 
 
 WITH THE CRUDITY OF RIVAL 
 
 INTERPRETATIONS 
 
 It is remarkable to contrast the maturity, the 
 balance, the judgement, with which Darwin put 
 forward his views, with the rash and haphazard 
 objections and rival suggestions advanced by 
 critics. It is doubtful whether so striking a con- 
 trast is to be found in the history of science 
 on the one side, twenty years of thought and 
 investigation pursued by the greatest of natura- 
 lists ; on the other, off-hand impressions upon 
 a most complex problem hastily studied and 
 usually very imperfectly understood. It is not 
 to be wondered at that Darwin found the early 
 criticisms so entirely worthless. The following 
 extract from an interesting letter to John Scott, 
 
 1 Life and Letters, ii. 250.
 
 EASHNESS OP EIVAL HYPOTHESES 19 
 
 written on Dec. 3, 1862 ?, shows how well aware 
 he was of difficulties unnoticed by critics : 
 
 ' You speak of difficulties on Natural Selection : there are 
 indeed plenty ; if ever you have spare time (which is not 
 likely, as I am sure you must be a hard worker) I should be very 
 glad to hear difficulties from one who has observed so much 
 as you have. The majority of criticisms on the Origin are, 
 in my opinion, not worth the paper they are printed on.' * 
 
 From the very first the most extraordinarily 
 crude and ill-considered suggestions were put for- 
 ward by those who were unable to recognize the 
 value of the theory of Natural Selection. A good 
 example is to be found in Andrew Murray's 
 principle of sexual selection based on contrast : 
 
 ' It is trite to a proverb, that tall men marry little women 
 ... a man of genius marries a fool . . . and we are told that 
 this is the result of the charm of contrast, or of qualities 
 admired in others because we do not possess them. I do 
 not so explain it. I imagine it is the effort cf nature to 
 preserve the typical medium of the race.' 2 
 
 Even in these later years the wildest imagin- 
 ings may be put forward in all seriousness as the 
 interpretation of the world of living organisms. 
 Thus in Beccari's interesting work on Borneo, 3 
 the author compares the infancy and growth of 
 the organic world with the development and 
 education of an individual. In youth the indi- 
 vidual learns easily, being unimpeded by the 
 
 1 More Letters, ii. 811. 
 
 2 Life and Letters, ii. 261 n. The original paper is to be found 
 in the Proc. B. Soc. Edin., 1860. 
 
 8 Wanderings in the Great Forests of Borneo, 209-16, English 
 translation, London, 1904. 
 
 c2
 
 20 FIFTY YEARS OF DARWINISM 
 
 force of habits, while * with age heredity acts 
 more strongly, instincts prevail, and adaptation 
 to new conditions of existence and to new ideas 
 become more difficult ; in a word, it is much less 
 easy to combat hereditary tendencies '. Similarly, 
 in the state of maturity now reached by the 
 organic world, Beccari believes that the power of 
 adaptation is wellnigh non-existent. Heredity, 
 through long accumulation in the course of endless 
 generations, has become so powerful that species 
 are now stereotyped and cannot undergo advan- 
 tageous changes. For the same reason, he con- 
 siders, acquired characters cannot now be trans- 
 mitted to offspring. Beccari imagines that 
 everything was different in early ages, when, as 
 he supposes, life was young and heredity weak. 
 In this assumed ' Plasmatic Epoch ' the environ- 
 ment acted strongly upon organisms, evoking the 
 responsive changes which have now been ren- 
 dered fixed and immovable by heredity. 
 
 Even the hypothesis proposed as a substitute 
 for Natural Selection by so distinguished a botanist 
 as Carl Nageli turns out to be most unsatisfactory 
 the moment it is examined. The idea of evolution 
 under the compulsion of an internal force residing 
 in the idioplasm is in essence but little removed 
 from special creation. On the subject of Niigeli's 
 criticisms Darwin wrote, Aug. 10, 1869, to Lord 
 Farrer : 
 
 ' It is to me delightful to see what appears a mere morpho- 
 logical character found to be of use. It pleases me the more
 
 DARWIN'S DEBT TO HOOKER 21 
 
 as Carl Nageli has lately been pitching into me on this head. 
 Hooker, with whom I discussed the subject, maintained that 
 uses would be found for lots more structures, and cheered 
 me by throwing my own orchids into my teeth.' 1 
 
 DARWIN'S GREATEST FRIENDS IN THE TIME 
 OF STRESS 
 
 It is interesting to put side by side passages 
 from two letters 2 written by Darwin to Hooker, 
 one in 1845 at the beginning of their friendship, 
 the other thirty-six years later, a few months 
 before Darwin's death. The first shows the 
 instant growth of their friendship : * Farewell ! 
 What a good thing is community of tastes ! I 
 feel as if I had known you for fifty years. 
 Adios.' 
 
 The second letter expresses at the end of 
 Darwin's life the same feelings which find 
 utterance ever and again throughout the long 
 years of his friendship (see pp. 66, 67). 
 
 ' Your letter has cheered me, and the world does not look 
 a quarter so black this morning as it did when I wrote 
 before. Your friendly words are worth their weight in 
 gold.' 
 
 It was to Hooker that Darwin first confided, 
 Jan. 11, 1844, his belief in evolution, but did not 
 at the time, even to him, give any account of 
 natural selection : 
 
 'At last gleams of light have come, and I am almost 
 convinced (quite contrary to the opinion I started with) that 
 
 1 More Letters, ii. 380. 
 
 2 Ibid., i. 39. The passages here quoted are placed side by side 
 by the editors of this work.
 
 22 FIFTY YEARS OF DARWINISM 
 
 species are not (it is like confessing a murder) immutable. . . . 
 I think I have found out (here 's presumption !) the simple 
 way by which species become exquisitely adapted to various 
 ends. You will now groan, and think to yourself, " on 
 what a man have I been wasting my time and writing to." 
 I should, five years ago, have thought so . . .' * 
 
 Elaborate investigations of all kinds during the 
 long years which led up to the central work of 
 Darwin's life were discussed in detail with the 
 greatest of his friends, and it was an inestimable 
 advantage that the ideas of the Origin were thus 
 searchingly tried beforehand by so critical and, 
 in the best sense, sceptical a mind as Hooker's 
 ' you terrible worrier of poor theorists ! ' 2 as 
 Darwin called him. Again in 1868 : 
 
 ' I have got your photograph over my chimney-piece, and 
 like it much ; but you look down so sharp on me that I 
 shall never be bold enough to wriggle myself out of any 
 contradiction.' 3 
 
 The friendship with Asa Gray began with a 
 meeting at Kew some years before the pubh'cation 
 of Natural Selection. Darwin soon began to ask 
 for help in the work which was ultimately to 
 appear as the Origin. The following letter to 
 Hooker, June 10, 1855, shows what he thought of 
 the great American botanist : 
 
 ' I have written him a very long letter, telling him some of 
 
 1 Life and Letters, ii. 23, 24. See also on p. 32 the letter, dated 
 Oct. 12, [1845], in which Darwin confided his belief 'that species 
 are mutable ' to the Rev. L. Jenyns (Blomefield). The passage 
 from a letter dated Feb. 14, 1845, to the same correspondent, 
 quoted on p. 42 n. 1, suggests that the communication of Oct. 12 
 was written in 1844 and not 1845. 
 
 2 Feb. 28, [18581. More Letters, i. 105. 
 8 More Letters, ii. 376, 377.
 
 DARWIN'S DEBT TO ASA GRAY 23 
 
 the points about which I should feel curious. But on my 
 life it is sublimely ridiculous, my making suggestions to 
 such a man.' ' 
 
 The friendship ripened very quickly, so that on 
 July 20, 1856, Darwin gave Asa Gray an account 
 of his views on evolution, 2 and on Sept. 5 of 
 the following year, a tolerably full description of 
 Natural Selection. 3 From this last letter Darwin 
 chose the extracts which formed part of his 
 section of the joint essay published July 1, 1858. 
 
 Asa Gray's opinion on first reading the Origin 
 was expressed not to Darwin but to Hooker in a 
 letter written Jan. 5, 1860 : 
 
 ' It is done in a masterly manner. It might well have 
 taken twenty years to produce it. It is crammed full of 
 most interesting matter thoroughly digested well ex- 
 pressed close, cogent, and taken as a system it makes out 
 a better case than I had supposed possible. . . .' 
 
 After referring to Agassiz's unfavourable 
 opinion of the book he continues : ' Tell Darwin 
 all this. I will write to him when I get a chance. 
 As I have promised, he and you shall have 
 fair-play here. . . .'* A little later, when on 
 Jan. 23 he wrote to Darwin himself, Asa 
 Gray concluded : ' I am free to say that I never 
 learnt so much from one book as I have from 
 yours. There remain a thousand things I long 
 to say about it.' 5 
 
 1 More Letters, i. 418. Asa Gray's generous reply appears on 
 p. 421. 
 
 2 Life and Letters, ii. 78. 3 Ibid., 120-5. 
 4 Ibid., 268. R Ibid., 272.
 
 24 FIFTY YEARS OF DARWINISM 
 
 It is impossible to do justice on the present 
 occasion to the numerous letters in which Darwin 
 expressed his gratitude for the splendid manner 
 in which Asa Gray kept his word and fought ' like 
 a hero in defence'. 1 At a time when few 
 naturalists were able to understand the drift of 
 Darwin's argument, the acute and penetrating 
 mind of Asa Gray had in a moment mastered 
 every detail. Thus Darwin wrote on July 22, 1860, 
 concerning the article in the Proceedings of the 
 American Academy for April 10 : 
 
 1 . . . I cannot resist expressing my sincere admiration for 
 your most clear powers of reasoning. As Hooker lately said 
 in a note to me, you are more than any one else the 
 thorough master of the subject. I declare that you know 
 my book as well as I do myself; and bring to the question 
 new lines of illustration and argument in a manner which 
 excites my astonishment and almost my envy ! . . . Every 
 single word seems weighed carefully, and tells like a 
 32-pound shot.' * 
 
 Some weeks later, on Sept. 26, 1860, Darwin 
 again expressed the same admiration, and 
 stated that Asa Gray understood him more 
 perfectly than any other friend : 
 
 '. . . you never touch the subject without making it 
 clearer. I look at it as even more extraordinary that you 
 never say a word or use an epithet which does not express 
 fully my meaning. Now Lyell, Hooker, and others, who 
 perfectly understand my book, yet sometimes use expressions 
 to which I demur.' 3 
 
 1 Life and Letters, ii. 310. J Ibid., 326. 
 
 3 Ibid., 344, 345.
 
 DARWIN'S DEBT TO HUXLEY 25 
 
 Darwin also sent 1 Asa Gray's defence of the 
 Origin to Sir Charles Lyell, whom he was 
 extremely anxious to convince of the truth of 
 evolution. Asa Gray's religious convictions 
 prevented the full acceptance of Natural Selection. 
 He was ever inclined to believe in the Providen- 
 tial guidance of the stream of variation. He also 
 apparently differed from Darwin in the extent to 
 which he was inclined to interpret instincts as 
 inherited habits. 2 
 
 The same close intimacy and mutual help begun 
 in the preparation of the Origin was continued in 
 Darwin's later botanical works. Thus Darwin 
 owed his Climbing Plants to the study of a paper 
 by Asa Gray, and he dedicated his Forms of 
 Flowers to the American botanist ' as a small 
 tribute of respect and affection'. Concerning 
 some of the researches which afterwards appeared 
 in this book, Darwin wrote : 
 
 ' I care more for your and Hooker's opinion than for that 
 of all the rest of the world, and for Lyell's on geological 
 points.' 3 
 
 Another great name, that of Huxley, is 
 especially associated in our minds with the 
 defeat of those who would have denied that the 
 subject was a proper one for scientific investiga- 
 tion. In the strenuous and memorable years 
 that followed the appearance of the Origin, the 
 mighty warrior stands out as the man to whom 
 
 1 More Letters, i. 169. 2 Life and Letters, iii. 170. 
 
 3 Ibid., 300.
 
 26 FIFTY YEARS OF DARWINISM 
 
 more than to any other we owe the gift of free 
 speech and free opinion in science, the man so 
 admirably described by Sir Kay Lankester at 
 the Linnean Celebration as ' the great and beloved 
 teacher, the unequalled orator, the brilliant 
 essayist, the unconquerable champion and literary 
 swordsman Thomas Henry Huxley '. ' 
 
 Comparing the friendships to which Darwin 
 owed so much, Lyell was at first the teacher but 
 finally the pupil, unwilling and unconvinced at 
 the outset, in the end convinced although still 
 unwilling ; Hooker in England and Asa Gray in 
 America were the two intimate friends on whom 
 Darwin chiefly depended for help in writing the 
 Origin, and for support to its arguments ; Huxley 
 was the great general in the field where religious 
 convictions, expressed or unexpressed, were the 
 foundation of a fierce and bitter antagonism. 
 
 THE ATTACKS OF RICHARD OWEN AND 
 ST. GEORGE MIVART 
 
 An unnecessary bitterness was imported into 
 the early controversies in England, because of the 
 personality of the scientific leaders in the attacks 
 on the Origin. Of these the chief was the great 
 comparative anatomist, Sir Richard Owen. In 
 spite of his leading scientific position, this 
 remarkable man withdrew from contact with his 
 brother zoologists, living in a self-imposed isola- 
 
 1 Darwin-Wallace Celebration of the Linnean Society of London 
 (1908), 29. See also pp. 66-8 of the present work.
 
 THE ATTACKS OF OWEN 27 
 
 tion which tended towards envy and bitterness. 
 The same unavailing detachment had been 
 carried much further by the great naturalist 
 W. J. Burchell, who, as from a watch-tower, 
 looked upon the world he strove to avoid with an 
 absorbed and jealous interest. Prof. J. M. Baldwin 
 has shown how inevitable and inexorable is the 
 grip of the social environment : the more we 
 attempt to evade it, the more firmly we seem to 
 be held in its grasp. 
 
 In the first years of the struggle, Owen's bitter 
 antagonism made itself felt in the part he took as 
 1 crammer ' to the Bishop of Oxford, and in his 
 anonymous article in the Edinburgh Review for 
 April, 1860. But Owen could not bear to remain 
 apart from the stream of thought when there was 
 no doubt about the way it was flowing, so that in 
 a few years he was maintaining some of the chief 
 conclusions of the Origin, although retracting 
 nothing, but rather keeping up a bitter attack 
 upon Darwin. This treatment received from one 
 who was all affability when they met, 1 was natu- 
 rally resented by Darwin, whose feelings on the 
 subject are expressed in the following passage 
 from a letter to Asa Gray, July 23, 1862. 
 
 ' By the way, one of my chief enemies (the sole one who 
 has annoyed me), namely Owen, I hear has been lecturing on 
 birds ; and admits that all have descended from one, and 
 advances as his own idea that the oceanic wingless birds 
 
 1 ' Mrs. Carlyle said that Owen's sweetness always reminded her 
 of sugar of lead.' Life and Letters of T. H. Huxley, London, ii. 167.
 
 28 FIFTY YEARS OF DARWINISM 
 
 have lost their wings by gradual disuse. He never alludes 
 to me, or only with bitter sneers, and coupled with Buffon 
 and the Vestiges.' 1 
 
 In the historical sketch added to the later 
 editions of the Origin, Owen is the only writer 
 who is severely dealt with. In this introductory 
 section Darwin said that he was unable to decide 
 whether Owen did or did not claim to have 
 originated the theory of Natural Selection. 2 
 
 If Owen had withdrawn from his former 
 attitude of antagonism, as did Lyell, he would be 
 entitled to the same honourable place in the 
 memory of future generations. As it is, we must 
 regret that he did not keep up the struggle to the 
 
 1 More Letters, i. 203. 
 
 2 Origin of Species, 6th Ed., xviii. See also the writer's article 
 in the Quarterly Renew for July, 1909, 4-6. The following remark- 
 able episode, which I owe to the kindness of my friend Mr. Roland 
 Trimen, F.R.S., is quoted from p. 5 : 
 
 'At Down, about the end of the year 1867, when conversing 
 with Mr. Darwin about the already steadily increasing acceptance 
 of the " Origin " among thinking naturalists, in contrast to the 
 active hostility it encountered on and long after its first appearance 
 only eight years before, I referred to the heavy artillery brought to 
 bear against it in the "Quarterly" and "Edinburgh'' Reviews, 
 besides the host of other discharges from arms of minor calibre. 
 Mr. Darwin asked me if I knew who wrote the " Edinburgh " article, 
 and on my replying that I did not, but that I had heard Owen's name 
 suggested amongst others, he said, " Owen was the man." I ven- 
 tured to enquire whether he came to this conclusion from other 
 evidence than that afforded by the style, tone, etc., of the article 
 itself; and he answered, "The internal evidence made me almost 
 sure that only Owen could have written it ; but when I taxed him with 
 the authorship and he absolutely denied it then I was quite certain." 
 
 ' Words of such keen satire came with extraordinary effect from 
 a man so eminently gentle and considerate, and so free from any 
 touch of jealousy or self-assertion as Darwin. They made a deep 
 and lasting impression on me all the more because they were 
 spoken very quietly and deliberately, and because they were the 
 only words of censure I heard used by the greatest of naturalists.'
 
 OWEN AND EVOLUTION IN 1881 29 
 
 end. How completely he abandoned it, and how 
 sharp was the contrast between him and a still 
 surviving warrior of the ' Old Guard ', remains as 
 one of my earliest and clearest memories of the 
 scientific world. The stage was the meeting of 
 the British Association at York, in 1881, when 
 Prof. O. C. Marsh described the Berlin skeleton 
 of Archaeopteryx. The lizard-like characteristics 
 of the earlier fossil in the British Museum 
 bought, it was said, at the price of a dowry for a 
 professor's daughter were far more clearly 
 displayed in the later find. Prof. Marsh told me 
 that he would have given almost any sum to 
 secure this probably the most valuable and 
 interesting fossil in the world for the museum 
 at Yale. ' I dare not do it,' was the reply. * We 
 let the other go, and I really believe they would 
 kill me if I sold this one.' So Prof. Marsh, 
 obliged to study the wonderful ancestral bird in 
 Berlin, came, fresh from his work, to tell us 
 about it at York. 
 
 Owen, presiding over the zoological section at 
 which the paper was read, seemed quite enthu- 
 siastic over Archaeopteryx, and had not a word of 
 criticism for the evolutionary history which it 
 unfolded. He discoursed sweetly upon the teeth, 
 believed to have been discovered in embryonic 
 parrots, and, with his suave manner and venerable 
 appearance, created a very pleasant impression. 
 An entirely different scene was enacted, a day or 
 two later, in the geological section, where Prof.
 
 30 FIFTY YEARS OF DARWINISM 
 
 H. G. Seeley exhibited a restoration of the same 
 fossil. Dr. Wright, the palaeontologist, old and 
 deaf, but staunch as ever, would have none of it. 
 1 Archaeopteryx hasn't got a head. How can it 
 possibly have teeth ? ' he asked angrily, thinking 
 of the older specimen in the British Museum. 
 But even in this, the remains of the head, 
 detached from the body, had been made out by 
 Sir John Evans in a corner of the block of oolite, 
 while the teeth were found scattered over the 
 surface of the stone. Prof. Newton's emphatic 
 assertion that the bird had teeth left him quite 
 unshaken, and even after Prof. Marsh, called on 
 by the chairman, had drawn their form on the 
 blackboard, and the section was proceeding to 
 other business, Dr. Wright could be heard 
 muttering savagely, 'Archaeopteryx is a very 
 good bird.' And its excellence was in his 
 opinion obviously incompatible with reptilian 
 affinity. Disbelief in evolution was with him a 
 matter of faith and could never have been 
 affected by any amount of evidence. 
 
 About twelve years after the appearance of the 
 Origin, another opponent, St. George Mivart, 
 produced something of the same bitterness as 
 Owen, and for a similar reason. Thus Darwin 
 wrote to Hooker, Sept. 16, 1871, as follows : 
 
 ' You never read such strong letters Mivart wrote to me 
 about respect towards me, begging that I would call on him, 
 etc., etc. ; yet in the Q. Review [July, 1871] he shows the 
 greatest scorn and animosity towards me, and with un-
 
 MIVART'S INCONSISTENCY 31 
 
 common cleverness says all that is most disagreeable. He 
 makes me the most arrogant, odious beast that ever lived. 
 I cannot understand him ; I suppose that accursed religious 
 bigotry is at the root of it. Of course he is quite at liberty 
 to scorn and hate me, but why take such trouble to express 
 something more than friendship? It has mortified me 
 a good deal.' ' 
 
 On other occasions at a much later date I have 
 myself observed that there was something peculiar 
 about the poise of Mivart's mind, which seemed 
 ever inclined to pass, with abrupt transition, 
 from the extreme of an unnecessary effusiveness 
 to an unnecessarily extreme antagonism. 
 
 Mivart's attack, contained in his book, The 
 Genesis of Species, was effectively dealt with by 
 Chauncey Wright in the North American Review 
 for July, 1871. Darwin was so pleased with this 
 defence that he obtained the author's permission 
 for an English reprint, 2 and with further additions 
 it was published as a pamphlet by John Murray 
 in 1871. A copy presented by Darwin to the 
 late J. Jenner Weir, and now in the library of 
 the Hope Department of the Oxford University 
 Museum, contains an interesting holograph letter 
 referring to the pamphlet and bearing upon the 
 controversy that followed upon the appearance of 
 Mivart's book. This letter is, by kind permission 
 of Mr. Francis Darwin, now made public : 
 
 1 More Letters, i. 333. See also Life and Letters, Hi. 146-50. 
 
 8 The pamphlet was published at Darwin's expense. For his 
 keenly appreciative letters to the author, see Life and Letters, iii. 
 145, 146.
 
 32 FIFTY YEARS OF DARWINISM 
 
 Down, 
 Beckenham, Kent. 
 
 Oct. 11, 1871. 
 MY DEAR SIB 
 
 I am much obliged for your kind note and invitation. 
 I sh d like exceedingly to accept it, but it is impossible. 
 I have been for some months worse than usual, and can 
 withstand no exertion or excitement of any kind, and in 
 consequence have not been able to see anyone or go any- 
 where. As long as I remain quite quiet, I can do some 
 work, and I am now preparing a new and cheap Edit n of the 
 Origin in which I shall answer Mr. Mivart's chief objections. 
 Huxley will bring out a splendid review on d in the 
 Contemporary R., on November 1st. 
 
 I am pleased that you like Ch. Wright's article. It seemed 
 to me very clever for a man who is not a naturalist. He is 
 highly esteemed in the U. States as a Mathematician and 
 sound reasoner. 
 
 I wish I could join your party. 
 My dear Sir 
 
 Yours very sincerely 
 
 CH. DARWIN.' 
 
 Chauncey Wright speaks of presenting, in his 
 review of Mivart, considerations ' in defence and 
 illustration of the theory of Natural Selection. 
 My special purpose/ he continues, 'has been to 
 contribute to the theory by placing it in its proper 
 relations to philosophical inquiries in general.' 2 
 
 This able critic in America, and Heniy Fawcett 
 in England, represent a class of thinkers who 
 have taken and still take a very important part 
 in upholding the theory of Natural Selection. It 
 
 1 The letter is addressed to J. Jenner Weir, Esq., 6 Haddo 
 Villas, Blackheath, London, S.E. 
 
 2 In a letter to Darwin, June 21, 1871. Life and Letters, iii. 
 143, 144.
 
 THE VALUE OF EXTERNAL SUPPORT 33 
 
 is not necessary to be a biologist in order to 
 comprehend the details and the bearings of this 
 theory. At the outset, when naturalists them- 
 selves were often hopelessly puzzled, the theory 
 was clearly understood by able thinkers who were 
 not students of biology, or indeed in some cases 
 of any of the sciences. And at the present time 
 such support is of the highest importance when, 
 within the boundaries of the sciences most nearly 
 concerned, the intense and natural desire to try 
 all things is not always accompanied by the 
 steadfast purpose to hold fast that which is good. 
 
 LAMARCK'S HYPOTHESIS AND THE HEREDITARY 
 TRANSMISSION OF ACQUIRED CHARACTERS 
 
 The greatest change in evolutionary thought, 
 since the publication of the Origin, was wrought, 
 after Darwin's death, by the appearance of that 
 wonderful and beautiful theory of heredity which 
 looks on parents as the elder brother and sister of 
 their children. In this theory, itself an outcome 
 of minute and exact observation (see p. 39), 
 Weismann raised the question of the hereditary 
 transmission of acquired characters, the very 
 foundation of Lamarckian and Spencerian evolu- 
 tion. Darwin accepted this transmission, and it 
 was in order to account for 'such facts as the 
 inherited effects of use and disuse, &C.,' 1 that 
 he thought out his marvellous hypothesis of 
 
 1 See the letter to Huxley, July 12 (1865 ?), in Life and Letters, 
 iii. 44. 
 
 D
 
 34 FIFTY YEARS OF DARWINISM 
 
 pangenesis. If such effects be not transmitted, 
 pangenesis becomes unnecessary and Weismanri s 
 simpler, more convincing, and better supported 
 hypothesis of the continuity of the germ-plasm 
 takes its place. It is impossible on the present 
 occasion to speak in any detail of the controversy 
 which has raged intermittently during the past 
 twenty years on this fascinating subject. I will, 
 however, briefly consider a single example of the 
 error into which, as I believe, Darwin was led by 
 following the Lamarckian theory of hereditary 
 experience. I refer to the interpretation which 
 he suggests for feelings of ' the sublime ', applying 
 this term to the effect upon the brain of a vast 
 cathedral, a tropical forest, or a view from a 
 mountain height. Thus, writing to E. Gurney, 
 July 8, 1876, Darwin said on this subject : 
 ' . . . possibly the sense of sublimity excited by 
 a grand cathedral may have some connection with 
 the vague feelings of terror and superstition in 
 our savage ancestors, when they entered a great 
 cavern or gloomy forest.' J 
 
 An interesting account is given by Romanes 2 
 of Darwin's own experience of these feelings, 
 relating how he at first thought that they were 
 most excited by the magnificent prospect surveyed 
 from one of the summits of the Cordilleras, but 
 afterwards came down from his bed on purpose 
 to correct this impression, saying that he felt 
 most of the sublime in the forests of Brazil. 
 
 1 Life and Letters, iii. 186. 2 Ibid., 54, 55. See also i. 64, 65.
 
 FEELINGS OF THE SUBLIME 35 
 
 We may first observe that the remarkable 
 feelings induced by such experiences are very far 
 from unpleasant, as we should expect them to be 
 on the theory which refers them to the apprehen- 
 sions and dangers of our primitive ancestors. 
 Thus, on May 18, 1832, when the first impressions 
 of a Brazilian forest were freshest in Darwin's 
 mind, he wrote to Henslow, telling him of an 
 expedition of 150 miles from Rio de Janeiro to 
 the Rio Macao. 
 
 ' Here I first saw a tropical forest in all its sublime 
 grandeur nothing but the reality can give any idea how 
 wonderful, how magnificent the scene is. ... I never 
 experienced such intense delight. I formerly admired 
 Humboldt, I now almost adore him ; he alone gives any 
 notion of the feelings which are raised in the mind on first 
 entering the Tropics.' l 
 
 Furthermore, how are we to account on any 
 such hypothesis for the similarity of the feelings 
 excited by the forest, where enemies might lurk 
 unseen, and the mountain peak, the very spot 
 which offers the best facility for seeing them? 
 It is also difficult to understand why the terrors 
 of primitive man should be specially associated 
 with caves or with the most magnificent forests 
 on the face of the earth. 2 There is no valid 
 reason for believing that any less danger lurked 
 amid trees of ordinary size or lay in wait for him 
 by the riverside, in the jungle, or the rock-strewn 
 
 1 Life and Letters, i. 236, 237. 
 
 1 There is grave doubt whether the New World was inhabited 
 by man until long after the Palaeolithic Age. 
 
 D 2
 
 36 FIFTY YEARS OF DARWINISM 
 
 waste. In the midst of life he was in death in 
 every solitary place that could afford cover to an 
 enemy ; on the mountain-top probably least of all. 
 
 The feelings inspired by the interior of a 
 cathedral are especially instructive in seeking 
 the explanation of the psychological effect. We 
 may be sure that the result is here produced by 
 the unaccustomed scale of the aesthetic impres- 
 sion. A cathedral the size of an ordinary church 
 would not produce it. However intensely we 
 may admire, the sense of the sublime is not 
 excited or but feebly excited by the exterior of 
 a cathedral, nor does it accompany the profound 
 intellectual interest aroused by the sight of the 
 Pyramids. The thrill of the sublime, in the 
 sense in which the term is here used, is, I do 
 not doubt, the result of surprise and wonder 
 raised to their highest power a psychological 
 shock at the reception of an aesthetic visual 
 experience on an unwonted scale vast, as if 
 belonging to a larger world in which the insignifi- 
 cance of man is forced upon him. It is not 
 excited by the Pyramids, which are in form but 
 symmetrical hills of stone, nor does the exterior 
 of any building afford an experience sufficiently 
 remote to produce the feeling in any high degree. 
 
 W. J. Burchell, in one of his letters 1 to Sir 
 William Hooker, points out that the feelings of 
 awe and wonder aroused in a Brazilian forest 
 
 1 Preserved in the Library at Kew, but, I believe, as yet un- 
 published.
 
 FEELINGS OF THE SUBLIME 37 
 
 are not to be expected in those to whom the 
 sight is familiar. As regards the depth and 
 nature of the effects produced by the experiences 
 here referred to, it would be very interesting to 
 compare the savage with the civilized man, the 
 uneducated with the educated mind. That the 
 results are intimately bound up with the psycho- 
 logical differences between individuals in part 
 inherent, in part due to training and experience 
 is well illustrated in a story told by the late 
 Charles Dudley Warner, who took two English 
 friends to see for the first time the Grand Canyon 
 of the Colorado. When they reached the point 
 where the whole prospect boundless beyond 
 imagination is revealed in a moment of time, 
 one of his friends burst into tears, while the 
 other relieved his feelings by unbridled blasphemy. 
 The remarkable psychological effects of a 
 grandeur far transcending and far removed from 
 ordinary experience may be compared to the 
 thrill l so often felt on hearing majestic music 
 a thrill we do not seek to explain as a faint, 
 far-off reminiscence of dread inspired by the 
 savage war-cry. I do not doubt that an ex- 
 planation of the sublime based on the terrors 
 of our primitive ancestors is an example of the 
 mistaken interpretations into which even Darwin 
 was led by following the hypothesis of Lamarck. 
 
 1 Darwin spoke of his backbone shivering during the anthem in 
 King's College chapel. Life and Letters, i. 49 ; see also 170.
 
 38 FIFTY YEAES OF DARWINISM 
 
 FRANCIS DARWIN ON THE TRANSMISSION OF 
 ACQUIRED CHARACTERS 
 
 One of the most recent attempts to defend 
 the Lamarckian doctrine of the hereditary trans- 
 mission of acquired characters is contained in the 
 important Presidential Address of Mr. Francis 
 Darwin to the British Association at Dublin 
 (1908). In this interesting memoir the author 
 expresses the belief that such transmission is 
 implied by the persistence for unnumbered gene- 
 rations of the successive developmental stages 
 through which the individual advances towards 
 maturity. Following Hering and Richard Semon, 
 he is disposed to explain the hereditary trans- 
 mission of these stages by a process analogous 
 to memory. It is interesting to observe that 
 this very analogy had been brought before 
 Charles Darwin, but failed to satisfy him. He 
 wrote to G. J. Romanes, May 29, 1876 : 
 
 ' I send by this post an essay by Hackel attacking Pan. 
 and substituting a molecular hypothesis. If I understand 
 his views rightly, he would say that with a bird which 
 strengthened its wings by use, the formative protoplasm of 
 the strengthened parts became changed, and its molecular 
 vibrations consequently changed, and that these vibrations 
 are transmitted throughout the whole frame of the bird, and 
 affect the sexual elements in such a manner that the wings 
 of the offspring are developed in a like strengthened manner. 
 . . . He lays much stress on inheritance being a form of 
 unconscious memory, but how far this is part of his molecular 
 vibration, I do not understand. His views make nothing 
 clearer to me ; but this may be my fault.' ' 
 
 1 More Letters, i. 364. See also the following sentence in a letter
 
 WEISMANN'S THEORY SUFFICIENT 39 
 
 Should it hereafter be proved that acquired 
 characters are inherited, I cannot but think that 
 the interpretation will be on the lines of Charles 
 Darwin's hypothesis of Pangenesis. But the 
 probability that any such result will be estab- 
 lished, already shown to be extremely small, 
 has become even more remote in the light of 
 the recent investigations conducted by Mendelians 
 and Mutationists. 
 
 For the transmission of all inherent qualities, 
 including the successive stages of individual de- 
 velopment, Weismann's hypothesis of the con- 
 tinuity of the germ-plasm supplies a sufficient 
 mechanism. I remember, more than twenty 
 years ago, asking this distinguished discoverer 
 how it was that the hypothesis arose in his mind. 
 He replied that when he was working upon the 
 germ-cells of Hydrozoa he came to realize that 
 he was dealing with material which early and 
 late in the history of the individual was most 
 carefully preserved, as though it were of the 
 most essential importance for the species. If 
 
 on Pangenesis, written June 3, 1868, to Fritz Miiller : ' It often 
 appears to me almost certain that the characters of the parents 
 are " photographed " on the child, only by means of material atoms 
 derived from each cell in both parents, and developed in the child.' 
 More Letters, ii. 82 : also quoted in Life and Letters, iii. 84. The 
 following passage in a letter to Sir Joseph Hooker, Feb. 28, 1868, 
 is also of great interest : ' When you or Huxley say that a single 
 cell of a plant, or the stump of an amputated limb, has the 
 "potentiality" of reproducing the whole or "diffuses an in- 
 fluence ", these words give me no positive idea ; but, when it is 
 said that the cells of a plant, or stump, include atoms derived 
 from every other cell of the whole organism and capable of develop- 
 ment, I gain a distinct idea.' Life and Letters, iii. 81.
 
 40 FIFTY YEARS OF DARWINISM 
 
 the efficient cause of the stages of individual 
 development (ontogeny) resides in the fertilized 
 ovum as we cannot doubt then Weismann's 
 hypothesis satisfactorily accounts for their heredi- 
 tary transmission. For the portion of the ovum 
 set aside to form the germ-cells from which the 
 next generation will arise is reserved with all 
 its powers, and includes the potentiality of these 
 stages no less than the other inherent character- 
 istics of the individual. 
 
 It is, I think, unfortunate to seek for analogies 
 and vague analogies they must always be 
 between heredity and memory. However much 
 we have still to learn about it, memory is, on its 
 physiological side, a definite property of certain 
 higher cerebral tissues, a property which has 
 clearly been of the utmost advantage in the 
 struggle for life, and bears the stamp of adapta 
 tion. Compare, for instance, the difficulty in 
 remembering a name with the facility in recog- 
 nizing a face. Adaptation would appear to be 
 even more clearly displayed in the unconscious 
 registration in memory and the instant recogni- 
 tion of another individual as seen from behind 
 or when partially concealed. Such memory is 
 quite independent of the artistic power. Without 
 any intelligent appreciation of what is peculiar 
 to another individual, his characteristic features 
 are stored up unconsciously, so that when seen 
 again he is instantly recognized. 
 
 One other consideration brought forward by
 
 INDIVIDUAL ADJUSTABILITY 41 
 
 Mr. Francis Darwin may be briefly discussed. 
 It is well known that plants have the power of 
 adjusting themselves to their individual environ- 
 ment, and that such adjustment may beneficially 
 take the place of a rigid specialization. The fixed 
 condition of plants renders this power especially 
 necessary for them, and the hereditary trans- 
 mission of the results of its exercise especially 
 dangerous. Where the seed falls, there must 
 the plant grow. The parent was limited to one 
 out of many possible environments ; the offspring 
 may grow in any of them, and for one that would 
 hit off the precise conditions of the parent and 
 would benefit by inheriting the parental response, 
 numbers would have to live in different surround- 
 ings and might be injured by the hereditary bias. 
 
 Mr. Francis Darwin calls attention to the leaves 
 of the beech, which in the interior shaded parts 
 of the tree possess a structure different from that 
 exhibited on the outer parts more freely exposed 
 to light. The structure of the shaded leaves 
 resembles that apparently stereotyped in trees 
 always adapted to shade, and Mr. Francis Darwin 
 is inclined to regard the permanent condition as 
 a final result of the hereditary transmission of 
 the same response through a large number of 
 generations. 
 
 The development of shade foliage in the beech 
 is, I presume, a manifestation of a power widely 
 spread among animals and probably among plants 
 also a power of producing a definite individual
 
 42 FIFTY YEARS OF DARWINISM 
 
 adaptation in response to a definite stimulus. To 
 stereotype the result would be to convert a benefit 
 to the individual into an injury to the species. 
 The beech in a very shady place would presum- 
 ably develop the maximum of the shade foliage. 
 How disadvantageous would the hereditary bias 
 be to its offspring that happened to grow in more 
 exposed situations. But, it is argued, in plants 
 subject to a permanent condition we do meet 
 with a permanent structure, just as if repetition 
 had at length produced a hereditary result. The 
 answer to this argument seems to me to be 
 complete. When conditions are uniform and 
 no power of individual adaptation is required, 
 Natural Selection, without attaining the power, 
 would produce the permanent and hereditary 
 result in the usual way. If, however, a species, 
 already possessing the power, ultimately came 
 to live permanently in one set of conditions and 
 thus ceased to need it, the power itself, no longer 
 sustained by selection, would sooner or later be 
 lost. 
 
 DARWIN'S VIEWS ON EVOLUTION BY 
 'MUTATION' 
 
 It is interesting to note that the word ' Muta- 
 tion ' appears at one time to have suggested itself 
 to Darwin l in order to express the evolution or 
 
 This seems clear from the following passage in a letter 
 written Feb. 14 [1845], to Rev. L. Blomefield (Jenyns) : ' Thanks 
 for your hint about terms of " mutation ", etc. ; I had some 
 suspicions that it was not quite correct, and yet 1 do not yet see
 
 'MUTATION' EEJECTED BY DAKWIN 43 
 
 descent with modification of species, by no means 
 implying change by large and sudden steps as 
 in the usual modern acceptation of the term. 
 Indeed, the words * mutable ', ' mutability ', and 
 their opposites, have never been employed with 
 the special significance now attached to 'muta- 
 tion '. Every one believes in the mutability of 
 species, but opinions diifer as to whether they 
 change by mutation. 
 
 It is a mistake to suppose that Darwin did 
 not long and carefully consider large variations, 
 or 'mutations', as supplying the material for 
 evolution. Writing to Asa Gray as early as 
 August 11, 1860, he said of great and sudden 
 variation : 
 
 ' I have, of course, no objection to this, indeed it would be 
 a great aid, but I did not allude to the subject, for, after 
 much labour, I could find nothing which satisfied me of the 
 probability of such occurrences. There seems to me in 
 almost every case too much, too complex, and too beautiful 
 adaptation, in every structure to believe in its sudden pro- 
 duction.' 1 
 
 In the twenty years between 1860 and 1880 we 
 find that Darwin was continually brought back to 
 this subject by his correspondents, and by reviews 
 and criticisms of his works. Scattered over this 
 period we find numbers of letters in which he 
 expressed his disbelief in an evolution founded 
 
 my way to arrive at any better terms. It will be years before 
 I publish, so that I shall have plenty of time to think of better 
 words. Development would perhaps do, only it is applied to the 
 changes of an individual during its growth.' More Letters, i. 50. 
 See also p. 22 . 1. * Life and Letters, ii. 333.
 
 44 FIFTY YEARS OF DARWINISM 
 
 on ' sudden jumps ' or ' monstrosities ', as well as 
 on ' large ', ' extreme ', and ' great and sudden 
 variations' (see Appendix B, p. 254). Out of 
 many examples I select one more because of its 
 peculiar interest. 
 
 The Duke of Argyll, in his address to the 
 Royal Society of Edinburgh, Dec. 5, 1864, used 
 the following words : ' Strictly speaking, there- 
 fore, Mr. Darwin's theory is not a theory of the 
 Origin of Species at all, but only a theory on the 
 causes which lead to the relative success and 
 failure of such new forms as may be born into the 
 world.' 1 In a letter to Lyell, Jan. 22, 1865, 
 Darwin wrote concerning this argument : 
 
 ' I demur ... to the Duke's expression of "new births". 
 That may be a very good theory, but it is not mine, unless 
 indeed he calls a bird born with a beak T J-gth of an inch 
 longer than usual " a new birth " ; but this is not the sense 
 in which the term would usually be understood. The more 
 I work, the more I feel convinced that it is by the accumu- 
 lation of such extremely slight variations that new species 
 arise.' 2 
 
 We therefore find that when the Duke criti- 
 cized Darwin's theory of Natural Selection as 
 though it had been founded on mutation, the 
 interpretation was repudiated by Darwin himself. 
 
 I desire again to state most emphatically that, 
 during the whole course of his researches and 
 reflections upon evolution, Darwin was thoroughly 
 
 1 Scotsman, Dec. 6, 1864. 
 
 2 Life and Letters, iii. 33. See also Quarterly Revieic. July. 1909, 
 25, 26 ; also 10-12.
 
 DAKWIN'S SURE JUDGEMENT 45 
 
 aware of the widespread large variations upon 
 which the mutationist relies. He had the material 
 before him, he formed his judgement upon it, and 
 on this memorable day it seems specially appro- 
 priate to show how extraordinarily sure his scien- 
 tific instincts were wont to be. This will be 
 made clear by a few examples of the solutions 
 which Darwin found for problems which at the 
 time had either not been attempted at all or had 
 been very differently interpreted. 
 
 Darwin's explanation of coral islands and atolls, 
 at first generally accepted, was afterwards called 
 in question. Finally, the conclusive test of a 
 deep boring entirely confirmed the original theory. 
 Perhaps the most remarkable case is that of the 
 permanence of ocean basins and continental 
 areas, a view which Darwin maintained single- 
 handed in Europe, although supported by Dana 
 in America, against Lyell, Forbes, Wallace, 
 Hooker and all others who had written on the 
 subject. Darwin considered it mere waste of 
 time to speculate about the origin of life ; we 
 might as well, he said, speculate about the origin 
 of matter. Nothing hitherto discovered has 
 shaken this opinion, which is expressed almost 
 in Darwin's words in Prof. Arrhenius' recent 
 work. 1 In the fascinating subject of geographical 
 distribution we now know that Darwin antici- 
 pated Edward Forbes in explaining the alpine 
 arctic forms as relics of the glacial period (see 
 
 1 Worlds in the making. English transl., London (1908), 218.
 
 46 FIFTY YEARS OF DARWINISM 
 
 p. 123, n. 2), while he interpreted the poverty of 
 the Greenland flora and the reappearance of north 
 temperate species in the southern part of South 
 America as results of the same cause. Almost 
 as soon as the facts were before him in Wol- 
 laston's memoirs, Darwin had interpreted the 
 number of wingless beetles in oceanic islands 
 as due to the special dangers of flight. He 
 anticipated H. W. Bates' hypothesis of Mimicry, 
 but drove it from his mind because he did not 
 feel confident about the geographical coincidence 
 of model and mimic (see pp. 123, 124). Long 
 before the Origin appeared, Darwin had thought 
 over and rejected the idea that the same species 
 could have more than a single origin, or could 
 arise independently in two different countries 
 a hypothesis very popular in later years, but, 
 I believe, now entirely abandoned (see Appendix 
 A, p. 247). 
 
 I should wish to advance one further con- 
 sideration before concluding this section of my 
 address. Certain writers on mutation seem to 
 hold the view that Natural Selection alone pre- 
 vents large variations from often holding the 
 field and leading on to great and rapid changes of 
 species. Such a view is not supported by the 
 history of species which inhabit situations com- 
 paratively sheltered from the struggle, such as 
 fresh water, caves, certain islands, or the depths 
 of the ocean. Organisms in these places tend to 
 preserve their ancestral structure more persis-
 
 ISOLATED FOEMS ANCESTRAL 47 
 
 tently than in the crowded areas where Natural 
 Selection holds more potent sway. 
 
 The grounds for this conclusion, stated by 
 Darwin half a century ago, should be seriously 
 considered by those who are inclined to follow 
 de Vries in his rash speculations on the periodic 
 mutation of species. The following statements 
 are to be found in Darwin's letters to Lyell : 
 
 ' A monad, if no deviation in its structure profitable to it 
 under its excessively simple conditions of life occurred, might 
 remain unaltered from long before the Silurian Age to the 
 present day.' 1 
 
 ' With respect to Lepidosiren, Ganoid fishes, perhaps 
 Ornithorhynchus, I suspect, as stated in the Origin, that they 
 have been preserved, from inhabiting fresh-water and isolated 
 parts of the world, in which there has been less competition 
 and less rapid progress in Natural Selection, owing to the 
 fewness of individuals which can inhabit small areas ; and 
 where there are few individuals variation at most must be 
 slower.' 2 
 
 ' I quite agree with you on the strange and inexplicable fact 
 of Ornithorhynchus having been preserved, and Australian 
 Trigonia, or the Silurian Lingula. I always repeat to myself 
 that we hardly know why any one single species is rare or 
 common in the best-known countries. I have got a set of 
 notes somewhere on the inhabitants of fresh water ; and it is 
 singular how many of these are ancient, or intermediate 
 forms ; which I think is explained by the competition having 
 been less severe, and the rate of change of organic forms 
 having been slower in small confined areas, such as all the 
 fresh waters make compared with sea or land.' 3 
 
 1 Oct. 11, 1859. Life and Letters, ii. 210. 
 
 2 Feb. 18, 1860. More Letters, i. 143. See Origin of Species, 
 ed. vi, 83, 112. 
 
 3 Sept. 12, 1860. Life and Letters, ii. 340. See also Quarterly 
 Review, July, 1909, 21, 22.
 
 48 FIFTY YEAKS OF DARWINISM 
 
 EVOLUTION CONTINUOUS OR DISCONTINUOUS 
 
 Darwin fully recognized the limits which may 
 be set to the results achieved by the artificial 
 selection in one direction of individual variations. 
 Thus he wrote, Aug. 7, 1869, to Sir Joseph 
 Hooker : 
 
 ' I am not at all surprised that Hallett has found some 
 varieties of wheat could not be improved in certain desirable 
 qualities as quickly as at first. All experience shows this 
 with animals ; but it would, I think, be rash to assume, 
 judging from actual experience, that a little more improve- 
 ment could not be got in the course of a centuiy , and theoreti- 
 cally very improbable that after a few thousands [of years] 
 rest there would not be a start in the same line of variation.' l 
 
 The conception of evolution hindered or for 
 a time arrested for want of the appropriate varia- 
 tions is far from new. The hypothesis of organic 
 selection was framed by Baldwin, Lloyd Morgan, 
 and Osborn to meet this very difficulty, as ex- 
 pressed in the following paragraph quoted from 
 the present writer's address to the American 
 Association for the Advancement of Science at 
 the Detroit meeting, Oct. 15, 1897 : 
 
 ' The contention here urged is that natural selection works 
 upon the highest organisms in such a way that they have 
 become modifiable, and that this power of purely individual 
 adaptability in fact acts as the nurse by whose help the 
 species . . . can live through times in which the needed 
 inherent variations are not forthcoming.' 2 
 
 1 More Letters, i. 314. 
 
 2 Development and Evolution, J. M. Baldwin, New York (1902), 350.
 
 THE LIMITS TO VAEIATION 49 
 
 It has already been shown that Darwin entirely 
 recognized the limits which individual variations, 
 or, as they are called by de Vries, ' fluctuations,' l 
 may set to the progress achieved by artificial 
 selection, and that he admitted the necessity 
 of waiting for a fresh 'start in the same line'. 
 In this respect he agreed with modern writers on 
 mutation ; but differed from them in believing 
 that the fresh start would ultimately be made. 
 He also differed, as has been already abundantly 
 shown, in the magnitude assigned to the varia- 
 tions forming the steps of the onward march of 
 evolution. His observation and study of nature 
 led him to the conviction that large variations, 
 although abundant, were rarely selected, but 
 that evolution proceeded gradually and by small 
 
 1 It is to be feared that confusion will result from Dr. A. E. 
 Shipley's treatment of this subject in his address to the Zoological 
 Section of the British Association at Winnipeg as reported in the 
 Times of Aug. 28, 1909. The account of Dr. Shipley's address- 
 by now probably widely read - contains the following statement : - 
 ' Mutations were variations arising in the germ-cells and due to 
 causes of which we were wholly ignorant ; fluctuations were varia- 
 tions arising in the body or " soma " owing to the action of external 
 conditions. The former were undoubtedly inherited, the latter very 
 probably not.' The term 'Fluctuation ' or ' Fluctuating Variability ' 
 has been applied by de Vries to what Darwin called ' individual 
 variability ', ' determining the differences which are always to be 
 seen between parents and their children, or between the children 
 themselves ' (Species and Varieties, H. de Vries, 1906, 190). To 
 speak of these differences as ' very probably not ' inherited, is to 
 follow neither Darwin, nor Weismann, nor de Vries, but simply 
 to cause gratuitous confusion by questioning an accepted con- 
 clusion based upon universal experience. The reported statement 
 as to the nature of fluctuations would, if it were correct, prove that 
 the hereditary transmission of acquired characters takes place on 
 the vastest imaginable scale. But, although no one disputes that 
 fluctuations are hereditary, very few indeed will agree that they 
 are due ' to the action of external conditions ', or an other words 
 ' acquired characters '. See Appendix D, p. 258. 
 
 E
 
 50 FIFTY YEARS OF DARWINISM 
 
 steps, that it was f continuous ', not ' discon- 
 tinuous '. 
 
 In his Presidential Address 1 to the British 
 Association at Cape Town in 1905, Sir George 
 Darwin argued from analogy against the ' con- 
 tinuous transformation of species '. It is impor- 
 tant to observe that the word ' continuous ' here 
 expresses uniformity in the rate of specific change, 
 and does not refer, as in the present address, 
 to the minuteness of the steps by which the 
 change is effected. The argument itself, which 
 is of great interest, is as follows : 
 
 ' In the world of life the naturalist describes those forms 
 which persist as species ; similarly the physicist speaks of 
 stable configurations or modes of motion of matter ; and the 
 politician speaks of States. The idea at the base of all 
 these conceptions is that of stability, or the power of resist- 
 ing disintegration. In other words, the degree of persistence 
 or permanence of a species, of a configuration of matter, or 
 of a State depends on the perfection of its adaptation to its 
 surrounding conditions.' 
 
 After maintaining that the stability of states 
 rises and declines, culminating when it reaches 
 zero in revolution or extinction, and that the 
 physicist witnesses results analogous with those 
 studied by the politician and the historian, the 
 author continues : 
 
 1 Report Brit. Assoc. (1905), 8. In this address as originally 
 delivered and printed in Fifty Years of Darwinism I fell into the 
 error of believing that Sir George Darwin was advocating evolution 
 by large steps. I was misled by the consideration that the word 
 ' continuous ' as used in the present address is a subject of contro- 
 versy among biologists, whereas a ' continuous transformation ' in 
 Sir George's sense would not, as I believe, be supported by any 
 naturalist.
 
 KATE OF SPECIFIC CHANGE 51 
 
 1 These considerations lead me to express a doubt whether 
 the biologists have been correct in looking for continuous 
 transformation of species. Judging by analogy we should 
 rather expect to find slight continuous changes occurring 
 during a long period of time, followed by a somewhat sudden 
 transformation into a new species, or by rapid extinction.' 
 
 In order to clear up any doubts about the sense 
 in which the word ' continuous ' is here employed, 
 the following footnote is appended to Sir George 
 Darwin's address : 
 
 'If we may illustrate this graphically, I suggest that the 
 process of transformation may be represented by long lines 
 of gentle slope, followed by shorter lines of steeper slope. 
 The alternative is a continuous uniform slope of change. If 
 the former view is correct, it would explain why it should 
 not be easy to detect specific change in actual operation. 
 Some of my critics have erroneously thought that I advocate 
 specific change per saltum.' 
 
 Biologists are doubtless prepared to agree with 
 the author's conclusions. Indeed, there is no 
 reason for the belief that they have ever looked 
 for a continuous and uniform rate of specific 
 change, so clear has been the evidence afforded 
 by the persistence of ancestral forms in certain 
 areas as compared with their modification or 
 extinction in others (see pp. 46, 47). 
 
 THE FIFTIETH ANNIVERSARY OF THE ORIGIN 
 OF SPECIES A RETROSPECT 
 
 That the Origin of Species, of which Darwin said 
 ' It is no doubt the chief work of my life V should 
 
 1 These words are used in the autobiography (1876): Life and 
 Letters, i. 86. See also the following passage in the letter written 
 to Hooker in July, 1844, the month in which Darwin finished the 
 
 E2
 
 52 FIFTY YEARS OF DARWINISM 
 
 have been bitterly attacked and misrepresented 
 in the early years of the last half-century is quite 
 intelligible ; but it is difficult to understand the 
 position of a recent writer who maintains that 
 the book exercised a malignant influence upon 
 the interesting and important study of species 
 and varieties by means of hybridism. As regards 
 these researches its appearance, we are told, ' was 
 the signal for a general halt ' ; l upon them 
 Natural Selection ' descended like a numbing 
 spell ' ; 2 and, if we are still unsatisfied with his 
 fertility in metaphor, the author offers a further 
 choice between the forty years in the wilderness 3 
 and the leading into captivity. 4 
 
 Francis Galton, in his reply as a recipient 
 of the Darwin- Wallace Medal on July 1, 1908, 
 recalled the effect of the Linnean Society Essay 
 and the Origin. The dominant feeling, he said, 
 was one of freedom. 5 The liberty of which Galton 
 spoke was freely offered to every student of hy- 
 bridism. No longer brought up against the blank 
 wall of special creation, he could fearlessly follow 
 his researches into all their bearings upon the 
 evolution of species. And this had been clearly 
 
 second and full account of his views (see pp. 6, 87; : 'I hate 
 argument from results, but on my views of descent, really Natural 
 History becomes a sublimely grand result-giving subject (now you 
 may quiz me for so foolish an escape of mouth).' Life and Letters, 
 ii. 30. 
 
 1 Rep. Brit. Assoc. (1904), 575. 2 1. c., p. 576. 
 
 3 Mendel's Principles of Heredity, W. Bateson (1902), 104. 
 
 4 1. c., p. 208. 
 
 6 Darwin-Wattace Celebration of the Linnean Society of London 
 (1908), 26.
 
 DARWIN AND HYBRIDISM 53 
 
 foreseen by Darwin when, in 1837, he opened 
 his first notebook and set forth the grand pro- 
 gramme which the acceptance of evolution would 
 unfold. He there said of his theory that ' it 
 would lead to study of ... heredity ', that ' it 
 would lead to closest examination of hybridity 
 and generation '. In the Origin itself the admir- 
 able researches of Kolreuter and Gartner on these 
 very subjects received the utmost attention, and 
 were brought before the world far more promi- 
 nently than they have ever been either before or 
 since. Furthermore, the only naturalist who can 
 be described as a pupil of Darwin's was strongly 
 advised by him to repeat some of Gartner's 
 experiments. 1 It is simply erroneous to explain 
 the neglect of such researches as a consequence 
 of the appearance of the Origin and the study 
 of adaptation. So far from acting as a 'numbing 
 spell ' upon any other inquiry, adaptation itself 
 has been nearly as much neglected as hybridism, 
 and for the same reason the dominant influence 
 upon biological teaching of the illustrious com- 
 parative anatomist Huxley, Darwin's great general 
 in the battles that had to be fought, but not 
 a naturalist, far less a student of living nature. 
 
 The momentous influence of the Origin upon 
 the past half-century, as well as that strange lack 
 
 1 Darwin's letter of Dec. 11. 1862, to John Scott, contains the 
 following words : ' If you have the means to repeat Gartner's 
 experiments on variations of Verbascum or on maize (see the 
 Origin), such experiments would be pre-eminently important.' 
 More Letters, i. 221, 222.
 
 54 FIFTY YEARS OF DARWINISM 
 
 of the historic sense which alone could render 
 possible the comparisons I have quoted, require 
 for their appreciation the addition of yet another 
 metaphor to the series we have been so freely 
 offered. 
 
 The effect of the Origin upon the boundless 
 domain of biological thought was as though the 
 sun had at length dispelled the mists that had 
 long enshrouded a vast primaeval continent. It 
 might then perhaps be natural for some primi- 
 tive chief to complain of the strong new light 
 that was flooding his neighbours' lands no less 
 than his own, thinking in error not inexcusable 
 at the dawning of the intelligence of mankind, 
 that their loss must be his gain. 
 
 And now in my concluding words I have done 
 with controversy. 
 
 Fifty years have passed away, and we may be 
 led to forget their deepest lesson, may be tempted 
 to think lightly of the follies and the narrow- 
 ness, as they appear to us, of the times that are 
 gone. This in itself would be a narrow view. 
 
 The distance from which we look back on the 
 conflict is a help in the endeavour to realize its 
 meaning. Huxley's Address on The Coming of 
 Age of the Origin was a paean of triumph. Tyndall, 
 his friend, further removed from the struggle 
 by the nature of his life-work, realized its pathos 
 when he spoke in his Belfast Address of the pain 
 of the illustrious American naturalist who was 
 forced to recognize the success of the teachings he
 
 THE PATHOS OF THE CONFLICT 55 
 
 could not accept, the naturalist who dictated in 
 the last year of his life the unalterable conviction 
 that these teachings were false. 
 
 I name no names, but I think of leaders of 
 organic evolution in this Continent and in Europe, 
 sons of great men to whom the new thoughts 
 brought deepest grief, men who struggled 
 tenaciously and indomitably against them. And 
 full many a household unknown to fame was the 
 scene of the same poignant contrast, was torn by 
 the same dramatic conflict. 
 
 We have passed through one of the world's 
 mighty bloodless revolutions ; and now, standing 
 on the further side, we survey the scene and are 
 compelled to recognize pathos as the ruling 
 feature. 
 
 The sublime teachings which so profoundly 
 transformed mankind were given by Him who 
 came not to bring peace on earth but a sword. 
 And so it is in all the ages with every high creative 
 thought which cuts deep into ' the general heart 
 of human kind '. It must bring when it comes 
 division and pain, setting the hearts of the fathers 
 against the children and the children against the 
 fathers. 
 
 The world upon which the thoughts of Darwin 
 were launched was very different from the world 
 to which were given the teachings of Galileo and 
 the sublinie discoveries of Newton. The imme- 
 diate effect of the first, although leading to the 
 bitter persecution of the great Italian, was re-
 
 56 FIFTY YEARS OF DARWINISM 
 
 stricted to the leaders of the Church ; the influence 
 of the second was confined to the students of 
 science and mathematics, and was slow in pene- 
 trating even these. Nor did either of these high 
 achievements of the human intellect seriously 
 affect the religious convictions of mankind. It 
 was far otherwise with the teachings of the 
 Origin of Species ; for in all the boundless realm 
 of philosophy and science no thought has brought 
 with it so much of pain, or in the end has led to 
 so full a measure of the joy which comes of 
 intellectual effort and activity, as that doctrine 
 of Organic Evolution which will ever be asso- 
 ciated, first and foremost, with the name of 
 Charles Robert Darwin.
 
 II 
 
 THE PERSONALITY OF CHARLES 
 DARWIN 
 
 Written from the notes of a speech delivered at the 
 Darwin Banquet of the American Association for the 
 Advancement of Science, Baltimore, Jan. 1, 1909. 
 
 IT is of special interest, on the evening of this 
 New Year's Day so happily devoted to the memory 
 of Charles Darwin, to think of the man himself, 
 and trace the influence of his personal qualities 
 in helping to achieve the vast intellectual trans- 
 formation of the past half-century. 
 
 Professor H. H. Turner has shown how nearly 
 the mighty genius of Newton was lost to the 
 world (see pp. 85, 86), and in the case of Darwin 
 the margin of safety appears to have been even 
 narrower. In the first place it was necessary that 
 he should be freed from the continuous labour of 
 income-making and from all those strains which 
 are at times inevitable even in the easiest of pro- 
 fessional careers. Darwin always recognized his 
 dependence upon this indispensable condition, 
 and remembered the debt of gratitude which 
 he owed to the ability and generosity of his 
 father. ' You have no idea during how short
 
 58 THE PERSONALITY OF CHARLES DARWIN 
 
 a time daily I am able to work. If I had any 
 regular duties, like you and Hooker, I should 
 do absolutely nothing in science,' l he wrote to 
 Huxley. But financial independence was not 
 the only nor indeed the most essential condition 
 under which Darwin's life-work became possible. 
 Francis Darwin has told us, in touching and 
 beautiful words, of the loving care with which 
 his father's delicate health was safeguarded and 
 sustained. 
 
 'It is, I repeat, a principal feature of his life, that for 
 nearly forty years he never knew one day of the health of 
 ordinary men, and that thus his life was one long struggle 
 against the weariness and strain of sickness. And this 
 cannot be told without speaking of the one condition which 
 enabled him to bear the strain and fight out the struggle to 
 the end.' 2 
 
 Darwin's life, in the supreme need which can 
 be gathered from these pathetic words, was also 
 brightened by a full measure of the happiness 
 which comes to a father who is devoted to his 
 children. We are told of one of his sons, about 
 four years old, offering him sixpence if he would 
 only leave his work and come and play with 
 them. ' We all knew the sacredness of working 
 
 1 July 20, 1860. More Letters, i. 158. 
 
 8 Life and letters, i. 160. See also the beautiful passage in 
 Darwin's autobiography which expresses his indebtedness to his 
 wife. It was omitted from the Life and Letters published during 
 Mrs. Darwin's lifetime, but has now appeared in More Letters, i. 30. 
 The following sentence from a letter written by Darwin to his 
 brother Erasmus bears upon an opinion that has often been 
 expressed : ' I do not believe it [sea-sickness] was the cause of rny 
 subsequent ill-health, which has lost me so many years. 1 June 30, 
 1864. - More Letters, i. 247.
 
 THE CLAIM OF DAEWIN'S HEALTH 59 
 
 time, but that any one should resist sixpence 
 seemed an impossibility.' l His children followed 
 the custom of children in general in making the 
 delightful assumption that their own father's 
 work must be the work of every properly con- 
 stituted father. Thus, one of Darwin's children 
 is said to have asked in regard to a neighbour 
 ' Then where does he do his barnacles ? ' 2 Simi- 
 larly, one of my own daughters, at the fascinating 
 age when the letter ' r ' is apt to be an insoluble 
 mystery, invented a little romance in which she 
 supposed herself to be the child of a shepherd. 
 A. friend, who entered into the spirit of the game, 
 inquired ' Then where 's your father ? ', and re- 
 ceived as the most natural answer in the world, 
 ' Oh ! he 's in his labotwy.' 
 
 The interest of regular work was essential for 
 Darwin's health and comfort ; while his ill health, 
 by preventing work, raised a barrier against re- 
 covery. Thus for the sake of his health every- 
 thing was subordinated to work ; while for the 
 sake of the work his health was watched over 
 with a double care and anxiety. 
 
 The inexorable claim of Darwin's precarious 
 health leads naturally to a subject which has 
 been widely misunderstood and treated with 
 much mistaken judgement. In the brief auto- 
 biography, written for the members of his family, 
 Darwin states 3 that up to the age of thirty or 
 
 1 Life and Letters, i. 136. 2 More Letters, i. 38. 
 
 3 Life and Letters, i. 100-102, written in 1881. See also 33, 49, 
 and 69, written in 1876.
 
 60 THE PEESONALITY OF CHARLES DARWIN 
 
 beyond it he took great interest and felt intense 
 delight in poetry and music, and to a less extent 
 in pictures. Thus on the voyage of the Beagle, 
 when it was only possible to take a single volume 
 on an expedition, he always chose Milton. Later 
 on in life, he says that his mind underwent a 
 change. He found poetry intolerably dull and 
 could not endure to read a line of it ; he also 
 almost lost his taste for pictures and much of his 
 former exquisite pleasure in fine scenery, while 
 music set him thinking too energetically for his 
 comfort. This alteration, described with charac- 
 teristic candour and simplicity, but with too great 
 modesty, has often been the subject of comment, 
 and Darwin's life has in this respect been pointed 
 to as an example to be avoided. Yet it is easy to 
 understand how the change came on, and why it 
 is only a superficial reading of the facts which 
 can find anything in the illustrious naturalist's 
 career but the finest example for man to look 
 up to and attempt to imitate. 
 
 Dai-win's weakness of health came on between 
 the return from the voyage in 1836 and the 
 removal from London to Down in 1842, the 
 very period at which, as he tells us, his aesthetic 
 tastes began to alter. 
 
 The ill health seems to have increased rapidly 
 towards the close of this period. Thus he wrote 
 as late as Jan. 20, 1839, of being ' fond of talking ' 
 and * scarcely ever out of spirits ', ] while the letters 
 
 1 More Letters, i. 29.
 
 A COMMON ERROR CORRECTED 61 
 
 to Fitz-Boy in 1840 and to Lyell in 1841 speak 
 despondently of the prospects of future work and 
 seem to indicate that Darwin felt the weakness 
 even more severely than in the later years of his 
 life. 
 
 'These two conditions permanent ill-health and a 
 passionate love of scientific work for its own sake deter- 
 mined thus early in his career, the character of his whole 
 future life. They impelled him to lead a retired life of 
 constant labour, carried on to the utmost limits of his 
 physical power, a life which signally falsified his melancholy 
 prophecy.' 1 
 
 It was an inevitable result of this permanent 
 ill health which prevented Darwin in the later 
 years of his life from saying with Huxley, 1 1 
 warmed both hands before the fire of life.' 2 
 When his health was at its best Darwin could 
 only work four hours, or at most four and a half 
 hours in the day ; when it was worse than usual 
 the period was reduced to an hour or an hour and 
 a half, while for long stretches of time many 
 months together he could do no work at all. 
 I have already said that work was necessary for 
 
 1 Life and Letters, i. 272. See also iii. 91, where Mr. Francis 
 Darwin shows that the necessity for constant labour became even 
 more imperative in later years. ' He could not rest, and he 
 recognized with regret the gradual change in his mind that 
 rendered continuous work more and more necessary to him as he 
 grew older.' The passage refers to the years 1867 and 1868. 
 
 2 The first line of Lander's beautiful and dignified verse would 
 have been hardly appropriate to Huxley, although singularly so 
 to Darwin : 
 
 ' I strove with none, for none was worth my strife. 
 
 Nature I loved, and next to Nature, Art : 
 I warmed both hands before the fire of life : 
 It sinks, and I am ready to depart.'
 
 62 THE PERSONALITY OF CHARLES DARWIN 
 
 his health 'nothing else makes me forget my 
 ever-recurrent uncomfortable sensations.' and 
 in order to maintain it the most perfect regu- 
 larity was necessary, the absence of all eifort 
 in other directions, all excitement. During his 
 regular hours Darwin worked 'with a kind of 
 restrained eagerness ', expending his strength up 
 to the furthest possible limit, so that he would 
 suddenly stop in dictating, ' with the words, 
 "I believe I mustn't do any more".' It is 
 quite clear that, with his health as it was, no 
 other effort was possible to Darwin during that 
 day. Professor Bradley has spoken of the 
 errors of interpretation due to the reading of 
 Shakespeare with a slack imagination ; l and 
 any literature worth calling literature demands 
 effort on the part of the reader. Effort was the 
 one thing Darwin could not give. The ordering of 
 Darwin's life was entirely controlled by the two 
 inexorable and interdependent demands of work 
 and health. 
 
 ' It was a sure sign that he was not well when he was idle 
 at any times other than his regular resting hours ; for, as 
 long as he remained moderately well, there was no break 
 in the regularity of his life. Week-days and Sundays passed 
 by alike, each with their stated intervals of work and rest. 
 It is almost impossible, except for those who watched his 
 daily life, to realise how essential to his well-being was the 
 regular routine that I have sketched : and with what pain 
 and difficulty anything beyond it was attempted. Any 
 public appearance, even of the most modest kind, was an 
 
 1 Shakespearean Tragedy, London, 1904, 349.
 
 WOKK ESSENTIAL FOE DARWIN 63 
 
 effort to him. In 1871 he went to the little village church 
 for the wedding of his elder daughter, but he could 
 hardly bear the fatigue of being present through the short 
 
 The holidays and recreations in which men 
 find relief from overwork and gain renewed 
 strength were closed to Darwin. He rarely left 
 his home except when his researches were inter- 
 rupted by illness, and it was hoped that a change 
 of air or visit to a hydropathic establishment 
 would enable him to resume work on his return 
 home. This alone could bring him comfort, and, 
 although never entirely idle during his enforced 
 absence, for this he was longing all the time. 
 The inevitable conditions under which Darwin 
 could keep up his slender stock of health and 
 strength and continue his work are expressed 
 again and again in his correspondence. A few 
 passages bearing on the subject are quoted 
 below, and others will be found in Appendix C, 
 p. 256 ; and in the series of nineteen letters 
 to Mr. Koland Trimen on pp. 218-46. References 
 to the limits imposed by health are to be found 
 in nine of these letters, viz. Nos. 4, 5, 6, 7, 8, 14, 
 17, 18, and 19. Darwin has been wrongly judged 
 by many who have read his autobiography, is still 
 wrongly judged, as will be shown on pp. 79, 80, 
 and it is important, by repeated evidence, to show 
 the true cause of the changes which he described 
 in himself. 
 
 1 Life and Letters, i. 127, 128.
 
 64 THE PERSONALITY OF CHARLES DARWIN 
 
 The autobiography (1876) contains these 
 words : 
 
 'My chief enjoyment and sole employment throughout 
 life has been scientific work ; and the excitement from such 
 work makes me for the time forget, or drives quite away, my 
 daily discomfort.' 1 
 
 The four following passages are all taken from 
 letters to Sir Joseph Hooker : 
 
 1858. 'It is an accursed evil to a man to become so 
 absorbed in any subject as I am in mine.' 2 
 
 1861. ' . . . I cannot be idle, much as I wish it, and am 
 never comfortable except when at work. The word holiday 
 is wiitten in a dead language for me, and much I grieve 
 at it.' 3 
 
 1863. The same inability to find enjoyment in 
 a holiday is expressed in the following passage, 
 which also includes a humorous allusion to the 
 ease with which his work was interrupted : 
 
 ' . . . Notwithstanding the very pleasant reason you give 
 for our not enjoying a holiday, namely, that we have no 
 vices, it is a horrid bore. I have been trying for health's 
 sake to be idle, with no success. What I shall now have to 
 do, will be to erect a tablet in Down Church, " Sacred to the 
 Memory, &c.," and officially die, and then publish books, 
 " by the late Charles Darwin," for I cannot think what has 
 come over me of late ; I always suffered from the excitement 
 of talking, but now it has become ludicrous. I talked lately 
 1^ hours (broken by tea by myself) with my nephew, and I 
 was [ill] half the night. It is a fearful evil for self and 
 family.' 4 
 
 1868. '. . . I am a withered leaf for every subject except 
 Science. It sometimes makes me hate Science, though God 
 
 1 Life and Letters, i. 79. 2 Oct. 13. Life and Letters, ii. 139. 
 
 3 Feb. 4. Ibid., ii. 360. * Jan. 3. Ibid., iii. 5.
 
 WORK ESSENTIAL FOR DARWIN 65 
 
 knows I ought to be thankful for such a perennial interest, 
 which makes me forget for some hours every day my 
 accursed stomach.' l 
 
 Prof. Judd tells of the deep debt to science 
 which Darwin expressed to him on his last visit 
 to Down, and how, having recently become 
 possessed of an increased income, 
 
 ' he was most anxious to devote what he could spare to 
 the advancement of Geology or Biology. He dwelt in the 
 most touching manner on the fact that he owed so much 
 happiness and fame to the natural-history sciences which 
 had been the solace of what might have been a painful 
 existence ... I was much impressed by the earnestness, and, 
 indeed, deep emotion, with which he spoke of his indebted- 
 ness to Science, and his desire to promote its interests.' 2 
 
 Final and secure confirmation of the conclusion 
 that Darwin's health and comfort demanded the 
 employment of his whole strength and energy 
 upon scientific work is found in the following 
 touching passage from a letter written, less than 
 a year before his death, to the dearest of his 
 friends : 
 
 ' I am rather despondent about myself, and my troubles 
 are of an exactly opposite nature to yours, for idleness is 
 downright misery to me, as I find here, as I cannot forget 
 my discomfort for an hour. I have not the heart or strength 
 at my age to begin any investigation lasting years, which is 
 the only thing which I enjoy ; and I have no little jobs 
 which I can do. So I must look forward to Down grave- 
 yard as the sweetest place on earth.' 3 
 
 The dilemma of Darwin's life entirely explains 
 that limitation of interest which has been so often 
 
 1 June 17. Life and Letters, iii. 92. 2 Ibid. iii. 352, 353. 
 
 3 To Sir Joseph Hooker, June 15, 1881. More Letters, ii. 433. 
 
 F
 
 66 THE PERSONALITY OF CHARLES DARWIN 
 
 misunderstood, and it is certain that his keenly 
 sympathetic and emotional nature did not in the 
 slightest degree suffer the injury of which he 
 spoke in the autobiography (1881). 'The loss of 
 these tastes [the higher aesthetic tastes] is a loss 
 of happiness, and may possibly be injurious to the 
 intellect, and more probably to the moral character, 
 by enfeebling the emotional side of our nature. ' l A 
 single example must suffice, but it supplies over- 
 whelming proof. The most dramatic episode in 
 the history of Darwinism was the encounter 
 between Huxley and the Bishop of Oxford on 
 the Saturday (June 30) of the meeting of the 
 British Association at Oxford in I860. 2 The scene 
 of the struggle was the northern section of the 
 first floor room stretching along the whole western 
 front of the University Museum, then just 
 finished. Late on Sunday night Hooker wrote to 
 Darwin, giving him * some account of the awful 
 battles which .... raged about species at Oxford.' 
 Darwin replied at once, his letter being dated 
 July 2 (Monday) : 
 
 ' I have been very poorly, with almost continuous bad 
 headache for forty-eight hours, and I was low enough, and 
 thinking what a useless burthen I was to myself and all 
 others, when your letter came, and it has so cheered me ; 
 
 1 Life and Letters, i. 102. 
 
 8 A curious and interesting feature of the Saturday meeting 
 was the presence of Darwin's old captain on the Beagle, Fitz-Roy, 
 who, in a state of frantic excitement, brandished a bible and kept 
 trying to make impassioned appeals to the authority of ' the Book '. 
 I was told of this incident, as yet I believe unrecorded, by the late 
 Mr. George Griffith ; and my friend Dr. A. G. Vernon Harcourt, 
 F.R.S., who was also present, confirms the accuracy of the account.
 
 DARWIN AND HIS FRIENDS 67 
 
 your kindness and affection brought tears into ray eyes. 
 Talk of fame, honour, pleasure, wealth, all are dirt compared 
 with affection ; and this is a doctrine with which, I know, 
 from your letter, that you will agree with from the bottom 
 of your heart.' 1 
 
 These were the thoughts aroused in Darwin's 
 mind by tidings of the mighty conflict over ideas 
 which he had brought before the world. The appeal 
 of the new doctrine was to the reason and the 
 reason alone ; but the mind of man is something 
 more than an intellectual engine, and we can well 
 understand that here was a man for whom 
 others would fight more fiercely and tenaciously 
 than they would ever have done for themselves. 
 
 The touching words written to Hooker must 
 not obscure the fact that Darwin saw and appre- 
 ciated the whole significance of the fight at 
 Oxford. He well knew its full value, as is clearly 
 proved by other parts of the letter and by those 
 written to Huxley on July 3rd and 20th. In the 
 latter he said : 
 
 ' From all that I hear from several quarters, it seems that 
 Oxford did the subject great good. It is of enormous im- 
 portance, the showing the world that a few first-rate men are 
 not afraid of expressing their opinion.' 2 
 
 Twenty years later, only two years before 
 he died, Darwin recalled the great fight in a 
 letter to Huxley on the subject of his lecture 
 1 On the Coming of Age of the Origin of Species,' 
 given at the Koyal Institution, April 9, 1880 : 
 
 ' . . . I well know how great a part you have played in 
 establishing and spreading the belief in the descent-theory, 
 
 1 Life and Letters, ii. 323. 2 Life and Letters, ii. 324. 
 
 F2
 
 68 THE PERSONALITY OF CHARLES DARWIN 
 
 ever since that grand review in the Times and the battle 
 royal at Oxford up to the present day/ * 
 
 Not less important than Darwin's attitude 
 towards his friends was his bearing towards 
 opponents, a bearing admirably described in 
 George Henry Lewes's review of Animals and 
 Plants under Domestication in the Pall Mall 
 Gazette : 
 
 'We must call attention to the rare and noble calmness 
 with which he expounds his own views, undisturbed by the 
 heats of polemical agitation which those views have excited, 
 and persistently refusing to retort on his antagonists by 
 ridicule, by indignation, or by contempt. Considering the 
 amount of vituperation and insinuation which has come from 
 the other side, this forbearance is supremely dignified.' 
 
 ' Nowhere has the author a word that could wound the 
 most sensitive self-love of an antagonist ; nowhere does he, 
 in text or note, expose the fallacies and mistakes of brother 
 investigators . . . but while abstaining from impertinent 
 censure, he is lavish in acknowledging the smallest debts 
 he may owe ; and his book will make many men happy.' 11 
 
 The charming spirit in which Darwin sent a 
 copy of the Origin to the great American natura- 
 list, Louis Agassiz, is an excellent example of 
 his bearing towards those whom he knew to be 
 antagonistic : 
 
 ' As the conclusions at which I have arrived on several 
 points differ so widely from yours, I have thought (should 
 you at any time read my volume) that you might think that 
 I had sent it to you out of a spirit of defiance or bravado ; 
 but I assure you that I act under a wholly different frame of 
 
 1 April 11, 1880. Life and Letters, iii. 241. 
 
 1 Pall Mall Gazette of Feb. 10, 15, and 17, 1868. The above- 
 quoted passages are well selected by Mr. Francis Darwin. See 
 Life and Letters, iii. 76, 77.
 
 DARWIN AND HIS OPPONENTS 69 
 
 mind. I hope that you will at least give me credit, however 
 erroneous you may think my conclusions, for having 
 earnestly endeavoured to arrive at the truth.' * 
 
 To his over-pugnacious friend Haeckel he 
 wrote : 
 
 '. . . I think . . . that you will excite anger, and that 
 anger so completely blinds every one, that your arguments 
 would have no chance of influencing those who are already 
 opposed to our views. Moreover, I do not at all like that you, 
 towards whom I feel so much friendship, should unneces- 
 sarily make enemies, and there is pain and vexation enough 
 in the world without more being caused.' 2 
 
 Another and very potent cause of the rapid 
 growth of the new teachings is to be found in 
 Darwin's attitude towards his readers. It is 
 extraordinarily well described by Francis Darwin 
 in the great Life and Letters : 
 
 ' The tone of ... the ' Origin ' is charming, and almost 
 pathetic ; it is the tone of a man who, convinced of the truth 
 of his own views, hardly expects to convince others ; it is 
 just the reverse of the style of a fanatic, who wants to force 
 people to believe. The reader is never scorned for any 
 amount of doubt which he may be imagined to feel, and his 
 scepticism is treated with patient respect. A sceptical 
 reader, or perhaps even an unreasonable reader, seems to 
 have been generally present to his thoughts.' 3 
 
 The mind of man is ever attracted by the flame 
 and the hurricane of war rather than by the appeal 
 of the still small voice of reason. Nevertheless 
 it is by the still small voice that the thoughts 
 of the world are widened and transformed. 
 
 1 Nov. 11, 1859. Life and Letters, ii. 215. 
 
 2 May 21, 1867. Life and Letters, iii. 69. 
 
 3 Life and Letters, i. 156.
 
 70 THE PERSONALITY OF CHARLES DARWIN 
 
 A good example of Darwin's beautiful and 
 sympathetic treatment of the younger workers 
 who asked for help is to be found in his letter 
 to Prof. E. B. Wilson, quoted on p. 107. John 
 Scott, employed in the Botanical Garden at 
 Edinburgh, writing about his experiments con- 
 ducted along lines suggested by Darwin's pub- 
 lished researches, became, in a measure, a pupil 
 of the illustrious naturalist. For years Darwin 
 devoted much time and thought not only to 
 Scott's work but to giving the encouragement 
 so necessary to a proud, reserved, sensitive man, 
 with qualities very superior to those usually 
 found in the position in which he was placed. 
 1 1 should be proud to be the author of the paper,' l 
 he wrote, when he had at length persuaded Scott 
 to prepare an account of some of his investiga- 
 tions for the Linnean Society. And referring 
 to its publication he wrote to Hooker: 
 * Remember my urgent wish to be able to send 
 the poor fellow a word of praise from any one.' 2 
 To the same friend he said of Scott's letters, 
 ' these show remarkable talent, astonishing per- 
 severance, much modesty, and what I admire, 
 determined difference from me on many points.' 3 
 
 A delightful spirit, boyish in its gaiety, is 
 revealed in Darwin's correspondence with his 
 friends, and especially with the greatest of them 
 
 1 Nov. 7, 1863. More Letters, ii. 325. The paper was read 
 Feb. 4, 1864, and is published in Linn. Soc. Journ., viii. 1865. 
 
 2 Jan 24. 1864. More Letters, ii. 326. 
 
 3 Apr. 1, 1864. Ibid., ii. 330.
 
 DAEWIN AND YOUNGER WORKERS 71 
 
 all, Sir Joseph Hooker. The two following pas- 
 sages from letters to Sir Joseph have been 
 selected not only as examples but also because 
 of their intrinsic interest. In the first, Darwin 
 is speaking of the deplorable loss of the ancestral 
 flora of St. Helena. 
 
 'You have no faith, but if I knew any one who lived in 
 St. Helena I would supplicate him to send me home a cask 
 or two of earth from a few inches beneath the surface from 
 the upper part of the island, and from any dried-up pond, 
 and thus, as sure as I'm a wriggler, I should receive a mul- 
 titude of lost plants.' 1 
 
 * Clematis glandulosa was a valuable present to me. My 
 gardener showed it to me and said, "This is what they call 
 a Clematis,'' evidently disbelieving it. So I put a little twig 
 to the peduncle, and the next day my gardener said, " You 
 see it is a Clematis, for it feels." That's the way we make 
 out plants at Down.' 2 
 
 Although the gardener showed an intelligent 
 understanding of this point in the investigation of 
 climbing plants, he does not appear to have been 
 equally appreciative of other work. Lord Avebury 
 tells the following story : 
 
 ' One of his friends once asked Mr. Darwin's gardener 
 about his master's health, and how he had been lately. " Oh! ", 
 he said, "my poor master has been very sadly. I often wish 
 he had something to do. He moons about in the garden, 
 and I have seen him stand doing nothing before a flower for 
 ten minutes at a time. If he only had something to do 
 I really believe he would be better." ' 3 
 
 1 Jan. 15, 1867. More Letters, i. 494. 
 
 2 Apr. 5, 1864. More Letttrs, ii. 330. 
 
 3 The Darwin- Wall ace Celebration of the Linnean Society of 
 London (1908), 57, 58.
 
 72 THE PEKSONALITY OF CHARLES DARWIN 
 
 From all Darwin's writings there shines forth 
 the most charming sympathy and even affection 
 for the animals and plants which he studied. 
 ' . . . I can hardly believe that any one could be 
 so good-natured as to take such trouble and do 
 such a very disagreeable thing as kill babies,' 
 he wrote, referring to a young chicken and nest- 
 ling pigeon required for his investigations ; l and 
 in another letter 'I appreciate your kindness 
 even more than before, for I have done the black 
 deed and murdered an angelic little fantail, and 
 a pouter at ten days old.' 2 ' I love them to that 
 extent I cannot bear to kill and skeletonise 
 them/ 3 he wrote of his pigeons a few months 
 later. 
 
 The same strong humanity and love of animals 
 is shown in the depth of his feelings on the 
 subject of vivisection. * It is a subject which 
 makes me sick with horror, so I will not say 
 another word about it, else I shall not sleep 
 to-night.' 4 At the same time, he had no doubt 
 about the necessity or the wisdom of permitting 
 such experiments, and of course saw clearly that 
 'the benefits will accrue only indirectly in the 
 search for abstract truth. It is certain,' he con- 
 tinued, ' that physiology can progress only by 
 
 1 To W. D. Fox, Mar. 19 and 27, 1855. Life and Letters, ii. 
 46-8. 
 
 2 July, 1855. Ibid , 50. 
 
 3 Nov., 1855. More Letters, i. 87 n. I. From the context it 
 appears probable that the letter was written to Sir Joseph Hooker. 
 
 4 To Sir Ray Lankester, Mar. 22, 1871. Life cuid Letters, iii. 200. 
 See also 199-210.
 
 DARWIN'S LOVE FOR ANIMALS 73 
 
 experiments on living animals. Therefore the 
 proposal to limit research to points of which we 
 can now see the bearings in regard to health, 
 &c., I look at as puerile.' 1 Some years later, 
 only a few weeks before his death, he wrote, 
 referring to Edmund Gurney's articles on vivi- 
 section : 
 
 ' . . . I agree with almost everything he says, except with 
 some passages which appear to imply that no experiments 
 should be tried unless some immediate good can be predicted, 
 and this is a gigantic mistake contradicted by the whole 
 history of science.' 2 
 
 We also meet with clear evidence of Darwin's 
 love, almost always humorously expressed, for 
 the children of his brain, his hypotheses. Thus, 
 when studying the development of tendrils, he 
 was able to show a beautiful gradation between 
 these organs and leaves, but was utterly puzzled 
 by the vine, in which they are known to be 
 modified branches. He discussed the point in 
 a letter to Hooker, and finished up with the 
 words: 'I would give a guinea if vine-tendrils 
 could be found to be leaves.' 3 Later on he dis- 
 covered a plant with branches possessing the 
 qualities which seemed essential in the fore- 
 runners of these sensitive organs, and he wrote 
 
 1 To his daughter, Mrs. Litchfield, Jan. 4, 1875. Life and Letters, 
 iii. 202. 
 
 2 To Sir Lander Brunton, Feb. 14, 1882. Ibid., 210 ; also More 
 Letters, ii. 441. Edmund Gurney's articles appeared in the 
 Fortnightly Review, 1881, xxx. 778 and CornhiU Magazine, 1882, 
 xlv. 191. 
 
 3 Feb., 1864 (?). More Letters, ii. 342.
 
 74 THE PERSONALITY OF CHARLES DARWIN 
 
 to the same friend, ' . . . tell Oliver I now do not 
 care at all how many tendrils he makes axial, 
 which at one time was a cruel torture to me.' l 
 Alluding to a hypothesis on the relation between 
 the order of development of parts in the individual 
 and the complexity of its organization, he wrote 
 to Huxley, who had expressed an adverse 
 opinion : ' I shall, of course, not allude to this 
 subject, which I rather grieve about, as 1 wished 
 it to be true ; but, alas ! a scientific man ought 
 to have no wishes, no affections a mere heart of 
 stone.' 2 These quotations taken alone would 
 give an utterly wrong impression of Darwin as 
 a scientific man. Two passages will be sufficient 
 to show that his well-balanced mind was secure 
 against the dangers of a too great devotion to the 
 creations of his brilliant imagination. ' It is 
 a golden rule,' he wrote to John Scott, ' which 
 I try to follow, to put every fact which is opposed 
 to one's preconceived opinion in the strongest 
 light. Absolute accuracy is the hardest merit 
 to attain, and the highest merit. Any deviation 
 is ruin.' 3 Again, he wrote in his autobiography 
 in 1881 : 
 
 ' I have steadily endeavoured to keep my mind free so as 
 to give up any hypothesis, however much beloved (and 
 I cannot resist forming one on every subject), as soon as facts 
 are shown to be opposed to it. Indeed, I have had no 
 choice but to act in this manner, for with the exception of 
 
 1 June 2, 1864. More Letters, ii. 343. 2 July 9, 1857. Ibid., i. 98. 
 
 8 July 2, 1863 (?). More Letters, ii. 324. See also Life and Letters, 
 iii. 54, and ibid., i. 87, where Darwin speaks of always making 
 a note of hostile facts.
 
 DARWIN AND HIS HYPOTHESES 75 
 
 the Coral Reefs, I cannot remember a single first-formed 
 hypothesis which had not after a time to be given up or 
 greatly modified. This has naturally led me to distrust 
 greatly deductive reasoning in the mixed sciences.' l 
 
 It is impossible on the present occasion to 
 attempt any analysis of Darwin's genius. I wish, 
 however, to show how clearly he recognized that 
 the love of knowledge for its own sake was the 
 one essential qualification for a scientific man. 
 In his autobiography (1881) he puts ' the love 
 of science ' first among the qualities to which 
 he owed his success. 2 But far earlier in his life, 
 when he was under 40, Darwin wrote to his old 
 teacher Henslow : 
 
 ' I rather demur to one sentence of yours viz., '* However 
 delightful any scientific pursuit may be, yet, if it should be 
 wholly unapplied, it is of no more use than building castles 
 in the air." Would not your hearers infer from this that 
 the practical use of each scientific discovery ought to be 
 immediate and obvious to make it worthy of admiration ? 
 What a beautiful instance chloroform is of a discovery made 
 from purely scientific researches, afterwards coming almost 
 by chance into practical use ! For myself I would, however, 
 take higher ground, for I believe there exists, and I feel 
 within me, an instinct for truth, or knowledge or discovery, 
 of something of the same nature as the instinct of virtue, 
 
 1 Life and Letters, i, 103, 104. See also 149, where Mr. Francis 
 Darwin states : ' It naturally happened that many untenable 
 theories occurred to him ; but fortunately his richness of imagina- 
 tion was equalled by his power of judging and condemning the 
 thoughts that occurred to him. He was just to his theories, and 
 did not condemn them unheard . . .' 
 
 2 Life and Letters, i. 107. See also 103, where he says (1881) : - 
 ' What is far more important [ihan powers of observation, industry, 
 &c.], my love of natural science has been steady and ardent. 
 This pure love has, however, been much aided by the ambition to 
 be esteemed by my fellow naturalists.'
 
 76 THE PERSONALITY OF CHARLES DARWIN 
 
 and that our having such an instinct is reason enough for 
 scientific researches without any practical results ever ensu- 
 ing from them.' l 
 
 The same high motive was expressed in similar 
 language in a letter to his second cousin, W. D. 
 Fox :- 
 
 ' You do me injustice when you think that I work for 
 fame ; I value it to a certain extent ; but, if I know myself, 
 I work from a sort of instinct to try to make out truth.' 2 
 
 The * higher ground ' taken by Darwin is now 
 recognized as the only motive cause which can 
 lead to scientific work at its best. The scientific 
 spirit is essentially and intensely antimateria- 
 list. The expression of an opposite opinion, in 
 spite of the superficial plausibility that made it at 
 one time popular, can only lead in these days 
 to humorous exaggerations such as that contained 
 in the toast said to have been drunk at a Cam- 
 bridge mathematical society : ' To the latest 
 discovery in pure mathematics, and may it never 
 be of the slightest use to anybody.' 
 
 One other dominant element in Darwin's genius 
 which has been sometimes forgotten, must be 
 referred to. I mean the power thus described 
 in the autobiography (1881) : 
 
 ' . . . I think that I am superior to the common run of 
 men in noticing things which easily escape attention, and in 
 observing them carefully.' 3 
 
 1 April 1, 1848. More tetters, i. 61. 
 
 2 Mar. 24, 1859. Life and Letters, ii. 150. 
 
 3 Life and Letters, i. 103. The editors of More Letters (I 72) 
 speak of ' that supreme power of seeing and thinking what the 
 rest of the world had overlooked, which was one of Darwin's most 
 striking characteristics '.
 
 DARWIN AND NEWTON 77 
 
 In attempting to estimate the position of Darwin 
 in the intellectual history of his country and of 
 the world, I will quote the opinion of one whose 
 interests are literary rather than scientific. Lord 
 Courtney, proposing the toast of ' The Royal 
 Society ' at the anniversary dinner a few years 
 ago, compared the scientific with the literary con- 
 tribution made by the English-speaking nations to 
 the brief list of the world's greatest men. In 
 literature of course there was Shakespeare, but 
 who could be placed as a second? 'Many,' 
 said the speaker, 'would propose Milton. Our 
 continental friends might suggest for us Byron ' ; 
 but for himself Lord Courtney was inclined to 
 think that Shakespeare stood in that great world- 
 list alone, without an English-speaking rival or 
 even a second. When, however, he turned to 
 science, the speaker expressed his belief that 
 two names must be admitted as our contribution. 
 I accept the opinion and believe that it will be 
 widely accepted. So far as we can estimate such 
 positions and make such comparisons, Newton 
 and Darwin stand together and for all time in 
 the select company of the greatest men the 
 world has ever seen.
 
 Ill 
 
 THE DARWIN CENTENARY AT OXFORD 
 
 The Oxford Celebration of the hundredth anniversary of 
 the birth of Charles Darwin, Feb. 12, 1809. 
 
 THE hundredth anniversary of the birth of 
 Charles Darwin was celebrated at Oxford on 
 the evening of Feb. 12, 1909, by a reception 
 held in the Examination Schools by Professors 
 S. H. Vines, G. C. Bourne, and E. B. Poulton. 
 The reception was honoured by the presence 
 of four sons of Charles Darwin Mr. William 
 Erasmus Darwin, Sir George Darwin, Mr. Francis 
 Darwin, and Major Leonard Darwin ; as also by 
 that of Professor Judd and Professor Meldola. 
 No attempt was made to extend the commemora- 
 tion widely beyond the limits of Oxford, but 
 invitations were sent to all the names upon the 
 list of Congregation, and the great anniversary 
 was celebrated, as had been intended, by a large 
 gathering of members of the University. Among 
 these several non-residents were able to be present, 
 including Sir William Thiselton-Dyer, Dr. D. H. 
 Scott, President of the Linnean Society of London, 
 Professor J. B. Farmer, and Dr. P. Chalmers 
 Mitchell. 
 
 Mr. Julian Huxley, a grandson of the late 
 Professor Huxley, Mr. H. Moseley, son of the
 
 OLD ERRORS REPEATED 79 
 
 late Professor H. N. Moseley, Mr. Geoffrey 
 Smith, Mr. K. Bourne, Mr. A. F. Coventry, and 
 Mr. E. P. Poulton acted as stewards. 
 
 Special distinction was conferred upon the 
 celebration by the deeply interesting speeches 
 of Sir George Darwin and Mr. Francis Darwin. 
 An address by the present writer was based upon 
 material contained in the two previous addresses, 
 a special point being made of the true interpreta- 
 tion to be placed upon those changes in Darwin's 
 mind, described on pp. 59, 60, which have been 
 so widely and unfortunately misunderstood. It 
 was to the speaker a supreme pleasure to find 
 that the interpretation was entirely accepted by 
 Darwin's sons, and to hear it brought forward 
 in Mr. William Darwin's speech at the Cambridge 
 banquet on June 23rd, a speech which charmed 
 and delighted every one who had the privilege 
 of listening to it. 
 
 There was good and sufficient reason for direct- 
 ing special attention to this point; for on the 
 previous day (Feb. 11) the first and principal 
 article in the Literary Supplement of the Times, 
 entitled Literature and Science, was devoted to 
 this very subject, repeated the old errors and 
 spoke of them as unquestioned facts. The author 
 referred to 
 
 'The unchallenged assumption, so widespread in these 
 days, that science is not truly science unless it is free from 
 all suspicion of poetic exaltation, and that poetry is a place 
 of dreams and divinations which are chilled by the touch of
 
 80 THE DARWIN CENTENARY AT OXFORD 
 
 He considered that we must reckon with 
 
 ' the fact that to give the mind full and free play in one 
 direction seems as yet to imply the atrophy of its activities 
 in the other.' 
 
 The article was evidently written for the 
 anniversary, and that the visionary antagonism 
 which so unnecessarily distressed the author was 
 founded on the misinterpretation of Darwin's life 
 is clear from the following passage : 
 
 ' If a man so utterly incapable of taking an intolerant or 
 a contemptuous view of the life of art could yet find that his 
 own work produced in him the decay of all faculty of 
 artistic enjoyment, we have indeed a proof of the extent to 
 which the two temperaments have diverged.' 
 
 The author spoke also of the fine intellectual 
 training, conferred by the combined ' austerity and 
 responsiveness' of Darwin's work, as one which 
 nevertheless * leaves untouched and undeveloped, 
 positively even starves, the faculty of aesthetic 
 enjoyment'. And he finally touched the high- 
 water mark in these astounding words : 
 
 ' The case of a man given up to scientific investigations, 
 who yet reads Shakespeare without finding him so dull as 
 to be nauseating, is a case which stands out, which is 
 remarked, which is felt to be notable. As long as this is so 
 we must take Darwin's case to be typical of the rule.' 
 
 I will not call this statement an exaggeration, 
 and thus imply that it contains a minute kernel 
 of truth : I unhesitatingly affirm that it is wholly 
 and utterly false. Few can be happier than 
 I in the intimate friendship of scientific men,
 
 AN INDEFENSIBLE CHAKGE 81 
 
 British, American, and Continental, men fol- 
 lowing every branch of science ; and yet, with this 
 wide experience, I do not know a single one to 
 whom the author's words could be fairly applied. 
 Speaking for myself, if I may venture upon what, 
 in the circumstances is not a piece of unnecessary 
 egotism, I would gratefully record the refresh- 
 ment and delight which I have ever found in the 
 works of the English poets. I allude to it, because 
 one who keenly feels this pleasure only too easily 
 detects and is chilled by the want of appreciation 
 of it in others. I should not indeed be surprised 
 if the author's charge against scientific men were 
 true of certain students of literature, men who 
 seem to have triumphed over our conventional 
 tests in the letter so exacting, so heedless of 
 the spirit by means of a knack or trick, and 
 emerge victorious without any perceptible trace 
 of refinement or of interest in any subject, even 
 their own. Such men compare unfavourably 
 with one of our greatest professional exponents 
 of the most difficult of all games, who confessed 
 that, although he did not really care for golf, he 
 was devoted to poaching. 
 
 In this protest, which I have felt it my duty to 
 make, I do not in any way question the author's 
 good faith. It is evident in every line, while the 
 article, when not concerned with the supposed 
 tastes of scientific men, shows great breadth of 
 view and keen penetration. The extraordinary 
 misstatements are due in the first place to the
 
 82 THE DAKWIN CENTENAKY AT OXFORD 
 
 common misinterpretation of Darwin's experience, 
 in the second to false assumptions about a class of 
 workers of whom the author evidently knows 
 nothing. His views on the relation between the 
 creative efforts of the imagination in science and 
 in art are true and clear-sighted. They are admir- 
 ably expressed in the following passage : 
 
 'Darwin had, of course, like many lesser men, an 
 immense power of observing and storing facts ; but that 
 after all concerned merely the preparation of the stage, so 
 to speak, which was thus swept and lighted for his genius 
 to occupy. The work of his genius was, as he put it, to 
 grind out general laws, or, rather, as we may more sym- 
 pathetically phrase it, to take the sudden imaginative leap, 
 seizing the exact moment which justifies it, from the 
 particular to the general. To that moment all the patient 
 and impartial amassing of evidence was subsidiary. We 
 may see in that moment, when it arrived, a strong appeal 
 to the imagination on one side, met by an immediate 
 response to it on the other. To fix the eye successively 
 upon detail, and at the critical instant to shift the focus so 
 as to embrace the whole mass that is not a process which 
 implies the suppression of imagination. It is a process 
 which means for the imagination a continual and austere 
 exercise austere because every vague or unmeaning impulse 
 is forbidden, continual because the mind must be unceasingly 
 alert to catch the moment for its leap. It approaches very 
 near, we surely begin to see, to the process by which, for 
 the artist, a thousand different fragments of perception are 
 transmuted into the single symbolic image which embraces 
 and explains them all.' 
 
 It is an unfortunate result of the inevitable 
 specialization of the present day that one who 
 could write so well of science should know 
 absolutely nothing of scientific workers. It is
 
 SCIENCE AND LITERATUEE 83 
 
 still more unfortunate that, knowing nothing, he 
 should publish his conclusions about them. And 
 yet scientific men, extreme specialists as they 
 are and must be in their researches, are not 
 without some knowledge of the lives and interests 
 of their literary and artistic comrades. 
 
 It is not necessary or desirable to consider here 
 the hypothesis by which the author explains 
 to his own satisfaction an antagonism which only 
 exists in his imagination. But it is right to say 
 a few words about his treatment of science as 
 something essentially modern. The sciences are 
 not new. Aristotle, it has been well said, was 
 just the kind of man one would expect to meet at 
 the Koyal Society or in the Athenaeum. But the 
 spirit of science goes back far beyond the days of 
 Aristotle, to the dawning of the love of knowledge 
 in the developing mind of man, to that primaeval 
 time when wonder first became mingled with 
 delight as he looked upon the world around him. 
 But the ancient desire to find out the ways of 
 nature is gratified in an inexhaustible field where 
 every fulfilment brings a new desire and fresh 
 territory. For this reason the comradeship of 
 scientific men is both stimulating and encouraging 
 to the followers of literature, poring, as so many of 
 them do, over world-worn themes of matchless 
 dignity and beauty, but breathing all the time 
 an atmosphere which tends to over-develop the 
 purely critical faculties and to leave the creative 
 imagination dwarfed and stunted. 
 G2
 
 IV 
 
 CHARLES DARWIN AND THE UNIVER- 
 SITY OF CAMBRIDGE 
 
 Kevised from the shorthand notes of a speech delivered 
 on June 23rd, 1909, at the Banquet given by the University 
 of Cambridge in honour of the Delegates to the Darwin 
 Celebration. 
 
 CHANCELLOK, your Excellencies, my Lords and 
 Gentlemen, it is a proud position to be asked, as 
 a representative of the University of Oxford, to 
 propose, on this memorable occasion, the toast 
 of 'The University of Cambridge'. It is with 
 considerable diffidence that I attempt to fill it. 
 
 The greatness of a University may be most 
 truly measured by the greatness of its sons, and 
 by the force of the intellectual movements to 
 which it has given rise. Mr. Balfour has spoken 
 of the mighty names borne by sons of Cambridge. 
 I trust that I shall enlist your sympathy in 
 dwelling for a few moments on the University 
 life of one of the greatest of these, the illustrious 
 man whom we commemorate to-day, and also in 
 attempting very briefly to show how his mature 
 thoughts were received in both the ancient 
 Universities of this country. It was in Cam- 
 bridge, as you know well, that Charles Darwin
 
 DARWIN'S DEBT TO HENSLOW 85 
 
 came under the guidance of Professor Henslow, 
 a circumstance which, as he said, influenced 
 his whole career more than any other. To 
 Henslow he owed the possibility of sailing in 
 the Beagle, the greatest event, as he believed, in 
 his scientific life the one event which made all 
 the rest possible. 1 We must also remember how 
 Darwin's interest in geology was aroused by 
 Professor Sedgwick. It was on his return from 
 a geological tour in North Wales with Sedgwick 
 that Darwin found the letter from Henslow, 
 offering him the post on the Beagle. However 
 lightly it was regarded by Darwin himself, there 
 can be no doubt of the great depth of his debt to 
 Cambridge. 
 
 In thinking over the names of the great 
 men who have sprung from the University of 
 Cambridge, I have been led to reflect on the long 
 harmonious years of sisterhood between our two 
 ancient Universities, to remember how the 
 thoughts that have arisen in the one have been 
 strengthened by resonance in the other, to call to 
 mind the dependence of the greatest of men upon 
 appreciation and sympathy. 
 
 Professor H. H. Turner has recently shown 
 that the shy and sensitive genius of Newton, 
 irritated by the correspondence with Hooke, 
 might perhaps have been altogether lost to 
 
 1 ' The voyage of the Beagle has been by far the most important 
 event in my life, and has determined my whole career ... I have 
 always felt that I owe to the voyage the first real training or 
 education of my mind . . .' Life and Letters, i. 61.
 
 86 DARWIN AND CAMBRIDGE 
 
 Science, were it not for the * immortal journey ' 
 to Cambridge made by the Oxford man Halley 
 in August, 1684. 
 
 Through the relationship and mutual inter- 
 dependence between great minds we can also 
 trace the influence of Oxford upon Darwin. 
 Sir Ray Lankester spoke this morning of the 
 debt which Lyell owed to the teaching of 
 Buckland at Oxford, and how similar it was to 
 the debt which Darwin owed to Henslow at 
 Cambridge. But there is the strongest evidence, 
 given in Darwin's own words, that he also owed 
 a deep debt to Lyell, and therefore indirectly to 
 Buckland and Oxford. 
 
 The first volume of the first edition of Ly ell's 
 Principles of Geology came out in 1830, just 
 before Darwin started on the voyage of the 
 Beagle. He was advised by Henslow to read it, 
 but on no account to believe the views therein 
 contained; but Darwin was proud to remember 
 that, at the very first opportunity of testing Lyell's 
 reasoning, he recognized the infinite superiority 
 of his teachings over those of all others. Many 
 years later he wrote to L. Horner : ' I always 
 feel as if my books came half out of Lyell's 
 
 brain I have always thought that the great 
 
 merit of the Principles was that it altered the 
 whole tone of one's mind, and therefore that, 
 when seeing a thing never seen by Lyell, one yet 
 saw it partially through his eyes.' * 
 1 See also pp. 5-7.
 
 DAKWIN'S DEBT TO LYELL 87 
 
 When did Darwin acknowledge his debt in 
 this way ? It was on Aug. 29th, 1844. In 1842 
 he had written the first brief account of his 
 theory of evolution that sketch which will now 
 be for the first time in the hands of the public 
 that sketch of which, thanks to your generosity, a 
 gift has been made to every guest whom you are 
 welcoming to Cambridge, a work which I for my 
 part look forward to reading with greater pleasure 
 and greater interest than any book I have ever 
 possessed. In 1844 Darwin had further 
 elaborated this sketch into a completed essay 
 which he felt, whatever happened, would contain 
 a sufficient account of his views ; and on July 5 
 he made his 'solemn and last request' to his 
 wife, begging her, in the event of his death, to 
 make arrangements for its publication. Only a 
 few weeks after this, the psychological moment 
 in his career, Darwin acknowledged his debt to 
 Lyell; and when we consider how intensely 
 Lyellian were the three lines of argument two 
 based on geographical distribution, and one on 
 the relation between the most recent fossils and 
 the forms now living in a country by which 
 Darwin was first convinced of the truth of 
 evolution, we cannot avoid the conclusion that 
 he was right in feeling the debt to be a very 
 heavy one. 
 
 Although Darwin spoke of the three years at 
 Cambridge as ' the most joyful in my happy life ', 
 neither he nor Lyell appear to have thought that
 
 88 DAEWIN AND CAMBRIDGE 
 
 they owed very much to their Universities. In 
 this respect I cannot but believe that both these 
 great men were mistaken, and I think it would 
 be interesting to inquire what would be likely to 
 happen to such men as Darwin or Lyell if they 
 entered Cambridge or Oxford at the present day. 
 I remember many years ago seeing in the 
 papers among the news from India a message 
 which read, with the quaint humour oftentimes 
 conferred by the abbreviation of telegraphic 
 dispatch : ' A new Saint has appeared in the 
 Northern Provinces. The police are already on 
 his track.' In not dissimilar language we must 
 own that when fresh genius appears at the 
 Universities, the examiners are hard upon its 
 track ; and the effect of the pressure of examina- 
 tions upon genius is apt to be similar to that of 
 the removal of Pharaoh's chariot wheels, so that 
 they drave heavily. And with regard to Darwin's 
 teacher Henslow, would the Henslow of to-day 
 have the time and the opportunity to discover and 
 to influence a student who did not care to read 
 for Honours, but preferred to go into the country 
 to collect beetles or into the Fens to collect 
 plants? I do not ask these questions in any 
 pessimistic spirit. There is no need for despair ; 
 for I believe that we are all aware of the danger 
 of the excessive pressure of examinations at the 
 present moment in both our ancient Universities, 
 and indeed to an even greater extent throughout 
 the whole of the British Empire. Cambridge has
 
 GENIUS AND THE EXAMINER 89 
 
 recently made great and important changes 
 precisely in the direction I am indicating 
 changes tending to relieve this pressure ; and we 
 in Oxford have made alterations intended to 
 produce the same effect. I believe we are 
 likely to improve still further in this matter, and, 
 without losing our modern efficiency, regain a 
 greater freedom and greater elasticity, and a freer 
 recognition of unusual powers in these respects 
 assimilating more closely to the Universities of 
 three-quarters of a century ago. 
 
 Turning now to the ancient Universities as the 
 lists where new ideas are compelled to undergo 
 the trial of combat, we observe that the battle of 
 evolution began with the dramatic encounter 
 between Huxley and Wilberforce at the meeting 
 of the British Association at Oxford, in 1860, 
 and, according to Professor Alfred Newton, came 
 to a close with the victory of the new teachings, 
 only two years later, at the meeting of the same 
 Association at Cambridge. 
 
 Whatever happened in the great arena 
 furnished by the two ancient Universities, there 
 can be no doubt that for many years neither of 
 them was at all willing to accept the conclusions 
 of Darwin. One of the most strongly antagonistic 
 letters received by Darwin was written by his 
 old teacher, Sedgwick. Whewell kept the Origin 
 of Species out of the library at Trinity College 
 for some years ; while Professor Westwood 
 seriously proposed to the last Oxford University
 
 90 DARWIN AND CAMBRIDGE 
 
 Commission the establishment of a permanent 
 lectureship for the exposure of the fallacies of 
 Darwinism. 
 
 Charles Darwin was offered the honorary degree 
 of D.C.L. by Lord Salisbury, on his installation as 
 Chancellor of the University of Oxford in 1870. 
 After the lapse of nearly forty years there can be 
 no harm in the candid admission that Lord 
 Salisbury's list was opposed, although unsuc- 
 cessfully, in the Hebdomadal Council. There is 
 no evidence that any special exception was taken 
 to the name of Darwin, but certain members 
 of Council objected to the high proportion of 
 scientific men. The opposition was unsuccessful, 
 the Chancellor's list was passed as a whole, and 
 became the list of the Council ; but, unfortunately 
 for Oxford, Darwin's health prevented him from 
 accepting the degree. Cambridge was happier, 
 and Darwin became an honorary LL.D. of his 
 own University in 1877. 
 
 And now there is one other subject to which I 
 desire to allude before proposing the toast. What 
 would we give to know as much about the life of 
 Shakespeare and of Newton as we know about 
 the life of Darwin ? That we do happily possess 
 a wide and detailed knowledge of the life of this 
 great man we owe to one of his sons, who, with 
 a fine and delicate sense of pathos as well as 
 performance, has done his work, who has hurried 
 in no way but has made every step secure, so that 
 we can with the utmost confidence receive the
 
 THE DEBT TO FRANCIS DARWIN 91 
 
 great result as historical truth that will stand the 
 test of time a sure foundation on which the 
 future can build. This great debt we owe. It is 
 difficult to express our gratitude in adequate 
 terms, but I should wish to say on behalf of 
 those of us who are here as guests of the University 
 of Cambridge that we look with a sympathy of 
 the utmost depth upon the majestic ceremony 
 that will take place to-morrow, when you will 
 make the great exception and dignify with an 
 honorary degree a resident Cambridge man. 
 
 I give you the toast of the 'University of 
 Cambridge', venerable yet ever young, the 
 mother of great men. And I know that when 
 you honour it you will think of one mighty name, 
 the noble, illustrious name of him through whom 
 Cambridge may not unjustly claim that she has 
 taught and inspired the world.
 
 THE VALUE OF COLOUR IN THE 
 STRUGGLE FOR LIFE 
 
 Essay XV in Daricin and Modern Science : Essays in com- 
 memoration of tlie centenary of the birth of Charles Darwin and 
 of the fiftieth anniversary of the publication of ' Tlie Origin of 
 Species ', edited by Prof. A. C. Seward, Cambridge University 
 Press (1909), 271-297. Somewhat extended. 
 
 INTRODUCTION. 
 
 THE following pages have been written chiefly 
 from the historical standpoint. Their principal 
 object has been to give some account of the 
 impressions produced on the mind of Darwin 
 and his great compeer Wallace by various difficult 
 problems suggested by the colours of living nature. 
 In order to render the brief summary of Darwin's 
 thoughts and opinions on the subject in any way 
 complete, it was found necessary to say again 
 much that has often been said before. No attempt 
 has been made to display as a whole the vast con- 
 tribution of Wallace ; but certain of its features 
 are incidentally revealed in passages quoted from 
 Darwin's letters. It is assumed that the reader 
 is familiar with the well-known theories of Pro- 
 tective Resemblance, Warning Colours, and Mimi- 
 cry both Batesian and Miillerian. It would have
 
 THE TKEATMENT HISTORICAL 98 
 
 been superfluous to explain these on the present 
 occasion ; for a far more detailed account than 
 could have been attempted in these pages has 
 recently appeared. 1 Among the older records 
 I have made a point of bringing together the 
 principal observations scattered through the note- 
 books and collections of W. J. Burchell. These 
 have never hitherto found a place in any memoir 
 dealing with the significance of the colours of 
 animals. A few new observations which seemed to 
 be of special interest have been included, together 
 with some fresh considerations deserving of atten- 
 tion in the study of Mimicry in relation to sex. 
 
 INCIDENTAL COLOURS 
 
 Darwin fully recognized that the colours of 
 living beings are not necessarily of value as 
 colours, but that they may be an incidental result 
 of chemical or physical structure. Thus he wrote 
 to T. Meehan, Oct. 9, 1874: 
 
 ' I am glad that you are attending to the colours of di- 
 oecious flowers; but it is well to remember that their 
 colours may be as unimportant to them as those of a gall, 
 or, indeed, as the colour of an amethyst or ruby is to these 
 gems.' 2 
 
 Incidental colours remain as available assets of 
 the organism ready to be turned to account by 
 Natural Selection. It is a probable speculation 
 
 1 Poulton, Essays on Evolution, Oxford, 1908, 293-382. 
 
 2 More letters, i. 354, 355. See also the admirable account 
 of incidental colours in Descent of Man (2nd edit., 1874), 261, 
 262.
 
 94 THE VALUE OF COLOUR 
 
 that all pigmentary colours were originally inci- 
 dental ; but now and for immense periods of 
 time the visible tints of animals have been modi- 
 fied and arranged so as to assist in the struggle 
 with other organisms or in courtship. The domi- 
 nant colouring of plants, on the other hand, is an 
 essential element in the paramount physiological 
 activity of chlorophyll. In exceptional instances, 
 however, the shapes and visible colours of plants 
 may be modified in order to promote conceal- 
 ment. 1 
 
 TELEOLOGY AND ADAPTATION 
 
 In the department of Biology, which forms the 
 subject of this essay, the adaptation of means to an 
 end is probably more evident than in any other ; 
 and it is therefore of interest to compare, in 
 a brief introductory section, the older with the 
 newer teleological views. 
 
 The distinctive feature of Natural Selection as 
 contrasted with other attempts to explain the 
 process of evolution is the part played by the 
 struggle for existence. All naturalists in ah 1 ages 
 must have known something of the operations of 
 * Nature red in tooth and claw ' ; but it was left 
 for this great theory to suggest that vast exter- 
 mination is a necessary condition of progress, 
 and even of maintaining the ground already 
 gained. 
 
 Kealizing that fitness is the outcome of this 
 
 1 See pp. 96-8, 102, 103.
 
 PALEY AND ADAPTATION 95 
 
 fierce struggle, thus turned to account for the first 
 time, we are sometimes led to associate the recog- 
 nition of adaptation itself too exclusively with 
 Natural Selection. Adaptation had been studied 
 with the warmest enthusiasm nearly forty years 
 before this great theory was given to the scientific 
 world, and it is difficult now to realize the impetus 
 which the works of Paley gave to the study of 
 Natural History. That they did inspire the 
 naturalists of the early part of the last century 
 is clearly shown in the following passages. 
 
 In the year 1824 the Ashmolean Museum at 
 Oxford was entrusted to the care of J. S. Duncan 
 of New College. He was succeeded in this office 
 by his brother, P. B. Duncan, of the same College, 
 author of a history of the Museum, which shows 
 very clearly the influence of Paley upon the study 
 of nature, and the dominant position given to his 
 teachings : * Happily at this time [1824] a taste 
 for the study of natural history had been excited 
 in the University by Dr. Paley's very interesting 
 work on Natural Theology, and the very popular 
 lectures of Dr. Kidd on Comparative Anatomy, 
 and Dr. Buckland on Geology/ In the arrange- 
 ment of the contents of the Museum the illustra- 
 tion of Paley's work was given the foremost place 
 by J. S. Duncan : 
 
 ' The first division proposes to familiarize the eye to those 
 relations of all natural objects which form the basis of argu- 
 ment in Dr. Paley's Natural Theology ; to induce a mental 
 habit of associating the view of natural phenomena with the 
 conviction that they are the media of Divine manifestation ;
 
 96 THE VALUE OF COLOUK 
 
 and by such association to give proper dignity to every 
 branch of natural science.' l 
 
 The great naturalist, W. J. Burchell, in his 
 classical work shows the same recognition of 
 adaptation in nature at a still earlier date. Upon 
 the subject of collections he wrote 2 : 
 
 ' It must not be supposed that these charms [the pleasures 
 of Nature] are produced by the mere discovery of new 
 objects : it is the harmony with which they have been 
 adapted by the Creator to each other, and to the situations 
 in which they are found, which delights the observer in 
 countries where Art has not yet introduced her discords.' 
 
 The remainder of the passage is so admirable 
 that I venture to quote it : 
 
 'To him who is satisfied with amassing collections of 
 curious objects, simply for the pleasure of possessing them, 
 such objects can afford, at best, but a childish gratification, 
 faint and fleeting ; while he who extends his view beyond 
 the narrow field of nomenclature, beholds a boundless ex- 
 panse, the exploring of which is worthy of the philosopher, 
 and of the best talents of a reasonable being. ' 
 
 On Sept. 14, 1811, Burchell was at Zand Valley 
 (Vlei), or Sand Pool, a few miles south-west of 
 the site of Prieska, on the Orange Kiver. Here 
 he found a Mesembryanthemum (M. turbiniforme, 
 now M. truncatum) and also a Gryllus (Acridian), 
 closely resembling the pebbles with which their 
 locality was strewn. He says of both of these, 
 
 1 From History and Arrangement of the Ashmolean Museum, by 
 P. B. Duncan, A Catalogue of the Ashmolean Museum, Oxford, 
 (1836), vi, vii. 
 
 2 Travels in the Interior of Southern Africa, London, i. (1822), 
 505. The references to Burchell's observations in the present 
 essay are adapted from the author's article in Report of the British 
 and South African Associations, 1905, iii. 57-110.
 
 BURCHELL AND ADAPTATION 97 
 
 'The intention of Nature, in these instances, seems to 
 have been the same as when she gave to the Chameleon the 
 power of accommodating its color, in a certain degree, to 
 that of the object nearest to it, in order to compensate for 
 the deficiency of its locomotive powers. By their form and 
 color, this insect may pass unobserved by those birds, which 
 otherwise would soon extirpate a species so little able to 
 elude its pursuers, and this juicy little Mesembryanthemum 
 may generally escape the notice of cattle and wild animals.' J 
 
 Burchell here seems to miss, at least in part, 
 the meaning of the relationship between the 
 quiescence of the Acridian and its cryptic colour- 
 ing. It is a relationship of co-operation rather 
 than compensation ; for quiescence is an essential 
 element in the protective resemblance to a stone 
 probably even more indispensable than the details 
 of the form and colouring. Furthermore, the 
 chameleon can make certain movements quickly 
 enough when occasion requires. My friend Pro- 
 fessor Lloyd Morgan has seen an African cha- 
 meleon, when a snake was brought near it, 
 instantaneously quit its hold of the branch, draw 
 in its legs, and fall like a stone to the ground. 
 Although Burchell appears to overlook this point 
 
 1 Ibid., 310, 811. See Sir William Thiselton-Dyer, 'Morpho- 
 logical Notes,' xi. ; ' Protective Adaptations,' i. ; Annals of Botany, 
 xx. 124. In plates vii. viii. and ix. accompanying this article, the 
 author represents the species observed by Burchell, together with 
 others in which analogous adaptations exist. He writes: 'Burchell 
 was clearly on the track on which Darwin reached the goal. But 
 the time had noo come for emancipation from the old teleology. 
 This, however, in no respect detracts from the merit or value of his 
 work. For, as Huxley has pointed out (Huxley's Life and Letters, 
 1900, i. 457), the facts of the old teleology are immediately transfer- 
 able to Darwinism, which simply supplies them with a natural in 
 place of a supernatural explanation.'
 
 98 THE VALUE OF COLOUE 
 
 he fully recognized the community between pro- 
 tection by concealment and more aggressive modes 
 of defence ; for, in the passage of which a part is 
 quoted above, he specially refers to some earlier 
 remarks on p. 226 of his vol. i. We here find 
 that when the oxen were resting by the Juk 
 rivier (Yoke river), on July 19, 1811, Burchell 
 observed * Geranium spinosum, with a fleshy stem 
 and large white flowers . . .; and a succulent species 
 of Pelargonium ... so defended by the old panicles, 
 grown to hard woody thorns, that no cattle could 
 browze upon it.' He goes on to say, ' In this arid 
 country, where every juicy vegetable would soon 
 be eaten up by the wild animals, the Great Creating 
 Power, with all-provident wisdom, has given to 
 such plants either an acrid or poisonous juice, 
 or sharp thorns, to preserve the species from 
 annihilation . . .' All these modes of defence, 
 especially adapted to a desert environment, have 
 since been generally recognized, and it is very 
 interesting to place beside BurchelTs statement 
 the following passage from a letter written by 
 Darwin, Aug. 7, 1868, to G. H. Lewes : 
 
 1 That Natural Selection would tend to produce the most 
 formidable thorns will be admitted by every one who has 
 observed the distribution in South America and Africa (vide 
 Livingstone) of thorn-bearing plants, for they always appear 
 where the bushes grow isolated and are exposed to the attacks 
 of mammals. Even in England it has been noticed that all 
 spine-bearing and sting-bearing plants are palatable to quad- 
 rupeds, when the thorns are crushed.' * 
 
 1 More Letters, i. 308.
 
 THE NEWER AND OLDER TELEOLOGY 99 
 
 ADAPTATION AND NATURAL SELECTION 
 
 I have preferred to show the influence of the 
 older teleology upon Natural History by quotations 
 from a single great and insufficiently appreciated 
 naturalist. It might have been seen equally well 
 in the pages of Kirby and Spence and those of 
 many other writers. If the older naturalists who 
 thought and spoke with Burchell of ' the intention 
 of Nature ' and the adaptation of beings ' to each 
 other, and to the situations in which they are 
 found', could have conceived the possibility of 
 evolution, they must have been led, as Darwin 
 was, by the same considerations, to Natural Selec- 
 tion. This was impossible for them, because the 
 philosophy which they followed contemplated the 
 phenomena of adaptation as part of a static immu- 
 table system. Darwin, convinced that the system 
 is dynamic and mutable, was prevented by these 
 very phenomena from accepting anything short 
 of the crowning interpretation offered by Natural 
 Selection. 1 And the birth of Darwin's unalterable 
 conviction that adaptation is of dominant import- 
 ance in the organic world, a conviction confirmed 
 and ever again confirmed by his experience as 
 a naturalist may probably be traced to the in- 
 
 1 ' I had always been much struck by such adaptations [e. g. 
 woodpecker and tree-frog for climbing, seeds for dispersal], and 
 until these coukl be explained it seemed to me almost useless to 
 endeavour to prove by indirect evidence that species have been 
 modified.' Autobiography in Life and Letters, i. 82. The same 
 thought is repeated again and again in Darwin's letters to his 
 friends. It is forcibly urged in the Introduction to the Origin 
 (1859), 3. 
 
 H2
 
 100 THE VALUE OF COLOUR 
 
 fluence of the great theologian. Thus Darwin, 
 speaking of his Undergraduate days, tells us in his 
 Autobiography that the logic of Paley's Evidences of 
 Christianity and Moral Philosophy gave him as much 
 delight as did Euclid. 
 
 ' The careful study of these works, without attempting to 
 learn any part by rote, was the only part of the academical 
 course which, as I then felt and as I still believe, was of the 
 least use to me in the education of my mind. I did not at 
 that time trouble myself about Paley's premises ; and taking 
 these on trust, I was charmed and convinced by the long 
 line of argumentation.' l 
 
 When Darwin came to write the Origin he 
 quoted in relation to Natural Selection one of 
 Paley's conclusions. ' No organ will be formed, 
 as Paley has remarked, for the purpose of causing 
 pain or for doing an injury to its possessor.' 2 
 
 The study of adaptation always had for Darwin, 
 as it has for many, a peculiar charm. His words, 
 written Nov. 28, 1880, to Sir W. Thiselton-Dyer, 
 are by no means inappropriate at the present day, 
 nor is their application by any means to be 
 restricted to a single nation : ' Many of the 
 Germans are very contemptuous about making 
 out use of organs ; but they may sneer the souls 
 out of their bodies, and I for one shall think it 
 the most interesting part of natural history.' 3 
 
 Mr. Francis Darwin truly says : 
 
 ' One of the greatest services rendered by my father to the 
 
 1 Life and Letters, i. 47. 
 
 2 Origin of Species (let edit.), 1859, 201. 
 8 More Letters, ii. 428.
 
 NATUKAL SELECTION AND TELEOLOGY 101 
 
 study of Natural History is the revival of Teleology. The 
 evolutionist studies the purpose or meaning of organs with 
 the zeal of the older Teleology, but with far wider and more 
 coherent purpose.' 1 
 
 PROTECTIVE AND AGGKESSIVE KESEMBLANCE: 
 PKOCKYPTIC AND ANTICEYPTIC COLOURING 
 
 Colouring for the purpose of concealment is 
 sometimes included under the head Mimicry, a 
 classification adopted by H. W. Bates in his 
 classical paper. Such an arrangement is incon- 
 venient, and I have followed Wallace in keeping 
 the two categories distinct. 
 
 The visible colours of animals are far more 
 commonly adapted for Protective Resemblance 
 than for any other purpose. The concealment of 
 animals by their colours, shapes and attitudes, 
 must have been well known from the period at 
 which human beings first began to take an intel- 
 ligent interest in Nature. An interesting early 
 record is that of Samuel Felton, F.R.S., who 
 (Dec. 2, 1763) figured and gave some account of 
 an Acridian (Phyllotettix) from Jamaica. Of this 
 insect he says ' the tJwrax is like a leaf that is 
 raised perpendicularly from the body '. 2 
 
 Both Protective and Aggressive Resemblances 
 were appreciated and clearly explained by 
 Erasmus Darwin in 1794: 'The colours of 
 many animals seem adapted to their purposes 
 
 I Life and Letters, iii. 255. 
 
 II Phil. Trans. Boy. Soc., liv. Tab. vi. 55.
 
 102 THE VALUE OF COLOUR 
 
 of concealing themselves either to avoid danger, 
 or to spring upon their prey.' 1 
 
 Protective Resemblance of a very marked 
 and beautiful kind is found in certain plants 
 inhabiting desert areas. Examples observed by 
 Burchell almost exactly a hundred years ago 
 have already been mentioned on pp. 96-8. In 
 addition to the resemblance to stones Burchell 
 observed, although he did not publish the fact, 
 a South African plant concealed by its likeness to 
 the dung of birds. 2 The observation is recorded 
 in one of the manuscript journals kept by the 
 great explorer during his journey. I owe the 
 opportunity of studying it to the kindness of 
 Mr. Francis A. Burchell of the Khodes University 
 College, Grahamstown. The following account is 
 given under the date July 5, 1812, when Burchell 
 was at the Makkwarin River, about half-way 
 between the Kuruman River and Litakun the old 
 capital of the Bachapins (Bechuanas) : 
 
 ' I found a curious little Crassula (not in flower) so snow 
 white, that I should never has [have] distinguished it from 
 the white limestones. ... It was an inch high and a little 
 
 1 Zoonomia, i. London, 1794, 509. 
 
 2 Sir William Thiselton-Dyer has suggested the same method of 
 concealment (Annals of Botany, xx. 123). Referring to Anacamp- 
 seros papyracea, figured on plate ix., the author says of its adaptive 
 resemblance : ' At the risk of suggesting one perhaps somewhat 
 far-fetched, I must confess that the aspect of the plant always 
 calls to my mind the dejecta of some bird, and the more so owing 
 to the whitening of the branches towards the tips' (ibid., 126). 
 The student of insects, who is so familiar with this very form of 
 protective resemblance in larvae, and even perfect insects, will not 
 be inclined to consider the suggestion far-fetched.
 
 CRYPTIC RESEMBLANCE IN PLANTS 103 
 
 branchy, . . . and was at first mistaken for the dung of 
 birds of the passerine order. I have often had occasion to 
 remark that in stony place[s] there grow many small succu- 
 lent plants and abound insects (chiefly Grylli) which have 
 exactly the same color as the ground and must for ever 
 escape observation unless a person sit on the ground and 
 observe very attentively.' 
 
 The cryptic resemblances of animals impressed 
 Darwin and Wallace in very different degrees, 
 probably in part due to the fact that Wallace's 
 tropical experiences were so largely derived from 
 the insect world, in part to the importance 
 assigned by Darwin to Sexual Selection, ' a subject 
 which had always greatly interested me,' as he says 
 in his Autobiography. 1 There is no reference to 
 Cryptic Kesemblance in Darwin's section of the 
 Joint Essay, although he gives an excellent short 
 account of Sexual Selection (see pp. 139, 140). 
 Wallace's section on the other hand contains the 
 following statement : 
 
 'Even the peculiar colours of many animals, especially 
 insects, so closely resembling the soil or the leaves or the 
 trunks on which they habitually reside, are explained on the 
 same principle ; for though in the course of ages varieties of 
 many tints may have occurred, yet those races haviny colours 
 lest adapted to concealment from their enemies would inevitably 
 survive the longest.' 2 
 
 It would occupy too much space to attempt any 
 discussion of the difference between the views of 
 
 1 Life and Letters, i. 94. 
 
 2 Journ. Proc. Linn. Soc., iii. 1859, 61. The italics are Wallace's.
 
 104 THE VALUE OF COLOUE 
 
 these two naturalists, but it is clear that Darwin, 
 although fully believing in the efficiency of 
 Protective Resemblance and replying to St. George 
 Mivart's contention that Natural Selection was 
 incompetent to produce it, 1 never entirely agreed 
 with Wallace's estimate of its importance. Thus 
 the following extract from a letter to Sir Joseph 
 Hooker, May 21, 1868, refers to Wallace : ' I find 
 I must (and I always distrust myself when I 
 differ from him) separate rather widely from 
 him all about birds' nests and protection ; he is 
 riding that hobby to death.' 2 It is clear from 
 the account given in The Descent of Man* that 
 the divergence was due to the fact that Darwin 
 ascribed more importance to Sexual Selection 
 than did Wallace, and Wallace more importance 
 to Protective Resemblance than Darwin. Thus 
 Darwin wrote to Wallace, Oct. 12 and 13, 1867 : 
 ' By the way, I cannot but think that you push 
 protection too far in some cases, as with the 
 stripes on the tiger.' 4 Here too Darwin was 
 preferring the explanation offered by Sexual 
 Selection, 5 a preference which, considering the 
 relation of the colouring of the lion and tiger to 
 their respective environments, few naturalists 
 will be found to share. It is also shown on 
 
 Origin (6th edit.), London, 1872, 181, 182. See also 66. 
 More Letters, i. 304. 
 
 London, 1874, 452-8. See also Life and Letters, iii. 123-5. and 
 M re Letters, ii. 59-63, 72-4, 76-8, 84-90, 92, 93. 
 More Letters, i. 283. 
 Descent of Man (2nd edit.), 1874, 545, 546.
 
 SEXUAL VERSUS NATURAL SELECTION 105 
 
 p. 127 that Darwin contemplated the possibility 
 of cryptic colours, such as those of Patagonian 
 animals, being due to Sexual Selection influenced 
 by the aspect of surrounding nature. 
 
 Nearly a year later Darwin in his letter of 
 May 5, 1868?, expressed his agreement with 
 Wallace's views: 'Except that I should put 
 sexual selection as an equal, or perhaps as even 
 a more important agent in giving colour than 
 Natural Selection for protection.' 1 The con- 
 clusion expressed in the above quoted passage is 
 opposed by the extraordinary development of 
 Protective Eesemblance in the immature stages 
 of animals, especially insects. 
 
 It must not be supposed, however, that Darwin 
 ascribed an unimportant role to Cryptic Resem- 
 blances, and as observations accumulated he came 
 to recognize their efficiency in fresh groups of 
 the animal kingdom. Thus he wrote to Wallace 
 May 5, 1867 : * Hackel has recently well shown 
 that the transparency and absence of colour in 
 the lower oceanic animals, belonging to the most 
 different classes, may be well accounted for on 
 the principle of protection.' 2 Darwin also 
 admitted the justice of Professor E. S. Morse's 
 contention that the shells of molluscs are often 
 adaptively coloured. 3 But he looked upon cryptic 
 colouring and also Mimicry as more especially 
 Wallace's departments, and sent to him and to 
 
 1 More Letters, ii. 77, 78. 
 
 2 More Letters, ii. 62. See also Descent of Man (1874), 261. 
 
 3 More Letters, ii. 95.
 
 106 THE VALUE OF COLOUK 
 
 Professor Meldola observations and notes bearing 
 upon these subjects. Thus the following letter 
 given to me by Dr. A. R Wallace, and now, by 
 kind permission, published for the first time, 
 accompanied a photograph of the chrysalis of 
 Papilio sarpedon choredon, Feld., suspended from 
 a leaf of its food-plant : 
 
 July 9th DOWN, 
 
 BECKENHAM, KENT. 
 MY DEAR WALLACE 
 
 Dr. G. Krefft has sent me the enclosed from Sydney. 
 A nurseryman saw a caterpillar feeding on a plant and 
 covered the whole up, but when he searched for the cocoon 
 [pupa], was long before he c d find it, so good was its 
 imitation in colour and form to the leaf to which it was 
 attached. I hope that the world goes well with you. Do 
 not trouble yourself by acknowledging this, 
 
 Ever yours 
 
 CH. DARWIN. 
 
 Another deeply interesting letter of Darwin's, 
 bearing upon Protective Kesemblance, has only 
 recently been shown to me by my friend 
 Professor E. B. Wilson, the great American 
 Cytologist. With his kind consent and that of 
 Mr. Francis Darwin, this letter, written four 
 months before Darwin's death on April 19, 1882, 
 is reproduced here l : 
 
 1 The letter is addressed : ' Edmund B. Wilson, Esq., Assistant iu 
 Biology, John[s] Hopkins University, Baltimore Md., U. States.'
 
 DARWIN AND CEYPTIC COLOURS 107 
 
 December 21, 1881. DOWN, 
 
 BECKENHAM, KENT. 
 (Railway Station, 
 Orpington, S.E.R) 
 
 DEAR SIB, 
 
 I thank you much for having taken so much trouble 
 in describing fully your interesting and curious case of 
 mimickry. 
 
 I am in the habit of looking through many scientific 
 Journals, and though my memory is now not nearly so good as 
 it was, I feel pretty sure that no such case as yours has been 
 described (amongst the nudibranch) molluscs. You perhaps 
 know the case of a fish allied to Hippocampus (described 
 some years ago by Dr. Gunther in Proc. Zoolog. Soc. v ) which 
 clings by its tail to sea- weeds, and is covered with waving 
 filaments so as itself to look like a piece of the same sea- weed. 
 The parallelism between your and Dr. Gtinther's case makes 
 both of them the more interesting ; considering how far 
 a fish and a mollusc stand apart. It w* 1 be difficult for 
 anyone to explain such cases by the direct action of the 
 environment. I am glad that you intend to make further 
 observations on this mollusc, and I hope that you will give 
 a figure and if possible a coloured figure. With all good 
 wishes from an old brother naturalist. 
 
 I remain, 
 
 Dear Sir, 
 
 Yours faithfully, 
 
 CHARLES DARWIN. 
 
 Professor E. B. Wilson has kindly given the 
 following account of the circumstances under 
 which he had written to Darwin : 
 
 ' The case to which Darwin's letter refers is that of the 
 nudibranch mollusc Scyllaea, which lives on the floating 
 Sargassum and shows a really astonishing resemblance to 
 the plant, having leaf-shaped processes very closely similar
 
 108 THE VALUE OF COLOUR 
 
 to the fronds of the sea-weed both in shape and in color. 
 The concealment of the animal may be judged from the fact 
 that we found the animal quite by accident on a piece of 
 Sargassum that had been in a glass jar in the laboratory for 
 some time, and had been closely examined in the search for 
 hydroids and the like without disclosing the presence upon 
 it of two large specimens of the Scyllaea (the animal, as 
 I recall it, is about two inches long). It was first detected 
 by its movements alone, by someone (I think a casual visitor 
 to the laboratory) who was looking closely at the Sargassum 
 and exclaimed, " Why, the sea-weed is moving its leaves ! " 
 We found the example in the summer of 1880 or 1881 at 
 Beaufort, N.C., where the Johns Hopkins laboratory was 
 located for the time being. It must have been seen by many 
 others, before or since. 
 
 ' I wrote and sent to Darwin a short description of the 
 case at the suggestion of Brooks, with whom I was at the 
 time a student. I was, of course, entirely unknown to 
 Darwin (or to anyone else) and to me the principal interest 
 of Darwin's letter is the evidence that it gives of his extra- 
 ordinary kindness and friendliness towards an obscure 
 youngster who had of course absolutely no claim upon his 
 time or attention. The little incident made an indelible 
 impression upon my memory and taught me a lesson that 
 was worth learning.' 
 
 VARIABLE PROTECTIVE RESEMBLANCE 
 
 The wonderful power of rapid colour adjust- 
 ment possessed by the cuttle-fish was observed 
 by Darwin in 1832 at St. Jago, Cape de Verd 
 Islands, the first place visited during the voyage 
 of the Beagle. From Rio he wrote to Henslow, 
 giving the following account of his observations, 
 May 18, 1832 : 
 
 ' I took several specimens of an Octopus which possessed 
 a most marvellous power of changing its colours, equalling
 
 DAKWIN AND COLOUR ADJUSTMENT 109 
 
 any chameleon, and evidently accommodating the changes 
 to the colour of the ground which it passed over. Yellowish 
 gi'een, dark brown, and red, were the prevailing colours ; 
 this fact appears to be new, as far as I can find out.' 1 
 
 Darwin was well aware of the power of indi- 
 vidual colour adjustment now known to be 
 possessed by large numbers of Lepidopterous 
 pupae and larvae. An excellent example was 
 brought to his notice by C. V. Riley, 2 while the 
 most striking of the early results obtained with 
 the pupae of butterflies those of Mrs. M. E. Barber 
 upon Papilio nireus was communicated by him 
 to the Entomological Society of London. 3 
 
 Before leaving the subject of Protective Resem- 
 blance I wish to take the opportunity of referring 
 to an observation on the chameleon, read by 
 J. S. Beuttler, Nov. 1, 1873, before the Rugby 
 School Natural History Society and published 
 in the Reports for that date. In this paper 
 the author remarks, ' The side of the animal 
 nearest the light is invariably the darkest.' The 
 same fact was observed in South Africa (1905) 
 by Dr. G. B. Longstaff, who kindly supplied 
 the above quotation, Professor C. V. Boys and 
 the present writer. An interpretation of the 
 later observation was sought along the lines of 
 A. H. Thayer's classical explanation of the white 
 under surfaces of animals, and the conclusion 
 
 1 Life and Letters, i. 235, 236. See also the Journal of Researches, 
 1876, 6-8, where a far more detailed account is given, together 
 with a reference to Encycl. of Anat. and Physiol. 
 
 2 More Letters, ii. 385, 386. 
 
 8 Trans. Ent. Soc. Lond., 1874, 519. See also More Letters, ii. 403.
 
 110 THE VALUE OF COLOUR 
 
 was reached that the colour differences on the 
 two sides neutralize the differences in illumination, 
 and remove the appearance of solidity. 1 
 
 It is also necessary to direct attention to 
 C. W. Beebe's 2 recent discovery that the pig- 
 mentation of the plumage of certain birds is 
 increased by confinement in a superhumid atmo- 
 sphere. In Scardafella inca, on which the most 
 complete series of experiments was made, the 
 changes took place only at the moults, whether 
 normal and annual or artificially induced at 
 shorter periods. There was a corresponding 
 increase in the choroidal pigment of the eye. 
 At a certain advanced stage of feather pigment- 
 ation a brilliant iridescent bronze or green tint 
 made its appearance on those areas where iri- 
 descence most often occurs in allied genera. 
 Thus in birds no less than in insects, characters 
 previously regarded as of taxonomic value, can 
 be evoked or withheld by the forces of the en- 
 vironment. 
 
 WAENING OK APOSEMATIC COLOURS 
 
 From Darwin's description of the colours and 
 habits it is evident that he observed, in 1833, 
 an excellent example of warning colouring in a 
 little South American toad (Phryniscus nigricans). 
 He described it in a letter to Henslow, written 
 
 1 Zool. Journ. Linn. Soc., xxx. 45. 
 
 8 Zoologica: N.Y. Zool. Soc., i. No. 1, Sept. 25, 1907: Geographic 
 variation in birds with especial reference to the effects of humidity.
 
 A TOAD WITH WARNING COLOURS 111 
 
 from Monte Video, Nov. 24, 1832: 'As for 
 one little toad, I hope it may be new, that it 
 may be christened " diabolicus ". Milton must 
 allude to this very individual when he talks of 
 " squat like a toad " ; its colours are by Werner 
 [Nomenclature of Colours, 1821] ink black, vermi- 
 lion red and buff orange.' 1 In the Journal of 
 Researches 2 its colours are described as follows : 
 'If we imagine, first, that it had been steeped 
 in the blackest ink, and then, when dry, allowed 
 to crawl over a board, freshly painted with the 
 brightest vermilion, so as to colour the soles of 
 its feet and parts of its stomach, a good idea 
 of its appearance will be gained.' 'Instead of 
 being nocturnal in its habits, as other toads are, 
 and living in damp obscure recesses, it crawls 
 during the heat of the day about the dry sand- 
 hillocks and arid plains, . . . ' The appearance 
 and habits recall T. Belt's well-known description 
 of the conspicuous little Nicaragua!! frog which 
 he found to be distasteful to a duck. 3 
 
 The recognition of the Warning Colours of 
 caterpillars is due in the first instance to Darwin, 
 who, reflecting on Sexual Selection, was puzzled 
 by the splendid colours of sexually immature 
 organisms. He applied to Wallace, * who has an 
 innate genius for solving difficulties.' 4 Darwin's 
 
 1 More Letters, L 12. 2 1876, 97. 
 
 3 The Naturalist in Nicaragua (2nd edit.), London, 1888, 321. 
 
 4 Descent of Man, 325. On this and the following page an 
 excellent account of the discovery will be found, as well as in 
 Wallace's Natural Selection, 1875, 117-22.
 
 112 THE VALUE OF COLOUE 
 
 original letter exists, 1 and in it we are told that 
 he had taken the advice given by Bates : * You 
 had better ask Wallace.' After some considera- 
 tion Wallace replied that he believed the colours 
 of conspicuous caterpillars and perfect insects 
 were a warning of distastefulness and that such 
 forms would be refused by birds. Darwin's reply 2 
 is extremely interesting both for its enthusiasm at 
 the brilliancy of the hypothesis and its caution in 
 acceptance without full confirmation : 
 
 * Bates was quite right ; you are the man to apply to in a 
 difficulty. I never heard anything more ingenious than 
 your suggestion, and I hope you may be able to prove it 
 true. That is a splendid fact about the white moths ; 3 it 
 warms one's very blood to see a theory thus almost proved 
 to be true.' 
 
 Two years later the hypothesis was proved to 
 hold for caterpillars of many kinds by J. Jenner 
 Weir and A. G. Butler, whose observations have 
 since been abundantly confirmed by many natu- 
 ralists. Darwin wrote to Jenner Weir, May 13, 
 1869 : * Your verification of Wallace's suggestion 
 seems to me to amount to quite a discovery.' 4 
 
 RECOGNITION OK EPISEMATIC CHARACTERS 
 This principle does not appear to have been 
 in any way foreseen by Darwin, although he draws 
 special attention to several elements of pattern 
 
 1 Life and Letters, iii 93, 94. 2 Life and Letters, iii. 94, 95. 
 
 8 A single white moth which was rejected by young turkeys, 
 while other moths were greedily devoured, Natural Selection, 
 1875, 78. 
 
 4 More Letters, ii. 71 (footnote).
 
 SEXUAL VEKSUS NATURAL SELECTION 113 
 
 which would now be interpreted by many natu- 
 ralists as episemes. He believed that the markings 
 in question interfered with the cryptic effect, and 
 came to the conclusion that, even when common 
 to both sexes, they * are the result of sexual 
 selection primarily applied to the male'. 1 The 
 most familiar of all recognition characters was 
 carefully described by him, although here too 
 explained as an ornamental feature now equally 
 transmitted to both sexes : ' The hare on her 
 form is a familiar instance of concealment through 
 colour ; yet this principle partly fails in a closely- 
 allied species, the rabbit, for when running to 
 its burrow, it is made conspicuous to the sports- 
 man, and no doubt to all beasts of prey, by its 
 upturned white tail.' 2 
 
 The analogous episematic use of the bright 
 colours of flowers to attract insects for effecting 
 cross-fertilization and of fmits to attract verte- 
 brates for effecting dispersal is very clearly ex- 
 plained in the Origin. 3 
 
 It is not, at this point, necessary to treat sematic 
 characters at any greater length. They will form 
 the subject of a large part of the following section, 
 where the models of Batesian (Pseudaposematic) 
 Mimicry are considered as well as the Milllerian 
 (Synaposematic) combinations of Warning Colours. 
 
 1 Descent of Man, 544. * Descent of Man, 542. 
 
 3 Ed. 1872, 161. For a good example of Darwin's caution in 
 dealing with exceptions see the allusion to brightly coloured fruit 
 in More Letters, ii. 348.
 
 114 THE VALUE OF COLOUR 
 
 MIMICRY-BATESIAN OR PSEUDAPOSEMATIC, 
 MULLERIAN OR SYNAPOSEMATIC 
 
 The existence of superficial resemblances be- 
 tween animals of various degrees of affinity must 
 have been observed for hundreds of years. Among 
 the early examples, the best known to me have 
 been found in the manuscript notebooks and 
 collections of W. J. Burchell, the great traveller 
 in Africa (1810-15) and Brazil (1825-30). The 
 most interesting of his records on this subject 
 are brought together in the following paragraphs. 
 
 Conspicuous among well-defended insects are 
 the dark steely or iridescent greenish blue fos- 
 sorial wasps or sand-wasps, SpJiex and the allied 
 genera. Many Longicorn beetles mimic these in 
 colour, slender shape of body and limbs, rapid 
 movements, and the readiness with which they 
 take to flight. On Dec. 21, 1812, Burchell 
 captured one such beetle (Promeces viridis) at Kosi 
 Fountain on the journey from the source of the 
 Kuruman River to Klaarwater. It is correctly 
 placed among the Longicorns in his catalogue, 
 but opposite to its number is the comment 'Sphex ! 
 totus purpureus '. 
 
 In our own country the black-and-yellow colour- 
 ing of many stinging insects, especially the 
 ordinary wasps, affords perhaps the commonest 
 model for Mimicry. It is reproduced with more 
 or less accuracy on moths, flies and beetles. 
 Among the latter it is again a Longicorn which
 
 MIMICRY EECOKDED BY BURCHELL 115 
 
 offers one of the best-known, although by no 
 means one of the most perfect, examples. The 
 appearance of the well - known ' wasp - beetle ' 
 (Glytus arietis) in the living state is sufficiently 
 suggestive to prevent the great majority of people 
 from touching it. The dead specimen is less 
 convincing, and when I showed a painting of it 
 to Dr. Alfred Kussel Wallace in 1889 he doubted 
 whether it was an example of Mimicry at all. 
 I replied that he would not question the inter- 
 pretation if he had noticed the beetle in life ; 
 and he at once recalled the movements of allied 
 forms in the Eastern Archipelago, and admitted 
 the mimetic resemblance. In fact, the slender, 
 wasp-like legs of the beetle are moved in a rapid, 
 somewhat jerky manner, very different from the 
 usual stolid coleopterous stride, but remarkably 
 like the active movements of a wasp, which 
 always seem to imply the perfection of training. 1 
 In Burchell's Brazilian collection there is a nearly 
 allied species (Neoclytus curvatus) which appears 
 to be somewhat less wasp-like than the British 
 beetle. The specimen bears the number '1188', 
 and the date March 27, 1827, when Burchell was 
 collecting in the neighbourhood of St. Paulo. 
 Turning to the corresponding number in the 
 Brazilian notebook we find this record : * It runs 
 rapidly like an ichneumon or wasp, of which it 
 has the appearance.' 
 
 The formidable, well-defended ants are as freely 
 
 1 Poulton, The Colours of Animals, London, 1890, 249, 250.
 
 116 THE VALUE OF COLOUR 
 
 mimicked by other insects as the sand-wasps, 
 ordinary wasps and bees. Thus on Feb. 17, 
 1901, Guy A. K. Marshall captured, near Salis- 
 bury, Mashonaland, three similar species of ants 
 (Hymenoptera) with a bug (Hemiptera) and a 
 Locustid (Orthoptera), the two latter mimicking 
 the former. All the insects, seven in number, 
 were caught on a single plant, a small bushy 
 vetch. 1 
 
 This is an interesting recent example from 
 South Africa, and large numbers of others might 
 be added the observations of many naturalists 
 in many lands ; but nearly all of them known 
 since that general awakening of interest in the 
 subject which was inspired by the great hypotheses 
 of H. W. Bates and Fritz Miiller. We find, how- 
 ever, that Burchell had more than once recorded 
 the mimetic resemblance to ants. An extremely 
 ant-like bug (the larva of a species of Alydus) 
 in his Brazilian collection is labelled ' 1141 ', with 
 the date Dec. 8, 1826, when Burchell was at the 
 Rio das Pedras, Cubatao, near Santos. In the 
 notebook the record is as follows : '1141 Cimex. 
 I collected this for a Formica.' 
 
 Some of the chief mimics of ants are the active 
 little hunting spiders belonging to the family 
 Attidae. Many examples have been brought for- 
 ward during recent years, especially by my friends 
 Dr. and Mrs. Peckham, of Milwaukee, the great 
 authorities on this group of Arachnids. Here too 
 
 1 Trans. Ent. Soc. Lond., 1902, 535, plate six, figs. 53-9.
 
 MIMICRY EECORDED BY BURCHELL 117 
 
 we find an observation of the mimetic resemblance 
 recorded by Burchell, and one which adds in the 
 most interesting manner to our knowledge of the 
 subject. A fragment, all that is now left, of 
 an Attid spider, captured on June 30, 1828, at 
 Goyaz, Brazil, bears the following note, in this 
 case on the specimen and not in the notebook : 
 ' Black . . . runs and seems like an ant with large 
 extended jaws.' My friend Mr. K. I. Pocock, 
 to whom I have submitted the specimen, tells me 
 that it is not one of the group of species hitherto 
 regarded as ant-like, and he adds, 'It is most 
 interesting that Burchell should have noticed the 
 resemblance to an ant in its movements. This 
 suggests that the perfect imitation in shape, as 
 well as in movement, seen in many species was 
 started in forms of an appropriate size and colour 
 by the mimicry of movement alone.' Up to the 
 present time Burchell is the only naturalist who 
 has observed an example which still exhibits this 
 ancestral stage in the evolution of mimetic like- 
 ness. 
 
 Following the teachings of his day, Burchell 
 was driven to believe that it was part of the fixed 
 and inexorable scheme of things that these strange 
 superficial resemblances existed. Thus, when he 
 found other examples of Hemipterous mimics, 
 including one (Luteva macrophthalma) with * exactly 
 the manners of a Mantis ', he added the sentence, 
 'In the genus Cimex (Linn.) are to be found the 
 outward resemblances of insects of many other
 
 118 THE VALUE OF COLOUR 
 
 genera and orders,' Feb. 15, 1829. Of another 
 Brazilian bug, which is not to be found in his 
 collection, and cannot therefore be precisely 
 identified, he wrote : ' Cimex . . . Nature seems to 
 have intended it to imitate a Sphex, both in colour 
 and the rapid palpitating and movement of the 
 antennae,' Nov. 15, 1826. At the same time 
 it is impossible not to feel the conviction that 
 Burchell felt the advantage of a likeness to sting- 
 ing insects and to aggressive ants, just as he 
 recognized the benefits conferred on desert plants 
 by spines and by concealment (see pp. 96-8). Such 
 an interpretation of Mimicry was perfectly con- 
 sistent with the theological doctrines of his day. 1 
 
 The last note I have selected from Burchell's 
 manuscript refers to one of the chief mimics of 
 the highly protected Lycid beetles. The whole 
 assemblage of African insects with a Lycoid 
 colouring forms a most important combination 
 and one which has an interesting bearing upon 
 the theories of Bates and Fritz Miiller. This most 
 wonderful set of mimetic forms, described in 1902 
 by Guy A. K. Marshall, is composed of flower- 
 haunting beetles belonging to the family Lytidae, 
 and the heterogeneous series of varied insects 
 which mimic their conspicuous and simple scheme 
 of colouring. The Lycid beetles, forming the 
 centre or 'models' of the whole company, are 
 orange-brown in front for about two-thirds of the 
 
 1 See Kirby and Spence, An Introduction to Entomology (1st edit.), 
 London, ii. 1817, 223.
 
 BATES'S AND F. MULLER'S THEORIES 119 
 
 exposed surface, black behind for the remaining 
 third. They are undoubtedly protected by quali- 
 ties which make them excessively unpalatable 
 to the bulk of insect-eating animals. Some ex- 
 perimental proof of this has been obtained by 
 Mr. Guy Marshall. What are the forms which 
 surround them? According to the hypothesis 
 of Bates they would be, at any rate mainly, pala- 
 table hard-pressed insects which only hold their 
 own in the struggle for life by a fraudulent imita- 
 tion of the trade-mark of the successful and 
 powerful Lycidae. According to Fritz Miiller's 
 hypothesis we should expect that the mimickers 
 would be highly protected, successful and abun- 
 dant species, which (metaphorically speaking) have 
 found it to their advantage to possess an adver- 
 tisement, a danger-signal, in common with each 
 other, and in common with the beetles in the 
 centre of the group. According to the first view 
 the mimic is a danger to its model, according 
 to the second it is a benefit. If A, B, C, D, &c., 
 are all unpalatable and all recognized by the same 
 appearance, and if their enemies have to learn by 
 experience what to eat and what to reject, it 
 follows that when A is tasted and found un- 
 pleasant, B, C, D, &c., are benefited. They would 
 be tasted more cautiously, or perhaps abandoned 
 without tasting. On the next occasion B might 
 be tasted by some other inexperienced foe, and 
 the advantage would lie with A as well as C, D, 
 &c. It is hardly necessary to explain that under
 
 120 THE VALUE OF COLOUE 
 
 either hypothesis volition has nothing to do with 
 the growth of resemblance, but that it is believed 
 to be brought about by the survival in successive 
 generations of those individuals most like the 
 model or most like one another. The death of 
 individual A or B as a result of the tasting is 
 no difficulty. Far more individuals of A, B, C, D, 
 &c., would be killed by experimental tasting 
 if they had different patterns than if they had 
 the same, and this is advantage enough to cause 
 a strong trend in the direction of resemblance. 
 
 How far does the constitution of this wonderful 
 combination the largest and most complicated 
 as yet known in all the world convey to us the 
 idea of Mimicry working along the lines supposed 
 by Bates or those suggested by Milller ? Figures 
 1 to 52 of Mr. Marshall's coloured plate l represent 
 a set of forty-two or forty-three species or forms 
 of insects captured in Mashonaland, and all ex- 
 cept two in the neighbourhood of Salisbury. 
 The combination includes six species of Lycidae ; 
 nine beetles of five groups all specially protected 
 by nauseous qualities, Telepliwidae, Melyridae, 
 Phytophaga, Lagriidae, Cantharidae ; six Longi- 
 corn beetles ; one Coprid beetle ; eight stinging 
 Hymenoptera; three or four parasitic Hymen o- 
 ptera (Braconidae, a group much mimicked and 
 shown by some experiments to be distasteful) ; five 
 bugs (Hemiptera, another group in which unpalata- 
 
 1 Trans. Ent. Soc. Lond., 1902, plate xviii. See also 517, where 
 the group is analysed.
 
 MAKSHALL'S GREAT MIMETIC SERIES 121 
 
 bility is widespread) ; three moths (Arctiidae and 
 Zygaenidae, distasteful families) ; one fly. In fact 
 the whole combination, except perhaps one Phyto- 
 phagous, one Coprid and the Longicorn beetles, 
 and the fly, fall under the hypothesis of Milller 
 and not under that of Bates. And it is very 
 doubtful whether these exceptions will be sus- 
 tained : indeed the suspicion of unpalatability 
 already besets the mimetic Longicorns, and is 
 always on the heels I should say the hind tarsi 
 of a Phytophagous beetle. 
 
 This most remarkable example which illustrates 
 so well the problem of Mimicry and the alterna- 
 tive hypotheses proposed for its solution, was, 
 as I have said, first described in 1902. Among 
 the most perfect of the mimetic resemblances 
 in it is that between the Longicorn beetle, Amphi- 
 desmus analis, and the Lycidae. It was with the 
 utmost astonishment and pleasure that I found 
 this very resemblance had almost certainly been 
 observed by Burchell. A specimen of the AmpM- 
 desmus exists in his collection and it bears '651'. 
 Turning to the same number in the African 
 catalogue we find that the beetle is correctly 
 placed among the Longicorns, that it was cap- 
 tured at Uitenhage on Nov. 18, 1813, and that 
 it was found associated with Lycid beetles in 
 flowers (' consocians cum Lycis 78-87 in floribus '). 
 Looking up Nos. 78-87 in the collection and 
 catalogue, three species of Lycidae are found, all 
 captured on Nov. 18, 1813, at Uitenhage. Bur-
 
 122 THE VALUE OF COLOUR 
 
 chell recognized the wide difference in affinity, 
 shown by the distance between the respective 
 numbers ; for his catalogue is arranged to repre- 
 sent relationships. He observed, what students 
 of Mimicry are only just beginning to record 
 precisely and systematically, the coincidence 
 between model and mimic in time and space and 
 in habits. We are justified in concluding that he 
 observed the close superficial likeness, although 
 he does not in this case expressly allude to it. 
 One of the most interesting among the early 
 observations of superficial resemblance between 
 forms remote in the scale of classification was 
 made by Darwin himself, as described in the 
 following passage from his letter to Henslow, 
 written from Monte Video, Aug. 15, 1832: 
 
 ' Amongst the lower animals nothing has so much 
 interested me as finding two species of elegantly coloured true 
 Planaria inhabiting the dewy forest ! The false relation they 
 bear to snails is the most extraordinary thing of the kind 
 I have ever seen.' 1 
 
 Many years later, in 1867, he wrote to Fritz 
 Miiller suggesting that the resemblance of a 
 soberly coloured British Planarian to a slug 
 might be due to Mimicry. 2 
 
 The most interesting copy of Bates's classical 
 memoir on Mimicry, 3 read before the Linnean 
 Society in 1861, is that given by him to the man 
 who has done most to support and extend the 
 
 1 More Letters, i. 9. 2 Life and Letters, iii. 71. 
 
 3 'Contributions to an Insect Fauna of the Amazon Valley.' 
 Trans. Linn. Soc., xxiii. 1862, 495.
 
 BATES'S CLASSICAL MEMOIR 123 
 
 theory. My kind friend has given that copy to 
 me ; it bears the inscription : 
 
 Only a year and a half after the publication 
 of the Origin, we find that Darwin wrote to Bates 
 on the subject which was to provide such striking 
 evidence of the truth of Natural Selection : 
 
 ' I am glad to hear that you have specially attended to 
 " mimetic" analogies a most curious subject : I hope you 
 publish on it. I have for a long time wished to know 
 whether what Dr. Collingwood asserts is true that the 
 most striking cases generally occur between insects inhabit- 
 ing the same country.' J 
 
 The next letter, written about six months 
 later, reveals the remarkable fact that the illus- 
 trious naturalist who had anticipated Edward 
 Forbes in the explanation of arctic forms on 
 alpine heights, 2 had also anticipated H. W. Bates 
 in the theory of Mimicry : 
 
 ' What a capital paper yours will be on mimetic re- 
 
 1 The letter is dated April 4, 1861. More Letters, i. 183. 
 
 2 ' I was forestalled in only one important point, which my 
 vanity has always made me regret, namely, the explanation by 
 means of the Glacial period of the presence of the same species 
 of plants and of some few animals on distant mountain summits 
 and in the arctic regions. This view pleased me so much that 
 I wrote it out in extenso, and I believe that it was read by Hooker 
 some years before E. Forbes published his celebrated memoir on 
 the subject. In the very few points in which we differed, I still 
 think that I was in the light. I have never, of course, alluded 
 in print to my having independently worked out this view.' 
 Autobiography in Life and Letters, i. 88.
 
 124 THE VALUE OF COLOUR 
 
 semblances ! You will make quite a new subject of it. I had 
 thought of such cases as a difficulty ; and once, when corre- 
 sponding with Dr. Collingwood, I thought of your explanation ; 
 but I drove it from my mind, for I felt that I had not 
 knowledge to judge one way or the other. Dr. C., I think, 
 states that the mimetic forms inhabit the same country, but 
 I did not know whether to believe him. What wonderful 
 cases yours seem to be ! ?1 
 
 The above passage will probably be as great 
 a surprise to other naturalists as it was to the 
 present writer. It would be very interesting to 
 know whether Collingwood published any state- 
 ments on the subject. His book, 2 quoted by 
 Darwin in the Descent of Man, is dated 1868. 
 
 Bates read his paper before the Linnean 
 Society, Nov. 21, 1861, and Darwin's impressions 
 on hearing it were conveyed in a letter to the 
 author dated Dec. 3 : 
 
 ' Under a general point of view, I am quite convinced 
 (Hooker and Huxley took the same view some months ago) 
 that a philosophic view of nature can solely be driven into 
 naturalists by treating special subjects as you have done. 
 Under a special point of view, I think you have solved one 
 of the most perplexing problems which could be given to 
 solve.' 3 
 
 The memoir appeared in the following year, 
 and after reading it Darwin wrote as follows, 
 Nov. 20, 1862 : 
 
 ' ... In my opinion it is one of the most remarkable and 
 admirable papers I ever read in my life. ... I am rejoiced 
 
 1 The letter is dated Sept. 25, 1861. More Letters, i. 197. 
 
 2 C. Collingwood, Rambles of a Naturalist on the shores and 
 waters of the China Seas, London, 1868. 
 
 3 Life and Letters, ii. 378.
 
 DARWIN AND BATES'S MEMOIR 125 
 
 that I passed over the whole subject in the Origin, for I 
 should have made a precious mess of it. You have most 
 clearly stated and solved a wonderful problem. . . . Your 
 paper is too good to be largely appreciated by the mob of 
 naturalists without souls ; but, rely on it, that it will have 
 lasting value, and I cordially congratulate you on your first 
 great work. You will find, I should think, that Wallace 
 will fully appreciate it. ' x 
 
 Four days later, Nov. 24, Darwin wrote to 
 Hooker on the same subject : 
 
 ' I have now finished this paper . . . ; it seems to me 
 admirable. To my mind the act of segregation of varieties 
 into species was never so plainly brought forward, and there 
 are heaps of capital miscellaneous observations.' J 
 
 Darwin was here referring to the tendency of 
 similar varieties of the same species to pair 
 together, and on Nov. 25 he wrote to Bates asking 
 for fuller information on this subject. 3 If Bates's 
 opinion were well founded, Sexual Selection would 
 bear a most important part in the establishment 
 of such species. 4 It must be admitted, however, 
 that the evidence is as yet quite insufficient to 
 establish this conclusion. It is interesting to 
 observe how Darwin at once fixed on the part of 
 Bates's memoir which seemed to bear upon Sexual 
 Selection. A review of Bates's theory of Mimicry 
 was contributed by Darwin to the Natural History 
 
 1 Life and Letters, ii. 391-3. 
 
 2 More Letters, i. 214. 
 
 3 More Letters, i. 215. See also parts of Darwin's letter to Bates 
 in Life and Letters, ii. 392. 
 
 * See Poulton, Essays on Evolution, 1908, 65, 85-8.
 
 126 THE VALUE OF COLOUR 
 
 Review l and an account of it is to be found in the 
 Origin 1 and in the Descent of Man. 3 
 
 Darwin continually writes of the value of 
 hypothesis as the inspiration of inquiry. We find 
 an example in his letter to Bates, Nov. 22, 1860: 
 * I have an old belief that a good observer really 
 means a good theorist, and I fully expect to find 
 your observations most valuable.' 4 Darwin's 
 letter refers to many problems upon which Bates 
 had theorized and observed, but as regards 
 Mimicry itself, the hypothesis was thought out 
 after his return home from the Amazons, when 
 he no longer had the opportunity of testing it by 
 the observation of living Nature. It is by no 
 means improbable that, had he been able to apply 
 this test, Bates would have recognized that his 
 division of butterfly resemblances into two 
 classes one due to the theory of Mimicry, the 
 other to the influence of local conditions could 
 not be sustained. 
 
 Fritz Muller's contributions to the problem of 
 Mimicry were all made in S.E. Brazil, and 
 numbers of them were communicated, with other 
 observations on natural history, to Darwin, and 
 by him sent to Professor R Meldola who 
 published many of the facts. Darwin's letters to 
 Meldola 5 contain abundant proofs of his interest 
 in Muller's work upon Mimicry. One deeply 
 
 1 New Ser., iii. 1863, 219. 2 Ed. 1872, 375-8. 
 
 3 Ed. 1874, 323-5. * More Letter, I 176. 
 
 8 Poulton, Charles Danvin and the theory of Natural Selection, 
 Lond. (1896), 199-218.
 
 SEXUAL VERSUS NATURAL SELECTION 127 
 
 interesting letter 1 dated Jan. 23, 1872, proves 
 that Fritz Miiller before he originated the theory 
 of Common Warning Colours (Synaposematic 
 Resemblance or Miillerian Mimicry), which will 
 ever be associated with his name, had conceived 
 the idea of the production of mimetic likeness by 
 Sexual Selection. 
 
 Darwin's letter to Meldola shows that he was 
 by no means inclined to dismiss the suggestion as 
 worthless, although he considered it daring. 
 
 'You will also see in this letter a strange speculation^ 
 which I should not dare to publish, about the appreciation 
 of certain colours being developed in those species which 
 frequently behold other forms similarly ornamented. I do 
 not feel at all sure that this view is as incredible as it may 
 at first appear. Similar ideas have passed through my mind 
 when considering the dull colours of all the organisms 
 which inhabit dull-coloured regions, such as Patagonia and 
 the Galapagos Is.' 2 
 
 A little later, on April 5, he wrote to Professor 
 August Weismann on the same subject : 
 
 'It may be suspected that even the habit of viewing 
 differently coloured surrounding objects would influence 
 their taste, and Fritz Miiller even goes so far as to believe 
 that the sight of gaudy butterflies might influence the taste 
 of distinct species.' 3 
 
 This remarkable suggestion affords interesting 
 evidence that F. Miiller was not satisfied with 
 the sufficiency of Bates's theory. Nor is this 
 surprising when we think of the numbers of 
 
 1 Ibid., 201, 202. 
 
 8 Darwin wrote, Aug. 2, 1871 , in very similar terms to Fritz Muller 
 himself. Life and Letters, iii. 151. 3 Life and Letters, iii. 157.
 
 128 THE VALUE OF COLOUR 
 
 abundant conspicuous butterflies which he saw 
 exhibiting mimetic likenesses. The common 
 instances in his locality, and indeed everywhere 
 in tropical America, were anything but the hard- 
 pressed struggling forms assumed by the theory 
 of Bates. They belonged to the groups which 
 were themselves mimicked by other butterflies. 
 Fritz Mailer's suggestion also shows that he did 
 not accept Bates's alternative explanation of a 
 superficial likeness between models themselves, 
 based on some unknown influence of local physico- 
 chemical forces. At the same time Miiller's own 
 suggestion was subject to this apparently fatal 
 objection, that the Sexual Selection he invoked 
 would tend to produce resemblances in the males 
 rather than the females, while it is well known 
 that when the sexes differ the females are almost 
 invariably more perfectly mimetic than the males 
 and in a high proportion of cases are mimetic 
 while the males are non-mimetic. 
 
 The difficulty was met several years later by 
 Fritz Miiller's well-known theory, published in 
 1879, 1 and immediately translated by Meldola 
 and brought - before the Entomological Society. 2 
 Darwin's letter to Meldola dated June 6, 1879, 
 shows ' that the first introduction of this new and 
 most suggestive hypothesis into this country was 
 due to the direct influence of Darwin himself, 
 who brought it before the notice of the one man 
 who was likely to appreciate it at its true value 
 
 1 Kosmos, May, 1879, 100. Proc. Ent. Soc. Lond., 1879, xx.
 
 MELDOLA AND MULLEE'S THEORY 129 
 
 and to find the means for its presentation to 
 English naturalists.' 1 Of the hypothesis itself 
 Darwin wrote, ' F. Mtiller's view of the mutual 
 protection was quite new to me.' 2 The hypothesis 
 of Mtillerian Mimicry was at first strongly 
 opposed. Bates himself could never make up his 
 mind to accept it. As the Fellows were walking 
 out of the meeting at which Professor Meldola 
 explained the hypothesis, an eminent entomolo- 
 gist, now deceased, was heard to say to Bates : 
 ' It's a case of save me from my friends ! ' The 
 new ideas encountered and still encounter to a 
 great extent the difficulty that the theory of 
 Bates had so completely penetrated the literature 
 of natural history. The present writer has 
 observed that naturalists who have not thoroughly 
 absorbed the older hypothesis are usually far 
 more impressed by the newer one than are those 
 whose allegiance has already been rendered. The 
 acceptance of Natural Selection itself was at first 
 hindered by similar causes, as Darwin clearly 
 recognized : 
 
 'If you argue about the non-acceptance of Natural 
 Selection, it seems to me a very striking fact -that the New- 
 tonian theory of gravitation, which seems to every one now so 
 certain and plain, was rejected by a man so extraordinarily 
 able as Leibnitz. The truth will not penetrate a preoccupied 
 mind.' s 
 
 1 Charles Dai-win and the theory of Natural Selection, 214. 
 
 2 Ibid., 213. 
 
 3 To Sir J. Hooker, July 28, 1868, More Letters, i. 305. See also 
 the letter to A. R. Wallace, April 30, 1868, in More Letters, ii. 77, 
 lines 6-8 from top.
 
 130 THE VALUE OF COLOUR 
 
 There are many naturalists, especially students 
 of insects, who appear to entertain an inveterate 
 hostility to any theory of Mimicry. Some of 
 them are eager investigators in the fascinating 
 field of geographical distribution, so essential for 
 the study of Mimicry itself. The changes of 
 pattern undergone by a species of Erebia as we 
 follow it over different parts of the mountain 
 ranges of Europe is indeed a most interesting 
 inquiry, but not more so than the differences 
 between e.g. the Acraea johnstoni of S.E. Rhodesia 
 and of Kilimanjaro. A naturalist who is interested 
 by the Erebia should be equally interested by the 
 Acraea ; and so he would be if the student of 
 Mimicry did not also record that the characteristics 
 which distinguish the northern from the southern 
 individuals of the African species correspond with 
 the presence, in the north but not in the south, 
 of certain entirely different butterflies. That 
 this additional information should so greatly 
 weaken, in certain minds, the appeal of a 
 favourite study, is a psychological problem of 
 no little interest. This curious antagonism is 
 I believe confined to a few students of insects. 
 Those naturalists who, standing rather farther off, 
 are able to see the bearings of the subject more 
 clearly, will usually admit the general support 
 yielded by an ever-growing mass of observations 
 to the theories of Mimicry propounded by 
 H. W. Bates and Fritz Miiller. In like manner 
 Natural Selection itself was in the early days
 
 PREJUDICE AGAINST MIMICRY 131 
 
 often best understood and most readily accepted 
 by those who were not naturalists. Thus Darwin 
 wrote to D. T. Ansted, Oct. 27, 1860 : 
 
 'I am often in despair in making the generality of 
 naturalists even comprehend me. Intelligent men who are 
 not naturalists and have not a bigoted idea of the term 
 species, show more clearness of mind.' l 
 
 Even before the Origin appeared Darwin 
 anticipated the first results upon the mind of 
 naturalists. He wrote to Asa Gray, Dec. 21, 
 1859 : 
 
 ' I have made up my mind to be well abused ; but I 
 think it of importance that my notions should be read by 
 intelligent men, accustomed to scientific argument, though 
 not naturalists. It may seem absurd, but I think such men 
 will drag after them those naturalists who have too firmly 
 fixed in their heads that a species is an entity.' 2 
 
 Mimicry was not only one of the first great 
 departments of zoological knowledge to be studied 
 under the inspiration of Natural Selection, it is 
 still and will always remain one of the most 
 interesting and important of subjects in relation 
 to this theory as well as to evolution. In Mimicry 
 we investigate the effect of environment in its 
 simplest form : we trace the effects of the 
 pattern of a single species upon that of another 
 far removed from it in the scale of classification. 
 When there is reason to believe that the model 
 is an invader from another region and has only 
 recently become an element in the environment 
 
 1 More Letters, i. 175. 
 
 2 Life and Letters, ii. 245. See also pp. 32-3 of the present work. 
 
 K2
 
 132 THE VALUE OF COLOUR 
 
 of the species native to its second home, the 
 problem gains a special interest and fascination. 1 
 We are chiefly dealing with the fleeting and 
 changeable element of colour, and we expect to 
 find and we do find evidence of a comparatively 
 rapid evolution. The invasion of a fresh model 
 is for certain species an unusually sudden change 
 in the forces of the environment, and in some 
 instances we have grounds for the belief that the 
 mimetic response has not been long delayed. 
 
 MIMICRY AND SEX 
 
 Ever since Wallace's classical memoir on 
 Mimicry in the Malayan swallow-tail butterflies, 
 those naturalists who have written on the subject 
 have followed his interpretation of the marked 
 prevalence of mimetic resemblance in the female 
 sex as compared with the male. They have 
 believed with Wallace that the greater dangers of 
 the female, with slower flight and often alighting 
 for oviposition, have been in part met by the high 
 development of this special mode of protection. 
 The fact cannot be doubted. It is extremely 
 common for a non-mimetic male to be accom- 
 panied by a beautifully mimetic female and often 
 by two or three different forms of female, each 
 mimicking a different model. Indeed in these 
 latter cases the male is usually non-mimetic 
 (e. g. Papilio dardanus = merope), or if a mimic 
 
 1 See pp. 159-77, which are devoted to the detailed considera- 
 tion of an example of this kind.
 
 WALLACE AND FEMALE MIMICEY 133 
 
 (e. g. the Nymphaline genus Euripus) resembles 
 a very different model. On the other hand, a 
 non-mimetic female accompanied by a mimetic 
 male is excessively rare. An example is afforded 
 by the Oriental Nymphaline, Cethosia, in which 
 the males of some species are rough mimics of 
 the brown Danaines. When both sexes mimic, it 
 is very common for the females to be better and 
 often far better mimics than the males. 
 
 Predominant female Mimicry is character- 
 istic of butterflies and very rare in moths. If 
 examples occur at all among the numberless 
 mimetic Diptera, Coleoptera, &c., they are 
 probably excessively scarce. In some of the orb- 
 weaving spiders, however, the males mimic ants, 
 while the much larger females are non-mimetic. 
 
 Although still believing that Wallace's 
 hypothesis in large part accounts for the facts 
 briefly summarized above, the present writer has 
 recently been led to doubt whether it offers a 
 complete explanation. Mimicry in the male, 
 even though less beneficial to the species than 
 Mimicry in the female, would still surely be 
 advantageous. Why then is it so often entirely 
 restricted to the female ? While the attempt to 
 find an answer to this question was haunting 
 me, I re-read a letter written by Darwin to 
 Wallace, April 15, 1868, containing the following 
 sentences : 
 
 'When female butterflies are more brilliant than their 
 males you believe that they have in most cases, or in all
 
 134 THE VALUE OF COLOUR 
 
 cases, been rendered brilliant so as to mimic some other 
 species, and thus escape danger. But can you account for 
 the males not having been rendered equally brilliant and 
 equally protected? Although it may be most for the 
 welfare of the species that the female should be protected, 
 yet it would be some advantage, certainly no disadvantage, 
 for the unfortunate male to enjoy an equal immunity from 
 danger. For my part, I should say that the female alone 
 had happened to vary in the right manner, and tint the 
 beneficial variations had been transmitted to the same sex 
 alone. Believing in this ; I can see no improbability (but 
 from analogy of domestic animals a strong probability) that 
 variations leading to beauty must often have occurred in the 
 males alone, and been transmitted to that sex alone. Thus I 
 should account in many cases for the greater beauty of the male 
 over the female, without the need of the protective principle.' l 
 
 The consideration of the facts of Mimicry thus led 
 Darwin to the conclusion that the female happens 
 to vary in the right manner more commonly than 
 the male, while the secondary sexual characters of 
 males supported the conviction ' that from some 
 unknown cause such characters [viz. new charac- 
 ters arising in one sex and transmitted to it alone] 
 apparently appear oftener in the male than in the 
 female '.- 
 
 Comparing these conflicting arguments, we are 
 
 1 More Letters, ii. 73, 74. On the same subject 'the gay- 
 coloured females of Pieris ' (Perrhybris (Mylofhris) pyrrha of Brazil), 
 Darwin wrote to Wallace, May 5, 1868, as follows: '1 believe 
 I quite follow you in believing that the colours are wholly due 
 to mimicry ; and I further believe that the male is not brilliant 
 from not having received through inheritance colour from the 
 female, and from not himself having varied ; in short, that he has 
 not been influenced by selection.' It should be noted that the 
 male of this species does exhibit a mimetic pattern on the under 
 surface. More Letters, ii. 78. 
 
 2 Letter from Darwin to Wallace, May 5, 1867, More Letters, 
 ii. 61.
 
 DARWIN AND FEMALE MIMICRY 135 
 
 led to believe that the first is the stronger. 
 Mimicry in the male would be no disadvantage 
 but an advantage, and when it appears would be 
 and is taken advantage of by selection. The 
 secondary sexual characters of males would be no 
 advantage but a disadvantage to females, and, as 
 Wallace thinks, are withheld from this sex by 
 selection. It is indeed possible that Mimicry has 
 been hindered and often prevented from passing 
 to the males by Sexual Selection. We know that 
 Darwin was much impressed l by Thomas Belt's 
 daring and brilliant suggestion that the white 
 patches which exist, although ordinarily concealed, 
 on the wings of mimetic males of certain Pierinae 
 (Dismorphia), have been preserved by preferential 
 mating. He supposed this result to have been 
 brought about by the females exhibiting a deep- 
 seated preference for males that displayed the 
 chief ancestral colour, inherited from periods 
 before any mimetic pattern had been evolved in 
 the species. But it has always appeared to me 
 that Belt's deeply interesting suggestion requires 
 much solid evidence and repeated confirmation 
 before it can be accepted as a valid interpretation 
 of the facts. 
 
 In the present state of our knowledge, at any rate 
 of insects and especially of Lepidoptera, it is pro- 
 bable that the female is more apt to vary than the 
 male, and that an important element in the inter- 
 pretation of prevalent female Mimicry is provided 
 
 1 Descent of Man, 325.
 
 136 THE VALUE OF COLOUE 
 
 by this fact. In order adequately to discuss the 
 question of Mimicry and sex it would be necessary 
 to analyse the whole of the facts, so far as they 
 are known in butterflies. On the present occasion 
 it is only possible to state the inferences which 
 have been drawn from general impressions in- 
 ferences which it is believed will be sustained by 
 future detailed inquiry. 
 
 (1) Mimicry may occasionally arise in one sex 
 because the differences which distinguish it from 
 the other sex happen to be such as to afford 
 a starting-point for the resemblance. Here the 
 male is at no disadvantage as compared with 
 the female, and the rarity of Mimicry in the 
 male alone (e.g. CetJwsia) is evidence that the 
 great predominance of female Mimiciy is not 
 to be thus explained. 
 
 (2) The greater colour-variability of the female, 
 observed at least in certain groups of butterflies, 
 and especially her more pronounced tendency 
 to dimorphism and polymorphism, have been 
 of much importance in determining this pre- 
 dominance. Thus if the female appear in two 
 different forms and the male in only one, it will 
 be twice as probable that she will happen to 
 possess a sufficient foundation for the evolution 
 of Mimicry. 
 
 (3) The appearance of melanic or partially 
 melanic forms in the female has been of very 
 great service, providing as it does a change of 
 ground-colour. Thus the Mimicry of the black
 
 CONCLUSIONS ON MIMICRY AND SEX 137 
 
 generally red-marked American ' Aristolochia 
 swallow-tails ' (Pharmacophagus) by the females of 
 Papilio swallow-tails was probably begun in this 
 way. 
 
 (4) It is probably incorrect to assume with 
 Haase that Mimicry always arose in the female 
 and was later acquired by the male. Both sexes 
 of the third section of swallow-tails (Cosmodesmus} 
 mimic Pharmacophagus in America, far more per- 
 fectly than do the females of Papilio. But this 
 is not due to Cosmodesmus presenting us with 
 a later stage of the history begun in Papilio ; for 
 in Africa Cosmodesmus is still mimetic (of Danainae) 
 in both sexes although the resemblances attained 
 are imperfect, while many African species of 
 Papilio have non-mimetic males with beautifully 
 mimetic females. The explanation is probably 
 to be sought in the fact that the females of 
 Papilio are more variable and more often tend 
 to become dimorphic than those of Cosmodesmus, 
 while the latter group has more often happened 
 to possess a sufficient foundation for the origin 
 of the resemblance, in patterns which, from the 
 start, were common to male and female. 
 
 (5) In very variable species with sexes alike, 
 Mimicry can be rapidly evolved in both sexes 
 out of very small beginnings. Thus the reddish 
 marks which are common in many individuals 
 of Limenitis arthemis were almost certainly the 
 starting-point for the evolution of the beautifully 
 mimetic L. archippus. Nevertheless in such
 
 188 THE VALUE OF COLOUR 
 
 cases, although there is no reason to suspect 
 any greater variability, the female is commonly 
 a somewhat better mimic than the male and 
 often a very much better mimic. Wallace's 
 principle seems here to supply the obvious in- 
 terpretation ; but it is to be noted that the evo- 
 lution of Mimicry is taking place in colours that 
 are associated with sex. Otherwise, it is impos- 
 sible to explain the fact that the more perfect 
 Mimicry attained by one sex is not immediately 
 transferred to the other. 
 
 (6) When the difference between the patterns 
 of model and presumed ancestor of mimic is very 
 great, the female is often alone mimetic ; when 
 the diiference is comparatively small, both sexes 
 are commonly mimetic. The Nymphaline genus 
 Hypolimnas is a good example. In Hypolimnas 
 itself the females mimic Daiwinae with patterns 
 very different from those preserved by the non- 
 mimetic males: in the sub-genus Euralia, both 
 sexes resemble the black and white Ethiopian 
 Danaines with patterns not very dissimilar from 
 that which we infer to have existed in the non- 
 mimetic ancestor. 
 
 (7) Although a melanic form or other large 
 variation may be of the utmost importance hi 
 facilitating the start of a mimetic likeness, it is 
 impossible to explain the evolution of any detailed 
 resemblance in this manner. And even the 
 large colour variation itself may well be the 
 expression of a minute and ' continuous ' change
 
 CONCLUSIONS ON MIMICRY AND SEX 139 
 
 in the chemical and physical constitution of pig- 
 ments. 
 
 (8) Female Mimicry is not by any means always 
 a question of colour and pattern alone. Thus, 
 the mimetic females of some Papilionidae lose the 
 4 tails ' which are retained by the non-mimetic 
 males (e. g. P. dardanus = merope), and the females 
 of the tropical American Nymphaline genus 
 Eresia and Pierine genus Dismorphia and its 
 allies, are not only better mimics in colour and 
 pattern but also in shape of the wings. 
 
 SEXUAL SELECTION (EPIGAMIC CHARACTERS) 
 We do not know the date at which the idea 
 of Sexual Selection arose in Darwin's mind, but 
 it was probably not many years after the ' sudden 
 flash of insight ' which, in October, 1838, gave to 
 him the theory of Natural Selection. An excel- 
 lent account of Sexual Selection occupies the 
 concluding paragraph of Part I of Darwin's 
 Section of the Joint Essay on Natural Selection, 
 read July 1, 1858, before the Linnean Society. 1 
 The principles are so clearly and sufficiently 
 stated in these brief sentences that it is appro- 
 priate to quote the whole : 
 
 ' Besides this natural means of selection, by which those 
 individuals are preserved, whether in their egg, or larval, or 
 mature state, which are best adapted to the place they fill in 
 nature, there is a second agency at work in most unisexual 
 animals, tending to produce the same effect, namely, the 
 struggle of the males for the females. These struggles are 
 1 Journ. Proc. Linn. Soc., iii. 1859, 50.
 
 140 THE VALUE OF COLOUR 
 
 generally decided by the law of battle, but in the case of 
 birds, apparently, by the charms of their song, by their 
 beauty or their power of courtship, as in the dancing rock- 
 thrush of Guiana. The most vigorous and healthy males, 
 implying perfect adaptation, must generally gain the victory 
 in their contests. This kind of selection, however, is less 
 rigorous than the other ; it does not require the death of 
 the less successful, but gives to them fewer descendants. 
 The struggle falls, moreover, at a time of year when food is 
 generally abundant, and perhaps the effect chiefly produced 
 would be the modification of the secondary sexual characters, 
 which are not related to the power of obtaining food, or to 
 defence from enemies, but to fighting with or rivalling 
 other males. The result of this struggle amongst the males 
 may be compared in some respects to that produced by those 
 agriculturists who pay less attention to the careful selection 
 of all their young animals, and more to the occasional use of 
 a choice mate.' 
 
 A full exposition of Sexual Selection appeared 
 in the Descent of Man in 1871, and in the greatly 
 augmented second edition, in 1874. It has been 
 remarked that the two subjects, The Descent of 
 Man and Selection in Relation to Sex, seem to 
 fuse somewhat imperfectly into the single work 
 of which they form the title. The reason for 
 their association is clearly shown in a letter to 
 Wallace, dated May 28, 1864 : ' . . . I suspect that 
 a sort of sexual selection has been the most 
 powerful means of changing the races of man.' l 
 
 Darwin, as we know from his Autobiography, 2 
 was always greatly interested in this hypothesis, 
 and it has been shown in the preceding pages 
 that he was inclined to look favourably upon it 
 
 1 More Letters, ii. 33. 2 Life and Letters, i. 94.
 
 DAKWIN AND SEXUAL SELECTION 141 
 
 as an interpretation of many appearances usually 
 explained by Natural Selection. Hence Sexual 
 Selection, incidentally discussed in other sections 
 of the present essay, need not be considered at 
 any length, in the section specially allotted to it. 
 Although so interested in the subject and not- 
 withstanding his conviction that the hypothesis 
 was sound, Darwin was quite aware that it was 
 probably the most vulnerable part of the Origin. 
 Thus he wrote to H. W. Bates, April 4, 1861 : 
 
 'If I had to cut up myself in a review I would have 
 [worried ?] and quizzed sexual selection ; therefore, though 
 I am fully convinced that it is largely true, you may imagine 
 how pleased I am at what you say on your belief.' l 
 
 The existence of sound-producing organs in 
 the males of insects was, Darwin considered, 
 the strongest evidence in favour of the operation 
 of Sexual Selection in this group. 2 Such a con- 
 clusion has received strong support in recent 
 years by the numerous careful observations of 
 Dr. F. A. Dixey 3 and Dr. G. B. Longstaff 4 on 
 the scents of male butterflies. The experience 
 of these naturalists abundantly confirms and ex- 
 tends the account given by Fritz Muller 5 of the 
 scents of certain Brazilian butterflies. It is a 
 remarkable fact that the apparently epigamic 
 scents of male butterflies should be pleasing to 
 
 1 More Letters', i. 183. 2 Life and Letters, iii. 94, 138. 
 
 3 Proc. Ent. Soc. Lond., 1904, Ivi. ; 1905, xxxvii., liv. ; 1906, ii. 
 
 4 Proc. Ent. Soc. Lond., 1905, xxxv. ; Trans. Ent. Soc. Lond., 1905, 
 136 ; 1908, 607. 
 
 5 Jen. Zeit., xi., 1877, 99; Trans. Ent. Soc. Lond., 1878, 211.
 
 142 THE VALUE OF COLOUR 
 
 man while the apparently aposematic scents in 
 both sexes of species with warning colours should 
 be displeasing to him. But the former is far 
 more surprising than the latter. It is not per- 
 haps astonishing that a scent which is ex liypotliesi 
 unpleasant to an insect-eating Vertebrate should 
 be displeasing to the human sense ; but it is 
 certainly wonderful that an odour which is ex 
 liypothesi agreeable to a female butterfly should 
 also be agreeable to man. 
 
 Entirely new light upon the seasonal appear- 
 ance of epigamic characters is shed by the recent 
 researches of C. W. Beebe, 1 who caused the 
 scarlet tanager (Piranga erytJiromelas) and the 
 bobolink (Doliclionyx oryzivorus) to retain their 
 breeding plumage through the whole year by 
 means of fattening food, dim illumination and 
 reduced activity. Gradual restoration to the 
 light and the addition of meal-worms to the diet 
 invariably brought back the spring song, even 
 in the middle of winter. A sudden alteration 
 of temperature, either higher or lower, caused 
 the birds nearly to stop feeding, and one tanager 
 lost weight rapidly and in two weeks moulted 
 into the olive-green winter plumage. After a 
 year, and at the beginning of the normal breeding 
 season, 'individual tanagers and bobolinks were 
 gradually brought under normal conditions and 
 activities,' and in every case moulted from nuptial 
 plumage to nuptial plumage. ' The dull colors of 
 
 1 The Atnerican Naturalist, xlii. No. 493, Jan. 1908, 34.
 
 CONTROL OF NUPTIAL PLUMAGE 143 
 
 the winter season had been skipped.' The author 
 justly claims to have established 'that the se- 
 quence of plumage in these birds is not in any 
 
 way predestined through inheritance , but 
 
 that it may be interrupted by certain factors in 
 the environmental complex '. -<l*l 
 
 Mr. Beebe's deeply interesting investigations on 
 birds prove that external stimulus may be as 
 necessary for the production of the tints displayed 
 in courtship as for other colours that are character- 
 istic of the species (p. 1 10). Birds may thus exhibit 
 the individual susceptibility to environment so 
 well known in numbers of insect larvae and pupae 
 (p. 109). Although certain naturalists, especially 
 the students of plant oecology, 1 consider that re- 
 sults of this kind are opposed to a Darwinian 
 interpretation, it is perfectly clear that * the 
 changes so produced must, like any other varia- 
 tions, pass through the ordeal of the survival of 
 the fittest'. 2 And when each possible response 
 is appropriate to the special environment which 
 provides the stimulus, it is obvious that, so far 
 from witnessing the elimination of Natural Selec- 
 tion, we are in presence of its highest manifesta- 
 tion. 
 
 1 See J. M. Coulter in Fifty Years of Darwinism, New York, 
 1909, 61-3. 
 
 2 Editors of More Letters, i. 214 n. 1.
 
 VI 
 
 MIMICRY IN THE BUTTERFLIES OF 
 NORTH AMERICA 
 
 Written from the notes of the Anniversary Address de- 
 livered to the Entomological Society of America, Baltimore, 
 Thursday, December 31, 1908. 
 
 INTRODUCTORY 
 
 WITHIN a few weeks of the hundredth anni- 
 versary of Darwin's birth, and nearly midway 
 between the fiftieth anniversaries of the publica- 
 tion of Natural Selection on July 1 last and the 
 Origin of Species on Nov. 24 next, it seemed to me 
 specially appropriate to select for this address 
 a subject that is closely associated with Darwinian 
 teachings. Although he did not publish it during 
 his lifetime, we now know from his correspond- 
 ence that Darwin independently originated the 
 interpretation of Mimicry which was afterwards 
 suggested by H. W. Bates. 1 Its development 
 in the mind of the naturalist of the Amazons and 
 the rival theory afterwards suggested by Fritz 
 Miiller, were both of them the direct outcome, in 
 Bates's case the very speedy outcome, of the Origin. 
 The deep interest which Darwin took in the 
 
 1 See pp. 123-4.
 
 MIMICRY AND EVOLUTION 145 
 
 hypotheses of both naturalists is proved by many 
 a letter in his published correspondence. 1 All 
 this forms a peculiarly fascinating chapter of 
 ancient history, nevertheless ancient history ; 
 but if we desire to choose a subject because of the 
 light it can throw to-day and is certain to throw 
 to-morrow upon evolution and its causes, there is 
 no study which for promise as well as performance 
 can be set on a higher level than Mimicry. 
 
 In the course of the following address the word 
 ' Mimicry ' will be used with the restricted mean- 
 ing attached to it by A. R. Wallace. It will 
 be applied solely to the superficial resemblances 
 between animals, and not to their likeness to 
 vegetable or mineral surroundings for the purpose 
 of concealment. 
 
 The study of Mimicry is of the highest value in 
 relation to both evolution itself and the motive 
 causes of evolution. 
 
 Apart from all question of the means by which 
 Mimicry has been produced, it will be generally 
 admitted that the mimetic species has in some 
 way evolved a superficial resemblance to the 
 pattern of one or more species, more or less 
 remote from it in the scale of classification. 
 Looking on the changes by which the resem- 
 blance has been produced as a piece of evolu- 
 tionary history, and, as I have said, disregarding 
 for the moment their causes, we have one of the 
 
 1 See pp. 123-9. 
 L
 
 146 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 very simplest and sharpest pictures of organic 
 transformation presented for our investigation. 
 An effect generally a strongly marked and con- 
 spicuous effect has been brought about in those 
 elements which make up the superficial appear- 
 ance of a species, and this important change is 
 manifestly in the direction of only a minute 
 fraction of the infinitely complex organic environ- 
 ment, viz. that fraction contributed by the super- 
 ficial appearance of one or more very different 
 species, commonly indeed of but a single one. 
 When, as in North America, a recent invader 
 becomes the model determining the direction of 
 evolution in some constituent of the ancient 
 butterfly fauna, the case becomes especially 
 striking. 
 
 The effects produced on the mimic are 
 generally sharper and more distinct than those 
 seen in the concealing resemblances to bark, 
 lichen, earth, &c., the difference corresponding 
 to the more definite and individual appearance 
 usually presented by the pattern of the model 
 as compared with such elements in the vegetable 
 and mineral surroundings. There are also other 
 important differences. The models of Mimicry 
 are generally more restricted in their range, 
 and differ more widely in different areas and in 
 different parts of the same area than the models 
 of cryptic resemblance. Differences between the 
 local forms of the same model imply that the 
 mimicked species has itself been subject to rapid
 
 MIMETIC AND CRYPTIC COLOURS 147 
 
 change, while the models of cryptic resemblance 
 appear by comparison to be stereotyped and 
 permanent. Furthermore the models as well as 
 their mimics within the same area are liable to 
 changes of distribution, whereas the models of 
 cryptic resemblance are as a rule comparatively 
 fixed. A mimetic species may often be found 
 passing into an area where its model exists in 
 a different form or does not exist at all, and 
 highly instructive conclusions may be drawn 
 from the study of the corresponding changes. 
 
 In accordance with the facts briefly summarized 
 in the above statements, we find that better and 
 more numerous examples of rapid recent change 
 are to be found in mimetic patterns than in those 
 which promote concealment. Not only is this 
 evident when we trace the geographical changes 
 of model and mimic over a wide continuous 
 area, but in many cases the same genus includes 
 both mimetic and non-mimetic species, the latter 
 enabling us to infer with more or less certainty 
 the ancestral appearance of the former. The 
 history thus unravelled may often be further 
 confirmed by a study of the non-mimetic males 
 of mimetic females. 
 
 Many naturalists at the present day incline to 
 return to the old belief that the history of evolu- 
 tion has bieen 'discontinuous', proceeding by 
 ' mutations ' or large and definite steps of change. 
 The comprehensive and detailed study of Mimicry 
 as a piece of biological history certainly provides 
 
 L2
 
 148 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 one of the best and safest means perhaps the 
 very best of forming a judgement between this 
 revived opinion and Darwin's conclusion that, 
 although the rate of transformation varied greatly 
 and might slow down to nothing for long periods, 
 the steps of change were small, forming a gradual 
 and ' continuous ' transition between the successive 
 forms in the same evolutionary history. 1 
 
 The study of the causes of Mimicry is more 
 difficult than that of the history of Mimicry, the 
 conclusions far less certain. Nevertheless the 
 evidence at present available yields much support 
 to the theory of Natural Selection as the motive 
 cause of evolution. The facts certainly do not 
 point to any other interpretation. They negative 
 the conclusion that mimetic resemblances have 
 been produced by the direct action of external 
 forces (Hypothesis of External Causes) or by 
 variation unguided by selection (Hypothesis of In- 
 ternal Causes). Nor do they support Fritz Muller's 
 earlier and daring speculation (see pp. 127-8) 
 that female preferences were influenced by the 
 sight of the patterns displayed by the models 
 (Hypothesis of Sexual Selection). The only 
 hypotheses which are in any way consistent with 
 the body of facts, considered as a whole, are those 
 which assume that the resemblances in question 
 have been built up by the selection of variations 
 beneficial in the struggle for life. 
 
 In its concentration on a minute fraction of the 
 
 1 See pp. 42-51; also Appendix B, p. 254.
 
 SUGGESTED CAUSES OF MIMICRY 149 
 
 total organism as well as in the rapidity of the 
 results achieved, the operation of Natural Selection 
 in the production of Mimicry is more than ordi- 
 narily akin to the methods of Artificial Selection. 
 Indeed a very fascinating and promising line 
 of investigation in a suitable locality would be 
 the attempt to initiate or improve a mimetic 
 likeness by means of Artificial Selection. 
 
 Mimetic resemblances are of two kinds, re- 
 spectively interpreted by two well-known hypo- 
 theses, both based on the theory of Natural 
 Selection. 
 
 1. Mimicry as interpreted by H. W. Bates 
 is an advantageous deceptive resemblance borne 
 by palatable or harmless species (the mimics) to 
 others that are unpalatable or otherwise specially 
 defended (the models). Such resemblance will 
 be spoken of as Batesian Mimicry, the examples 
 as Batesian mimics, the interpretation as the 
 Batesian Hypothesis. 
 
 2. The resemblances between specially defended 
 species themselves, although well known to Bates, 
 were not explained by his hypothesis as he con- 
 ceived it. He suggested that they were an 
 expression of the common results produced by 
 forces common to the environment of the species 
 in question. Such likenesses l were subsequently 
 interpreted by Fritz Mtiller as the advantageous 
 adoption of a common advertisement by specially 
 
 1 It is probable that these were the examples which Fritz 
 Miiller had previously sought to explain by the thpory of Sexual 
 Selection. See pp. 127-8 of the present volume.
 
 150 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 defended species, whereby the loss of life incurred 
 during the education of young inexperienced 
 enemies was contributed between the similar 
 forms, instead of by each species independently 
 as would have been the case if they had been 
 dissimilar, and possessed patterns requiring each 
 a separate education. Such resemblance will be 
 spoken of as Mullerian Mimicry, the examples as 
 Mtillerian mimics, the interpretation as the Mul- 
 lerian Hypothesis. 
 
 SPECIAL ADVANTAGES OF THE NORTH 
 
 AMERICAN BUTTERFLY FAUNA FOR 
 
 THE STUDY OF MIMICRY 
 
 The butterfly fauna of North America affords 
 probably the best field in which to begin the 
 study of Mimicry, a subject which has been 
 shown to possess the most profound significance 
 in relation to the deepest problems by which the 
 naturalist is confronted. The examples are sharp 
 and striking, but not too numerous, and the 
 inquiry can be approached without the confusion 
 and excessive strain on the memory which must 
 inevitably at first beset the student of Mimicry in 
 the tropics. But outside the tropics it is also the 
 best field for this study, as will be shown below. 
 
 The western section of the Palaearctic Region is 
 sharply cut off by the Sahara from the Ethiopian, 
 and its few examples of Mimicry are not such 
 as would be likely to awaken the interest and 
 enthusiasm of the beginner. The eastern Palae-
 
 SPECIAL ADVANTAGES OF N. AMERICA 151 
 
 arctic section suffers from the opposite defect. 
 Separated by imperfect barriers from the Oriental 
 Kegion, its butterfly fauna is complicated by 
 much invasion of specially protected species from 
 the tropics, and the examples of Mimicry are too 
 numerous and too little known. North America 
 occupies a position conveniently intermediate 
 between the two sections of the Palaearctic por- 
 tion of the circumpolar land-belt. It has been 
 invaded by models from the eastern tropics of 
 the Old World and also probably from the tropics 
 of the New ; but the species are few and their 
 effects upon the indigenous butterflies sharp and 
 distinct. The Mimicry itself affords striking and 
 remarkable evidence of the lines of migration 
 followed by some of the intruding models. The 
 ancestral forms from which the mimics were 
 derived, have nearly always persisted, and enable 
 us to unravel the history of the change, with 
 exceptional clearness. The examples bear hi a 
 most interesting manner upon the two great 
 hypotheses associated respectively with the names 
 of H. W. Bates and Fritz Mtiller. Although the 
 butterfly fauna is as well known as that of any 
 part of the world, the mimetic resemblances 
 supply material for a large amount of much- 
 needed original investigation, inviting the atten- 
 tion of American naturalists in almost every 
 locality.
 
 152 MIMICEY IN N. AMERICAN BUTTERFLIES 
 
 THE DANAINE MODELS OF NORTH AMERICA, 
 
 AND THEIR RELATIONSHIP TO THE SOUTH 
 
 AMERICAN AND OLD WORLD DANAINAE 1 
 
 The Danainae are the most important and most 
 extensively mimicked of all specially protected 
 butterflies in the Old World tropics. The Acraei- 
 nae, so abundant in Africa, are also greatly 
 mimicked, but to a far less extent than the com- 
 paratively few species of Danainae found in the 
 same Region, all belonging to the section Danaini. 
 The Ethiopian Acraeas in fact supply several 
 mimics of the Danaines, but no example of the 
 opposite relationship is known. In the tropical 
 East, the Acraeinae are poorly represented, while 
 the Danainae (Danaini, Euploeini, Hestia, Hama- 
 dryas) are dominant in numbers as well as in the 
 power of influencing the patterns of other butter- 
 fly groups. In both Africa and the East, Miil- 
 
 1 The subject of the address from this point onwards is treated 
 in considerable detail in the author's memoir, Mimetic North 
 American species of the Genus Limenitis (. /.) and their models, 
 in Trans. Ent. Soc. Lond., 1908, 447-88. Dr. Jordan's later con- 
 clusions as to the affinities of Danaida plexippus, added to the 
 memoir in a terminal note (488) and somewhat at variance with 
 his earlier conclusions quoted in the text, are here adopted 
 throughout. A broader and less detailed treatment is followed 
 in this address, special attention being directed to the numerous 
 points on which further observations are required. Where no 
 other authority is mentioned I have followed the synonymy and 
 geographical distribution of Scudder's great work, Butterflies of 
 the Eastern United States and Canada, and, for the Papilionidae, 
 Rothschild and Jordan's fine monograph (Nov. Zool., xiii, 1906, 
 411-752). I have not, however, followed Scudder in the general 
 use of Basilarchia as a generic name, because I think that the 
 whole group of Limenitis, in its widest acceptation, requires revision, 
 and that until this has been accomplished it is inexpedient to 
 adopt the terminology proposed for a portion of it.
 
 THE WOELD MODELS FOR MIMICRY 153 
 
 lerian Mimicry is evident between the different 
 genera and sections of the specially protected 
 groups themselves. 
 
 In the richest and most remarkable butterfly 
 fauna in the world, that of South America, the 
 dominant specially protected group is composed 
 of the Ithomiinae, allied to the Danainae, and 
 called by Bates * Danaoid Heliconidae '. Next in 
 importance come the Heliconinae, allied to the 
 Acraeinae, and called by Bates ' Acraeoid Heli- 
 conidae '. Both of these are extensively mimicked, 
 especially the Ithomiinae : in fact it was the close 
 and obvious Mimicry of these by certain species of 
 the Heliconinae that puzzled Bates and ultimately 
 received an interpretation in the Miillerian Hy- 
 pothesis. In addition to the above, this rich and 
 varied Region contains numerous true Acraeinae, 
 mimicked considerably, and a small number of 
 true Danaine species. These latter, which are of 
 extreme interest, fall into two groups. One of 
 them, the Lycoraeini, containing the two genera 
 Lycorea and Ituna, is confined to South America, 
 and bears evident traces of long residence in the 
 Region. The whole of the species are mimetic of 
 various dominant Ithomiine genera, while at the 
 same time some of them appear also to act as 
 models for other butterflies, in a single case 
 (Ituna phenarete) even for one of the rarer species 
 (Eutresis imitatrix) belonging to the Ithomiinae 
 themselves. It was the resemblance between 
 the Lycoraeine genus Ituna and the Ithomiine
 
 154 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 genus Thyridia that led Fritz Miiller to his 
 hypothesis, and formed the title of the paper 
 in which he first expounded it. The Lycoraeini 
 are widely different from any of the Old World 
 Danainae and are sometimes separated from them 
 as a distinct sub-family. The second group of 
 Danaines, found in North America as well as 
 South, belongs to the Old World section Danaini, 
 and is in every respect strongly contrasted with 
 the Lycoraeini. Its species, divided into two 
 genera Anosia and Tasitia by Moore, are not 
 known to enter into mimetic relations with any 
 of the other butterflies of this southern Region. 1 
 Furthermore, they not only belong to a dominant 
 Old World section of the Danaines, but are even 
 closely allied to particular species within it. It 
 is probable that there are only two well-marked 
 species of Danaini on the American Continent, 
 and that the various forms encountered over this 
 vast area are the geographical races or sub-species 
 of these two. In north temperate America they 
 are the well-known models for mimicry, Anosia 
 plexippus extending far into Canada, and Tasitia 
 Berenice and its form strigosa not ranging beyond 
 the southern States. 
 
 In 1897, at the Detroit meeting of the American 
 Association for the Advancement of Science, I 
 suggested - that the Mimicry of Anosia pkxippus 
 
 1 It is possible, however, that there are incipient resemblances 
 to Anosia in certain S. American Acraemae, 
 * Proc. Am. Assoc. Adv. Sd., 1897, xlvi. 244.
 
 HISTORY INFERRED FROM MIMICRY 155 
 
 by Limenitis (BasilarcUa) archippus was evidence 
 that the model had long resided in North 
 America, and that we might on this ground alone, 
 even if we had not abundant positive evidence of 
 its gradually increasing spread in the Old World 
 during the past half-century, infer that Anosia 
 had reached Fiji, Australia, Hong-Kong, &c., in 
 comparatively recent times. This conclusion can 
 hardly be doubted, and the argument might have 
 been extended to enable us to infer the ancestral 
 line of migration by which North America itself 
 had been reached by this form. But in 1897 I 
 followed what appeared to be the general view, 
 that, in the New World, the original stream of 
 Danaine invasion had run from the American 
 tropics northward, 1 nor did I observe that the 
 evidence based on the growth of mimetic resem- 
 blance warranted the interesting conclusion that 
 its flow had taken the opposite direction, and 
 that the south had been peopled by way of the 
 north. Accepting this conclusion the question 
 arises : Whence came the Danaini of North 
 America? The answer requires a somewhat 
 careful comparison between the New and Old 
 World butterflies of this group. 
 
 Among the commonest of the Old World 
 Danaini, are certain species with tawny colouring, 
 a black border, and black white-barred apex to 
 the fore wing. The under surface is even more 
 
 1 Verhandl. d. V. Internat. Zool. Congr. z. Berlin, 1901, Jena, 
 1902, 171. See also Essays on Evolution (1908), 274: also errata.
 
 156 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 conspicuous than the upper, being brighter in 
 colour and the black border marked with white 
 in a more striking manner. In one set of 
 Oriental species, placed by Moore in his genus 
 Salatura, the veins are heavily marked with black 
 on both surfaces, conferring a very characteristic 
 appearance, especially upon the hind wing. The 
 other set of species in which the veins are com- 
 paratively inconspicuous is placed by Moore in 
 Limnas, including L. chrysippus, perhaps the 
 commonest butterfly in the world, ranging from 
 the Cape to Hong-Kong and perhaps to Japan. 
 It is clear, however, that Africa is its ancestral 
 home ; for it is there mimicked far more exten- 
 sively than in any other country. 1 In the Malay 
 Archipelago, both Salatura and Limnas are repre- 
 sented by various forms, and in some of these 
 the tawny colouring becomes much darkened. 
 This tendency appears to be more frequent in 
 Limnas, and when both forms have darkened in 
 the same island (e. g. Java) it is probable that 
 Limnas has acted as the model for Salatura. There 
 is a close general resemblance in colouring and 
 pattern between Salatura of the Old World and 
 Anosia of the New, as also between Limnas of the 
 Old World and Tasitia of the New. Furthermore 
 the two New World species differ from each other 
 in the same points as do those of the Old. The 
 dark, white-barred apex of the fore wing, so 
 conspicuous in the Old World forms, is less 
 
 1 Proc. Am. Assoc. Adv. Sci., 1. c., 244.
 
 NEW AND OLD WORLD DANAIDAS 157 
 
 emphasized in those of the New, being especially 
 evanescent in Tasitia where, however, traces of 
 the white markings remain distinct. It is sig- 
 nificant, however, that the black and white apex 
 is also lost in one of the forms of L. clirysippus, 
 viz. the variety dorippus ( = klugii), abundant in 
 many parts of Africa and also extending by way 
 of Aden and the west coast of India as far as 
 Ceylon. There is, in fact, much resemblance 
 between the pattern of dorippus and such a form 
 of Tasitia as lerenice, the likeness being especially 
 apparent in the indications of the former presence 
 of the white apical bar. In the forms of Tasitia, 
 as in some of Limnas, the ground-colour becomes 
 darker and richer a development especially well 
 seen in T. Berenice of Florida. Thus the two chief 
 points in which the pattern of Tasitia differs from 
 that of typical L. chrysippus, viz. the darker, 
 richer ground-colour and the evanescent apical 
 markings, are both presented by abundant Old 
 World forms of the latter species. The superficial 
 resemblances between these Old and New World 
 Danaines are precise and often extend to minute 
 details. Thus the scent-pouch on the hind wings 
 of the male, best seen from the under surface, is 
 similar in Salatura and Anosia, while the resem- 
 blance between Limnas and Tasitia in this respect 
 is even more striking. 
 
 The resemblances above described suggested the 
 investigation and comparison of structural charac- 
 ters in order still further to test the relationship
 
 158 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 between these Old and New World Danaines, and 
 also the validity of the genera created by Moore. 1 
 Such a comparison had already been partially made 
 by Kothschild and Jordan, who in 1903 published 
 the conclusion that Limnas and Tasitia cannot be 
 generically separated. 2 I therefore wrote to my 
 friend Dr. Jordan, asking if he would kindly 
 extend his survey over all the four so-called genera. 
 He found that in Salatura genutia and Anosia 
 plexippus, having larvae with two pairs of fila- 
 ments, 3 the male genitalia are of the same type ; 
 while hi Limnas chrysippus and Tasitia berenice, 
 having larvae with three pairs of filaments, these 
 genitalia are of a second type. The final opinion 
 of this distinguished authority on the relationships 
 between the Rhopalocera, was given in the fol- 
 lowing words 4 : 
 
 ' It appears to be certain that Anosia plexippus does not 
 stand apart from the others. Therefore, if Tasitia berenice, 
 Limnas chrysippus and Salatura genutia are placed in one 
 
 1 Proc. Zool. Soc. Lond., 1883, 201. 
 
 2 Nov. Zool. vol. x, Dec., 1903, 502. 
 
 3 Dr. Jordan was at first inclined to think that Anosia plexippus 
 should he separated generically, basing his conclusion in part on 
 the larval characters (Trans. Ent. Soc. Lond., 1908, 450). A more 
 extended review of the Tring material pointed in the opposite 
 direction, and Dr. Jordan wrote on December 10, 1908, as follows: 
 ' I find from our specimens [of preserved larvae] that 
 
 (1) in Euploea (in the wide sense) there are 4 pairs of filaments, 
 or three (the 3rd being absent), or two (the 3rd and 4th being 
 absent). 
 
 (2) In Danaidae, incl. of Anosia & Limnas, there are 3 pairs (the 
 3rd of the 4 pairs of Euploea being absent), or 2 pairs (the 2nd 
 and 3rd being absent). I find that, for instance, genutia and 
 purpurata have 2 pairs only, like plexippus. The larva therefore 
 does not furnish any argument for separating plexippus as a 
 genus.' 
 
 * In a letter to the author, dated December 15, 1908,
 
 ALL DANAIDAS CLOSELY BELATED 159 
 
 genus, 1 plexippus also must be included. I do not think you 
 need hesitate thus to simplify the classification of these 
 insects. ' 
 
 I have no hesitation in accepting this advice, 
 and in fusing all the four genera created by 
 Moore into the single genus Danaida. Within 
 this genus it has been made evident that the 
 group of forms ranged around Danaida plexipptis 
 is the New World representative and close ally 
 of the group of D. yenutia,-, while that of D. 
 berenice is similarly representative of the group of 
 D. chrysippus. It is interesting to note that both 
 the American Danaidas have become much larger 
 than the corresponding Old World species, and 
 that the most northern forms are larger than the 
 southern in both hemispheres the probable 
 result of a slower metamorphosis in a more 
 temperate climate. 
 
 EVIDENCE THAT DANAIDA IS AN OLD WORLD 
 GENUS THAT HAS INVADED THE NEW 
 
 The suggestion might perhaps be made that 
 the New World forms of Danaida are the more 
 ancestral, and that those of the Old World have 
 been derived from them by migration westward. 
 There is no reason for concluding that the 
 Danaidas of either geographical area possess a 
 more primitive structure than those of the other ; 
 we are therefore driven to consult other lines of 
 
 1 Dr. Jordan's opinion that these three genera should be united 
 is quoted in Trans. Ent. Soc. Lond., 1908, 450.
 
 160 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 evidence. The following comparisons clearly indi- 
 cate that Danaida is an Old World genus which has 
 invaded America at no very remote period : (1) 
 the far larger number of the Old World forms 
 and the greater degree of specialization by which 
 some of them are distinguished ; (2) the place of 
 Danaida as one out of a number of nearly related 
 genera making up the Danaini, a large and 
 dominant Old World group, per contra its isolated 
 position in the New World ; (3) The highly 
 developed and complex mimetic relationships of 
 the Old World Danaidas. 
 
 This last statement requires some expansion 
 and exemplification. Allusion has already been 
 made to the resemblances which have grown up 
 between different species of Danaida in the same 
 island, resemblances in which the forms of 
 chrysippus appear to act as models. Even more 
 striking is the mimetic approach of certain Old 
 World Danaidas to species of the other dominant 
 Oriental section of the Danainae the Euploeini. 
 Thus in the Solomons, Danaida (Salatum) insolata 
 is a beautiful mimic of the dark white-margined 
 Euploea brenchleyi, while in the same islands, 
 Danaida (Salatura) decipiens mimics the dark, 
 white-spotted Euploea asyllus. 1 Finally, and most 
 convincing as evidence of long residence, are the 
 numbers of mimics which in the Old World have 
 taken on the superficial appearance of species of 
 
 1 See J. C. Moulton in Trans. Ent. Soc. Lond., 1908, 603, 604 : 
 PL XXXIV, figs. 5, 10.
 
 MIMICRY OF OLD WORLD DANAIDAS 161 
 
 Danaida. In addition to the extraordinary degree 
 to which the Mimicry of D. chrysippm is carried 
 in Africa, it is mimicked in the Oriental Eegion 
 by the females of Hypolimnas misippus and of 
 Argynnis niphe, and by the males of certain species 
 of Cethosia. Danaida genutia and the forms related 
 to it are also mimicked by male Cethosias and 
 extensively by the females of species of Elymniinae, 
 while incipient Mimicry is seen in the males of 
 some of them. With the exception of Hypolimnas 
 misippus, common to both Regions, the Oriental 
 mimics of Danaida do not approach the degree of 
 resemblance attained by the best African mimics 
 of D. chrysippus. It has already been pointed out 
 that the Oriental mimics of this genus are far 
 less numerous than the African. On the other 
 hand, it is a curious fact that the only North 
 American mimic of D. plexippus, Limenitis 
 (Basilarchia) archippus reaches a far higher 
 degree of resemblance than that attained by 
 any of the characteristically Oriental mimics of 
 Danaida. 
 
 The evidence as a whole enables us to decide 
 that Danaida is an Old World genus and a com- 
 paratively recent intruder into America, while 
 the perfection of the likeness attained by an 
 indigenous American mimic proves that, under 
 favourable circumstances, such resemblances may 
 be rapidly produced. I do not, of course, mean 
 to imply that the transformation was in any way 
 sudden, or by other than minute transitional 
 
 M
 
 162 MIMICKY IN N. AMERICAN BUTTERFLIES 
 
 steps. The evidence for this conclusion will be 
 clearer when some of these steps have been 
 described in detail (see pp. 164-8). 
 
 THE LINE OF MIGRATION BY WHICH DANAIDA 
 ORIGINALLY ENTERED AMERICA 
 
 There can be little doubt that D. plexippus 
 invaded America by way of the north, probably 
 following the line of the Aleutian Islands. In 
 North America it possesses an astonishing distri- 
 bution for a member of so tropical a group, 
 ranging immensely further north than any other 
 Danaine in the world. Furthermore, D. genutia, 
 the probable representative of its Old World 
 ancestor, extends far beyond the tropics into 
 Western and Central China. A study of the 
 distribution of the Asclepiad food-plants on the 
 eastern coast of Asia might perhaps throw light 
 on the problem. D. plexippus was certainly the 
 earlier of the two invaders of the New World. 
 This is clearly shown by the extent of its own 
 modification no less than by the changes it has 
 itself produced. Its immense size, the shape of 
 the hind-wing cell, and the form of the fore wings 
 indicate that it is far more widely separated 
 than is D. Berenice from the nearest Old World 
 species. It has furthermore been resident in North 
 America long enough to effect profound changes 
 in the pattern of an indigenous Nymphaline 
 butterfly, rendering it an admirable mimic ; 
 whereas D. berenice, and probably its form strigosa
 
 INVASION FROM THE NORTH 163 
 
 also, have only effected comparatively slight 
 modifications in the mimetic pattern already 
 produced under the influence of plexippus (see 
 pp. 168-72). It is impossible to feel equal 
 confidence in suggesting the line by which the 
 later invasion of the more tropical D. Berenice 
 took place ; but it is on the whole probable that 
 it too came by way of the north during some 
 temporary period of warmth. It is tolerably 
 certain that it did not invade North America 
 from the south. For although D. Berenice and 
 strigosa have produced as is shown above far 
 less change in the indigenous N. American 
 fauna than plexippus, they have still caused 
 distinct and perfectly effective modifications in a 
 single species ; whereas in South America their 
 representatives have not been shown to have had 
 any effect at all. It is probable that both the 
 American Danaidas as they pressed southward 
 were 'held up' for a considerable time at the 
 northern borders of the Neotropical Region, 
 unable at first to penetrate that crowded area. 
 Finally they burst their way through and are now 
 abundant throughout all the warmer parts of the 
 Region, the forms of plexippus extending further 
 into the temperate south, just as in the Northern 
 Hemisphere they range further north than those 
 of Berenice. We are made to realize the recent 
 date of the invasion of South America when we 
 remember that nowhere else in the world do 
 Danaine butterflies of equal abundance 'range
 
 164 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 through a crowded area without producing any 
 effect on any member of the Lepidopterous 
 fauna, or without themselves being affected 
 thereby. ' l Abundant wide-ranging Danaines 
 in the Old World, even when much smaller 
 and with a less marked appearance, invariably 
 produce some effect, and often themselves 
 exhibit Miillerian resemblances. 
 
 THE EVOLUTION OF LIMENITIS (BASIL ARCH IA) 
 ARCHIPPUS AS A MIMIC OF THE INVADING 
 DANAIDA PLEXIPPUS 
 
 It has already been mentioned that a single 
 species, undergoing corresponding modifications, 
 provides a mimic for each of the three Danaine 
 models (including strigosa). We will first con- 
 sider the well-known beautiful mimic of D. pkx- 
 ippus', for it undoubtedly arose earlier than the 
 others. 
 
 The abundant Limenitis or Basilarcliia arcliippus 
 is closely related to the Palaearctic species of 
 Limenitis, a group which includes the well-known 
 British 'White Admiral' (L. sylilla). The ex- 
 ample is unusually instinctive, because the non- 
 mimetic ancestor of the mimic is still very 
 abundant in Canada and the north-eastern States, 
 and we thus possess the material for reconstruct- 
 ing the history by which the one form originated 
 from the other. We know that this ancestor, 
 Limenitis arthemis, has persisted almost unchanged, 
 
 1 Tmns. Ent. Soc. Lond, (1908), 452.
 
 NON MIMETIC PARENT OF MIMIC 165 
 
 because of the resemblance between its pattern 
 and that of other species of Limenitis (using the 
 name in the broad sense) from all parts of the 
 circumpolar land-belt, including North America 
 itself. The difference between the pattern of 
 the mimic and that of its non-mimetic parent 
 is enormous probably as great as that between 
 any two butterflies in the world ; but the steps 
 by which the transition was effected were long 
 ago suggested by S. H. Scudder, 1 and have 
 recently been worked out in considerable detail 
 by the present writer. 2 
 
 L. arthemis exhibits the characteristic * White 
 Admiral' pattern possessing on the upper sur- 
 face a dark ground-colour with a broad white 
 band crossing both wings, and white markings 
 within the apex of the fore wing. Eeddish or 
 orange spots between the white bands and the 
 margin are found in the hind wings of many 
 individuals, more rarely in the fore wings. These 
 latter markings are of the utmost importance, 
 for, as Scudder long ago pointed out (1. c., 714), 
 they undoubtedly provided the foundation for 
 the change into the mimetic arcMppus. 
 
 A careful comparison between arthemis and 
 arcMppus reveals the most conclusive evidence 
 of selection. The one species has become changed 
 into the other precisely as if an artist were to 
 paint the pattern of arcMppus upon the wings 
 
 1 Butterflies of the Eastern United States and Canada, Cambridge, 
 Mass. (1889), 278, 714. 
 
 2 Trans. Ent. Soc. Lond. (1908), 454-60.
 
 166 MIMICKY IN N. AMERICAN BUTTERFLIES 
 
 of artJiemis, retaining unchanged every minute 
 part of the old markings that could be worked 
 into the new, and obliterating all the rest. Thus, 
 extending in this direction and wiping out in 
 that, the great transformation has been effected 
 and one of the most beautiful mimics in the 
 world produced. 
 
 The evolution of the mimetic pattern on the 
 under surface has involved an even more elabo- 
 rate change than on the upper ; but it is not 
 necessary to repeat here the details which have 
 been only recently fully described. 1 I will, how- 
 ever, allude to the fate of the most conspicuous 
 feature of arthemis, the broad white band crossing 
 both wings. Save for the traces mentioned below, 
 this marking has disappeared from both surfaces 
 of the hind wing of archippus, but its black outer 
 border is retained, and, cutting across the radi- 
 ate pattern formed by the strongly blackened 
 veins, detracts considerably from the mimetic 
 resemblance. 2 On the under surface distinct 
 
 1 Trans. Ent. Soc. Land. (1908), 454-60. 
 
 2 In the course of the address on December 31, 1908, 1 remarked 
 that if we could revisit the earth in a few hundred years we might 
 expect to find that this black line had disappeared from the hind 
 wing, and the mimetic resemblance correspondingly heightened. 
 Atthe conclusion, Mr. John H. Cook of Albany, N.Y., informed 
 me that he had discovered near his home many individuals in 
 which the black line was wanting from the upper surface. A few 
 days later he very kindly sent me a record of his observations, of 
 which an abstract is printed as a note at the end of this address 
 (see pp. 211-12). The study of Mr. Cook's facts shows that near the 
 city of Albany not only did the stripeless variety occur commonly 
 (1 in 14', during the three seasons in which the observations were 
 conducted, but also transitional forms with more or less broken 
 stripes were far commoner than the normal archippus (18 to 1). The
 
 ANCESTRAL TRACES IN THE MIMIC 167 
 
 traces of the white band may commonly be seen 
 along the inner edge of the persistent black 
 border. So far as my experience goes these 
 traces are only to be found on the upper surface 
 in the form hulsti (Edw.). The modification of 
 the same marking in the fore wing is more in- 
 teresting. Here towards the costal margin the 
 black outer border is much expanded, invading 
 the white band and cutting off from two to four 
 white spots from its outer part. While the rest 
 of the band disappears except on the costa itself, 
 these black-surrounded white spots now repre- 
 sent the sub-apical pale-spotted black bar of the 
 model. The new marking is larger and more 
 conspicuous on the under surface, corresponding 
 with the strong development of white on this 
 surface of the model. The costal margin of the 
 fore wing of the latter is streaked with long 
 narrow white markings. In correspondence with 
 this we find, commonly on the under surface, 
 more rarely on the upper, that the extreme 
 
 fact that entirely stripeless individuals were invariably males is 
 contrary to the rale that mimetic resemblance tends to develop 
 more rapidly and fully in the other sex. But in this species I have 
 observed another point in which the female tends to be more 
 ancestral than the male, viz. the more frequent and complete 
 development of the white spot in the cell of the fore-wing upper 
 surface (a common feature of Limenitis, although now generally 
 absent from L. arfhemis). 
 
 Mr. Cook's observations show that a single marking- and one 
 so simple that we might have expected it to act as a 'unit 
 character ', so small a fraction of the pattern that we could hardly 
 speak of its sudden disappearance as ' discontinuous ' evolution 
 that even this behaves differently on the two surfaces of the 
 wing, while the individuals from which it has disappeared are 
 immensely outnumbered by those in which it is transitional.
 
 168 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 costal end of the white band is retained, often 
 for the full breadth of the marking, forming 
 a linear streak. 
 
 I have dwelt upon the changes undergone by 
 the white band as an example of the way in which 
 the new markings have been carved out of the 
 old. The changes in the elaborate marginal 
 pattern would have been equally convincing as 
 evidence for a gradual and 'continuous' trans- 
 formation. 
 
 THE MODIFICATION OF THE LIMENITIS MIMIC 
 OF DANAIDA PLEXIPPUS INTO A MIMIC OF 
 D. BERENICE IN FLORIDA 
 
 Danaida plexippus occurs together with D. bere- 
 nice in Florida, but the latter far outnumbers the 
 former, and the modification of Linienitis arcliippus 
 into the form floridensis, Strecker (= eros, Edw.) 
 is probably entirely due to the predominance of 
 one model over the other. Data for determining 
 the exact proportions in various localities would 
 be of high interest. There is no reason for 
 believing that Berenice is in any way more or less 
 distasteful than plexippus, but its abundance makes 
 it a more conspicuous feature in the environment. 
 
 It is evident that the change has been of the 
 kind expressed in the above heading ; for, as has 
 been already implied on pp. 1 62-3, traces of the 
 former Mimicry of plexippus persist in floridensis 
 and tend to detract from the resemblance more
 
 NEW MIMIC EVOLVED FROM OLD 169 
 
 recently developed. This is especially the case 
 with the conspicuously blackened veins of archip- 
 pus, which are so important a feature in the like- 
 ness to plexippus. These, although obscured by 
 the general darkening, are still recognizable in 
 floridensis, diminishing its resemblance to Berenice 
 on the upper surface of both wings and on the 
 under surface of the fore wing. Inasmuch as 
 the details have been recently published else- 
 where, 1 I will only dwell on one further point in 
 the resemblance of floridensis to Berenice and 
 that because the extensive observation of large 
 numbers of specimens is greatly needed. I spoke 
 on pp. 166-7 of the persistent traces of the white 
 band on the hind-wing under surface in many 
 individuals of L. arcliippus. These are ancestral 
 features, diminishing the mimetic resemblance 
 to D. plexippus. But in D. Berenice there are 
 conspicuous white spots towards the centre of 
 the hind-wing under surface, and these, at any 
 rate upon the wing, would bear some resemblance 
 to the ancestral spots of the Limenitis mimic. 
 Now in my very limited experience of floridensis 
 these spots were sometimes exceptionally deve- 
 loped and, outlined with black on their inner 
 edges, were certainly far more distinct and con- 
 spicuous than in L. archippus. The appearances 
 I witnessed suggested the possibility of the 
 recall of a vanishing feature in consequence of 
 
 1 Trans. Ent. Soc. Land. (1908), 460, 461. See also Scudder, 
 1. c., 718.
 
 170 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 selection based on a likeness to certain white 
 spots present in the new model (berenice) but 
 absent from the old (plexippus). But many 
 hundreds of specimens from different localities 
 scattered over the total area of distribution re- 
 quire to be examined from this point of view. 
 An even more interesting inquiry would be to 
 trace the range of the floridensis form northward 
 and determine the relationship of its limits to 
 the zone in which berenice becomes scarce and 
 disappears, and above all to ascertain whether 
 floridensis on the borders of its range interbreeds 
 with archippus and how far transitional varieties 
 occur. Interbreeding between the two forms, 
 if possible, would be of extraordinary interest. 
 It is also of importance to ascertain precisely 
 how far the one form penetrates the area of the 
 other. Scudder indeed states that floridensis 
 ranges into the Mississippi Valley and Dakota, 
 far beyond the limits of Danaida berenice. It 
 would be deeply interesting to make an exact 
 comparison between such specimens and those 
 from Florida, and also to ascertain the proportion 
 which they bear to typical arcliippus. By far 
 the most important feature in the evolution of 
 floridensis is the general darkening of the ground- 
 colour, and the material for such a transformation 
 certainly exists freely in archippus, for the shade 
 of brown varies immensely and may often be 
 seen of as dark a tint as in floridensis, but not 
 in my experience of precisely the same shade.
 
 INVESTIGATIONS REQUIRED 171 
 
 The proportion of such dark forms in various 
 parts of the immense range of archippus would 
 be another interesting inquiry. 
 
 THE MODIFICATION OF THE LIMENITIS MIMIC 
 OF DANAIDA PLEXIPPUS INTO A MIMIC OF 
 THE STRIGOSA FORM OF D. BERENICE IN 
 ARIZONA 
 
 The differences between L. archippus and the 
 form hulsti (Edw.) are more striking than those 
 which distinguish floridensis from the former. 
 The upper surface of the hind wing of hulsti 
 retains or more probably has recalled distinct 
 traces of the white band, although the black 
 stripe is evanescent. It is probable that, upon 
 the wing, these vestigial white markings produce 
 a general likeness to the pale-streaked hind-wing 
 upper surface of strigosa. Other points in which 
 hulsti differs from archippus and approaches stri- 
 gosa are the reduction of black and the general 
 appearance of the white spots in the subapical 
 region of the fore wing, and the dull tint of the 
 ground-colour. I have had hardly any experi- 
 ence of this interesting form and owe the above 
 details to Dr. W. J. Holland's figure and descrip- 
 tion. 1 It is obvious that all the investigations 
 suggested in the case of floridensis are, mutatis 
 mutandis, equally available and equally important 
 in the form hulsti. 
 
 1 Butterfy Boole, 84, 185, PI. vii. f. 5. Dr. Holland fully recog- 
 nizes the mimetic significance of the pattern and colouring of 
 hulsti.
 
 172 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 The geographical distribution of Imlsti strongly 
 supports the conclusion that it was derived from 
 arcJiippus and not immediately from an arthemis-like 
 ancestor. I have not yet had the opportunity of 
 ascertaining whether this hypothesis is supported 
 by evidence derived from a careful study of the 
 pattern. 
 
 It is deeply interesting to observe that the same 
 Linienitis artkemis-like species, from which archip- 
 pus, floridensis and Imlsti mimics respectively 
 of the three Danaidas, plexippus, Berenice and 
 strigosa have been directly or indirectly evolved, 
 has also given rise to L. astyanax (ursula), the mimic 
 of a Papilionine model. Evidence in favour of the 
 comparatively recent origin of these mimicking 
 forms is to be found in the well-supported facts 
 which indicate that astyanax still interbreeds with 
 arthemis along their geographical overlap, and 
 that it may even occasionally pair with the sister 
 species arcJiippus. 1 
 
 The earlier stages of arcJiippus and astyanax are, 
 according to Scudder (l.c., 254, 255), with difficulty 
 distinguished from those of arthemis, but astyanax 
 presents the closer likeness of the two ; a fact 
 which, together with those referred to in the last 
 paragraph, points to the conclusion that it arose 
 even more recently than archippus. 
 
 The further consideration of astyanax is best 
 deferred until some account has been given of the 
 
 1 Scudder, 1. c., 283, 289. Trans. Ent. Soc. Lond. (1908), 473, 474-
 
 RECENT ORIGIN OF MIMICS 173 
 
 Papilionine models, and until certain general 
 conclusions have been discussed in the following 
 section. 
 
 BEARING UPON THEORIES OF MIMICRY OF 
 THE TRANSFORMATION WROUGHT BY THE 
 INVADING DANAIDAS 
 
 It has been shown that the Danaine models 
 invaded America from the Old World tropics, 
 probably following a northward route. Their 
 patterns are but little changed in the new sur- 
 roundings, and they still keep the characteristic 
 appearance of Old World Danaidas. Furthermore, 
 such changes as have taken place in the older 
 invader, D. pkxippus, during its residence in the 
 New World, are also retained in those colonies 
 which, during the past half-century, have been 
 re-establishing themselves in the Old World. 
 These facts support Darwin's conclusion that the 
 physico-chemical influences of soil, climate, &c., 
 are of comparatively slight importance, a conclu- 
 sion which made him feel * inclined to swear at 
 the North Pole, and ... to speak disrespectfully 
 of the Equator V 
 
 The mimics on the other hand are derived from 
 characteristic and ancient inhabitants of the 
 northern land-belt. If, as the followers of the 
 theory of External Causes (see p. 148) maintain, 
 species are the expression of the physical and 
 
 1 In a letter to Sir Charles Lyell, Oct. 11, 1859. Life and 
 Letters, ii. 212.
 
 174 MIMICKY IN N. AMERICAN BUTTERFLIES 
 
 chemical forces of the environment, then the 
 Danaidas express the Old World tropics and the 
 species of Limenitis the northern land-belt. We 
 might expect on this theory that the Danaidas, 
 when they invaded the northern zone, might come 
 to resemble the Limenitis ; but the transformation 
 that has actually occurred is entirely inconsistent 
 with any such hypothesis. Although the Danaidas 
 have undergone no important change in the new 
 environment, their presence has entirely trans- 
 formed and brought into a close superficial re- 
 semblance to themselves the descendants of a 
 member of an ancient group. Such a fact is in- 
 consistent with any interpretation as yet offered 
 except that which refers the change to the accu- 
 mulation by selection of variations which promote 
 a likeness to the Danaidas. 
 
 The facts also bear upon the two theories of 
 Mimicry associated with the names of H. W. Bates 
 and Fritz Miiller. According to Bates's theory, 
 Mimicry is a special form of protective or cryptic 
 resemblance. In the ordinary examples of this 
 principle, species are aided in the struggle by 
 concealment, by a likeness to some object of no 
 interest to their enemies (such as bark, earth, &c.) ; 
 in these special examples (called mimetic) species 
 are aided by resembling some object which is un- 
 pleasant or even dangerous to their foes. Fritz 
 Miiller's theory of Mimicry includes the cases 
 in which the mimics, as well as their models, 
 are specially defended, although generally to an
 
 DOMINANT FORMS BECOME MIMICS 175 
 
 unequal degree. 1 The resemblance is due to the 
 advantages of a common advertisement. Before 
 the growth of a mimetic likeness, Batesian mimics, 
 it is reasonable to assume, belonged to the immense 
 group of species possessing a cryptic appearance ; 
 Mlillerian mimics on the other hand may be 
 assumed to have possessed warning or aposematic 
 colours of their own previous to the adoption of 
 those of another species. This test is more readily 
 applied than might be supposed ; for a comparison 
 with allied non-mimetic species, and with the 
 non-mimetic males of mimetic females, will gene- 
 rally indicate whether the ancestral pattern of 
 a species now mimetic belonged to the group of 
 concealing colours or to that of warning. 
 
 The Danaidas invaded North America and 
 entered an assemblage of butterflies of which the 
 dominant species are ancient inhabitants of the 
 northern land-belt. Among them are several, such 
 as the species of Grapta or Polygonia, (the 'Comma' 
 butterflies), with beautifully cryptic patterns on 
 the parts of the wing surface exposed in the rest- 
 ing position. No such forms have been influenced 
 by the invaders, but with the whole fauna before 
 them they have only produced changes in the 
 dominant group Limenitis, known throughout the 
 northern belt for a conspicuous under surface and 
 a floating flight ; also believed to be mimicked by 
 other butterflies, e. g. the females of the Apaturas 
 
 1 It is probable that relative abundance may determine the 
 relationship of model and mimic in cases where there is no reason 
 for suspecting any difference in the degree of unpalatability.
 
 176 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 (' Purple Emperors') and the later brood of Arasch- 
 nia levana. 1 Furthermore, the close allies of Li- 
 menitis in South America, the abundant Adelphas, 
 are beautifully mimicked, not only by females of 
 the genus Chlorippe, which represents Apatura, but 
 also by Erycinidae. In another point the facts are 
 at variance with Bates's interpretation but har- 
 monize with Miiller's. Bates supposed Mimicry to 
 be an adaptation by which a scarce, hard-pressed 
 form is enabled to hold its own in the struggle 
 for existence. But L. arthemis, which represents 
 with little or no change the species from which 
 the mimics were derived, persists as a very abun- 
 dant and flourishing species, while its mimetic 
 descendant archippus has gained an immensely 
 extended range and become almost universally 
 commoner than any other species of its group 
 (Scudder, l.c., 266). L. archippus extends from 
 Hudson's Bay to the Gulf of Mexico; over this vast 
 area it is only rare in the west, and only unknown 
 in Colorado, Arizona, and New Mexico (I.e., 278). 
 It is to be observed that the range of archippus 
 includes the whole of the area (Canada and the 
 north-eastern States) occupied by the ancestral 
 form arthemis. 
 
 The facts indicate that the changes produced 
 by the invaders were wrought in the conspicuous 
 pattern of a dominant indigenous species, and 
 that the transformed butterfly having adopted the 
 
 1 See also the mimetic resemblance to L. astyanax described on 
 pp 189-91.
 
 FACTS SUPPOET MULLER'S THEORY 177 
 
 advertisement of the still more unpalatable Danaida, 
 became even more dominant and gained a far 
 wider range than before. The mimetic resem- 
 blance arose in a species which we have reason to 
 believe possessed warning colours and some form 
 of special protection before the change occurred. 
 There is no evidence that the special protection 
 was diminished after the assumption of Mimicry, 
 and, if it remain, the new appearance is still 
 a warning character, only one that is learnt by 
 enemies more readily than the old because of the 
 wide advertisement given to it by Danaida plex- 
 ippus. The facts harmonize with the theory of 
 Fritz Mttller rather than with that of H. W. Bates. 
 
 THE 'POISON-EATING' SWALLOW-TAIL BUTTER- 
 FLIES (PHARMACOPHAGUS) AS MODELS FOR 
 MIMICRY 
 
 The late Erich Haase gave the name of Pliar- 
 macophagus or * Poison-eater ' to the section of 
 swallow-tail butterflies whose larvae feed upon 
 Aristolochia or allied species, and he made the 
 probable suggestion that the qualities which render 
 them distasteful are derived from the juices of 
 the food-plant. The poison-eating swallow-tails 
 are abundant in tropical America and the Oriental 
 Region, but with the exception of anterior in 
 Madagascar are wanting from the Ethiopian 
 Region. They are extensively mimicked by 
 swallow-tails of the other two sections : Papilw, 
 of which tmcliaon may be taken as a type, and 
 
 N
 
 178 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 Cosmodesmus, of which podalirius serves as an 
 example. The distinction between these three 
 sections of Papilionidae extends to larval and 
 pupal stages, as was originally discovered by 
 Horsfield. It was made the basis of Haase's 
 classification, 1 recently confirmed and amplified 
 by Rothschild and Jordan. 2 The latter authori- 
 ties propose the names ' Aristolochia Swallow- 
 tails ', ' Fluted Swallow-tails ', and * Kite Swallow- 
 tails ', respectively for Haase's sections Plwrma- 
 cophagm, Papilio, and Cosmodesmus. 
 
 The Pharmacopkagus swallow-tails are not so 
 well known as models for Mimicry as are the 
 Danainae, Acraeinae, &c., and it is therefore ex- 
 pedient to say a few words about the section 
 before considering the effect produced by one 
 of its members in North America. 
 
 In tropical America not only are the species of 
 Pharmacophagus extensively mimicked but Mimicry 
 is also strongly developed within the limits of the 
 section itself, viz. between the two dominant 
 groups Aeneas and Lysander. In these groups 
 the males are commonly very different in appear- 
 ance from the females and frequent more open 
 habitats such as the banks of rivers, &c., the 
 females being found in the forest. In the internal 
 Mimicry between Aeneas and Lysander the males 
 resemble the males, the females the females, but 
 the female patterns are alone extensively mimicked 
 
 1 Researches on Mimicry, Pt. ii, Stuttgart, 1896, English trans- 
 lation. 
 
 2 Not. Zool., xiii (1906), 411-752.
 
 THE 'POISON-EATING' MODELS 179 
 
 by other groups Papilw, Cosmodesmus and certain 
 Pierinae. I have as yet only come across a single 
 example (a Cosmodesmus) in which the pattern and 
 green markings of the males are mimicked. One 
 or two species (e. g. Ph. liahneli] of Pharmacophagus 
 are themselves mimics of dominant Ithomiine 
 genera. 
 
 It has already been pointed out on p. 137 that 
 in the Papilio mimics of Pharmacoplmgus the re- 
 semblance is often attained by the females alone, 
 a tendency exemplified in North America as shown 
 on pp. 181-4. In Cosmodesmus, on the other hand, 
 where the Mimicry of these models reaches a far 
 higher level of perfection, it is equally pronounced 
 in both sexes. In Africa, on the other hand, 
 where, in default of Pharmacophagus models, the 
 swallow-tails of both groups frequently mimic 
 Danainae and Acraeinae, the resemblances attained 
 by Cosmodesmus are far less striking than those of 
 the other section ; yet the relationship of Mimicry 
 to sex remains unchanged. 
 
 In the Oriental Region the female Mimicry 
 of Plwrmacophagus is still characteristic of Papilio, 
 also appearing in certain Cosmodesmus mimics of 
 Danainae. Two remarkable features appear in 
 this Kegion : (1) the development within Pharma- 
 cophagus of the gigantic Ornithopteras which do 
 not appear to be mimicked at all ; (2) the appear- 
 ance within the section Papilio of groups which 
 are mimicked as extensively, perhaps even more 
 extensively, than Pharmacophagus itself. Among 
 
 N2
 
 180 MIMICKY IN N. AMERICAN BUTTERFLIES 
 
 the mimics of these Papilios are not only species 
 of other groups in the same section but also, 
 although in small proportion, Satyrine butterflies 
 and day-flying moths. 
 
 The fact that Pharmacophagus and certain groups 
 of Papilio should be mimicked pre-eminently by 
 other Papilionidae is evidence that Mimicry is 
 most easily attained when there are initial resem- 
 blances of size, shape, habits, and modes of flight 
 upon which to build. 
 
 PHARMACOPHAGUS (PAPILIO) PHILENOR, L., AS 
 A MODEL FOR MIMICRY IN NORTH AMERICA 
 
 Pharmacophagus is a tropical assemblage, but 
 a few species have found their way into the 
 northern belt in both the Old World and the 
 New. Pharm. polydamas, with an immense range 
 in South and Central America, also extends into 
 the northern continent but does not there become 
 the object of Mimicry. Pharm. philenor, ranging 
 through Mexico and the United States (except 
 the central district from Colorado northwards) 
 but only as a straggler in New England and 
 southern Canada, is on the other hand an important 
 model for Mimicry. 
 
 There is here no such interesting history of past 
 migrations to unfold as we were able to trace 
 in the American Danaidas. Ph. philenor is a 
 member of the distinctively New World species 
 of Pharniacophagus, associated together and sepa- 
 rated from the Old World species by structural
 
 PHILENOR AN AMERICAN MODEL 181 
 
 characters. Rothschild and Jordan state that 
 every species can be recognized as American by 
 the examination of a single joint of one leg, and 
 they are therefore justified in concluding that all 
 the New World species were derived from a single 
 ancestor possessing this character. There is no 
 sufficient evidence that any of the numerous 
 patterns are ancestral as compared with the others, 
 although it is tolerably safe to conclude that the 
 presence of hind-wing ' tails ' is primitive as com- 
 pared with their absence. Following this indica- 
 tion, we find that as a general rule the specialized 
 and modern forms are predominant nearer to the 
 Equator, the comparatively ancestral tailed forms 
 occurring in latitudes more remote from it both 
 north and south. 
 
 Ph. phiknor is a * tailed ' form, although its sub- 
 species orsua in the Tres Marias Islands is nearly 
 tailless. It is probably an intruder into North 
 America from the tropics of the same Continent. 
 It is well known to possess the characteristics 
 of distasteful species gregarious larvae, tenacity 
 of life, and a strong, disagreeable scent. 
 
 THE THREE PAPILIO MIMICS OF PH. PHILENOR 
 IN NORTH AMERICA 
 
 The three swallow-tail mimics of philenor belong 
 to separate groups of Haase's section Papilio. All 
 of them range from the Atlantic to the Mississippi 
 basin.
 
 182 MIMICEY IN N. AMERICAN BUTTERFLIES 
 
 The female of Papilio polyxenes asterius (Or.) 
 belonging to the MACHAON GROUP mimics philenor 
 on both surfaces, the male on the under surface 
 alone, except at Guerrero, Mexico, where a form 
 (ampliata) mimetic on the upper surface is tran- 
 sitional into the ordinary male. 
 
 Papilio glaucus glaucus (L.) belongs to the 
 GLAUCUS GROUP, next but one to the group con- 
 taining asterius. The female is dimorphic, one form 
 resembling the male and the other (the tttmus 1 
 form, mimetic of philenor) becoming commoner in 
 the southern part of the range. In the closely 
 allied sub-species P. glaucus canadensis (Rothsch. 
 and Jord.) the mimetic female form is unknown. 
 
 Papilio troilus troilus (L.) belongs to the next 
 succeeding TROILUS GROUP, allied to the tropical 
 and highly mimetic ANCHISIADES GROUP, with 
 gregarious larvae. Both male and female of 
 troilus mimic philenor on both wing surfaces. 
 
 The most remarkable fact about these three 
 mimics is not their moderate resemblance to the 
 primary model philenor, but their extraordinary 
 likeness to one another. Upon the wing or at 
 rest at a little distance they would be indistin- 
 guishable, and even in the cabinet they may be 
 easily confused. It is to be expected that the 
 species of allied groups, with patterns converging 
 towards that of a single model, and approaching 
 it by variations which tend to be produced in the 
 
 1 The species is commonly called P. turnus and its mimetic 
 female the glaucus form. I follow Rothschild and Jordan in trans- 
 posing these names.
 
 MIMICRY BETWEEN MIMICS 183 
 
 section to which they belong, should incidentally 
 approach one another. But the strong likeness 
 between the mimetic forms of troilus, asterius, and 
 glaucus seems to require something more than this, 
 and supports the conclusion that there is secondary 
 Mimicry between the mimics themselves. It is 
 not necessary to repeat here the details of these 
 secondary resemblances, 1 and as a matter of fact 
 the likeness itself is stronger than might be 
 inferred from a consideration of the details them- 
 selves. It is necessary to see it in order to 
 appreciate it. 
 
 It is probable that troilus, mimetic in both 
 sexes, is the oldest mimic ; asterius, non-mimetic 
 on the upper surface of the male or with very 
 rough incipient Mimicry, the next to appear ; and 
 glaucus, mimetic in only one form of the female, 
 the youngest. These conclusions as to relative 
 age are on the whole supported by the relative 
 strength of the detailed resemblances to philenor 
 in the three mimics. 
 
 In attempting to trace the past history, here 
 again we have the great advantage of knowing the 
 more ancestral patterns from which the three 
 mimics were derived : troilus from a palamedes- 
 like form ; asterius from the pattern of its male, 
 which again leads back to the typical pattern 
 of the MACHAON GBOUP; the turnus female of 
 glaucus from the male and non-mimetic female 
 of the same species. 
 
 1 See Trans. Ent. Soc. Lond. (1908), 467-71.
 
 184 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 It is highly probable that the earliest steps 
 in the direction of Mimicry in asterius and glaucus 
 were favoured by the appearance of partially 
 melanic varieties of the female, thus effecting 
 suddenly that essential change which enables a 
 butterfly with a yellow ground-colour to become 
 the mimic of one in which it is black. But this 
 transformation, immensely important as it is, 
 supplies nothing more than a tinted paper for the 
 new picture. That the melanic varieties were 
 partial is clearly shown by the persistence (in 
 glaucus) in a subdued and inconspicuous form of 
 certain ancestral features that do not contribute 
 to the Mimicry, but above all by the retention 
 of every element in the original pattern that can 
 be worked up into the new. By the modification 
 of these elements in form or colour, often in both 
 form and colour, the detailed mimetic pattern 
 has been wrought upon the darkened surface. 
 
 Valuable confirmation of the history suggested 
 in the last paragraph is to be found in the dark 
 fonn melasina (Rothsch. and Jord.) found in both 
 sexes of P. polyxenes americus (Kollar), extending 
 from North Peru to Colombia and Venezuela. This 
 melanic variety probably represents the darkened 
 form of asterius before the initiation of the detailed 
 mimicry ofphilenor. The sub-species americus does 
 not enter the range of pliilenor, and those ancestral 
 elements which have been retained by its melanic 
 form have not developed into the mimetic likeness 
 seen in the more northern sub-species asterius.
 
 MIMICRY AND MELANISM 185 
 
 It is well known that all four species (including 
 philenor) fly together. Even in my own limited 
 experience I have taken three of them in adjacent 
 streets on the outskirts of Chicago on the same 
 day (Aug. 10, 1897), and the fourth in the same 
 locality a little earlier (July 28). But precise 
 knowledge of their relative proportions in different 
 parts of their range would be of high interest. 
 Again, troilus extends to the North- West Territory 
 of Canada, probably far beyond the area in which 
 philenor occurs as a straggler ; and it would be 
 very interesting to compare minutely large num- 
 bers of such specimens with those from districts 
 where the model is dominant. A similar study 
 should be made of the Canadian specimens of 
 asterius, although this species does not extend 
 so far beyond the northern limits of the poison- 
 eating model. 
 
 From another point of view the interbreeding 
 of the turnus female of glaucus with a male from 
 some northern district where turnus is unknown or 
 very scarce would be of the highest interest. 
 We should here be able to test whether the 
 Mendelian relationship exists between the parent 
 form and its partially melanic variety further 
 transformed by selection, not a mere melanic 
 * mutation '. I trust that my friend Prof. C. B. 
 Davenport may be able to undertake this experi- 
 ment at the Cold Spring Experimental Station. 
 I cannot doubt that breeding could be easily 
 carried through two generations in a large enclosed
 
 186 MIMICEY IN N. AMERICAN BUTTERFLIES 
 
 space exposed to the sun and planted with abun- 
 dant flowers and the food-plant of the species. It 
 would probably be safe to use Long Island males, 
 while female pupae or the freshly bred females 
 themselves could be readily obtained from further 
 south. 
 
 THE EVOLUTION OF LIMENITIS (B.) ASTYANAX 
 (F.) AS A MIMIC OF PH. PHILENOR AND ITS 
 PAPILIO MIMICS 
 
 Scudder states that L. astyanax l ranges from 
 the Atlantic westward to the Mississippi Valley, 
 and from the Gulf of Mexico northward to about 
 the 43rd parallel of latitude/ 1 It thus falls 
 entirely within the area ofphiknor. The northern 
 boundary of astyanax corresponds with the 
 southern limit of its parent arthemis, and Scudder 
 (1. c., 289) considers that they interbreed and that 
 the intermediate form proserpina, found along the 
 narrow belt where the two species or sub-species 
 meet, is the resulting hybrid. Both arthemis and 
 proserpina have been bred from the eggs of the 
 latter. There seems little doubt that astyanax is 
 a very recent development from arthemis in the 
 southern part of its range, so recent that the 
 areas of distribution still remain distinct and 
 parent and offspring only meet along a narrow 
 line. It is probable that archippits arose in the 
 same manner in part of the area of arthemis, but 
 
 1 A closely allied species or probably a form of the same species 
 is recorded by Godman and Salvin from Mexico.
 
 EVOLUTION OF L. ASTYANAX 187 
 
 that later, after the separation had become com- 
 plete, it spread northward over the whole range 
 of its parent. 
 
 The evolution of astyanax from arthemis was far 
 simpler than that of archippus. The great 
 difference in appearance between parent and 
 offspring is brought about, as regards the upper 
 surface, by the disappearance of the broad white 
 band of arthemis together with all but a trace of 
 the sub-apical white markings of the fore wings. 
 Over and within the area formerly occupied by 
 the white band a bluish or greenish iridescence 
 spreads from the marginal region where it exists 
 in arthemis. This marginal iridescence just as 
 in astyanax is bluish in some individuals of 
 arthemis, greenish in others. Reddish sub- 
 marginal spots, although rarer in the hind wing 
 of astyanax, are actually commoner in the fore 
 wing than in arthemis. This curious fact, together 
 with the evidence that astyanax and archippus 
 may occasionally interbreed, suggests the pos- 
 sibility of some connexion between the origins 
 of the two mimics. 
 
 The under surface of astyanax has not only 
 similarly lost the white markings, but the 
 chocolate-brown ground-colour of artJiemis has 
 become transformed into a dark iridescent 
 greenish-brown. Against this background the 
 reddish spots near the margin and base of the 
 wings become far more conspicuous than in the 
 parent form. The material for this transforma-
 
 188 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 tion in tint is still to be seen in the great variation 
 of the ground-colour in arthemis. 
 
 Although, as Scudder rightly maintains (1. c., 
 287), L. astyanax is a very poor mimic of Pharm. 
 philenor, it bears considerable resemblance to 
 the three Papilio mimics, especially troilus. Al- 
 though the iridescent blue or green of its upper 
 surface approaches rather more closely than the 
 Papilios to the brilliant, steely lustre of philenor, 
 it is still in this respect widely separated from 
 the primary model and near to the mimics. The 
 reddish spots of the under surface offer but a 
 rough likeness to those of any of the above- 
 named species, but there can be no doubt that 
 their emphasis is an element in the mimetic 
 resemblance. 
 
 A careful examination of large numbers of 
 astyanax from the extreme south of the range 
 where it passes out of the area of glaucus and 
 troilus but remains within that of philenor and 
 asteriits, might yield interesting results. An 
 investigation of the proportion it bears to the 
 four PapiUonidae in various parts of their common 
 range would also be of deep interest. Of the 
 highest importance would be the attempt which 
 would probably be successful to breed astyanax 
 and arthemis and to ascertain whether the 
 Mendelian proportions appear in the offspring 
 of the hybrids. The pairing of astyanax and 
 archippus, although in this case failure is probable, 
 ought also to be attempted.
 
 DIANA THE MIMIC OF A MIMIC 189 
 
 THE FEMALE OF ARGYNNIS (SEMNOPSYCHE) 
 DIANA (CE.) A MIMIC OF LIMENITIS AST Y AN AX 
 
 The comparatively narrow range of this species 
 is, as Scudder points out, wholly included within 
 that of astyanax (I.e., 1802). The Mimicry is 
 confined to the upper surface, where the blue tint 
 has even less sheen than that of any other member 
 of the group clustered round the brilliant philenor. 
 Apart from the blue expanse, which he admits to 
 be mimetic, Dr. F. A. Dixey considers that the 
 female of diana belongs to a set of dark female 
 forms well known in Argynnis, forms which he 
 believes to be ancestral. 1 It is probable that ' the 
 recent evolution of L. astyanax provided this 
 ancestral form with a model which it could 
 approach by small and easy steps of variation '. 2 
 
 THE BEARING UPON THEORIES OF MIMICRY OF 
 PHARM. PHILENOR AND ITS MIMICS 
 
 Haase, who always shows an imperfect appre- 
 ciation of the scope of Fritz Muller's principle, 
 apparently regarded all the species mentioned in 
 the preceding section as simple Batesian mimics 
 of philenor, neglecting the mimetic relationships 
 between the mimics themselves. This interpre- 
 tation is unconvincing, and most naturalists will 
 agree with Scudder in his hesitation to accept 
 the two Nymphalines, astyanax and diana (female), 
 as simple mimics of philenor. The Miillerian 
 
 1 Trans. Ent. Soc. Lond. (1890), 89-129. 2 Ibid. (1908), 475.
 
 190 MIMICKY IN N. AMERICAN BUTTERFLIES 
 
 hypothesis at once explains relationships that are 
 mere coincidences under that of Bates. 
 
 Pharm. philenor, a probable intruder from the 
 American tropics, produced its effect upon the 
 three large Papilios butterflies with a conspicuous 
 under surface pattern, in large part reproducing 
 that of the upper surface, butterflies belonging to 
 a section that provides models for extensive 
 Mimicry in the Oriental Region. They may be 
 regarded as Miillerian Mimics of the primary 
 Pharmacophagus model, exhibiting a certain 
 amount of Secondary Mimicry of one another. 
 
 The four above-named Papilionidae, but 
 especially the three mimics acting as secondary 
 models, then produced an effect upon L. arthemis 
 that same conspicuous, specially defended element 
 in the North American butterfly fauna which was 
 influenced in an entirely different direction by 
 the Danaine invaders. The result of the former 
 influence is seen in L. astyanax, a secondary 
 mimic of the three Papilio mimics of philenor. 
 
 One of the most interesting elements in this 
 complex mimetic system is the final appearance 
 of a tertiary mimic of astyanax, viz. the female of 
 Argynnis diana. This was recognized by Scudder, 
 although, not fully appreciating the Miillerian 
 hypothesis, he was much puzzled by the fact. 1 
 
 The under surface of the female diana is incon- 
 spicuous, and, considering also the restricted 
 
 1 I.e., 718, 1802: see, however, 266, where Scudder suggests that 
 astyanax may possibly be specially protected.
 
 MIMICRY OF MIMICS 191 
 
 range and relative rarity of the species, it is 
 probable that this member of the assemblage of 
 species convergent round philenor is a Batesian 
 mimic. But its resemblance to astyanax supports 
 the conclusion that this latter and the sister- 
 species archippus (and its forms) are Miillerian 
 mimics and the parent arthemis a specially 
 protected species. The resemblance of astyanax 
 to the three species of the section Papilio, as well 
 as the secondary resemblances between the three, 
 similarly supports the conclusion that these mimics 
 are Mullerian. 
 
 I have not hitherto called attention to the 
 paramount need for experimental research and 
 field observations directed to test for the presence 
 of distasteful qualities and to estimate their effect 
 upon enemies of the most varied kinds. It is of 
 the utmost importance that such investigations 
 should be undertaken on the largest possible 
 scale. In the meantime the Mullerian Hypothesis 
 appears to explain a series of remarkable relation- 
 ships which remain coincidences under any other 
 hypothesis. 
 
 THE RESEMBLANCES BETWEEN LIMENITIS 
 (ADELPHA) CALIFOKNICA (BUTL.) AND LIME- 
 NITIS (NAJAS) LORQUINI (BOISD.) 
 
 The examples of Mimicry which we have 
 been considering hitherto are, with the exception 
 of the widespread L. archippus, characteristic of 
 the eastern side of North America. The present
 
 192 MIMICKY IN N. AMEKICAN BUTTEEFLIES 
 
 instance, the last of the examples known in this 
 portion of the northern land-belt, is found on the 
 Pacific coast. The resemblances are somewhat 
 crude but of quite remarkable interest. 
 
 Limenitis californica, because of its pattern and 
 colouring, is often placed in Adelpha, a large genus 
 with over seventy species all confined to tropical 
 America. Adelpha is separated from the closely 
 allied northern genus Limenitis by the hairiness 
 of the eyes in front. Californica is by this 
 character as well as its more northern range 
 associated with the heterogeneous assemblage 
 1 Limenitis ', which so much requires a thorough 
 revision. In adopting this view I accept the posi- 
 tion assigned to the species by Scudder in 1875. 1 
 
 Closely allied to californica, of Oregon, Cali- 
 fornia, and Nevada, is L. bredowi (Hubn.) of 
 Arizona, Mexico, and Guatemala. A much 
 needed investigation is the determination 
 whether these two forms meet, and interbreed 
 along the line of contact. 
 
 The southern species or sub-species bredowi, is 
 associated in Mexico and Guatemala with many 
 true species of Adelpha of which no less than 
 thirty-one extend into Central America. To 
 these it, and to a less extent the northern cali- 
 fornica, bear much likeness, especially to A. 
 dyonysa (Hew.), massilia (Feld), lerna (Hew.), and 
 fessonia (Hew.). This likeness is probably a 
 mimetic resemblance which extends beyond the 
 
 1 Bull. Buffalo Soc. N. Sc. (Feb., 1875), 233.
 
 MIMICRY ON THE PACIFIC COAST 193 
 
 range of the models into Arizona, and, with 
 diminished effect, still further north into the 
 allied sub-species. Although the details of the 
 resemblance leave little doubt that this interpre- 
 tation is correct for the southern bredowi, it is 
 possible that californica represents an ancestral 
 form connecting the Adelphas with Limenitis, a 
 form left isolated and comparatively unchanged 
 in the north, 1 while its southern allies have been 
 modified by the presence of the dominant 
 Adelphas. At any rate in one feature neither 
 sub-species appears to be mimetic, viz. in the 
 yellowish tint of the conspicuous band crossing 
 both wings ; for in all the Central American 
 Adelphas at all resembling them this marking is 
 pure white or bluish-white. We cannot hope 
 to determine how far the pattern of californica 
 is ancestral until the structural relationships 
 and the early stages of Limenitis in the widest 
 sense and Adelpha have been most minutely 
 investigated. 
 
 Limenitis lorquini, occurring with L. californica 
 in Nevada, California, and Oregon, also extends 
 far north of this species into British Columbia 
 and Vancouver Island. Among all the North 
 American species of Limenitis it is the one which 
 comes nearest to the Old World forms, as Scudder 
 recognized when he included it with the European 
 L. populi in the genus Najas, separating all the 
 other American forms of Limenitis except cali- 
 
 1 See, however, pp. 198-9.
 
 194 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 fornica and Basilarchia. Even such fleeting charac- 
 ters as the markings show the Old World 
 affinities of lorquini in the strong development 
 of the pale spot in the fore wing cell and the 
 position and form of the pale band crossing both 
 wings. It is to be noted furthermore that its 
 distribution, and especially its extension north- 
 ward, along the Pacific coast, bring lorquini into 
 closest proximity to the Old World species. 
 
 In certain important respects the upper surface 
 pattern of L. lorquini is certainly mimetic of 
 californica : 
 
 The conspicuous fulvous apical area of the fore 
 wing ; the yellowish tint of the band crossing both 
 wings; and, although here the interpretation is 
 less certain, the fulvous marking at the anal angle 
 of the hind wing. 
 
 1. In the first and most important of these 
 points of superficial resemblance there is, so far 
 as my experience goes, a much greater average 
 development of the fulvous patch in specimens 
 of lorquini which enter the range of californica in 
 Oregon and California than in those which come 
 from Canada, entirely beyond the range of the 
 model. 
 
 The close relationship between californica and 
 lorquini may incline naturalists to look on their 
 resemblance as due to affinity and not to Mimicry. 
 'It is commonly forgotten that mimicry, being 
 independent of affinity, occurs between forms of 
 all degrees of relationship, the closest as well as
 
 LORQUINI MIMICS CALIFORNICA 195 
 
 the most remote'; 1 although of course the latter 
 are easy to interpret, while the former may be 
 excessively difficult. In this case, however, there 
 is neither doubt nor difficulty, for not only is 
 there the geographical coincidence between the 
 model and the average increase of the marking 
 in the mimic, but the fulvous apical marking of 
 lorquini of a somewhat richer, deeper shade than 
 the tawny patch of californica is due to the in- 
 ward growth of a marginal marking, while that 
 of the model occupies a clearly defined sub- 
 marginal and sub-apical position. The resem- 
 blance is, in fact, produced by markings which 
 are essentially different ; yet in some of the 
 southern examples of lorquini in which the mark- 
 ings extend inward to the greatest distance the 
 superficial resemblance is very considerable. 
 
 The above-stated conclusion that the chief 
 mimetic element of lorquini is on the average 
 subject to considerable strengthening in the 
 southern part of its range, is founded on an 
 examination of the few dozen specimens I have 
 been able to study in English collections, and 
 especially the Godman-Salvin material in the 
 British Museum. I now trust that the subject 
 may be taken up by American naturalists and 
 many hundreds of specimens compared from 
 all parts of the north and south range of the 
 species. 
 
 2. In the second point also, the yellowish tint 
 
 1 Trans. Ent. Soc. Lond. (1908), 482. 
 02
 
 196 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 of the principal band, the resemblance is certainly 
 mimetic and not due to affinity ; for lorquini, 
 ancestral in certain other features, has here lost 
 the original whiteness of this marking, preserved 
 not only in the Old World but in Limenitis 
 arthemis and L. weidermeyeri (Edw.) of the New. 
 An excessively slight deepening of the yellow 
 tint could be made out in southern individuals 
 from the area occupied by the model. In order 
 to detect the difference, a long series of northern 
 specimens should be placed beside a similar 
 series from the south and the two compared in 
 a strong light. But far larger numbers than 
 I have seen ought to be examined from this point 
 of view, and, if it were possible to make it, the 
 comparison of perfectly fresh specimens would 
 be most desirable. 
 
 3. The fulvous marking at the anal angle of 
 the hind wing is excessively variable and often 
 absent from specimens in all parts of the range. 
 The comparison of a very large amount of mate- 
 rial is necessary before we can reach any safe 
 conclusions as to the existence of mimetic re- 
 semblance in this feature, and the same is true 
 of the extremely variable under surface of lor- 
 quini, in which the development of the inner 
 row of sub-marginal bluish lunules may be mime- 
 tic of californica. This feature was generally 
 suppressed in the Vancouver Island specimens 
 I have seen. 
 
 We now come to the consideration of certain
 
 PROBABLE RECIPROCAL MIMICRY 197 
 
 differences between L. californica and its southern 
 form bredowi which promote a likeness to lorquini. 
 If these are not mere coincidences, we can hardly 
 escape the conclusion that there is Reciprocal 
 Mimicry (Diaposematism) between californica and 
 bredowi. 
 
 1. The wings of both sexes of californica are 
 more rounded than those of the males of bredowi, 
 in this respect resembling both sexes of lorquini. 
 The fact that the southern females have rounded 
 wings may indicate that this character is ances- 
 tral in both sexes, the males alone having been 
 modified in Mimicry of Adelpha. But it is a 
 probable hypothesis that the presence of lorquini 
 has prevented this mimetic feature from passing 
 northward into the males of californica. It does 
 pass far beyond Adelpha in the northernmost 
 part of the range of bredowi in Arizona. 
 
 2. The fulvous marking at the anal angle of 
 the hind wing which forms so characteristic 
 a feature of bredowi, is greatly reduced in cali- 
 fornica, approximating to lorquini, which in this 
 respect may be advancing to meet its model 
 (see p. 196). 
 
 3. The following points concern the band cross- 
 ing the fore wing. Owing to the small size of 
 the last spot in californica and the different direc- 
 tion of the spot next to it, the junction between 
 the bands of fore and hind wing forms a step-like 
 break in californica, whereas in bredowi the bands 
 tend to be continuous, approximating more closely
 
 198 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 to the single smooth streak crossing both wings 
 in the Adelphas. In lorquini this step-like break 
 and want of continuity in direction is even more 
 pronounced. Again, the fore wing band of lor- 
 quini one of its ancestral features forms, with 
 the adjacent hind wing spot, a drawn-out zigzag 
 like a flattened-down W. By a modification in the 
 position and direction of the spots of californica 
 as compared with bredowi, it also gains the ap- 
 pearance of a very flattened W, although a far 
 less regular one than that of lorquini. The re- 
 semblance is only superficial ; for corresponding 
 spots do not occupy the upper angle of the W 
 in the two species. But the attainment of a 
 likeness by means that are different from those 
 employed in another species supports the inter- 
 pretation of the resemblance as mimetic. 
 
 Whatever be the true interpretation of the 
 resemblances above described, it is of the utmost 
 importance and interest to study the relative 
 numbers of californica and lorquini at as many 
 different points as possible in their common 
 range, to observe how far they fly together and 
 present the same appearance on the wing and at 
 rest from a little distance, and to test their relative 
 palatability on a variety of insect-eating animals 
 found in the same area. 
 
 The following general considerations support 
 the conclusion that californica is not an ancient 
 element in the Pacific fauna of North America, 
 but a comparatively recent intruder from the
 
 CALIFOKNICA A EECENT MODEL 199 
 
 south an intruder that has modified the indi- 
 genous inhabitant lorquini and has been also 
 reciprocally modified thereby. 
 
 Limenitis in the broad sense is part of the 
 ancient northern butterfly fauna of North America. 
 It has here split up into several well-marked 
 species characteristic of the area. It is highly 
 susceptible to mimetic influence far more so 
 than any other North American group and 
 contributes the majority of the examples of 
 Mimicry from this part of the world. L. archippus 
 has been shown to be the result of a recent 
 invasion, its southern and eastern forms to be 
 still newer products of the changes in archippus 
 itself. The sensitiveness of the group is shown 
 by the fact that, in spite of this recent origin, 
 all except astyanax are most beautiful and striking 
 mimics ; and even astyanax is a better mimic 
 than lorquini. The fact that lorquini, the member 
 of so sensitive a group, is an undoubted mimic, 
 but a very poor mimic, supports the conclusion 
 that the association with its model has endured 
 for but a brief period, a conclusion also supported 
 by the diminution of the resemblance outside 
 the range of caUfornica. 
 
 If the relationships which I have found to 
 exist in the available material in quantity very 
 insufficient for such minute comparisons if these 
 are confirmed by extensive investigations in 
 America, it will follow that the resemblances 
 between L. caUfornica and L. lorquini will be one
 
 200 MIMICRY IN N. AMEEICAN BUTTERFLIES 
 
 of the most interesting and instructive examples 
 of Mimicry in the world. Its value will lie in 
 the early stage reached by the resemblance, to- 
 gether with the diminution of the likeness in 
 californica to the south and, especially, in lorquini 
 to the north. There is no reasonable doubt that 
 lorquini forms a single Syngamic community 
 along the Pacific coast of North America, and 
 we should therefore witness, first, the marked 
 strengthening of characters in an area of selec- 
 tion ; secondly, their transmission with diminished 
 effect into other areas. 
 
 If what I have observed be the phenomena 
 presented by the growth, at an early stage, of 
 a mimetic likeness in lorquini, then that growth 
 is 'continuous' and transitional to the last and 
 finest degree. 
 
 It is perhaps appropriate to state in a few lines 
 how we may imagine that the selection of minute 
 characteristics such as the presence or the position 
 of a single spot may be made. We ourselves 
 may observe that one individual butterfly is a 
 better mimic than another. We may then 
 analyse the pattern, as I have attempted to do 
 in this address, and realize that the improvement 
 is due to differences in one or more relatively 
 minute elements. Recognizing the cause of the 
 change, we are perhaps prone erroneously to 
 suppose that enemies recognize it also and that 
 selection has been brought to bear directly and 
 consciously upon it. Such a view is almost cer-
 
 SELECTION OF MIMETIC LIKENESS 201 
 
 tainly wrong. The only probable hypothesis is 
 that sharpsighted enemies, without analysing the 
 markings, recognize differences in degrees of 
 likeness, and that the selective pressure exercised 
 by them is influenced by the recognition. 
 
 A great deal of attention is rightly directed at 
 the present day to the value of experiment, and 
 indeed it is impossible to over-estimate its impor- 
 tance. But while human performance is of the 
 deepest interest for the solution of mysteries 
 innumerable, of more profound significance still, 
 for the comprehension of the method of evolution, 
 is the vast performance of Nature herself. 1 Be- 
 cause of the bright promise it holds for the under- 
 standing of Nature's experiments, I have brought 
 before you the subject of Mimicry in North 
 American butterflies. 
 
 In the introductory words I spoke of the relation- 
 ship of my subject to the teachings of Darwin, and 
 now I am anxious to connect this address by 
 a closer link to the personality of the illustrious 
 naturalist. With the kind consent of Mr. Francis 
 Darwin, I am able to achieve this object by print- 
 ing, for the first time, a letter, recently discovered 
 in the archives of the Hope Department at Oxford, 
 written by Darwin to the Founder in 1837. It is 
 concerned with the insect material collected on 
 
 1 See Carl H. Eigenmann in Fifty Years of Dartvinism, New 
 York (1909), 208.
 
 202 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 the Beagle, and is of peculiar interest because so 
 few of Darwin's letters of this early date have 
 been preserved. The letter clearly exhibits the 
 keen interest which Darwin took in the working 
 out of his collections, and the free and generous 
 use he made of his material. A number of Diptera 
 captured by him in Australia and Tasmania 
 evidently gifts to Mr. Hope exist in the Hope 
 Department, and are still in excellent condition. 
 It is probable that species of other groups collected 
 by him are also present. 
 
 DEAR HOPE 
 
 I called yesterday on you and left a tin box with 
 a few Hobart Town beetles, which I had neglected to put 
 with the others. Is not there not [sic] a Chrysomela among 
 them, very like the English species which feeds on the 
 Broom. I have spoken to Waterhouse about the Australian 
 insects ; you can have them when you like. The collections 
 in the pill boxes come from Sydney, Hobart town, and 
 King George's Sound. Do you want all orders for your 
 work? Some are already I believe in the hands of 
 Mr. Walker, and you know Waterhouse has described some 
 minute Coleoptera in the papers read to the Entomological 
 Soc : To these descriptions of course you will refer. You 
 will be glad to find that many of the minute Coleoptera 
 from Sydney are mounted on cards. Will you send me as 
 soon as you conveniently can, one of my boxes, as I am in 
 want of them to transplant some more insects. Perhaps you 
 had better return the Carabi, as they came from several 
 localities I am afraid of some mistake. We must put out 
 specimens for the Entomolog : Soc : and your Cabinet. 
 May I state in a note on your authority that a third or 
 a half of the insects which you already have of mine from 
 Sydney and Hobart town are undescribed. It is a striking 
 fact, if such is the case, for it shows how imperfectly known
 
 INSECTS COLLECTED ON THE VOYAGE 203 
 
 the insects are, even in the close neighbourhood of the two 
 Australian Capitals. 
 
 Floreat Entomologia 
 
 Yours most truly 
 Wednesday. CHAS. DARWIN. l 
 
 The last words of Darwin's letter are surely 
 a most fitting conclusion to this Anniversary 
 address, and I conclude by quoting his humorous 
 repetition of them probably twenty years later. 
 
 1 " Floreat Entomologia " ! to which toast at Cambridge 
 I have drunk many a glass of wine. So again, " Floreat 
 Entomologia." N.B. I have not now been drinking any 
 glasses full of wine.' 2 
 
 CONCLUSIONS 
 
 It will probably be convenient to sum up 
 rather fully the chief conclusions contained in 
 the foregoing address. 
 
 1. The study of Mimicry possesses special ad- 
 vantages for an understanding of the history and 
 causes of evolution. 
 
 1 The letter is addressed : ' The Revd. F. W. Hope, 56, Upper 
 Seymour Street.' At the head Mr. Hope had written ' D ', and the 
 date '1837'. The red-stamped post-mark gives the date 'Ju. 22, 
 1837'. Darwin's own address (36, Great Marlborough Street) 
 does not appear. At the date of the letter the Entomological 
 Society of London possessed a large collection of insects, long 
 since dispersed. Darwin knew Mr. Hope before the Voyage, and 
 speaks in letters to W. D. Fox (1829-30) of his splendid collection 
 and of his generosity with specimens. He also went for an ento- 
 mological trip in North Wales with Hope (June, 1829), unfortunately 
 broken short for Darwin by ill health. See Life and Letters, i. 
 174, 175, 178, 181. G. R. Waterhouse and Francis Walker, 
 referred to in the letter, were both on the staff of the British 
 Museum. 
 
 * To Sir John Lubbock (Lord Avebury), some date before 1857. 
 Life and Letters, ii. 141.
 
 204 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 2. North America is the most suitable area in 
 the world in which to begin the study of Mimicry. 
 
 3. The great American Danaine butterflies, 
 formerly included in the genera Anosia and 
 Tasitia, are a foreign element in the New World 
 fauna. They bear the closest affinity to a large 
 group of indigenous Old World Danainae, and 
 should be fused with the nearest of these (Limnas 
 and Salatura) into a single genus, Danaida. 
 
 4. The Old World origin of Danaida is also 
 proved by the extent and variety of its mimetic 
 relationships ; while the path of its invasion of 
 the New World and of South by way of North 
 America, may be traced by foot-prints, as it were, 
 of mimetic effect. 
 
 5. That Danaida plexippus is the older invader 
 is equally shown by the depth of the impression 
 it has made and the amount of change it has itself 
 undergone in the New World. 
 
 6. Danaida berenice and its form strigosa show 
 comparatively slight changes in the New World, 
 and, as regards mimetic influence, have but deep- 
 ened the foot-prints left by plexippus. 
 
 7. Limenitis arihemis, the indigenous ancestor 
 of the mimic of plexippus, persists with little or 
 no change ; and it is possible to show how far the 
 very different markings of the mimetic daughter- 
 species, L. archippus, have been carved out of 
 those of the parent. 
 
 8. The recent date of this great superficial 
 transformation is proved by the close resemblances
 
 CHIEF CONCLUSIONS SUMMED UP 205 
 
 between the larval and pupal stages of parent and 
 offspring. L. archippus also probably occasionally 
 interbreeds with the mimetic L. astyanax a still 
 younger descendant of the same parent. 
 
 9. L. archippus probably arose on the southern 
 borders of arthemis, but afterwards ranged north- 
 wards over the area of the parent species. 
 
 10. The southern astyanax, meeting the northern 
 arthemis along a narrow belt, is probably repeating 
 the earlier history of archippus. 
 
 11. The forms or sub-species of archippus 
 floridensis in Florida and hulsti in Arizona have 
 arisen from the earlier mimic of D. plexippus as 
 a result of the predominance in these localities, re- 
 spectively, of Danaida Berenice and its form strigosa. 
 
 12. Details of the older Mimicry persist in 
 floridensis (and perhaps in hulsti), somewhat de- 
 tracting from the newer resemblance. 
 
 13. Certain features in the mimetic likeness 
 newly attained in Florida and Arizona are prob- 
 ably due to the recall or the re-emphasis of 
 elements in the pattern of arthemis which had 
 been greatly reduced in archippus. 
 
 14. The fact that the invading Danaidas have only 
 influenced, among the whole indigenous butterfly 
 fauna, the dominant conspicuous Nymphaline 
 genus Limenitis, supports a Miillerian as opposed 
 to a Batesian interpretation of the phenomena. 
 
 15. The fact that the ancestral pattern of a 
 species indigenous in the temperate zone of the 
 New World should be wholly transformed by
 
 206 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 a recent invader from the Old World tropics 
 the invader meanwhile retaining its original 
 characteristic pattern, is demonstrative of the 
 inadequacy of the theory which refers these 
 likenesses to the influence of soil, climate, &c. 
 
 16. The poison-eating * Aristolochia swallow- 
 tail' Pharmacophagus (Papilio) philenor belongs 
 structurally to the American division of this 
 tropical section, and is probably an intruder into 
 North America from the south. 
 
 17. Just as tropical species of Pharmacophagus 
 are mimicked, especially by other sections of 
 swallow-tails, so the invading philenor is mimicked 
 by three species of the section * Papilio '. 
 
 18. Of these three Papilio troilus, mimetic in 
 both sexes, is probably the oldest; P. asterius, 
 mimetic in female and on under surface of male, 
 the next ; and P. glaucus, mimetic in one out of 
 the two forms of female (the mimetic form be- 
 coming more numerous in the south of the range), 
 the youngest. 
 
 19. The ancestors of these mimics persist with 
 little or no change in the two last-named species, 
 the non-mimetic sex or form ; in the first-named, 
 the allied palamedes. By their aid we can recon- 
 struct the history of the transformation. 
 
 20. In asterius and glaucus partially melanic 
 forms of the female probably supplied a tinted 
 background on which the new and mimetic picture 
 was gradually built up by the modification of 
 elements in the original non-mimetic pattern.
 
 CHIEF CONCLUSIONS SUMMED UP 207 
 
 21. The close resemblance between the three 
 mimicking species cannot be entirely explained 
 by their convergence upon a single model, but 
 seems to imply the existence of Secondary Mimi- 
 cry between them. 
 
 22. Limenitis astyanax has arisen as a very 
 recent modification of arthemis in Mimicry of 
 philenor, and especially in Secondary Mimicry 
 of the three Papilio mimics. 
 
 23. The female of Argynnis (Semnopsyclie) diana 
 has arisen as a tertiary mimic, on the upper sur- 
 face, of L. astyanaoc. Its under surface, incon- 
 spicuous when contrasted with that of the male, 
 suggests that the species is palatable as compared 
 with the rest of this combination and that its 
 Mimicry is Batesian. 
 
 24. The dark ground and pale markings of the 
 female diana are probably analogous with those 
 of other dark female forms in Argynnidae, while 
 the blue colouring is an additional feature of 
 purely mimetic significance. 
 
 25. The arrangement of the North American 
 butterflies which converge on Pharm. philenor, 
 in concentric rings each mimetic of that lying 
 within it, strongly supports a Mlillerian interpre- 
 tation of all except the species (diana) in the outer- 
 most layer. 
 
 26. Limenitis (Adelpha) californica of the Pacific 
 coast is probably a Limenitis mimic of the South 
 American genus Adelpha, to which its southern 
 sub-species bredowi bears a stronger resemblance.
 
 208 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 27. Limenitis (Najas) lorquini, in some respects 
 the most ancestral of the North American species 
 of the group, is in other respects a mimic of 
 L. californica. 
 
 28. Certain features in which lorquini super- 
 ficially resembles californica are on the average 
 more strongly developed in the area where the 
 two species overlap, while they diminish when 
 lorquini passes northward of this area. 
 
 29. The differences between bredowi, ranging 
 entirely south of lorquini, and californica are such 
 as to promote a superficial resemblance between 
 the latter and lorquini, supporting the hypothesis 
 that the resemblances between them have been 
 caused by reciprocal approach (Diaposematism). 
 
 30. The differences which distinguish bredowi 
 from californica are such as to promote a resem- 
 blance to the tropical American genus Adelpha. 
 They are retained by bredowi in Arizona, north 
 of the range of any true Adelpha. 1 
 
 31. The detailed study of these resemblances 
 on the Pacific coast of North America leads to 
 the conclusion that the Mimicry is in an incipient 
 stage and that it has been reached and is probably 
 still advancing by minute increments, that the 
 evolution is ' continuous ' to the last degree. 
 
 32. In addition to their bearing upon the 
 problems of Mimicry, the examples considered 
 
 1 In the southernmost part of the range of bredouri, in Guatemala, 
 the resemblance to Adelpha was very slightly augmented in the 
 only two specimens from this locality I have had the opportunity 
 of studying (Trans. Ent. Soc. Lond., 1908, 485).
 
 AN OPPOETUNITY FOE NATURALISTS 209 
 
 in the address afford some of the very best 
 material for testing the operation of Mendel's 
 Law under natural conditions. 
 
 I wish again to caution my readers that the 
 above conclusions have been drawn from the 
 careful study of a limited number of examples. 
 Although insufficient in quantity, the English 
 material is as a whole excellent in quality. Thus, 
 many of the Pacific coast specimens were cap- 
 tured by Lord Walsingham, Dr. F. D. Godman, 
 and Mr. H. J. Elwes, and the geographical data 
 are of course as full and precise as we should 
 expect or wish. 
 
 I trust that my brother naturalists in America 
 will make a determined attack on the fascinating 
 problems offered by the phenomena of Mimicry 
 in the North American butterfly fauna. In this 
 favoured part of the world the problems have 
 been seen to be sharp and clear as compared 
 with the almost infinite complexity of the tropics. 
 If my assistance or advice be of any value it 
 is always at the service of those who desire to 
 undertake such investigations. 
 
 It has been abundantly shown in the course 
 of the address that immense numbers of speci- 
 mens are required from the most varied localities ; 
 and it is likely that difficulties may be presented 
 by the necessary manipulation, labelling, con- 
 venient arrangement, and permanent preservation 
 for the study of future as well as living natural- 
 p
 
 210 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 ists, of so large a mass of material. I shall, 
 however, be most pleased to undertake this part 
 of the investigation as regards all specimens 
 accompanied by adequate data of space and time. 
 Such material, preserved in the Hope Depart- 
 ment, may be readily compared with the ever- 
 increasing mass of examples illustrating the same 
 principles in other parts of the world. If the 
 indications observed in a small series are still 
 found to hold in a large one, the growth of such 
 a feature as the orange-brown apex of the fore 
 whig in Limenitis lorquini would be demonstrated 
 by a glance at its average condition in specimens 
 from the different localities as we pass from 
 north to south. Furthermore, we might reason- 
 ably hope that a similar series collected after an 
 interval not greatly prolonged would exhibit 
 differences in average composition the actual 
 measurable evidence of the evolution of a char- 
 acter in a species in the natural state. Even 
 though such evidence be left for our successors 
 to witness, it still remains our duty to provide 
 them with the standard by which alone they 
 will be able to detect and measure it. But I am 
 hopeful of more than this, and think it by no 
 means unlikely that a part of the reward may be 
 reaped by a single generation of workers. 
 
 An excellent example of work done in a single 
 locality is afforded by the data obtained by 
 Mr. J. H. Cook, and summarized in the following 
 note.
 
 J. H. COOK'S DISCOVERY AT ALBANY 211 
 
 NOTE. The capture of males of L. arcliippus in tvhich the black 
 stripe teas wanting from tlie upper surface of the hind wing, and 
 of transitional forms of both sexes, at Albany, N.T., by 
 John H. Cook. 
 
 Mr. Cook first met with the stripeless form in June, 1898, 
 near Hudson, N.Y. A second specimen was captured near 
 his home in Albany in 1901, and a third in the same field 
 in the following year. This latter was a beautiful specimen 
 apparently only just emerged from the pupa. Mr. Cook's 
 attention was now thoroughly aroused and he collected 
 assiduously at Albany during three seasons, always working 
 on the best ground to the west of the city, and taking over 
 90 specimens with the stripe wholly or nearly suppressed. 
 The following conclusions were reached : (1) All the stripe- 
 less arcliippus captured were males ; (2) The females shared 
 the tendency but never reached the extreme found in the 
 other sex ; (3) Most of the individuals taken showed some 
 weakening of the stripe, varying from a slight break (most 
 commonly between veins III and V 2 and between V 3 and 
 VII 2 , of the system of Comstock and Needham) to complete 
 suppression on the upper surface. (4) At Albany individuals 
 with a broken stripe outnumbered those with an entire 
 stripe in the proportion of about 18 to 1, while stripeless 
 specimens were taken in the average proportion of 1 to 14. 
 Mr. Cook also collected data from other localities and 
 endeavoured to interest con-respondents in the problem. 
 Including the Albany material he secured records of about 
 1600 specimens and was able to reach the conclusion that 
 in New England and the Middle States broken-striped in- 
 dividuals are not uncommon though generally outnumbered 
 by those with a continuous stripe. He did not meet with 
 any record of a perfectly stripeless form except for his own 
 observations and the two specimens to which the name 
 pseudodorippus has been given. Strecker's type of this form 
 exists in Dr. W. J. Holland's collection (Butterfly Book, 
 New York (1899), 185). These two pseudodorippus were also 
 taken in the Eastern States (the Catskill Mountains, and in 
 Massachusetts), but Mr. Cook, who has seen one and received
 
 212 MIMICRY IN N. AMERICAN BUTTERFLIES 
 
 from Dr. Holland an account of the other, believes that the 
 disappearance of the stripe is here part of a general blurring 
 of the colour-scheme in which some elements are obliterated 
 and there is a tendency towards the invasion of one colour-area 
 by another. The extreme varieties captured by Mr. Cook 
 himself, did not, on the other hand, differ at all from the 
 normal archippus except in the absence of the black stripe 
 from the upper surface of the hind wings. To this stripe- 
 less variety Mr. Cook and Mr. Watson have given the name 
 lanthanis. Mr. Cook's accurate data and most of his speci- 
 mens were unfortunately destroyed when the college build- 
 ings at Albany were burnt down on Jan. 6, 1906. It is 
 much to be hoped that he may be able to continue his most 
 interesting observations in this favourable locality, and that 
 naturalists may be stimulated, by these records, now by 
 Mr. Cook's kindness made public for the first time, to work 
 in other North American localities.
 
 VII 
 
 LETTERS FROM CHARLES DARWIN 
 TO ROLAND TRIMEN (1863-1871) 
 
 MY friend, Mr. Roland Trimen, Hon. M.A. 
 (Oxon.), F.R.S., was at the Cape when Mr. Francis 
 Darwin's great work was in course of preparation. 
 On this account his fine series of letters has 
 remained unpublished up to the present date. 
 Now, with his kind consent and that of Mr. Francis 
 Darwin, it is a great pleasure to be able to include 
 in this memorial volume a single complete set 
 of letters, moderate in number, but in every way 
 most characteristic of the writer. 
 
 Mr. Trimen has very kindly written the fol- 
 lowing deeply interesting account of his first 
 meeting with Darwin exactly half a century ago. 
 As we read the story, the intense antagonisms at 
 first aroused by the Origin seem again to rise into 
 life and activity : 
 
 * It was in the Insect Room of the Zoological Depart- 
 ment of the British Museum that I had my first glimpse 
 of the illustrious Darwin. Towards the close of 1859, 
 after my return from the Cape, I spent much time in the
 
 214 DARWIN'S LETTERS TO R. TRIMEN 
 
 Insect Room identifying and comparing the insects col- 
 lected with those in the National Collection. One day 
 I was at work in the next compartment to that in which 
 Adam White sat, and heard someone come in and 
 a cheery, mellow voice say, " Good-morning, Mr. White ; 
 I'm afraid you won't speak to me any more ! " While 
 I was conjecturing who the visitor could be, I was elec- 
 trified by hearing White reply, in the most solemn and 
 earnest way, " Ah, Sir ! if ye had only stopped with the 
 Voyage of the Beagle ! " There was a real lament in his 
 voice, pathetic to any one who knew how to this kindly 
 Scot, in his rigid orthodoxy and limited scientific view, 
 the epoch-making Origin, then just published, was more 
 than a stumbling-blockit was a grievous and painful 
 lapse into error of the most pernicious kind. Mr. Darwin 
 came almost directly into the compartment where I was 
 working, and White was most warmly thanked by him 
 for pointing out the insects he wished to see. Though 
 I was longing for White to introduce me, I knew 
 perfectly well that he would not do so ; and after Mr. 
 Darwin's departure White gave me many warnings 
 against being lured into acceptance of the dangerous 
 doctrines so seductively set forth by this most eminent 
 but mistaken naturalist. 
 
 * A little while afterwards, on the same day, I again 
 saw Darwin in the Bird Galleries, where it was, I think, 
 G. R. Gray who was showing him some mounted birds. 
 A clerical friend with me, also a naturalist, curiously 
 enough echoed White's warning by indicating Darwin 
 as " the most dangerous man in England ". 
 
 1 Years afterwards, when I had reached the honour 
 of correspondence and personal acquaintance with 
 Mr. Darwin, I gave him some amusement by my 
 account of the impressive manner in which, on the 
 first day of my seeing him, I had been warned by two
 
 THE PREJUDICES AROUSED IN 1859 215 
 
 naturalists, much my seniors, to give him a wide 
 berth.' * 
 
 In working out the various subjects referred 
 to in the letters, I have received the kindest 
 help from Mr. Trimen and Mr. Francis Darwin. 
 Although Mr. Trimen did not keep copies of 
 his own letters, he was able to remember the 
 details of nearly all the questions touched upon 
 in the correspondence, while other data were 
 recovered from Darwin's works. Without Mr. 
 Francis Darwin's help I should have been un- 
 able to decipher a few obscurely written words, 
 or to have obtained other information bearing 
 upon the conditions under which the letters 
 were written. 
 
 The letters are, as I have already implied, 
 a typical series. They show all the character- 
 istics of Darwin in his relations with younger 
 men who helped him in his work. * They are,' 
 as Mr. Trimen truly says, 'of value as an ad- 
 ditional illustration of one of the most charming 
 and attractive sides of Darwin's character the 
 gracious and glad welcome and recognition he 
 never failed to extend to every one who even 
 in the slightest degree endeavoured to render 
 some aid in his researches.' 
 
 In addition to the full recognition he accorded 
 
 in his published works, we find, in these letters 
 
 as in others, that Darwin not only urged his 
 
 correspondent to publish on his own account, 
 
 ] See p. 219.
 
 216 DARWIN'S LETTERS TO R. TRIMEN 
 
 but himself arranged the details of publication 
 and assisted in drawing up one of the memoirs. 
 It is easy to imagine the delight and encourage- 
 ment with which his generous words of praise 
 for every effort would be received, and how in- 
 fallibly they would become the inspiration to 
 further effort. And with all this stimulus and 
 encouragement there is ever present the warmest 
 sympathy with difficulties of every kind, and 
 the keenest anxiety not to overburden another 
 with trouble or expense. We recognize an un- 
 bounded love of nature and of discovery, and 
 the keenest appreciation for the same enthusiasm 
 in another. We feel, again and again, as we 
 read these letters, the presence of the bright, 
 courageous spirit that could pierce the dark 
 shadow of lifelong pain and discomfort, and 
 preserve undimmed its humour and its breadth 
 of view. And the brooding shadow is never 
 accorded the dignity of recognition on its own 
 account, being only revealed because of the veto 
 it had the power to impose work prevented 
 or long drawn out, interviews with friends cut 
 short or postponed. 
 
 For this reason brief notes of invitation, which 
 might otherwise be regarded as trivial, all bear 
 their part in creating the general impression, 
 and the whole correspondence remains untouched 
 and unabridged. 
 
 Of the nineteen letters printed in this section 
 of the book, one (No. 18) is from Mrs. Darwin.
 
 SUBJECTS OF EAELIEE LETTEES : 1863-4 217 
 
 Of the remainder, fourteen are holograph letters 
 by Charles Darwin, one (No. 7) is signed and 
 corrected, while three (Nos. 6, 11, 17) are only 
 signed by him. 
 
 The letters are arranged in the order of date. 
 Darwin, as was his custom, omitted to write the 
 year, but fortunately this was nearly always 
 added by Mr. Trimen himself, together with 
 the date at which the letter was received. 
 
 Publications and the names of species, &c., 
 although not underlined in the originals, are, 
 for the sake of convenience, printed in italics. 
 
 The first series of letters, seven in number, 
 deal with botanical subjects, especially Orchids, 
 and the inquiries which grew out of the investi- 
 gations upon them (such as the Peach-perforating 
 moths). These are referred to in all seven letters; 
 Oxalis as material for the study of heterostyled 
 flowers in Nos. 3-7 ; insect visitors to Asdepiadae, 
 Apocyneae, and Physianthus in No. 4 ; the fertili- 
 zation by birds of Strelitzia in Nos. 6, 7. 
 
 It will be observed that Darwin in the very 
 first letter began to urge his correspondent to 
 send home the records of observations for publi- 
 cation. His advice and help were very soon 
 accepted, and, in the Fertilisation of Orchids, 1 
 Darwin acknowledged the assistance he had 
 received, and referred to Trimen's papers, in 
 the publications of the Linnean Society, on Bonatea 
 speciosa and Disa grandiflora, in each case specify- 
 
 1 Second edit., sixth impression (1899), 40, 76-8.
 
 218 DARWIN'S LETTERS TO R. TRIMEN 
 
 ing briefly the peculiarities of structure which 
 the author had noted as governing access to the 
 nectary, so as almost to compel the removal of 
 the pollinia by insect visitors of the right kind. 
 
 1. 
 
 Jan. 31st [1863] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR SIR 
 
 I thank you most sincerely for your pleasant letter 
 and M.S. on Orchids. Your sketches seem to me very 
 good, and wonderful under circumstances of their execu- 
 tion. I cannot say how much interested I have been 
 in studying your descriptions. I think I understand 
 all; but these Orchids (except Eulophia) are so sur- 
 prisingly different from anything that I have seen that 
 I could hardly make them out for some time and even 
 fancied in some cases that you had miscalled upper 
 sepal and Labellum. But at last I see my way. I am 
 no more a Botanist than you say you are, and I know 
 nothing of any orchids except those seen by me. 
 Therefore I was astonished at the upper sepal being pro- 
 duced into a nectary ; even more astonished at stigma 
 standing high above the pollinia &c &c. How curious 
 is pollinium of Disperis ! What beautiful and new 
 contrivances you show, and how well you have studied 
 them ! Upon the whole I think No. V. & VI. unnamed 
 (I have sent your drawings to Prof. Harvey to name 
 for me) have interested me most : everything seems to 
 occur in a reversed direction compared with our true 
 Orchis. You do not mention any movement of the 
 pollinia, when attached to an object ; and as you are so 
 acute an observer, I infer that there are no such move-
 
 SOUTH AFRICAN ORCHIDS: 1863 219 
 
 ments ; and indeed in those you describe such move- 
 ments would be superfluous. If you have time to wander 
 about do watch some kinds and see insects do the work. 1 
 Those with long nectaries would be probably hopeless 
 to watch as probably fertilized by Moths. But since 
 my publication I have ascertained that with Orchis, 
 Diptera are chief workmen. They certainly do puncture 
 the walls of nectary, and so get juice. Disperis would 
 be grand to watch, and discover what attracts insects. 
 You draw so well, and have so seized on the subject, 
 that you ought really to take up 2 or 3 of the most 
 distinct genera, and watch them, experiment on them 
 by mutilation of parts, and describe them and send 
 over an excellent paper to Linnean Soc y or some other 
 Soc y . I have so much other work, that I hardly know 
 whether I shall ever publish again, not but what I have 
 already collected some curious new matter; for the 
 subject delights me, and I cannot resist observing. 
 
 I am very glad to hear that you do not now think me 
 so dangerous a person ! 2 You will gradually, I can see, 
 become as depraved, as I am. I believe, or am inclined 
 to believe, in one or very few primordial forms, from 
 community of structure and early embryonic resem- 
 blances in each great class. 
 
 With most cordial thanks I remain my dear Sir 
 Yours sincerely 
 
 CH. DARWIN 
 
 P.S. Would it be asking too great a favour to beg you 
 
 1 Mr. Trimen writes as follows of his attempts to carry out 
 Darwin's advice : ' I had no success with this, though I watched 
 a variety of orchids as opportunity offered. A good many visitors 
 of various orders came, but they were evidently not regular 
 customers (" unbidden guests," as Kerner says), and I never saw 
 a pollinium actually removed by any one of them.' 
 
 Trimen found, however, that one or both pollinia had been 
 removed from 12 out of 78 flowers of Disa grandiflora. Fertilisation 
 of Orchids (1877), 78. 2 See pp. 214-15.
 
 220 DARWIN'S LETTERS TO R. TRIMEN 
 
 to put 2 or 3 flowers of Satyrium or your No. V. or VI. 
 in bottle with spirits and water, and send home by any 
 opportunity. I would then compare your drawings and 
 add some remarks on your authority, if I ever publish 
 again. But I hope, what will be much better, to see 
 a paper by yourself. 
 
 If you come across Bonatea pray study it it seems 
 most extraordinary in description. 
 
 Feb. 16th[, 1863.] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 DEAR SIR 
 
 I have thought you would like to see copy enclosed 
 of letter by Prof. Harvey giving names of your two 
 orchids, PI. V. and VI, which were unnamed. 1 Now that 
 I hear that in Satyrium the nectaries belong to the true 
 Labellum ; 2 the relation of the parts is to me very 
 puzzling: discs, pollen-masses and stigmatic surface 
 seem all on the wrong side. If you pursue the subject, 
 I hope you will observe whether there is any relation 
 
 1 The copy of W. H. Harvey's letter (dated Feb. 3, 1863, Trin. Coll., 
 Dublin) states concerning the two unnamed forms : ' Both are of 
 the large genus Disa, and I feel confidence in calling them 
 (PI. V) D. barbata and (PI. VI) D. cornuta, both common near 
 Capetown.' 
 
 * The copy of Harvey's letter contains the following account : 
 'Nectariferous back sepals are quite frequent among Cape Orchids 
 and correspondently depauperated labella. The labellum is often 
 a mere little tongue [sketch] sometimes a mere thread [sketch] 
 and sometimes as in Brownleia, nearly disappears altogether, and 
 is adnate to the column.' 
 
 ' In Satyrium the two spurred affair is a true labellum the sepals 
 and petals small and crowded together at the front of flower the 
 opposite to Disa.'
 
 SOUTH AFEICAN OECHIDS : 1863 221 
 
 (as in English Orchids) between the rapidity of the 
 setting of the viscid matter and nectar being stored 
 ready for suction or confined in cellular tissue. 
 
 I was at Kew 2 or 3 days ago and was telling 
 Dr. Hooker and Mr H. Gower of your work : they 
 expressed a strong wish to try whether they could not 
 cultivate some of your wonderful forms ; and tempted 
 me by saying that if they could flower them, I sh d 
 have plants to examine. I said I would mention the 
 subject to you ; but that of course I doubted whether 
 you had time and inclination to get them dug up. 
 They said the roots might be packed in almost dry 
 peaty soil or charcoal in moss, and sent to " Royal 
 Gardens[.] Kew, London," marking what they were, i. e. 
 terrestrial orchids from the Cape. They ought to be 
 dug up, when completely dormant after seeding over. 
 It certainly would be a treat to see a blooming 
 Satyrium, or Disperis and the odd unnamed form ! 
 They said the safest way of all, but more troublesome, 
 to send them, would be to plant them in pots in a box, 
 with a [sic] little glazed windows on two sides under 
 charge of some passenger. The heat starting them 
 would be the great risk. But it is not at all likely 
 you could spare time from your own pursuits. 1 
 
 Pray believe me, my dear Sir 
 
 Yours sincerely and obliged 
 
 CH. DARWIN 
 
 1 Mr. Trimen informs me that a good many orchids were got 
 together and dispatched, but (probably owing to unsuitable treat- 
 ment) did not appear to prosper ; and by the time a few of them 
 contrived to flower, Darwin was too much occupied with other 
 pressing work to be able to examine them.
 
 222 DARWIN'S LETTERS TO R. TRIMEN 
 
 3. 
 May 1 23rd [1863.] DOWN. 
 
 BKOMLEY. 
 
 KENT. S.E. 
 
 MY DEAR SIR 
 
 I have delayed thanking you for your note and 
 photograph, as I have no photograph by me of myself. 
 I have never had a proper " carte " taken ; but I en- 
 close a photograph made of me by my son, which I 
 daresay will do as well. 
 
 Your accounts of the Disa and Herschelia are excellent, 
 and your drawings first-rate. I felt so sorry that such 
 excellent work sh'd remain locked up for an indefinite 
 period in my portfolio, that you have made me break 
 a solemn vow, and I have drawn up from your 
 notes (and selected 4 figures for woodcuts) an account 
 for Linnean Soc. I have enlarged a little and explained 
 and introduced a few remarks. I hope the Soc y will 
 publish the paper, and if so I will send you spare copies. 
 The title is " On the Fertilisation of Disa grandiflora 
 by Roland Trimen Esq r of the Colon. Off". C. Town : 
 drawn up from notes and drawings sent to C. Darwin 
 Esq r ." 2 I hope that you will approve of this, and not 
 object to anything in the little paper. I am very sorry 
 to hear so poor an account of your health and that you 
 have so little time to spare for the exercise of your 
 
 1 The month is indistinctly written and looks more like ' July ' 
 than 'May 1 . Mr. Trimen had, however, noted that he received 
 the letter at the Cape on July 20, so that this latter month can- 
 not have been intended. Confirmation of the reading as ' May ' is 
 afforded by the presence of an envelope (two only are preserved) 
 with the post-mark 'BROMLEY, KENT. MY 24. 63'. It also 
 bears post-marks of ' LONDON. MY 25 ' and ' DEVONPORT. MY 
 26 '. It is addressed, ' Roland Trimen, Esq., Colonial Office, Cape 
 Town, Cape of Good Hope.' 
 
 2 The paper was published in Journ. Proc. Linn. Soc. Bot., vii 
 (1863), 144.
 
 CAPE OKCHIDS AND OXALTS : 1863 223 
 
 admirable powers of observation. I did not know all 
 this ; otherwise I sh d not have thought of asking for 
 plants. Think not a moment more on subject. Indeed 
 I ought to work on other subjects. Yet I am going to 
 ask a favour, if you know any one who dabbles in 
 Botany, viz., for seed of any Cape Oxalis : several species 
 present two forms, one with long pistil and short 
 stamens; the other form with short pistil and longer 
 stamens. It is of high interest to me to get seed of any 
 such species. To return to Orchids, I now believe that 
 Hymenoptera and Diptera are generally the chief 
 workers more than Lepidoptera. With respect to the 
 limits of Rostellum ; it can in most cases be told only 
 conjee turally : in Disa the 2 discs (and no part of caudicle 
 of pollinia) and the part which connects the 2 discs 
 with the medial upward central fold or ridge, and whole 
 face of column down to the two confluent stigmas, may 
 all be considered as the rostellum or modified third 
 stigma. With sincere thanks and every good wish, 
 Believe me, my dear Sir 
 
 Yours sincerely 
 
 C. DARWIN 
 
 August 27th[, 1863] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR SIR 
 
 I am very much obliged for your very pleasant 
 letter. You have hit upon the right case in Oxalis, 
 and seeds will really be a treasure to me. I have posted 
 a paper for "you on the dimorphism of Linum which 
 if you will read, you will see why I am anxious for 
 Oxalis I have a more curious case unpublished ; but the 
 whole class of facts strike me as very surprising. You
 
 224 DARWIN'S LETTERS TO R. TRIMEN 
 
 may rely on my statements, for they have been verifyed 
 [sic]. Linum perenne agrees with your Oxalis. I am 
 also very glad indeed to hear about the Peaches, the 
 more so as it is an exotic in S. Africa. I am going 
 in a weeks time to Malvern for a month to try and get 
 a little strength, and when there I will probably draw up 
 a notice for Gardener's Chronicle on your peach case. 1 
 I daily expect proofs of your paper on Disa ; a rough 
 woodcut is made. You must not waste time in sending 
 me many specimens of Orchids in spirits, for I declare 
 I do not know whether I shall ever have time to work 
 up mass of new matter already collected on Orchids. 
 It is capital sport to observe and a horrid bore to pub- 
 lish. It pleases me to read your admiration on my 
 beloved Orchids. I quite agree they are intellectual 
 beings! By the bye, I believe I have blundered in 
 Cypripedium 2 ; Asa Gray suggested that small insects 
 
 1 Darwin had suggested in relation to fertilization by moths of 
 Orchids which seemed to secrete no nectar, that the insects 
 might possibly obtain palatable juices by perforating the softer 
 tissues of some parts of the flower. Trimen informed him, as 
 bearing on this suggestion, of two good-sized Noctuid moths 
 (Egybolis vaillantina, Stoll, and Achaea chamaeleon, Guen.), 
 abundant in Natal, where both were styled 'Peach Moth ' 
 though absolutely different in appearance because they sucked 
 peaches (both ripe on the trees and when fallen). Trimen caught 
 the latter in the act, and found that they had no difficulty in 
 piercing the peach-skin with their sharp and strong haustellum. 
 The observation is quoted by Darwin in Fertilisation of Orchids 
 (1877), 40. F. Darwin later published an account of the similar 
 behaviour of a much larger moth of the same tribe which was 
 accounted a nuisa.nce in Northern Australia owing to its piercing 
 and sucking oranges ! He showed how the proboscis in this moth 
 was armed near the tip with cutting and lacerating processes. 
 On the Structure of the Proboscis of Ophideres futlonica, an orange- 
 sucking Moth (Quarterly Journ. of Microscopical Science, N.S., xv. 
 384). The number (LX) containing the paper appeared in Oct., 
 1875, and it is a curious coincidence that the same organ of the 
 same species was briefly described and well figured almost simul- 
 taneously by Ktinckel in the Comptes Eendus for Aug. 30, 1875. 
 
 a When Darwin wrote the first edition of Fertilisation of Orchids 
 (1862), he misunderstood the mechanism of Cypripedium. In the
 
 INSECTS AND FLOWERS: 1863 225 
 
 enter by the toe and crawl out by the lateral windows. 
 I put in a small bee and it did so and came out with 
 its back smeared with pollen : I caught him and put him 
 in again, and again he crawled out by the window: 
 I cut open the flower and found the stigma smeared 
 with pollen ! 
 
 Read Bates Travels they will, I am sure, interest you. 
 With respect to Physianthus, I do not know whether 
 fact is known ; but I think it would be well worth 
 investigating. 1 It is certain that the Asclepiadw 
 require insect aid for fertilisation. The pollen-masses 
 are wonderfully like those of Orchids. You ought 
 to read R. Browns admirable paper on Asclepias in 
 Transact. Linnean Soc. about 15 or 20 years ago. In the 
 Apocynece, (which are allied to the Asclepiadw) there 
 is a genus, which catches Diptera by the hundred : 
 I have a plant but cannot make it flourish, as I have 
 always wished to investigate the case. It is said that 
 the Diptera are caught by the wedge-shaped spaces 
 between filaments of anthers. But I suspect the plant 
 somehow profits or requires visits of insects. You ought 
 to try whether Physianthiis will seed if insects are 
 excluded by a net. I have seen Hymenoptera from 
 N. America with numbers of pollen-masses of some 
 Asclepias sticking to their tarsi ; 2 and the pollen-masses 
 
 second edition (1877) he gives, on p. 230, Asa Gray's view, and his 
 own observations confirming it. Mr. Francis Darwin has kindly 
 given me these references. 
 
 1 Darwin was here referring to a note of Trimen's about the 
 curious manner in which Lepidoptera and many other insects are 
 caught by a mechanical (not viscid) contrivance in the flowers of 
 Fhysianthus albens, a native of temperate South America. It 
 seemed a case in which the plant overdid matters, the numerous 
 visitors being nipped by hard sharp ridges closing on the proboscis 
 when introduced into the nectaries, and the captives, in a great 
 many cases, failed to liberate themselves and carry off the 
 pollinia, eventually dying where they hung. 
 
 2 I have myself often observed the difficulty with which insects, 
 especially wasps and Fossors, dragged themselves free from the
 
 226 DARWIN'S LETTERS TO R. TRIMEN 
 
 are thus dragged over the stigmas. R. Brown's paper 
 has beautiful illustrations. This is a disjointed, dull 
 letter, but I have been working all day with very little 
 strength. 
 
 With every good wish and sincere thanks 
 Pray believe me 
 
 My dear Sir 
 
 Yours sincerely 
 
 CH DARWIN 
 
 5. 
 
 Nov. 25 [1863] 
 
 DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR SIR 
 
 I have been laid on the shelf for nearly three 
 months, and am ordered to do nothing for 6 months by 
 my doctors. To write this is against rules. Many 
 thanks for specimens of orchids and for your kind letter. 
 
 1 dare not look at Oxalis flowers. I regret much that 
 you cannot get seed, especially of your trimorphic 
 flowers. 1 Most species of Oxalis shed their seed by 
 a spurt and the capsules are sensitive to a touch. 
 Could you employ anyone to dig up the bulbs of the 
 
 2 or 3 forms and allow me to pay ; i. e. if they are bulb- 
 bearers. 
 
 The last job I began and broke down was a letter 
 
 hold of Asclepiad flowers in North America, and how frequently 
 their tarsi were bristling with pollen-masses. On one occasion 
 I found a dead humble-bee held fast by the flower. 
 
 1 In answer to Darwin's inquiries Trimen informed him that he 
 had found trimorphic heterostyled species of Oxalis, and sent draw- 
 ings and dried specimens. Darwin referred to this information 
 and material in The Different Forms of Flowers on Plants of the 
 same Species (1877), 169. Trimen's name is accidentally omitted 
 from the index of this work.
 
 SOUTH AFRICAN OXALIS : 1863-4 227 
 
 to G. Chronicle on your Peach case. 1 I must write 
 no more.-^I live in hopes some day to be able to work 
 a very little more, but it will be long before I can. 
 Sincere thanks for your very kind letter. 
 
 Yours very sincerely 
 
 C. DARWIN 
 
 I forwarded letter to Bates. Pray use me as often 
 as you like. 
 
 6. 
 Written by Mrs. Darwin, signed by Clmrles Darwin. 
 
 DOWN. 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR MR TRIM EN May 13. 1864 
 
 I received your letter of Mar 14, some time ago 
 and was fearful that the Oxalis would never arrive, but 
 yesterday to my joy they came safe and alive and are 
 now planted. 2 Please give my sincere thanks to 
 Mr Mac Gibbon and accept them yourself. The plants 
 will be invaluable. My only fear is that each kind has 
 been propagated by offsets from a single stock and if so 
 they will all belong to the same form. 
 
 I am sorry for my mistake about the Ditta. I have 
 sent an erratum to Linn. Jvurn* 
 
 Thanks for the additional facts about Disa, but I am 
 sure I do not know what I shall ever do with all 
 my wealth of new facts. 
 
 1 See p. 224 n. 1. 
 
 2 See the preceding letter (5) on p. 226. 
 
 3 This was an error in Darwin's description of the position 
 of the viscid discs of the pollinia in relation to the passages leading 
 to the nectary ; but it was partly due to the point of view from 
 which Mr. Trim en's fig. A was taken. The position was of import- 
 ance in relation to the only passages of access to- the nectary 
 where a proboscis could be pushed.
 
 228 DARWIN'S LETTERS TO R. TRIMEN 
 
 I am slowly recovering from my 10 months illness, 
 but I do not know when I shall regain my old modicum 
 of strength. I was pleased to see a nice little review 
 evidently by Mr Bates on your Cape butterflies in that 
 admirable journal The Nat. Hist. Review. 1 
 
 By the way do you see the " Reader ". No English 
 newspaper ever before gave half as good resumes of all 
 branches of science : the literature is likewise well treated. 
 I do not know who the Editor is so that my puffing 
 is honest. 
 
 Does Strditzia regince grow in any gardens at the 
 Cape ? I strongly suspect it must be fertilized by some 
 honey seeking bird ; the structure is very curious and 
 this w d be worth investigating. 2 With cordial thanks 
 believe me 
 
 Yours sincerely 
 
 CH. DARWIN 
 
 7. 
 
 Written by Mrs. Darwin, signed by Charles Darwin, 
 who also inserted the words and letters printed in small 
 
 DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 
 MY DEAR SIR Nw 25, 1864. 
 
 Your paper arrived quite safe. I have read it with 
 much interest, for I have long thought the Bonatea one 
 of the most curious Orchids in the world. Asa Gray 
 
 1 Bates's very appreciative review was of Part I of Trimen's 
 Rhopalocera Africae Australia, Cape Town, 1862. It appeared 
 in The Natural Histoi-y Review for April, 1864. 
 
 2 Trimen supplied some evidence that Darwin's suspicions were 
 well founded; for two species of Sun- bird (Cinnyris) frequented 
 the flowers of Strditzia. See Cross and Self Fertilisation in the 
 Vegetable Kingdom (1876), 371 n.
 
 CAPE OECHIDS. OXALLS, ETC.: 1864 229 
 
 has described in an American Habenaria a nearly similar 
 contrivance with respect to the nectary as yours. I have 
 sent your paper to Linn. Soc. and I hope it may be 
 printed, but that of course I cannot say and IT may 
 be influenced by cost of engraving. 1 
 
 With respect to the Satyrium I sh d think that the 
 pollen masses which you sent had been scraped off 
 the head of some insect BY THE INSECT ITSELF ; I do not 
 refer to the additional pollen-masses which you saw 
 growing in their cases. 
 
 Most of the Oxcdis which you so kindly sent me 
 flowerED, but all with 2 exceptions presented one form 
 alone. From what I know about Primula, I sh d be 
 astonished at the same bulb ever producing 2 forms. 
 In the 2 exceptional cases, one bulb in each lot produced 
 a distinct form ; but I have very little doubt there ought 
 to be 3 forms. I got some seed from one of the unions 
 and have some feeble hopes that they may germinate. 
 
 If I have strength (for I keep weak) I sh d like to 
 make out Oxalis, so if you have any opportunity I should 
 still be very glad of seed. 
 
 Many thanks about Strelitzia. 2 Would it be possible 
 to get a plant of the kind that seeds, protected from the 
 sugar-birds, with another plant unprotected near by "? 
 
 I am tired, and so will write no more. 
 
 With many thanks pray believe me 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 1 The paper was published in 1865. It is entitled: On tfo 
 Structure ofBonatea speclosa, Linn., with reference to its Fertilisation. 
 By Roland Trimen, Memb. Ent. Soc. Lond. Journ. Linn. Soc. 
 Botf.jix (1865), 156. Darwin mentions this paper in his Notes on 
 the Fertilisation of Orchids in Ann. and Mag. N.H. for September 
 (1869j, 8, 17 ; as also in Fertilisation of Orchids (1877), 76, 77. 
 
 2 See p. 228.
 
 230 DARWIN'S LETTERS TO R. TRIMEN 
 
 The invitation conveyed in the following letter 
 (No. 8) exhibits the characteristic features de- 
 scribed by Mr. Francis Darwin. 1 
 
 It was on this visit that Mr. Trimen heard 
 Darwin speak with such strong feeling on the 
 subject of Owen and the article in the Edinburgh 
 (see p. 28 n. 2). 
 
 8. 
 
 Dec. 24th [1867] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR SIR 
 
 If you are not engaged, will you give me the great 
 pleasure of your company here next Saturday, and stay 
 the Sunday with us. We dine at 7 oclock. You would 
 have to come by Train to Bromley, but I am sorry 
 to say this place is six miles from the Station. 
 
 I am bound to tell you that my health is very un- 
 certain and I am continually liable to bad days, and even 
 on my best days I cannot talk long with anyone ; but 
 if you will put up with the best will to see as much 
 of you as I can, I hope that you will come. Pray 
 believe me, My dear Sir 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 Of the remaining eleven letters six (Nos. 9-12, 
 15, 16) deal with subjects treated of in The 
 Descent of Man and Selection in relation to Sex-, 2 
 
 1 Life and Letters, i. 139. 
 
 2 The following references to information received from Roland 
 Trimen are printed in the index of this work (Ed. 1874, 682) : 'on 
 the proportion of the sexes in South African butterflies, 250 ; on
 
 SUBJECTS OF LATER LETTERS: 1867-71 231 
 
 a few words of encouragement on Trimen's great 
 paper on Mimicry are contained in No. 13 ; the 
 geographical distribution of beetles in No. 19. 
 Of four brief letters, two contain invitations 
 (Nos. 13, 14), and two are concerned with diffi- 
 culties caused by ill-health (Nos. 17, 18, the 
 latter written by Mrs. Darwin). 
 
 The first letter (No. 9) of the following series 
 introduces, and subsequent letters return to the 
 question of ocelli (ocellated spots or eye-spots) 
 on the wings of butterflies and moths. It is evi- 
 dent, from his reference to the male peacock and 
 inquiries as to ocelli restricted to male butterflies, 
 that Darwin was inclined to seek an interpreta- 
 tion based on the hypothesis of Sexual Selection. 1 
 It was not known until long after the date of 
 these letters that eye-spots together with certain 
 differences in shape 2 are in the vast majority 
 of cases characteristic of the butterfly broods of 
 the wet season. The existing interpretation of 
 them was first suggested by an observation made 
 by Professor Meldola and the present writer in 
 1887, when a lizard was seen to exhibit special 
 interest in an eye-spot on the wing of the English 
 ' Small Heath ' butterfly (Coenonympha pamphilus). 
 
 the attraction of males by the female of Lasiocampa quercus, 252 ; 
 on Pnevmom, 288 ; on difference of colour in the sexes of beetles, 
 294; on moths brilliantly coloured beneath, 315 ; on mimicry in 
 butterflies, 325 [324] ; on Gynanisa /si's, and on the ocellated 
 spots of Lepidoptera, 428 ; on Cyllo Leda, 429.' Nearly all the 
 above subjects are referred to in letters 9-12, 15, 16. 
 
 1 Compare pp. 104, 105, 113, 125, 127, 128, 133-5, 140-1. 
 
 2 Figured by Darwin in Descent of Man, &c. (1874), 429. See 
 also 428 . 48.
 
 232 DARWIN'S LETTERS TO R. TRIMEN 
 
 It examined the mark and more than once at- 
 tempted to seize it. This observation has been 
 repeated with birds and African butterflies by 
 Mr. Guy Marshall and others, while large numbers 
 of specimens have been collected with injuries 
 to the wing at or near an eye-spot. Hence the 
 conclusion that the usual value of these mark- 
 ings is to divert attention from the vital parts 
 and give the insect extra chance of escape. Their 
 disappearance from the dry season broods is in- 
 terpreted as due to the paramount necessity for 
 concealment during that time of special stress. 1 
 
 9. 
 
 Jan. 2nd [1868] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAB MR TRIMEN 
 
 What you say about the ocelli [ocellated spots or 
 eye-spots] is exactly what I want, viz the greatest range 
 of variation within the limits of the same species, 
 greater than in the Meadow Brown, if that be possible. 
 The range of difference within the same genus is of 
 secondary interest; nevertheless if you find any good 
 case of variation, I sh d much like to hear how far the 
 species of the same genus differ in the ocelli. As I know 
 from your Orchid Drawings how skilful an artist you 
 are, perhaps it would not give you much more trouble 
 to sketch any variable ocelli than to describe them. 
 I am very much obliged to you for so kindly assisting 
 
 1 For a further account of this and other uses of these markings, 
 together with references to the original memoirs, see ' eye-spots ' 
 in index of Essays on Evolution (1908), 424.
 
 EYE-SPOTS ON BUTTEKFLIES* WINGS: 1868 233 
 
 me, and for your two pieces of information in your note 
 about the sexes of the Batchian Butterfly and about the 
 Longicorn Beetle. 1 
 
 With many thanks, pray believe me 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 10. 
 
 Jan. 16th[, 1868.] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR MR TRIMEN 
 
 I really do not know how to thank you enough for 
 all the great trouble which you have taken for me. 
 I never saw anything so beautiful as your drawings. 2 
 I have examined them with the microscope ! ! When 
 I asked for a sketch I never dreamed of your taking 
 so great trouble. Your letter and Proof-sheet give me 
 exactly and fully the information which I wanted. I am 
 very glad of the description of the ocellus in the 
 S. African Saturnidce : 3 I had no idea it was so com- 
 
 1 In The Descent of Man (1874), 250, Darwin quotes A. R. 
 Wallace's observation, doubtless supplied to him by Trimen, and 
 here referred to, that the female of Omithoptera ctvesus was 
 commoner and more easily caught than the male. Mr. Trimen 
 thinks that this must be the ' Batchian Butterfly '. On p. 294 
 n. 63 Darwin states that he had been informed by Trimen that 
 the male of a species of the Lamellicorn genus Trichius is more 
 obscurely coloured than the female. Trimen's name is not men- 
 tioned in connexion with the similar relationship recorded for 
 certain Longicorn beetles on pp. 294, 295. 
 
 2 The drawings were illustrations of the extreme variation in the 
 development of the eye-spots on the wings of Cyllo (Melanitis) leda. 
 Darwin referred to these and figured some of them in Descent of 
 Man (1874), 428, 429. 
 
 3 Darwin is here evidently alluding to the description given 
 him by Trimen of the 'S. African moth (Gynanisa isis), allied 
 to our Emperor moth, in which a magnificent ocellus occupies 
 nearly the whole surface of each hinder wing'. Descent of Man 
 (1874), 428.
 
 234 DARWIN'S LETTERS TO R. TRIMEN 
 
 plex. If you know of any case in Lepidoptera of ocelli 
 regularly confined to the male. 1 I sh d much like to hear 
 of it, as it would illustrate a little better the case of the 
 peacock, which has often been thrown in my teeth. 
 I doubt whether such cases exist, and if I do not hear 
 I will understand that you know of no such case. 
 Again let me thank you cordially for your great kind- 
 ness, and I remain, 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 11. 
 Written ly Mrs. Darwin, signed by Charles Darwin. 
 
 DOWN. 
 
 BROMLEY. 
 KENT. S.E. 
 Feb 12 [1868.] 
 MY DEAR MR TRIMEN 
 
 I shall be very happy to put my name down for 
 your brother's book and he can hand over the enclosed 
 paper to Hardwick. 2 
 
 Since you were here I have become much interested 
 on the relative numbers of the males and females of all 
 animals. I am particularly anxious for other cases like 
 that from [A. R.] Wallace which you gave me of females 
 in excess ; 3 or to know that such cases are rare. If you 
 can, I am sure you will aid me. 4 Do you give many 
 
 1 Mr. Trimen informs me that he was unable to discover any 
 such case. 
 
 2 Mr. Trimen thinks that the book must have been the Flora 
 of Middlesex (octavo, London : 1869) written and published by 
 Henry Trimen and Sir William Thiselton-Dyer. 
 
 3 See p. 233 n. 1. 
 
 4 .This letter enclosed a slip of paper which is evidently Trimen's 
 copy of the list sent by him in reply to Darwin's inquiry. It con- 
 tains a full list of nineteen species of South African butterflies in 
 which males are more numerous than females, and of three species
 
 SEX RELATIONSHIPS OF INSECTS: 1868 235 
 
 instances in your book on S. African butterflies, of males 
 in excess. I remember writing down one or 2 cases 
 which you gave me. 
 
 Believe me 
 
 Yours very sincerely 
 CH. DARWIN 
 
 12. 
 
 Feb. 21st [1868.] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR MR TRIMEN 
 
 You are always most kind in aiding me. The 
 argument of the Lasiocampa l strikes me as very good 
 but what an intricate subject it is ! I have had excellent 
 letters from Stainton and Bates. The latter is much 
 staggered. Have you ever heard or observed other 
 cases like the Lasiocampa. I think I have seen in 
 England many Butterflies pursuing one. But here comes 
 a doubt may not the same male serve more than one 
 female. I think I will write to Dr. Wallace of Col- 
 chester. 2 
 
 in which the females are apparently the more numerous. These 
 numbers are quoted by Darwin in Descent of Man, &c. (1874), 250. 
 
 1 Mr. Trimen has kindly given me the following note : 
 
 ' E. Blanchard (in his Metamorphoses, Mceurs et Instincts des 
 Insectes) had attributed to some special and peculiar sense the 
 power exhibited by many males among moths of discovering the 
 distant and concealed females of their respective species. I con- 
 tended that it could only be the sense of smell that was brought 
 to bear in such cases, instancing my own experience in the case of 
 the English ' Oak Eggar ' (Lasiocampa quercus), where the males 
 assembled to an empty box in my pocket which had contained 
 a virgin female on the previous day.' The observation is referred 
 k. in Descent of Man (1874), 252. See also Darwin's argument in 
 letter 15, p. 242. 
 
 2 The experience of Dr. A. Wallace with the large silk-producing 
 moths is quoted in several places in the Descent of Man, c.
 
 236 DARWIN'S LETTERS TO R. TRIMEN 
 
 My women-kind have insisted on coming to London 
 for all March, much to my grief ; but I shall get some 
 good, for I shall see some of my friends, and you amongst 
 the number. 
 
 With very sincere thanks 
 Believe me 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 I shall go doggedly on collecting facts through the 
 animal kingdom, and possibly at the end some little 
 light may be acquired. I am getting some of the chief 
 domestic animals tabulated. 
 
 In the last sentence of the following letter 
 Darwin was referring to the evening of March 5, 
 1868, when Trimen read his remarkable and 
 important paper, published in the early part 
 of the following year : * On some remarkable 
 Mimetic Analogies among African Butterflies/ 1 
 Bates's classical paper on Mimicry (1862), re- 
 ferred to on pp. 122-6, was concerned with 
 tropical American butterflies and moths. A. R. 
 Wallace's paper 'On the Phenomena of Varia- 
 tion and Geographical Distribution as illustrated 
 by the Papilionidce of the Malayan Region ' - 
 (1866) dealt with the same subject as illustrated 
 by butterflies in the tropical East. Trimen's 
 paper completed the great series by extending 
 the hypothesis of Mimicry to the African con- 
 tinent. The chief example considered in the 
 paper, that of Papilio dardanus (merope), was by 
 
 1 Trans. Linn. Soc. Lo)id., xxvi. 497-522. 
 -' Trans. Linn. Soc. Land., xxv. 1-71.
 
 TRIMEN'S DISCOVERIES IN MIMICRY 237 
 
 far the most complex and difficult to interpret 
 of any in the world. When, in this masterly 
 memoir, he had at length unravelled the tangled 
 relationships, three ' species ', up to that time 
 regarded as entirely distinct, had been sunk as 
 the three different mimetic females of a single 
 non-mimetic male, then known as a fourth 
 * species '. Trimen's conclusions were not con- 
 firmed by the supreme test of breeding until 
 1902, and all three mimetic forms found in one 
 locality were not bred from the eggs of a single 
 parent until 1906. 1 
 
 One of the principal opponents of Trimen's 
 conclusions was the late W. C. Hewitson, who 
 said : ' it would require a stretch of the imagina- 
 tion, of which I am incapable, to believe that . . . 
 P. merope . . . indulges in a whole harem of 
 females, differing as widely from it as any other 
 species in the genus . . .' -' However, shortly 
 after he had written the above sentence Hewitson 
 received from one of his own collectors this 
 very male taken paired with one of the mimetic 
 females. 3 
 
 My friend Mr. Harry Eltringham has recently 
 pointed out to me a passage, marked by much 
 confusion of thought, in Hewitson's Exotic Butter- 
 flies,' 1 which might be read as an anticipation 
 
 1 See ' dardanus ' in index of Essays on Evolution (1908), 414 ; 
 also Plate XXIII in Trans. Ent. Soc. Loud. (1908), 427-45. 
 
 2 Trans. Ent. Soc. Loud. (1874 1 , 137. 
 
 3 E. M. M. (Oct., 1874), 113. 
 
 4 London, 1862-66, III: text of plate ' Nymphalidee. Diadema iii.': 
 (pages unnumbered).
 
 238 DARWIN'S LETTERS TO R. TRIMEN 
 
 of Fritz Miiller's earlier suggestion that Mimicry 
 may be due to Sexual Selection (see pp. 127-8). 
 I do not think that the words really bear this 
 interpretation, but even if they do, it is obvious 
 that a suggestion intended to be taken as a joke 
 cannot be looked upon as a serious anticipation ! 
 Inasmuch as Hewitson makes special reference 
 to the three papers of Bates, Wallace and Trimen, 
 it is not inappropriate to quote his criticisms 
 at this point. 
 
 After describing some of the wonderful forms 
 that would now be placed in the African genus 
 Pseudacraea mimetic of the Acraeine genus Plar 
 nema from the same localities, Hewitson proceeds 
 to remark : 
 
 'This strange resemblance to each other of distant 
 and very distinct groupes, which forms the romance of 
 natural history, has afforded wonder and delight to every 
 naturalist, and will do so to the end of time, the more 
 so because of its mystery, unless some much better ex- 
 planation is offered than that proposed by Darwin and 
 his followers, because, unluckily for them, it is just those 
 species which superficially bear the closest resemblance 
 to each other that differ most in their fundamental 
 structure.' 
 
 The objection urged by Hewitson is of course 
 the strongest of all reasons in favour of the views 
 he is attacking. Such fundamental differences 
 exclude an interpretation of resemblance based 
 simply on affinity. It is well that this important 
 statement should be proclaimed by an opponent
 
 THE TESTIMONY OF AN OPPONENT 239 
 
 of the theory of Mimicry. It is also well that 
 he should say of the * great leading aristocratic ' 
 groups which are resembled by other butterflies 
 Danais, Acraea, l Heliconidae ' (including under this 
 head Ithomiinae and Danainae as well as true 
 Heliconinae l ) : 
 
 ' One of the most marvellous things in this repre- 
 sentative system is that the great groupes are not only 
 imitated at home, but that the stragglers from two of 
 them in other lands have their mimics as well ; and in 
 the great South American groupe, the Heliconidae, the 
 butterflies of several genera, completely different in their 
 neuration, are inseparable by the unaided sight.' 
 
 It would be hardly possible to produce better 
 indirect evidence of some special quality in the 
 chief models than that afforded by the resem- 
 blances to them formed afresh when stragglers 
 have wandered into other lands. Section VI 
 of the present work is largely concerned with 
 one striking example of the mimetic resemblance 
 by indigenous New World species of invading 
 Danaines from the Old World. Hewitson for 
 a most singular reason rejects the conclusion 
 that the groups in question are specially pro- 
 tected, and concludes by making the jocular 
 suggestion to which Mr. Eltringham directed 
 my attention : 
 
 'Naturalists, Wallace, Bates, and Trimen, who have 
 each studied one of these great groupes in their native 
 land, tell us that they exude a liquid of an offensive 
 1 See pp. 152-4.
 
 240 DAKWIN'S LETTERS TO E. TRIMEN 
 
 smell. We have, however, no right to conclude that 
 what may be unpleasant to us is not to them a sweet- 
 smelling royal unction. May not all the imitators of 
 these scented aristocrats be simply votaries of fashion, 
 apeing the dress of their superiors, and, since the females 
 take the lead, " naturally selecting " those of the gayest 
 colours ? ' 
 
 Hewitson in the first part of the above para- 
 graph assumes that the liquid is considered to 
 be offensive to tlie insects tJiemselves, whereas of 
 course it is believed to protect against insect-eating 
 animals. In the last part I do not think he uses 
 the word ' naturally ' when he means * sexually ', 
 for the sake of the little play upon the former 
 word. I think by the words ' females take the 
 lead ' Hewitson refers to the greater prevalence 
 and perfection of female Mimicry, and that he 
 only intended to convey the facetious suggestion 
 of conscious and deliberate imitation. 
 
 To return to Trimen's paper, it is hardly 
 surprising that a memoir containing such novel 
 and startling conclusions should have been heard 
 by a hostile audience, and my Mend tells me 
 that l Darwin's congratulations were of immense 
 comfort, as the large meeting was for by far 
 the greater part opposed and discouraging'. 
 Darwin's keen interest in Bates's paper has 
 been shown on pp. 123-6, the part he took in 
 encouraging Fritz Muller in his successive amend- 
 ments of the Batesian Hypothesis, on pp. 126-9 ; 
 but the following letter is the first evidence I
 
 DARWIN AND TRIMEN'S PAPER: 1868 241 
 
 have come across of his personal interest in the 
 immensely important contribution made by Roland 
 Trimen. 
 
 13. 
 
 Monday 4. CHESTER PLACE l 
 
 [Mar. 20, 1868] REGENTS PARK 
 
 N.W. 
 MY DEAR MR TRIMEN 
 
 Would it suit you to corne and lunch here at 
 1. oclock on Friday or Saturday, or indeed almost any 
 day ; or if luncheon-time does not suit you, if you will 
 you will [sic] tell me at what hour you will call I will be 
 at home. I hear that you had a brilliant night at Linn. 
 Soc. and I regretted so much that I could not come. 
 
 Yours very sincerely 
 
 CH. DARWIN 
 
 14. 
 
 Saturday [1868] 4 CHESTER PLACE 
 
 N.W. 
 MY DEAR MR TRIMEN, 
 
 Tuesday w d suit me, but another man (Mr. Blyth 2 ) 
 is coming to lunch on that day, and as you know that 
 I am not up to more than an hour's talk, I sh d see less 
 of you ; so if equally convenient and I do not hear to 
 contrary, I will name Wednesday at 1 oclock. 
 
 Very many thanks for your information in note. 
 
 Yours very sincerely 
 
 C. DARWIN 
 
 1 The house of Mrs. Darwin's sister, Miss Elizabeth Wedgwood. 
 
 2 See More Lettei-s, i. 62 ., for an account of this naturalist.
 
 242 DARWIN'S LETTERS TO R. TRIMEN 
 
 15. 
 
 April 14th [1868] DOWN. 
 
 BROMLEY. 
 
 KENT. S.E. 
 MY DEAR MB TRIMEN 
 
 It is very kind of you to take the trouble of 
 making so long an extract, which I am very glad to 
 possess, as the case is certainly a very striking one. 
 Blanchard's argument about the males not smelling the 
 females, because we can perceive no odour, seems to me 
 curiously weak. It is wonderful that he sh d not have 
 remembered at what great distances Deer and many 
 other animals can scent the cleanest man. 1 
 
 Many thanks for your Photograph, and I send mine, 
 but it is a hideous affair merely a modified, hardly an 
 improved, Gorilla, 
 
 Mr [H.] Doubleday has suggested a capital scheme 
 for estimating the number of sexes in Lepidoptera, viz 
 by a German List, in which in many cases the sexes are 
 differently priced. 2 With Butterflies, out of a list of 
 about 300 Sp. and Vars. 114 have sexes of different prices, 
 and in all of them, with one single exception, the male 
 is the cheapest. On an average judging from price for 
 every 100 females of each species there ought to be 143 
 males of the same species. So I firmly believe that you 
 field collectors are correct. Nearly the same result with 
 Moths. 
 
 1 The ' extract ' probably refers to an account of the males 
 of the Oak Eggar rnoth assembling to a box that had contained the 
 female (see p. 235 n. 1). Blanchard's argument was revived in 
 1894 by Prof. F. Plateau, who, finding the taste ('saveur reelle ') of 
 the larva, pupa, and imago of the Magpie moth (Abraxas grossu- 
 lariata) to be somewhat pleasant to his own palate, concluded 
 that it was not distasteful to insectivorous animals. This con- 
 clusion is opposed by the present writer in Tram. Ent. Soc. Land. 
 (1902), 405-14. 
 
 2 Quoted by Darwin in Descent of Man, &c. (1874), 252.
 
 SEX RELATIONSHIPS OF INSECTS: 1868 248 
 
 I sincerely wish you health, happiness and success in 
 Nat. History in S. Africa. I should have much liked to 
 have asked you, if you could have spared time, to come 
 down here for a day or two ; but Mrs. Huxley is coming 
 here in a few days with all her six children and nurses, 
 for healths sake, and stop some weeks. And our House 
 will be, with others, so absolutely full, that today we 
 have had to tell our Brother-in-law, that we cannot 
 possibly receive him. 
 
 Most truly do I thank you for your great kindness in 
 aiding me in so many ways. Yesterday I was working 
 in much of your information. 
 
 Believe me 
 
 Yours very sincerely 
 
 C. DARWIN 
 16. 
 July 24th [1871] DOWN, 
 
 BECKENHAM, 
 
 KENT. 
 MY DEAR MR TRIMEN 
 
 I am much obliged for your long and interesting 
 letter. You asked me whether I have any notion about 
 the meaning of moths etc flying into candles, and birds 
 against light-houses. I have not. I have looked at the 
 case as one of curiosity, which is very strong with the 
 higher animals, and I presume even with insects. A light 
 is a very new object, and its distance cannot be judged, 
 but how it comes that an insect is so stupid as to go on 
 flying into the same candle I cannot conceive. It looks 
 as if they were drawn towards it. Sir C. Lyell, I re- 
 member, made years ago the difficulty greater by asking 
 me, what stops all the moths in the world flying every 
 moon-light night up to the moon, or as near as they could 
 get. Perhaps they have instinctively learnt that this 
 cannot be done. 
 
 B2
 
 244 DARWIN'S LETTERS TO R. TRIMEN 
 
 With respect to humour, I think dogs do have it, but 
 it is necessarily only of a practical kind. Everyone 
 must have seen a dog with a piece of a stick or other 
 object in his mouth, and if his master in play tries to 
 take it away, the dog runs with prancing steps a few 
 yards away, squats down, facing his master, and waits 
 till he comes quite close and then jumps up and repeats 
 the operation, looking, as if he said, ' you are sold ". 
 
 I have many letters to write so pray excuse brevity. 
 My book has been very successful as far as sale has been 
 concerned, and has hitherto been in most cases treated 
 very liberally by the press. My notions on the moral 
 sense have, however, been much reprobated by some 
 and highly praised by others. I have no news to tell, 
 for I have seen hardly any one for months. 
 
 I am extremely sorry to hear that you are no freer 
 of official duties, for I feel sure if you had more leisure 
 and especially if you lived in the country, you would 
 make some grand new observations. 
 
 With every good wish 
 
 Pray believe me 
 Yours sincerely 
 CH. DARWIN 
 
 17. 
 
 Written by Sir George Darwin, signed by 
 Charles Darwin. 
 
 DOWN 
 
 BEOKENHAM 
 
 MY DEAR MR. TRIMEN, Thursd. July 27. 71 
 
 I was much surprized to receive your letter and 
 I am sorry to hear of the cause of your hurried return 
 to England. 1 
 
 1 In consequence of the death of his father in March, 1871.
 
 DARWIN ON -DESCENT OF MAN': 1871 245 
 
 I have been a good deal out of health of late and we 
 have taken Haredene x for a month in order that I may 
 get a little rest. We start tomorrow morning. I shall 
 have very great pleasure in seeing you there after your 
 return from Edinburgh. I am sorry to say that I cannot 
 ask you to sleep with us as we shall have no beds to 
 spare ; but I suppose from what you say that you will 
 be staying in the neighbourhood. Many thanks for the 
 Review which I will read in the course of the day. 2 
 Believe me 
 
 Yours very sincerely 
 
 CHABLES DARWIN 
 
 18. 
 
 From Mrs. Darwin. 
 
 HAREDENE 3 Tuesday 
 
 [Jul. 28-Aug. 25, 1871] 
 DEAR MR TRIMEN 
 
 I am very sorry to say that Mr Darwin has been 
 so unwell (ill I may say) that we are hastening our return 
 home as soon as possible. He is quite unequal to seeing 
 you which he very much regrets. 
 
 Our stay in this charming place is a great disappoint- 
 ment, though I hope he will reap the benefit of the rest 
 afterwards. He desires me to repeat how very sorry he 
 is not to be able to see you 
 
 believe me 
 
 yours very truly 
 
 EMMA DARWIN 
 
 1 Mr. Francis Darwin informs me that Haredene is near Albury 
 in Surrey. 
 
 2 Mr. Trimen thinks that the Review spoken of was a notice of 
 the Descent of Man, &c., contributed by him to the Cape Monthly 
 Magazine in June, 1871. 
 
 3 See the above n. 1.
 
 246 DARWIN'S LETTERS TO R, TRIMEN 
 
 19. 
 
 Nov. 13th [1871] DOWN, 
 
 BECKENHAM, KENT. 
 MY DEAR MR TRIMEN 
 
 I write one line to say how sorry I am not to see you 
 before your return to the Cape, 1 which I presume will 
 be soon. But I cannot get my head steady enough to 
 see anyone. I have just returned from a visit to my 
 sister for a week, but I was forced to spend nearly all 
 the day in my bed-room. 
 
 I read with much interest some little time ago your 
 paper on Geographical Distribution of Beetles; and 
 agreed, I believe, with all your general remarks. 2 
 
 I wish you all success in your future researches and 
 remain 
 
 Yours very sincerely 
 CH. DARWIN 
 
 If on the point of starting do not trouble yourself to 
 answer this. 
 
 1 The letter was received Jan. 11, 1872, after Trimen had 
 returned to the Cape. 
 
 8 The paper referred to is : 
 
 Notes on the Geographical Distribution and Dispersion of Insects ; 
 chiefly in reference to a paper by Mr. Andrew Murray, F.L.S., ' on the 
 Geographical Relations of the chief Coleopterous Faunce ' By Roland 
 Trimen, F.L.S., &c.-Linn. Soc. Journal. Zool. xii (1871), 276-84. 
 
 Murray in a very dogmatic way had in his elaborate memoir 
 endeavoured to account for the greater part of the difficulties 
 presented by the known existing distribution of animals and 
 plants over the globe by the simple explanation of ' continuity of 
 soil at some former period '. Tnmen in his paper insisted on the 
 more important methods of dispersal always at work, and traversed 
 several of the author's statements, especially as regards oceanic 
 islands, which had been treated by Murray as obviously surviving 
 portions of otherwise vanished continental lands.
 
 APPENDIX A 
 
 CHARLES DARWIN AND THE 
 HYPOTHESIS OF MULTIPLE ORIGINS 
 
 I HAVE thought it of interest to consider in 
 some detail Darwin's attitude towards a single 
 one of the examples (pp. 45, 46) in which his 
 sure judgement shines forth so conspicuously 
 among his seniors, contemporaries and successors 
 alike. 
 
 I select the idea that species or groups of 
 species had arisen from * multiple ' (or ' polyphyl- 
 etic ' ) origins a hypothesis very fashionable, 
 during one brief period, both in America and 
 on the Continent. 
 
 According to this hypothesis, two or more 
 groups of animals were supposed to have arisen 
 independently, perhaps in different countries, 
 and subsequently by * convergence ' to have be- 
 come one. The most extreme development of 
 this view would be the incredible belief that 
 a single species might be formed from separate 
 bodies of individuals, arising independently from 
 very different lines of descent, but subsequently 
 fusing into an interbreeding community. Long 
 before this idea became popular, it had been 
 thought over by Darwin and seen to be worth-
 
 248 APPENDIX A 
 
 less. The following references to the subject 
 are to be found in his correspondence with 
 Sir Joseph Hooker in 1854 and 1856, years 
 before the publication of the Origin : 
 
 1854, July 2. 'I am glad to hear what you say about 
 parallelism : I am an utter disbeliever of any parallelism 
 more than mere accident.' * 
 
 1856, July 13. 'You say most truly about multiple 
 creations and my notions. If any one case could be proved, 
 I should be smashed ; but as I am writing my book, I try 
 to take as much pains as possible to give the strongest cases 
 opposed to me, and often such conjectures as occur to me.' 2 
 
 1856, July 19. ' ... it is absolutely necessary that I 
 should discuss single and double creations, as a very crucial 
 point on the general origin of species, and I must confess, 
 with the aid of all sorts of visionary hypotheses, a very 
 hostile one.' 3 
 
 The above-quoted sentences sum up very 
 briefly Darwin's conclusion that evolution as he 
 conceived of it implied that each species had 
 appeared once only in a single continuous area 
 and had then tended to spread from this as from 
 a centre implied in fact the soundness of the 
 belief in what were then called * single centres 
 of creation'. His arguments in favour of this 
 conviction are given in great detail in the first 
 edition of the Origin : first in chapter X, sup- 
 porting the conclusion, ' it is incredible that 
 individuals identically the same should ever have 
 been produced through natural selection from 
 
 1 More Letters, i. 77. 2 More Letters, i. 95. 
 
 8 More Letters, ii. 249.
 
 DAEWIN AND MULTIPLE OKIGINS 249 
 
 parents specifically distinct ' l ; secondly, in chap- 
 ters XI and XII, the vast array of facts which 
 are consistent with the belief in ' single centres of 
 creation ', and serve to explain the great apparent 
 difficulties. 
 
 Sir Charles Lyell had also arrived at the firm 
 conviction that species had spread from single 
 centres, and, within a few days of Darwin's 
 expression of the same conviction in July, 1856, 
 he also was writing to Hooker and telling of 
 his unnecessary fears : 
 
 1856, July 25. 'I fear much that if Darwin argues that 
 species are phantoms, he will also have to admit that single 
 centres of dispersion are phantoms also, and that would 
 deprive me of much of the value which I ascribe to the 
 present provinces of animals and plants, as illustrating 
 modern and tertiary changes in physical geography.' 2 
 
 It is clear that Darwin heard of Lyell's ap- 
 prehensions and was referring to them in the 
 two following passages in letters to Hooker : 
 
 1856, July 30. ; I cannot conceive why Lyell thinks 
 such notions as mine or of ' Vestiges ' will invalidate 
 specific centres.' 3 
 
 1856, Aug. 5. ' I suppose, in regard to specific centres, 
 we are at cross purposes ; I should call the kitchen garden 
 in which the red cabbage was produced, or the farm in which 
 Bakewell made the Shorthorn cattle, the specific centre of 
 these species I And surely this is centralisation enough ! ' 4 
 
 When, however, the Origin had appeared, and 
 Lyell was for a time resisting its appeal, he 
 
 1 Origin of Species (1859), 352. 
 
 2 Life and Letters, ii. 83. Quoted from Life of Sir Charles Lyell, 
 ii. 216. 3 Ibid., 81. 4 Ibid., 82.
 
 250 APPENDIX A 
 
 was not unwilling to contemplate multiple 
 centres with a vengeance; for he put forward 
 as a difficulty the fact that mammals had not 
 arisen independently on oceanic islands. Refer- 
 ring to this point, Darwin wrote to him (Sept- 
 ember 1, 1860) as follows : 
 
 ' With respect to a mammal not being developed on any 
 island, besides want of time for so prodigious a development, 
 there must have arrived on the island the necessary and 
 peculiar progenitor, having a character like the embryo of 
 a mammal ; and not an already developed reptile, bird or 
 fish. We might give to a bird the habits of a mammal, but 
 inheritance would retain almost for eternity some of the 
 bird-like structure, and prevent a new creature ranking 
 as a true mammal.' * 
 
 Lyell does not appear to have been convinced 
 by the argument, and Darwin wrote again on 
 September 23, 1860 : 
 
 ' I have a very decided opinion that all mammals must 
 have decended from a single parent [species]. Eeflect on the 
 multitude of details, very many of them of extremely little 
 importance to their habits (as the number of bones of the 
 head, &c., covering of hair, identical embryological develop- 
 ment, &c. &c.). Now this large amount of similarity I must 
 look at as certainly due to inheritance from a common stock. 
 I am aware that some cases occur in which a similar or 
 nearly similar organ has been acquired by independent acts 
 of natural selection. But in most of such cases of these 
 apparently so closely similar organs, some important homo- 
 logical difference may be detected.' 2 
 
 Lyell had argued that, just as man would now 
 keep down any new man that might be developed, 
 so the bats and rodents of oceanic islands may 
 
 1 Life and Letters, ii. 335. 2 1. c., ii. 341.
 
 DARWIN AND MULTIPLE ORIGINS 251 
 
 have prevented the independent origin of other 
 mammals. To this argument Darwin replied : 
 
 'I know of no rodents on oceanic islands (except my 
 Galapagos mouse, which may have been introduced by man) 
 keeping down the development of other classes. Still much 
 more weight I should attribute to there being now, neither 
 in islands nor elsewhere, [any] known animals of a grade of 
 organisation intermediate between mammals, fish, reptiles, 
 &c., whence a new mammal could be developed. If every 
 vertebrate were destroyed throughout the world, except our 
 now tvell-established reptiles, millions of ages might elapse 
 before reptiles could become highly developed on a scale 
 equal to mammals ; and, on the principle of inheritance, 
 they would make some quite neic class, and not mammals ; 
 though possibly more intellectual ! ' l 
 
 Many years later, in a letter to the Duke of 
 Argyll (September 23, 1878), Darwin gave a 
 more complete answer to the extreme supporters 
 of the hypothesis of multiple origins, at the same 
 time refuting the opinion not uncommon even 
 at the present day that a terrestrial species such 
 as man may exist on Mars or on some other 
 body outside the earth. For Darwin shows in 
 the following letter that, in order to produce the 
 same species twice over, the same material must 
 have been subject to the same selection at every 
 stage, right back to the unknown starting-point 
 of organic evolution. 
 
 ' As far as I can judge, the improbability is extreme that 
 the same well-characterised species should be produced in 
 two distinct countries, or at two distinct times. It is 
 certain that the same variation may arise in two distinct 
 places, as with albinism or with the nectarine on peach-trees. 
 
 1 Sept. 23, 1860. Life and Letters, ii. 344.
 
 252 APPENDIX A 
 
 But the evidence seems to me overwhelming that a well- 
 marked species is the product, not of a single or of a few 
 variations, but of a long series of modifications, each modi- 
 fication resulting chiefly from adaptation to infinitely complex 
 conditions (including the inhabitants of the same country), 
 with more or less inheritance of all the preceding modifica- 
 tions. Moreover, as variability depends more on the nature 
 of the organism than on that of the environment, the 
 variations will tend to differ at each successive stage of 
 descent. Now it seems to me improbable in the highest 
 degree that a species should ever have been exposed in two 
 places to infinitely complex relations of exactly the same 
 nature during a long series of modifications. An illustration 
 will perhaps make what I have said clearer, though it 
 applies only to the less important factors of inheritance and 
 variability, and not to adaptation viz., the improbability of 
 two men being born in two countries identical in body and 
 mind. If, however, it be assumed that a species at each 
 successive stage of its modification was surrounded in two 
 distinct countries or times, by exactly the same assemblage 
 of plants and animals, and by the same physical conditions, 
 then I can see no theoretical difficulty [in] such a species 
 giving birth to the new form in the two countries.' ' 
 
 The Duke misunderstood the letter, for he used 
 it as evidence to support his assertion ' that 
 Charles Darwin assumed mankind to have arisen 
 at one place, and therefore in a single pair '. 
 It is obvious that no such conclusion follows 
 from Darwin's argument ; but in order to settle 
 the question once for all, Sir William Thiselton- 
 Dyer published a letter 2 in which Darwin makes 
 the following statement : 
 
 1 Nature, xliii. 415. At the conclusion of the letter Darwin 
 refers his correspondent to p. 100 of the sixth ed. of the Origin. See 
 also More Letters, i. 377, 378. 
 
 * Nature, xliii. 535. See also More Letters, i. 378-81.
 
 DARWIN AND MULTIPLE ORIGINS 253 
 
 ' I dispute whether a new race or species is necessarily, or 
 even generally, descended from a single or pair of parents. 
 The whole body of individuals, I believe, become altered 
 together like our race-horses, and like all domestic breeds 
 which are changed through "unconscious selection" by man.' 
 
 This passage was written (Nov. 25, 1869) in a 
 letter to G. Bentham as a criticism of the follow- 
 ing passage in his presidential address to the 
 Linnean Society on May 24, 1869 : 
 
 ' We must also admit that every race has probably been 
 the offspring of one parent or pair of parents, and conse- 
 quently originated in one spot.' 
 
 The Duke of Argyll had inverted Bentham's pro- 
 position, as pointed out by Sir W. Thiselton- 
 Dyer. 
 
 On this remarkable page in the history of 
 thought we see how Darwin, by sure and pene- 
 trating genius, rises to heights far beyond those 
 attained by the men of his own and later days. 
 We see Lyell in fear and doubt lest his cherished 
 belief in ' single centres of creation ' should be 
 endangered by the one man who held the same 
 belief on much stronger grounds. We find the 
 great geologist, at a later stage, ready to give up 
 his belief if he can thereby obtain a weapon 
 against evolution ; and observe, in Darwin's 
 answer to him and to the Duke of Argyll, an 
 entire grasp of the problem conspicuously want- 
 ing in those authorities who expressed, at a 
 later date, an ill-founded enthusiasm for the 
 worthless hypothesis of multiple origins.
 
 254 
 
 APPENDIX B 
 DARWIN AND EVOLUTION BY MUTATION 
 
 I HAVE spoken on pages 43 and 44 of the 
 frequency with which Darwin, between 1860 
 and 1880, was brought back by others to a motive 
 cause of evolution based on * sudden jumps ', or 
 ' monstrosities', on 'large', * extreme', and 'great 
 and sudden ' variations. Such views were con- 
 tinually urged upon him by ' his correspondents, 
 and by reviews and criticisms of his work '. It 
 is I think of interest, in relation to the biological 
 fashions of the day, to show by many examples 
 how firmly he met such suggestions whenever they 
 were made to him. I therefore append the follow- 
 ing quotations from his letters to those on pages 43 
 and 44 and to be found in the Quarterly Review l : 
 
 (1) 1860. ' ... he [Harvey] assumes the permanence of 
 monsters, whereas, monsters are generally sterile, and not 
 often inheritable.' 2 
 
 (2) 1860. ' It would take a good deal more evidence to 
 make me admit that forms have often changed by saltum.' 3 
 
 (3) 1860. 'Although I fully agree that no definition can 
 be drawn between monstrosities and slight variations (such 
 as my theory requires), yet I suspect there is some dis- 
 tinction. Some facts lead me to think that monstrosities 
 supervene generally at an early age ; and after attending to 
 the subject I have great doubts whether species in a state of 
 nature ever become modified by such sudden jumps as 
 would result from the Natural Selection of monstrosities.' 4 
 
 1 July, 1909 ; 10-12, 25, 26. 
 
 2 To Sir Charles Lyell, Feb. 18, I860. Life and Letters, ii. 275. 
 8 To Sir Joseph Hooker, Feb., I860. Ibid., 274. 
 
 4 To Maxwell Masters, April 13, I860. More Letters, i. 147, 148.
 
 DARWIN AND MUTATION 255 
 
 (4) 1860. ' About sudden jumps : I have no objection to 
 them they would aid me in some'cases. All I can say is, 
 that I went into the subject, and found no evidence to make 
 me believe in jumps ; and a good deal pointing in the other 
 direction.' 1 
 
 (5) 1871. ' . . . I have now almost finished a new edition 
 of the Origin, which Victor Carus is translating. There is 
 not much new in it, except one chapter in which I have 
 answered, I hope satisfactorily, Mr. Mivart's supposed diffi- 
 culty on the incipient development of useful structures. I 
 have also given my reasons for quite disbelieving in great 
 and sudden modifications.' 2 
 
 (6) 1873. 'It is very difficult or impossible to define 
 what is meant by a large variation. Such graduate into 
 monstrosities or generally injurious variations. I do not 
 myself believe that these are often or ever taken advantage 
 of under nature. It is a common occurrence that abrupt 
 and considerable variations are transmitted in an unaltered 
 state, or not at all transmitted, to the offspring, or to some 
 of them. So it is with tailless or hornless animals, and 
 with sudden and great changes of colour in flowers.' 3 
 
 (7) 1880. 'It is impossible to urge too often that the 
 selection from a single varying individual or of a single 
 varying organ will not suffice.' 4 
 
 (8) 1880. Finally the letter to Nature, dated 
 November 5, 1880, was one of the strongest 
 things ever written by Darwin. It originally 
 contained a passage which the writer omitted 
 on the advice of his most combative friend 
 Huxley. The two grounds on which Darwin 
 based his emphatic protest are stated in the 
 following passage. A mutationist conception of 
 evolution based on ' extreme variation ' is the 
 
 1 To W. H. Harvey, August, 1860. -More Letters, i. 166. 
 
 2 To E. Hackel, December 27, 1871. More Letters, i. 335. 
 
 3 To R. Meldola, August 13, 1873. More Letters, i. 350. 
 
 4 To A. R. Wallace, January 5, 1880. More Letters, i. 384.
 
 256 APPENDIX C 
 
 first of them ; the assumption that he had made 
 Natural Selection the sole motive cause of evolu- 
 tion forms the second : 
 
 1 1 am sorry to find that Sir Wyville Thomson does not 
 understand the principle of Natural Selection, as explained 
 by Mr. Wallace and myself. If he had done so, he could 
 not have written the following sentence in the Introduction 
 to the Voyage of the Challenger : " The character of the 
 abyssal fauna refuses to give the least support to the theory 
 which refers the evolution of species to extreme variation 
 guided only by Natural Selection." ' 1 
 
 APPENDIX C 
 
 WORK ESSENTIAL FOR DARWIN'S 
 HEALTH AND COMFORT 
 
 THE alteration in tastes and interests which 
 Darwin described in himself has been wrongly 
 interpreted. The errors have been widely spread 
 and are repeated by able and influential writers 
 even at the present day. 2 It is important in 
 justice to scientific men as a body and especially 
 to Darwin himself to show by repeated evidence 
 the true cause of the changes set down in the 
 autobiography. I have therefore added a number 
 of quotations from Darwin's letters to the evi- 
 dence brought forward on pages 59-66 and 
 yielded by the correspondence with Roland Trimen 
 on pages 218 to 246. The two passages written 
 in 1859 refer to the preparation of the Origin 
 of Species : 
 
 1 More Letters, i. 388. See Nature, Nov. 11, 1880, p. 32. 
 
 2 See pp. 79-83.
 
 DARWIN'S HEALTH AND WORK 257 
 
 1859. ' I have been so poorly, the last three days, that 
 I sometimes doubt whether I shall ever get my little 
 volume done, though so nearly completed . . .' 1 
 
 1859. ' . . . I can truly say I am never idle ; indeed, 
 I work too hard for my much weakened health ; yet I can 
 do only three hours of work daily, and I cannot at all see 
 when I shall have finished.' 2 
 
 1864. ' I honour your wisdom at giving up at present 
 Society for Science. But, on the other hand, I feel it in 
 myself possible to get to care too much for Natural Science 
 and too little for other things.' 3 
 
 1865. ' What a wonderful deal you read ; it is a horrid 
 evil for me that I can read hardly anything, for it makes 
 my head almost immediately begin to sing violently. My 
 good womenkind read to me a great deal, but I dare not ask 
 for much science, and am not sure that I could stand it.' * 
 
 1868. ' It is really a great evil that from habit I have 
 pleasure in hardly anything except Natural History, for 
 nothing else makes me forget my ever-recurrent uncomfort- 
 able sensations.' 5 
 
 1868. The concluding sentences of the fol- 
 lowing passage are quoted on pages 64 and 65, 
 but it is of interest to print them again together 
 with the words that led up to them. The passage 
 first graphically describes the changes in Darwin's 
 mind, and then clearly explains and interprets 
 what has been so often and so injuriously mis- 
 understood. 6 
 
 ' I am glad you were at the ' Messiah ', it is the one 
 thing that I should like to hear again, but I dare say I 
 
 1 To J. D. Hooker : March b.Life and Letters, ii. 149. 
 
 2 To Asa Gray, Apr. 4. Life and Letters, ii. 155. 
 
 8 To T. H. Huxley, April 11. More Letters, i. 247. 
 
 4 To J. D. Hooker, Sept. 27. Life and Letters, iii. 40. 
 
 5 To J. D. Hooker, Feb. 3. Life and Letters, iii. 75. 
 
 6 See especially pp. 79-83. 
 
 S
 
 258 APPENDIX D 
 
 should find my soul too dried up to appreciate it as in old 
 days ; and then I should feel very flat, for it is a horrid bore 
 to feel as I constantly do, that I am a withered leaf for 
 every subject except Science. It sometimes makes me hate 
 Science, though God knows I ought to be thankful for such 
 a perennial interest, which makes me forget for some hours 
 every day my accursed stomach.' l 
 
 1869. ' I have been as yet in a very poor way ; it seems 
 as soon as the stimulus of mental work stops, my whole 
 strength gives way.' * 
 
 1876. ' and then home to work, which is my sole 
 pleasure in life.' 3 
 
 1878. ' Thank Heaven, we return home on Thursday, 
 and I shall be able to go on with my humdrum work, and 
 that makes me forget my daily discomfort.' 4 
 
 APPENDIX D 
 
 DE VBIES'S ' FLUCTUATIONS ' HEKEDITAKY AC- 
 CORDING TO DE VKIES, NON-TKANSMISSIBLE 
 ACCORDING TO BATESON AND PUNNETT 
 
 SINCE the note on p. 49 was written I have 
 had the opportunity of reading the whole of the 
 Presidential Address to the Zoological Section at 
 Winnipeg, a copy having been kindly sent to me 
 by my friend Dr. Shipley. I find that the account 
 of fluctuations which is so diametrically opposed 
 to that given by the author of this term in its 
 technical sense, is adopted from Mr. B. C. Punnett's 
 little work Mendelism (2nd edit., Cambridge, 1907), 
 a fact omitted from the necessarily abridged 
 
 1 To J. D. Hooker, June 17. Life and Letters, iii. 92. 
 
 2 To J. D. Hooker, June 22. Life attd Letters, iii. 106. 
 8 To G. J. Romanes, May 29. More Letters, i. 364. 
 
 4 To G. J. Romanes, Aug. 20. More Letters, ii. 48.
 
 BATESON ON 'FLUCTUATIONS' 259 
 
 report in the Times. While Dr. Shipley's words, 
 quoted on p. 49, are perhaps a little more precise 
 than those of Mr. Punnett, 1 Professor Bateson's 
 statement is more definite still : 
 
 'For the first time he [de Vries] pointed out the clear 
 distinction between the impermanent and n on- transmissible 
 variations which he speaks of as fluctuations, and the per- 
 manent and transmissible variations which he calls 
 mutations.' 2 
 
 Professor Bateson and Mr. Punnett are the 
 chief exponents of de Vries in this country. It 
 may be assumed, I think, that de Vries reaches 
 the British public through the 85 pages of 
 Mr. Punnett's booklet rather than through the 
 847 pages of the only volume by the Dutch 
 botanist which has until now appeared in the 
 English language. 3 The unfortunate misrepre- 
 sentation of de Vries is therefore certain to have 
 led, and, in spite of this correction, is still, I fear, 
 certain to lead, to utter confusion of thought in 
 a subject only too likely to become obscure 
 without adventitious assistance. 
 
 The extent of this unintentional, but very 
 serious, misrepresentation of an authority by his 
 exponent, can be most clearly shown by printing 
 together passages by de Vries and Bateson from 
 
 1 ' Of the inheritance of mutations there is no doubt. Of the 
 transmission of fluctuations there is no very strong evidence. It is 
 therefore reasonable to regard the mutation as the main, if not 
 the only, basis of evolution.' (p. 72.) 
 
 2 Mendel's Principles of Heredity, Cambridge (1909), 287. 
 
 3 Species and Varieties : their Origin by Mutation. Chicago and 
 London. Second edit., 1906. 
 
 S 2
 
 260 APPENDIX D 
 
 the same volume Darwin and Modern Science 
 (Cambridge, 1909). The following passage on 
 pp. 83 and 84 is written by de Vries : 
 
 ' Thus we see that the theory of the origin of species by 
 means of natural selection is quite independent of the 
 question, how the variations to be selected arise. They 
 may arise slowly, from simple fluctuations, or suddenly, by 
 mutations ; in both cases natural selection will take hold of 
 them, will multiply them if they are beneficial, and in the course 
 of time accumulate them, so as to produce that great diversity 
 of organic life, which we so highly admire.' 
 
 On p. 95, only eleven pages further on, we 
 find the following statement made by Professor 
 Bateson, a statement which entirely contradicts 
 the words I have italicized in the quotation from 
 de Vries : 
 
 ' First we must, as de Vries has shown, distinguish real, 
 genetic, variation from fluctuational variations, due to en- 
 vironmental and other accidents, which cannot be trans- 
 mitted.' 
 
 I freely grant that de Vries's statement, taken 
 as a whole, does not appear to be very consistent 
 with much that he has written. 1 He is stating 
 alternative views as to the origin of selected 
 variations, but the italicized words could never 
 have been written by one who did not maintain 
 the hereditary transmission of fluctuations ; and 
 this belief is, as will be shown below, implied in 
 many another passage, to be found with sufficient 
 labour in de Vries's voluminous and somewhat 
 obscurely written treatises. 
 
 1 See also Quartetiy Review (July, 1909;, 30.
 
 THE THREATENED CONFUSION 261 
 
 In a striking metaphor Professor Bateson has 
 objected to the use of the term 'variation' to 
 express certain different forms presented by the 
 individuals of a species : ' We might as well,' he 
 says with a fine scorn, ' use one term to denote 
 the differences between a bar of silver, a stick of 
 lunar caustic, a shilling, or a teaspoon.' 1 It 
 would indeed be unreasonable thus to denote 
 the differences between those objects, although 
 their agreement may be quite properly expressed 
 by the single phra.se * forms of silver '. ' Variation,' 
 too, may be reasonably used in a generic sense to 
 cover many widely different departures from what 
 is regarded as the normal form of a species. But, 
 to make use of Professor Bateson's metaphor, 
 we are now threatened with the sort of confusion 
 that would arise if (1) A declared that the word 
 ' teaspoon ' meant a teaspoon, and (2) B and C 
 spread broadcast the statement that A had really 
 applied this term not to a teaspoon at all, but to 
 a shilling. 
 
 It is probable that Professor Bateson's and 
 Mr. Punnett's error arose when they became 
 aware that de Vries attributed 'fluctuations' to 
 nutrition, using this term in a broad sense. They 
 do not appear to have realized that, whereas 
 regression rendered evident through heredity is 
 the essential element in de Vries's ' fluctuations ', 
 the opinion that they are acquired is quite 
 unessential. De Vries, in fact, treats the trans- 
 
 1 Report Brit. Assoc., Cambr. (1904), 576.
 
 262 APPENDIX D 
 
 mission of acquired characters with a levity justly 
 rebuked by Mr. R. H. Lock in the following 
 
 ' . . . de Vries believes that individual variability de- 
 pends entirely upon nutrition ; but under this head he 
 includes practically the whole environment of plants 
 light, space, soil, moisture, and the like. Characters ac- 
 quired in a similar way by previous generations are inherited, 
 and the effect of conditions upon the developing seed whilst 
 still borne upon the parent plant may be considerable. 
 Thus easily does de Vries dispose of the puzzling question 
 of the inheritance or non-inheritance of acquired characters. 
 Acquired characters are inherited ; they are not of any 
 importance in the origin of species.' 1 
 
 It will now be well to show from several 
 passages that de Vries considers ' fluctuations ' to 
 be hereditary, and that the limits which he 
 assigns to them only become manifest by means 
 of heredity. 
 
 ' . . . we must,' says Mr. Punnett, ' recognise 
 with de Vries the type of variation which he has 
 termed fluctuating.' 2 In order to ensure an 
 accurate recognition it will be safest to quote 
 de Vries's words. 
 
 (1) In the celebrated Mutationstheorie (Leipzig, 
 1901, I.) de Vries states that, in advocating the 
 use of the term ' fluctuation ', he is merely adopt- 
 ing a word often used by Darwin himself. Thus, 
 
 1 Variation, Heredity and Evolution, London, 1909, 2nd Ed., 
 155. See also passage (1) quoted from Mr. Lock on p. 270. 
 
 2 Mendelism, R. C. Punnett, 2nd Ed., Cambr. (1907), 70. 
 
 3 An example ofDarwin's use of the words 'fluctuating variability ' 
 is to be found in the following passage from a deeply interesting
 
 DE VRIES ON 'FLUCTUATIONS' 263 
 
 speaking of * individual variability *, he says on 
 pages 36 and 37 :' This [form of] variability has 
 been termed, fluctuating, gradual, continued, rever- 
 sible, limited, statistical, and individual. The latter 
 designation appears to be most widely spread in 
 the domain of zoology and anthropology, whilst 
 the term fluctuating or flowing which was 
 frequently used by Darwin, ought certainly to be 
 the best.' That regression, only evident through 
 heredity, is characteristic of fluctuations, is stated 
 on p. 38: 'Individual variability is, by propaga- 
 tion [literally by sowing], revertent into itself.' 
 Again, on pages 38 and 39 : 
 
 ' Auf dem Gebiete der individuellen Variabilitat fiihrt die 
 Selection zu der Entstehung der Rassen. Dabei ist aber, wie 
 wir bereits gesehen haben, dieses letztere Wort in einem 
 anderen Sinne gebrauchlich, als in der Anthropologie. 1 
 Die principielle Differenz dieser sogenannten veredelten 
 Rasse einerseits mit Varietaten, Unterarten, elementaren 
 
 letter, criticizing the hypothesis of the direct influence ot environ- 
 ment as a motive cause of evolution : 
 
 ' In ' regard to thorns and spines I suppose that stunted and 
 [illegible] hardened processes were primarily left by the abortion 
 of various appendages, but I must believe that their extreme 
 sharpness and hardness is the result of fluctuating variability and 
 the " survival of the fittest ".' In a letter to G. H. Lewes, Aug. 7, 
 1868. More Letters, i. 308. 
 
 1 De Vries is here referring to p. 29, where he distinguishes the 
 two kinds of races as follows. It will be seen that the hereditary 
 transmission of fluctuations selected by the breeder is even more 
 clearly expressed than in the passage quoted in the text: 
 
 ' Aber das Wort Rassen hat bekanntlich eine doppelte Bedeutung. 
 Es bedeutet sowohl die durch Selection veredelten Rassen unserer 
 Ziichter, als auch die vorhandenen, constanten Unterarten unbe- 
 kannter Abstammung.' 
 
 1 [' But the word races has, as we all know, a double meaning. It 
 signifies races improved by the selection of our breeders as well as 
 existing, constant sub-species of unknown origin.']
 
 264 APPENDIX D 
 
 Arten, incipient species u. s. w. andererseits, soil den 
 Gegenstand unseres dritten Kapitels bilden.' 
 
 ['Within the domain of individual variability selection 
 leads to the origin of races, but, in considering this question, 
 as we have already seen, this latter word [races] is used in 
 a different sense to that employed in Anthropology. The 
 essential characteristics of this so-called improved race, on 
 the one hand, and of, on the other hand, varieties, sub- 
 species, elementary species, incipient species, &c., &c., will 
 constitute the subject-matter of my third chapter.'] 
 
 I would ask how it is possible for races to arise 
 or to be improved by the selection of individual 
 variations (or fluctuations) if it be supposed that 
 those latter are non-transmissible by heredity. 
 
 The German of the latter part of the passage 
 quoted on pp. 263-4 is not very clearly expressed. 
 My friends who are experienced in the rendering 
 of German into English have generally found 
 themselves puzzled by it, at any rate on a first 
 reading. Professor A. A. Macdonell tells me 
 that the obscurity is due to the use of ' mit ' for 
 ' und der '. At the same time he is sure that the 
 ' einerseits ' and ' andererseits ' express a contrast 
 which is unintentionally softened down by the 
 use of ' mit '. This conclusion, based on purely 
 linguistic grounds, is confirmed by a consideration 
 of the subject-matter ; for every student of de 
 Vries knows that all the forms in the category 
 beginning ' Varieta' ten ' are explained by him as 
 ' mutations ', and are as a matter of fact in many 
 parts of his works sharply contrasted with the 
 products derived by selection from * fluctuations '.
 
 DE VRIES ON 'FLUCTUATIONS' 265 
 
 I have considered these passages in some 
 detail because Dr. Shipley informs me that the 
 interpretation of de Vries's * fluctuations ' as non- 
 transmissible by heredity is based upon this 
 portion of the first volume of the Mutationstlieorie. 
 
 (2) Speaking of the means by which the in- 
 dividual steps of evolution are brought about, 
 de Vries says : 
 
 ' On this point Darwin has recognized two possibilities. 
 One means of change lies in the sudden and spontaneous 
 production of new forms from the old stock. The other 
 method is the gradual accumulation of those always present 
 and ever fluctuating variations which are indicated by the 
 common assertion that no two individuals of a given race 
 are exactly alike. The first changes are what we now call 
 " mutations ", the second are designated as " individual 
 variations ", or as this term is often used in another sense, 
 as " fluctuations ". Darwin recognized both lines of evo- 
 lution ; Wallace disregarded the sudden changes and pro- 
 posed fluctuations as the exclusive factor.' * 
 
 It has been abundantly shown in the present 
 volume (pp. 43, 44, 254-6) that de Vries is wholly 
 mistaken in ascribing to Darwin a belief in 
 evolution by mutation, and in maintaining that 
 there was in this respect any difference between 
 the two discoverers of Natural Selection. It is 
 amusing to observe the reason given by de Vries 
 for preferring the term * fluctuation '. May we 
 hope that he will abandon the word now that it 
 too ' is often used in another sense ' ? 
 
 1 Hugo de Vries, Species and Varieties : their Origin by Mutation. 
 Second Ed., Chicago and London (1906), 7, 8.
 
 266 APPENDIX D 
 
 Fluctuations are, according to de Vries, unable, 
 however rigidly and however long selected, to 
 lead to progressive evolution. The following 
 passages in which this belief is expressed, assert 
 perfectly clearly that these limitations rashly 
 assumed to be permanent are revealed by means 
 of heredity. They also plainly show that de 
 Vries, in maintaining the uselessness of 'fluctua- 
 tions ' as the material for progressive evolution, is 
 merely availing himself of a principle established 
 much earlier and on far firmer grounds by 
 Francis Galton the well-known principle of 
 ' recession towards mediocrity ' : 
 
 (3) ' Fluctuations always oscillate round an average, and 
 if removed from this for some time, they show a tendency 
 to return to it. This tendency, called retrogression, has 
 never been observed to fail, as it should, in order to free the 
 new strain from the links with the average, while new 
 species and new varieties are seen to be quite free from 
 their ancestors and not linked to them by intermediates.' ' 
 
 In the following passage, as well as in (5), 
 de Vries is of course referring to * fluctuations ' : 
 
 (4) ' . . . Long-continued selection has absolutely no 
 appreciable effect. Of course I do not deny the splendid 
 results of selection during the first few years, nor the 
 necessity of continued selection to keep the improved races 
 to the height of their ameliorated qualities. I only wish 
 to state that the work of selection here finds its limit and 
 that centuries and perhaps geologic periods of continued 
 effort in the same direction are not capable of adding any- 
 thing more to the initial effect' 2 
 
 1 Species and Varieties, 18. Ibid., 790-1.
 
 DE VRIES ON 'FLUCTUATIONS' 267 
 
 After reading the impetuous conclusions ex- 
 pressed at the end of the last-quoted passage, it is 
 refreshing to turn to Darwin's calm and convinc- 
 ing statement in the letter quoted on p. 48. 
 
 (5) ' Even sugar-beets, the oldest " selected " agricultural 
 plants are far from having freed themselves from the 
 necessity of continuous improvement. Without this they 
 would not remain constant, but would retrograde with 
 great rapidity.' J 
 
 It will now be of interest to inquire howde Vries's 
 ' fluctuations ' have been understood by others, and 
 especially by his friend and fellow countryman, 
 Professor A. A. W. Hubrecht, the distinguished 
 zoologist. A few years ago Professor Hubrecht 
 wrote an account of de Vries's contributions to 
 evolutionary thought in the Popular Science 
 Monthly? The editor has added the following 
 note to the article (p. 205) : ' This article was 
 written in English by Professor Hubrecht, the 
 eminent Dutch zoologist, who has an equal com- 
 mand of the French and German languages.' 
 Every one who has the privilege of the friendship 
 of Professor Hubrecht and knows of his great 
 linguistic powers will agree that probably no 
 other man is so qualified to express de Vries's 
 precise meaning in the English language. I 
 select seven passages from the article in question. 
 All of them would be meaningless if ' fluctuations' 
 are supposed to be non-transmissible by heredity. 
 
 1 Species and Varieties, 109. 
 
 2 For J uly, 1904 : 205-23, ' Hugo de Vries's Theory of Mutations.'
 
 268 APPENDIX D 
 
 (1) 'The different degrees of fluctuating variability can 
 undoubtedly be seized upon by any one who wishes to make 
 them the starting-point for the breeding of certain distinct 
 variations. Thus, for instance, by constantly selecting for 
 the reproductive process those plants in which a given 
 deviation is strongly marked, after a certain time and after 
 a series of generations, a plant can be obtained for which the 
 Galton curve would indicate a displacement of its culminating 
 point in the direction of the selected variation. In this way an 
 increase in the yield of sugar obtained from the beet roots 
 has been arrived at from about 7 per cent, to 13 or 14 per 
 cent. Thus also ears of maize have been produced that 
 bore 20 rows of grain, whereas the kind from which the 
 experiment had started always bore 12 to 14 rows. 
 
 ' As soon, however, as such conscious and voluntary selec- 
 tion ceases, the next generations successively return to the 
 original curve.' (p. 209.) 
 
 (2) ' . . . breeding variations to the right or to the left 
 of the norm, can never exceed certain limits. Agencies are 
 at work there which prevent the fluctuating variability 
 from going any further. The existence of such limits 
 compels us to acknowledge that there is no possibility that 
 species might arise in nature according to the same plan 
 by which certain breeds originate under artificial selection.' 
 (pp. 209-10). 
 
 (3) 'We have seen that fluctuating variability leads to 
 slow changes and furnishes farmers with the material to 
 improve the races of animals and plants.' (p. 210.) 
 
 (4) * ... by means of fluctuating variability certain local 
 and improved races may indeed be bred, but that in nature 
 new species never arise through its agency.' (p. 210.) 
 
 (5) ' As long as the mutation has not appeared, there can 
 be no question of the origin of a new species ; the species is 
 then constant, and only submitted to fluctuating variability, 
 which can produce local races (not elementary species) under 
 the constant cooperation (either artificial or natural) of 
 selection, but which never leads to the formation of species.' 
 (p. 216.) 
 
 (6) ' The elementary species are stable. Selection calls
 
 HUBRECHT ON 'FLUCTUATIONS' 269 
 
 forth different races within the limits of these species, but 
 whenever selection ceases the race is turned back to the 
 parent form. The maximum deviation in these races is 
 generally obtained after three or four generations of con- 
 tinuous selection ; it takes about as many generations to 
 bring back the parent form.' (p. 219.) 
 
 (7) ' The fact that artificial selection of fluctuating varieties, 
 as well as hybridizing, etc., has already led to such indis- 
 putable improvements in the different races of animals and 
 plants may, however, etc.' (p. 223.) 
 
 Finally in an article only published about a 
 year ago in the Contemporary Review l Professor 
 Hubrecht says : 
 
 'Wherever our agriculturist succeeds by the most 
 careful artificial selection in producing (e. g.} a beetroot of 
 which the percentage of sugar has been raised, say, to 15 per 
 cent, out of roots which originally stood at 7 to 8 per cent., 
 he knows that the fluctuating variation of the beetroot has 
 permitted him to attain this end ; but he knows, at the 
 same time, that what he has obtained is not a new species 
 of beetroot, richer in sugar, but a product of nature which 
 the moment it is left to itself and freed from the bonds of 
 artificial selection goes back to an inferior sugar-producing 
 root again.' (p. 633.) 
 
 I will now prove, although more briefly, that 
 other writers have understood de Vries cor- 
 rectly. The sectional heading employed by 
 Professor C. B. Davenport * MUTATION vs. SUM- 
 MATION OF FLUCTUATIONS ' 2 is sufficient to show 
 this ; for summation would be impossible without 
 hereditary transmission. We do not, however, 
 
 if 
 
 1 For Nov., 1908, 'Darwinism versus Wallaceism.' 
 a Fifty Years of Darwinism, New York (1909), 173.
 
 270 APPENDIX D 
 
 need to base our proofs upon inference, for Prof. 
 Davenport makes the following clear statement : 
 
 * Does the breeder actually introduce new characters into 
 the organic world by summating fluctuations? De Vries 
 insists that the improvement that follows selection nearly 
 or wholly ceases after four or five generations, and if selection 
 be abandoned the race rapidly returns to its primitive 
 condition.' 1 
 
 The two following passages are quoted from 
 Mr. K.H. Lock's book 2 : 
 
 (1) ' There are some, including de Vries, who regard all 
 fluctuating variations (individual differences) as being of the 
 nature of acquired characters, and as being at the same time 
 capable of hereditary transmission, although de Vries 
 believes the amount of progress possible in this way to be 
 strictly limited.' (p. 75 ; see also the passage quoted from 
 Mr. Lock on p. 262.) 
 
 (2) ' The actual effect of this kind of selection is well 
 illustrated by the results of the processes employed in the 
 sugar-beet industry, in which elaborate care is taken to 
 select those roots which contain the highest percentage of 
 sugar for the purpose of propagation. This process was 
 followed at first by a rapid improvement, but the rate at 
 which the percentage of sugar increased soon fell off, until 
 at the present day all that selection can effect is to keep up 
 the standard of excellence already attained. 
 
 * * * 
 
 ' There is no reason to doubt that a thoroughly efficient 
 method of selection would have worked its full effect in 
 a few generations. 
 
 * * * 
 
 'From his own experiments, de Vries has come to the 
 conclusion that, when selection is really efficient, the full 
 possible effect of this process is exhausted in quite a small 
 
 1 Fifty Years of Darwinism, New York (1909), 173-4. 
 
 2 Variation, Heredity and Evolution. London, 1909. Second Ed.
 
 OTHER WEITERS ON 'FLUCTUATIONS' 271 
 
 number of generations, and that then the only further effect 
 of selection is to keep up the standard already arrived at.' 
 (pp. 135-6.) 
 
 Professor J. Arthur Thomson a in the first of 
 the following passages clearly states the germinal 
 origin of fluctuations, in the second correctly 
 expresses de Vries's conclusions : 
 
 (1) * . . . when we collect a large number of specimens of 
 the same age from the same place at the same time, we 
 often find that no two are exactly alike. They have peculi- 
 arities of germinal origin or, in other words, they show 
 individual or fluctuating variations.' (p. 78.) 
 
 (2) ' Fluctuations do not lead to a permanent change in 
 the mean of the species unless there be a very rigorous 
 selection, and even then, if the selection be slackened, there 
 is regression to the old mean : mutations lead per saltum to 
 a new specific position, and there is no regression to the old 
 mean.' (p. 98.) 
 
 I have brought perhaps unnecessarily ample 
 evidence in support of the fact that de Vries's 
 1 fluctuations ' are assumed by him to be trans- 
 missible by heredity, and that this assumption is 
 an essential element in the author's definition of 
 his technical term. When we remember that 
 they are just the * individual differences ' of 
 Darwin, and that de Vries's belief in their power- 
 lessness for continued evolution is based on Francis 
 Galton's well-known law of recession, it is really 
 waste of time to inquire whether they are trans- 
 missible. But such positive statements to the 
 contrary have been made by the most prominent 
 
 1 Heredity, London, 1908.
 
 272 APPENDIX D 
 
 supporter of de Vries in this country statements 
 accepted and widely circulated by others that it 
 appeared expedient to produce even redundant 
 proof that the Dutch botanist has been uninten- 
 tionally but fundamentally misrepresented in a 
 matter of supreme importance. 
 
 In conclusion I think it may be convenient to 
 sum up briefly a few opinions that have been 
 expressed during the past fifty years as to the 
 variations which form the steps of evolutionary 
 progress. Such a short statement, which I will 
 endeavour to express as clearly as possible, may 
 do something to bring within reasonable limits 
 those unduly exaggerated estimates of recent 
 achievement which tend in the long run to 
 diminish rather than to exalt the fame of an 
 investigator. 
 
 CHARLES DARWIN. It has been shown on 
 many pages of this book that Darwin recognized 
 large variations transitional into individual dif- 
 ferences, but that, with A. K. Wallace, he 
 believed the onward steps of evolution were 
 supplied by the latter and not by the former. 1 
 He admitted that advance might be arrested by 
 
 1 The following passage is quoted from p. 45 of the 1st Edition 
 of the Origin:' Again, we have many slight differences which may 
 be called individual differences, such as are known frequently to 
 appear in the offspring from the same parents, or which may be 
 presumed to have thus arisen, . . . ' ' These individual differences 
 are highly important for us, as they afford materials for natural 
 selection to accumulate, in the same manner as man can ac- 
 cumulate in any given direction individual differences in his 
 domesticated productions.'
 
 DAKWIN ON EVOLUTION 273 
 
 the limits of variation, but did not believe that 
 the limits were necessarily permanent. He held 
 that the appearance of variations was an indirect 
 response to the conditions of life, their character 
 being determined by internal causes and not by 
 the nature of the external stimulus. 
 
 It is generally assumed that Darwin did not 
 consider the question of the hereditary trans- 
 mission of acquired characters. Professor Meldola 
 has, however, pointed out to me the following 
 interesting passage which has appeared, with only 
 the slightest verbal change, in all editions of the 
 Origin : 
 
 ' Some authors use the term " variation " in a technical 
 sense, as implying a modification directly due to the 
 physical conditions of life ; and " variations " in this sense 
 are supposed not to be inherited : but who can say that 
 the dwarfed condition of shells in the brackish waters of 
 the Baltic, or dwarfed plants on Alpine summits, or the 
 thicker fur of an animal from far northwards, would not in 
 some cases be inherited for at least some few generations ? 
 and in this case I presume that the form would be called 
 a variety '(1st Ed., 44, 45). 
 
 Mr. Francis Darwin can throw no light upon 
 the * authors ' referred to. It is deeply interesting 
 to observe that Darwin did not, even in 1844, 
 believe in the inheritance of the effects of 
 mutilation or of mechanical pressure. 1 
 
 FRANCIS GALTON investigated the hereditary 
 transmission of individual differences and proved 
 
 1 Tlve Foundations of the Origin of Species, Cambridge (1909), 
 60-1. 
 
 T
 
 274 APPENDIX D 
 
 that many are subject to the law of ' recession 
 towards mediocrity '. He considered that evolu- 
 tion proceeds by the selection of large variations 
 (saltation) as well as of small. He suggested 
 that certain variations do not obey the law of 
 recession, but are the expression of a sudden leap 
 to a new position of genetic stability. He thus 
 anticipated de Vries in both ' Fluctuations ' and 
 1 Mutations ', proposing for the latter type of 
 variation the far better and far more descriptive 
 term ' transilient '. 
 
 The conclusion that evolution has been 'dis- 
 continuous', proceeding by means of relatively 
 large steps, was urged with much vigour by 
 Professor Bateson in his work On Variation (1894). 
 It was in a review of this book that Galton pro- 
 posed the term 'transilient', although the opinion 
 that evolution may take place by large steps 
 had been expressed by him at a much earlier 
 date. 
 
 AUGUST WEISMANN revealed the unsubstantial 
 nature of the evidence on which the hereditary 
 transmission of acquired characters l was believed. 
 
 1 It may be convenient to quote three passages from the author's 
 Essays on Evolution (1908) : 
 
 (1) ' For the question ' Are acquired characters hereditary ? ' 
 it would be more accurate to substitute ' Can the acquired char- 
 acters of the parent be handed down as inherent characters in the 
 offspring ? " (p. 144). 
 
 (2) ' It is in no way necessary that the acquired elements of a char- 
 acter should be disentangled from the inherent elements, if only we 
 can prove that the character as a whole is dependent upon a con- 
 trollable external cause, and is therefore itself controllable. In 
 fact we speak of a character as ' acquired ' just as we speak of an 
 article as ' manufactured', although the result itself is a complex
 
 GALTON AND WEISMANN 275 
 
 His teachings have led to the general, but not 
 the universal, abandonment of the Lamarckian 
 element in evolution as Darwin conceived of 
 it. They receive support from the numerous 
 Mendelian and Mutationist researches which 
 lead to the conviction that variation is essentially 
 of germinal origin. 
 
 Weismann's conceptions of evolution are as 
 much affected by the facts of adaptation as were 
 those of Darwin himself, and he is equally con- 
 vinced that the onward progress of evolution has 
 been by small steps and not by large ones. 
 
 In speaking of 'acquired characters' it may 
 not be out of place to point out that every 
 character contains acquired elements, because en- 
 vironmental influence of some kind is necessary 
 for the existence of all characters. When the 
 differences between corresponding characters in 
 different individuals can be traced to environmental 
 influences the characters are called acquired, when 
 they can be traced to germinal influence they are 
 called inherent. ' Environmental influence ' is 
 here used in the broadest sense and includes the 
 other parts of the same organism. Thus the use 
 or disuse of a part, when determined by the 
 brain, is no less an acquired character than when 
 it is imposed by the conditions of the external 
 world. 
 
 of the properties of natural substances and of changes introduced 
 by art' (p. 144). 
 
 (3) ' Whenever change in the environment regularly produces 
 appreciable change in an organism, such difference may be called 
 an acquired character ' (p. 143). 
 
 T2
 
 276 APPENDIX D 
 
 HUGO DE VRIES considered himself led by his 
 work on the Evening Primroses and by confirm- 
 ing Galton's law of 'recession towards medio- 
 crity ', to the conclusion that evolution proceeds 
 by Mutation or Transilience alone, and that 
 individual differences, called by him 'fluctua- 
 tions', do not lead to marked or permanent 
 change. He does not hesitate to conclude that 
 'fluctuations' are both hereditary and acquired, 
 and that evolution proceeds by the intermittent 
 explosive discharge of an internal transforming 
 force. According to de Vries, the role of Natural 
 Selection is to determine the survival of the fittest 
 among the Mutations scattered in all directions 
 by species during their explosive periods. 
 
 GKEGOR MENDEL. The thoughts of this wonder- 
 ful man should follow those of Darwin, but his 
 great discoveries were so long lost to the world, 
 that their final recognition has produced the most 
 recent of all the phases of evolutionary thought. 
 We are led by Mendel's researches, which it is 
 unnecessary to describe, to the conception of ' unit 
 characters ' : 
 
 'By a unit character in the sense of Mendel's law, we 
 mean any quality or part of an organism, or assemblage of 
 qualities or parts, which can be shown to be transmitted in 
 heredity as a whole and independently of other qualities 
 or parts.' * 
 
 We are also led to the conclusion that a unit 
 character is represented in the germ-cell by a 
 
 1 W. E. Castle, in Fifty Years of Darwinism (1909;, 146.
 
 DE VRIES AND MENDEL 277 
 
 determinant (which may consist of one or several 
 factors) or by many linked determinants. For 
 those who hold that the transformation of species 
 proceeds not by the modification but by the 
 addition of new or the subtraction of old unit 
 characters (in the above sense) these conclusions, 
 founded on Mendelian research, are of supreme 
 importance in evolution. Professor Bateson has 
 recently prophesied : 
 
 ' ... we see Variation shaping itself as a definite, physio- 
 logical event, the addition or omission of one or more definite 
 elements ; and Eeversion as that particular addition or 
 subtraction which brings the total of the elements back to 
 something it had been before in the history of the race.' l 
 
 To those who believe that the outcome of 
 Mendelian research does not bring any essential 
 change in the conception of evolution received 
 from Darwin, the results are still of supreme 
 interest and importance. Just as the splendid 
 cytological work of the past half century helps 
 us to form a picture of the mechanism of fertiliza- 
 tion and of heredity but does not alter our con- 
 ceptions of evolution, so is it with Mendelian 
 research. Upon fertilization and heredity it sheds 
 an even stronger, surer light than that thrown 
 by cytology. We are enabled to understand by 
 the help of examples which obey Mendel's law 
 something of the general, perhaps the universal, 
 mechanism of heredity. This performance and 
 the promise of deeper knowledge in the future 
 
 1 The Methods and Scope of Genetics, Cambridge (1908), 48.
 
 278 APPENDIX D 
 
 are enough to stamp Mendel's discovery as among 
 the greatest in the history of the biological sciences. 
 But it does not alter the Darwin- Wallace concep- 
 tion of evolution in nature. 
 
 The pattern of each mimetic form of the poly- 
 morphic female of Papilio dardanus is a complex 
 unit character as denned by Castle, yet all of 
 them exhibit clear evidence of a past history of 
 'continuous' improvement in the likeness to 
 their respective models. 
 
 Sports such as those which arise by the dropping 
 out of some definite element and the consequent 
 sudden change to white of the whole or a part 
 of the pigment of an animal or flower, are a type 
 of the appearances which are attractive and 
 interesting to man, and have become subject 
 to artificial selection. And it is with material 
 thus derived that nearly the whole of Mendelian 
 research has been hitherto concerned. Selection 
 may occasionally operate along similar lines in 
 nature, as when an animal migrates into some 
 snow-covered area, but no one who has reflected 
 much upon the struggle for existence can believe 
 that it is the usual method of evolution. 
 
 Similarly with regard to the limited advance 
 that is possible when fluctuating variability is 
 artificially selected. Man is able, in a few genera- 
 tions, to double the percentage of sugar produced 
 by the beet. By selecting for this quality alone, 
 he profoundly modifies the relationship of one 
 particular function to the plant as a whole, and
 
 ARTIFICIAL v. NATURAL SELECTION 279 
 
 after a time finds that, within the limited 
 period of his endeavour, he can go no further. 
 But Natural Selection does not operate in this 
 way upon single qualities. Every quality of direct 
 or indirect value to the organism and at the same 
 time the inter-relationships of all qualities, are 
 selected simultaneously. Artificial selection does 
 not give us a true picture of the method of nature. 
 
 Darwin, as I have said, held that the steps 
 of evolution were built out of small individual 
 differences. He did not doubt that these could 
 be accumulated by selection, but he was prepared 
 to believe that there would be halts. I have 
 always foreseen that the Mutationist would finally 
 'hedge' by claiming as mutations the minute 
 differences on which Darwin relied. 1 This 
 tendency is very clearly seen in Mr. Punnett's 
 little book 2 : 
 
 ' Doubtless some of the so-called fluctuations are in reality 
 small mutations, whilst others are due to environmental 
 influence ' (p. 72). 
 
 'A cursory examination of horticultural literature must 
 convince anyone, that it is by selection of mutations, often 
 very small, that the gardener improves his varieties. 
 Evolution takes place through the action of selection on 
 these mutations ' (p. 74). 
 
 As the Mutationist comes to study the details 
 of adaptation, and as further fossil records pre- 
 served under peculiarly favourable conditions are 
 
 
 
 1 Essays on Evolution, xxxviii, xxxix. 
 
 2 Mendelism.
 
 280 APPENDIX D 
 
 carefully examined, 1 we may feel confident that 
 the belief in an evolution founded on large 
 mutations will vanish, and we shall then come 
 back to mutations identical in every respect with 
 the small variations which were for Darwin the 
 steps of evolution. 
 
 A humorist has suggested that the Homer 
 controversy should be settled by a general agree- 
 ment that the Iliad was written not by Homer 
 but by another man with the same name. Those 
 who have heralded with such a flourish of trum- 
 pets the profound changes which they assume 
 to be necessary in the Darwinian conception of 
 evolution, may yet ' save their face ' by calling 
 the same thing by another name. 
 
 1 Dr. Arthur W. Howe's researches on the fossils of the white 
 chalk are an admirable example. See the Quarterly Review (July, 
 1909), 19, 20.
 
 INDEX 
 
 The words ' Darwin to ' refer to letters from Charles Darwin 
 quoted in this work. 
 
 Abraxas grossulariata, taste of. 
 242 n. 1. 
 
 Achaea chamaeleon piercing 
 peaches, 224 n. 1. 
 
 Acquired characters, early uses 
 of terms, 3 n. 2 ; Beccari on, 20 ; 
 Lamarckism and, 33-42; ' fluc- 
 tuations' and, 49 n.l ; Darwin 
 on the transmission of, 273 ; 
 de Vries do., 261-2, 270, 276; 
 Poulton do., 274 n. 1 ; Weis- 
 mann do., 274-5. 
 
 Acraea, 239. 
 
 johnstoni, 130. 
 
 Acraeinae, as models, 152-3, 
 178-9 ; as possible mimics, 
 154 n. 1. 
 
 ' Acraeoid Heliconidae ', of 
 Bates, 153. 
 
 Adaptation, memory and, 40 ; 
 teleology and, 94-8; natural 
 selection and, 98-101 ; muta- 
 tion and, 279. 
 
 Adelpha, mimicked in S.America 
 by Chlorippe, &c., 176 ; in N. 
 and Central America by Li- 
 menitis, 192-3, 197, 207-8, 
 208 n. 1 ; lerna, 192 ; 
 dyonysa, 192 ; fessonia, 192 ; 
 massilia, 192. 
 
 Aden, 157. 
 
 Aeneas group ofPharmacophagus, 
 178. 
 
 Africa, 157 ; thorn-bearing 
 plants in, 98; butterfly models 
 
 x in, 152-3 ; mimicry in, 161. 
 
 Agassiz, A., support to Darwin 
 
 by, 2. 
 
 Agassiz, L., opposed to Darwin, 
 23, 54-5 ; Darwin to, 68-9. 
 
 Albany, N.Y., stripeless L. arch- 
 ippus at, 166 n. 2, 211-12. 
 
 albens, Physianthtt*, 225, 225 n.l. 
 
 albinism, 251. 
 
 Aleutian Islands, 162. 
 
 Alpine forms often arctic,45, 123, 
 123 n. 2 ; plants dwarfed, 
 273. 
 
 Alydus, mimicking ants, 116. 
 
 Amazons, 126. 
 
 America : see also ' N. America ' 
 and ' S. America ' ; evolution 
 in, 1-3 ; palaeontology in, 2-3; 
 probably uninhabited by early 
 man, 35 n. 2 ; Pharmacopha- 
 gus in, 177-81. 
 
 American Assoc. Adv. Sci., viii, 
 1, 48, 57, 154, 156 ; Darwin 
 Centenary of the, viii, 1, 57. 
 
 American Naturalist, 142. 
 
 americus, subsp. of Pap. poly- 
 xenes, 184. 
 
 Amphidesmus analis, mimick- 
 ing a Lycid beetle, 121-2. 
 
 ampliata, f. of Pap. asterius, 182. 
 
 Anacampseros papyracea, re- 
 semblance to dung of birds, 
 102 n. 2. 
 
 Ancestral forms, preservation 
 of, 46-7. 
 
 Anchisiades, group of ' Papilio ', 
 182. 
 
 Animals and Plants under Do- 
 mestication, C. Darwin, 68. 
 
 Annals and Mag. Nat. Hist., 229 
 n. 1.
 
 INDEX 
 
 Annals of Botany, 97 n. 1, 102 
 n. 2. 
 
 Anosia, see also ' Danaida ' ; 
 154-8, 158 n. 3; a recent 
 colonist of Fiji, &c., 155; 
 plexippus, 152 n. 1, 154, 
 158-9, 158 . 3, 161-4, 168- 
 73, 177, 204-5 ; a foreign ele- 
 ment in N. World, 204. 
 
 Ansted, D. T., Darwin to, 131. 
 
 Antagonism falsely assumed be- 
 tween science and literature, 
 79-83. 
 
 antenor. Pharm., of Madagascar, 
 177. 
 
 Ants, as models for mimicry, 
 115-18. 
 
 Apatura, mimicking Limenitis, 
 175-6. 
 
 Apocyneae, 217 ; capturing Di- 
 ptera, 225. 
 
 Aposematic colours, 110-12. 
 
 Araschnia levnna, mimicking 
 Limenitis, 176. 
 
 Archaeopteryx, discussed at Brit. 
 Assoc. (1881), 29, 30. 
 
 atvhippus, Limenitis, 137, 155, 
 161, 164-72, 176, 186-8, 191, 
 199, 204-5; evolution of 
 mimicry in, 164-8 ; stripeless 
 var. at Albany, 166 n. 2, 
 211-12. 
 
 arctic alpine forms, 123, 123 
 n. 2. 
 
 Arctiidae, as mimics, 121. 
 
 Argyll, Duke of, on natural 
 selection, 44 ; criticisms by, 
 251-3 ; Darwin to, 251-2. 
 
 Argynnis diana, female of 
 mimics, L. astya- 
 nax, 189, 207. 
 niphe, female of 
 mimics, D. chry sip- 
 pus, 161. 
 
 arietta, Clytus, 115. 
 
 Aristolochia and allies, food- 
 plants ofPharmacophagu8,m. 
 
 1 Aristolochia swallow - tails ' 
 (Pharmacophagus), as models, 
 137, 177-81, 206-7. 
 
 Aristotle, 83. 
 
 Arizona, 176, 192-3, 205, 208. 
 
 Arrhenius, S., on origin of life, 
 45. 
 
 arthemis, Limenitis, 137, 164-6, 
 172, 176, 186-8, 196, 204-5, 
 207 ; the ancestor of L. arch- 
 ippus, 164-8, 204-5; and of 
 L. astyanax, 186-8, 205, 207. 
 
 artificial versus natural selec- 
 tion, 278-9. 
 
 | Asdepiadae, food-plant of Dan- 
 ainae, 162 ; insects and pol- 
 len-masses of, 217, 225-6, 225 
 n.2. 
 
 Ashmolean Museum, Oxford, 
 95-6. 
 
 ' assembling ' of males of ' Oak 
 Eggar ' moth, 230 n. 2, 235, 
 235 n. 1,242, 242 . 1. 
 
 asterius, subsp. of Papilio poly- 
 xenes, 182-5, 188, 206. 
 
 astyanax, Limenitis, 172, 186-91, 
 199, 205, 207. 
 
 asyllus, Euploea, mimicked by 
 a Danaida (Salatwa), 160. 
 
 Athenaeum, 15. 
 
 Atlantic States, 186. 
 
 Atolls, 45. 
 
 Attidae, mimickingants, 116-17. 
 
 Australia, 155 ; insects captured 
 by Darwin in, 202-3. 
 
 1 Autobiography of Charles Dar- 
 win ', 51, 58 n. 2, 59, 60, 63-4, 
 66, 74-6, 75 n. 2, 85 n. 1, 99 
 n. 1, 100, 103, 123 n. 2, 140. 
 
 Avebury, Lord, on Darwin's 
 gardener, 71 ; Darwin to, 203. 
 
 Bakewell, shorthorn cattle made 
 by, 492. 
 
 Baldwin, J. M., on organic selec- 
 tion, 3, 48; on Psychology 
 and natural selection, 3 ; on 
 grip of social environment, 
 27. 
 
 i Balfour, A. J., speech at Cam- 
 bridge centenary by, 84. 
 1 Baltic shells dwarfed, 273. 
 
 bartata, Disa, 220 n. 1. 
 
 Barber, Mrs. M. E., on P. nirevs 
 pupae, 109.
 
 INDEX 
 
 Basilarchia, a subgenus of 
 Limenitis, q. v. 
 
 Batchian, 233. 
 
 Bates, H. W., 46, 101, 112, 116, 
 118-19, 149, 151, 153, 174-7, 
 189, 191, 225, 227-8, 228 n. 1, 
 235; theories of F. Miiller 
 and, 114-32 ; Lycid mimicry 
 and theory of, 118-21 ; me- 
 moir on mimicry by, 122-6, 
 236, 238-9, 240; inscription 
 in Wallace's copy of, 123; 
 theory of, anticipated by Dar- 
 win, 46, 123-4 ; reviewed by 
 Darwin, 125-6; theory 
 thought out at home by, 126 ; 
 two classes of resemblance 
 distinguished by, 126; Miiller 
 dissatisfied with theory of, 
 127-8; Muller's theory op- 
 posed by, 129; Batesian 
 mimicry defined, 149 ; Dar- 
 win's interest in, 123-6, 144- 
 5 ; protective resemblance 
 and Batesian mimicry, 101, 
 146-7, 174-5 ; female of Arg. 
 diana probable example of 
 Batesian mimicry, 190-1, 207; 
 N. American mimicry as a 
 whole opposed to theory of, 
 174-7, 205, 207 ; Darwin to, 
 123-6, 141. 
 
 Bateson, W., on de Vries's 
 'fluctuations', xi, 259-61; 
 on an effect of the Origin, 
 52 ; on discontinuity in 
 evolution, 274 ; on causes 
 of variation and reversion, 
 277. 
 
 Beagle, voyage of the, 1,4-6, 60, 
 66 n. 2, 85-6, 108, 202, 203 
 n. 1, 214. 
 
 Beccari, views on evolution of, 
 19, 20. 
 
 bee, experiment with Orchid 
 and, 225. 
 
 Beebe, C. W., on moisture and 
 bird colours, 110; on con- 
 trol of birds' nuptial plumage, 
 142-3 ; natural selection and 
 experiments of, 143. 
 
 beech, light and shade foliacre 
 of, 41-2. 
 
 beet, selection of ' fluctuations ' 
 in, 267-70, 278-9. 
 
 Belt, T., on Nicaraguan frog, 
 111 ; on sexual selection and 
 mimicry, 135. 
 
 Bentham, G., 13-14, 253 ; effect 
 of joint essay and Origin on, 
 13 n. 2 ; Darwin to, 253. 
 
 berenice, Danaida (Tasitia), 154, 
 157-8, 162-3, 168-72, 204-5. 
 
 Beuttler, J. S., on colour adjust- 
 ment of chameleon, 109. 
 
 birds, Beebe's experiments on, 
 110, 142-3; fertilization of 
 Strelitzia and, 217, 228-9, 228 
 n. 2 ; light attractive to, 243. 
 
 Blanchard, E., on an unknown 
 sense in insects, 235 . 1, 242, 
 242 n. 1. 
 
 Blomefield, L., see ' Jenyns '. 
 
 Blyth, E., 241. 
 
 bobolink, 142. 
 
 Bonatea, Darwin and Trimen on, 
 217-18, 220, 228-9, 229 n. 1. 
 
 Borneo, 19. 
 
 Bourne, G. C., 78. 
 
 Bourne, E., 79. 
 
 Boys, C. V., on colour adjust- 
 ment of chameleon, 109. 
 
 Braconidae, as models and 
 mimics, 120. 
 
 Bradley, Andrew, on imagina- 
 tion, 62. 
 
 Brazil, S. E., F. Muller's theories 
 of mimicry worked out in. 
 126-8. 
 
 Iredowi, Limenitis, 192-3, 197-8, 
 207-8. 
 
 brenchleyi, Euploea, 160. 
 
 British and South African Associ- 
 ations, Report of the, 96 n. 2. 
 
 British Assoc. Adv. Sci., Meet- 
 ings and Reports of the, 17, 
 29, 30, 38, 49 . 1, 50 n. 1, 52, 
 54-5, 66-9, 89, 258-9, 261. 
 
 British Columbia, 193. 
 
 Brooks, W. K., 108. 
 
 broom, 202. 
 
 Brown, R., death of, and publi-
 
 284 
 
 INDEX 
 
 cation of the joint essay, 12- 
 14 ; on Asclepiadae, 225-6. 
 
 Brownleia, 220 n. 2. 
 
 Brunton, Sir Lauder, Darwin to, 
 73. 
 
 Buckland, Dr., influence of, on 
 Lyell and indirectly on Dar- 
 win, 7, 86, 95. 
 
 Buffalo Soc. N. Sc. Bull., 192. 
 
 Buff on, xiii, 15, 28. 
 
 bugs (Hemiptera), as mimics, 
 116-18, 120. 
 
 Burchell, F. A., manuscripts of 
 W. J. Burchell discovered by, 
 102. 
 
 Burchell, W. J., 93 ; present at 
 reading of joint essay, 13 ; 
 detachment of, 27 ; on the 
 sublime, 36-7 ; on adaptation, 
 96-9 ; on cryptic resemblance 
 to stones, 96-8, 102-3; on 
 defences of desert plants, 98 ; 
 examples of mimicry observed 
 by, 114-22. 
 
 Butler, A. Gr., on distastefulness 
 of conspicuous larvae, 112. 
 
 Butterflies, mimicry in, 128,130, 
 132-9; scents of, 141-2; 
 mimicry in N. American, 144- 
 212. 
 
 Butterflies of the Eastern United 
 States and Canada, Scudder, 
 152 n. 1,165; see also Scud- 
 der'. 
 
 Butterfly Book, Holland, 171, 
 211; see also 'Holland'. 
 
 Byron, 77. 
 
 califomica, Limenitis (Adelpha), 
 191-200, 207-8. 
 
 Cambridge, Darwin and Uni- 
 versity of, 84-91, 203 ; Darwin 
 celebrations at, ix, 79. 
 
 Canada, 176, 185, 194. 
 
 canadensis, subsp. of Papilio 
 glaucus, 182. 
 
 Cantharidae, as mimics, 120. 
 
 Cape and Cape Town, 156, 213, 
 220 n. 1 and n. 2, 221-2, 228, 
 228 n. 1, 246. 
 
 Cape de Verde Islands, 6, 108. 
 
 Cape Monthly Magazine, 245 
 
 n. 2. 
 
 Cardbi, of Beagle, 202. 
 Carlyle, Mrs., on R. Owen, 27 
 
 n. 1. 
 Carpenter, W. B., present at 
 
 reading of joint essay, 13. 
 Carus, Victor, 255. 
 Castle, W. E., on 'unit char- 
 acters ', 276, 278. 
 Catalogue of the Ashmolean 
 
 Museum, J. S. Duncan (in 
 
 work of P. B. Duncan), 95-6. 
 I Caterpillars, warning colours of, 
 
 111, 112. 
 
 I Catskill Mountains, 211. 
 Centres of creation, 248-9. 
 Cethosia, mimicry in, 133, 136, 
 
 161. 
 
 Ceylon, 157. 
 Chalk, continuous evolution in 
 
 the white, 280 n. 1. 
 Challenger, 256. 
 Chambers, E., 15. 
 chamaeleon, Achaea, 224 n. 1. 
 Chameleon, W. J. Burchell on, 
 
 97 ; Lloyd Morgan on, 97 ; 
 
 colour of, adjustable on two 
 
 sides independently, 109, 110. 
 Charles Dartcin and the Theory 
 
 of Natural Selection, Poulton, 
 
 126, 129. 
 Chicago, ' Papilio ' mimics of 
 
 philenor taken with their 
 
 model at, 185. 
 Chlorippe, mimicking Adelpha, 
 
 176. 
 
 chlorophyll, 94. 
 chrysippus, Danaida, 156-61. 
 Chrysomela, 202. 
 Cimex, as mimic, 116-18. 
 Cinnyris, 228 n. 2. 
 Clematis glandulosa, 71. 
 Climbing Plants, C. Darwin, 25. 
 Clytus arietis, mimicking wasp, 
 
 115. 
 Coenonympha pamphilus, use of 
 
 'eye-spots' of, 231, 232. 
 Colchester, 235. 
 Cold Spring Station, 185. 
 Coleoptera of Beagle, 202.
 
 INDEX 
 
 285 
 
 Collingwood, Dr., on mimicry, 
 
 123-4. 
 
 Colombia, 184. 
 Colorado, 176, 180. 
 Colorado R., Grand Canyon of 
 
 the, 37. 
 Colour, value of, in the struggle 
 
 for life, vii, 92-143. 
 Colours of Animals, Poulton, 115. 
 ' Coming of Age of the Origin ', 
 
 Huxley, 54, 67. 
 Comptes Bendus, 224 n. 1. 
 Comstock and Needham, system 
 
 of, 211. 
 
 Contemporary Review, 32, 269. 
 continental extension, 246 n. 2 ; 
 
 Darwin opposed to views of 
 
 Lyell, &c., on, 45 ; supported 
 
 by Dana, 2, 45. 
 ' continuity of the germ-plasm ', 
 
 33, 34; discovery by Weis- 
 
 mann of, 39-40. 
 continuous or discontinuous 
 
 evolution, 48-51 ; mimicry 
 
 and, 138-9, 147-8, 200,208; 
 
 fossils of the white chalk and, 
 
 280 n. 1. 
 Cook, J. H., on stripeless L. 
 
 archippus, 166 n. 2, 210-12; 
 
 lanthanis var. named by 
 
 Watson and, 212. 
 Cope, E. D., American Palae- 
 ontology and, 2. 
 Coprid beetles as mimics, 120-1. 
 Coral islands, Darwin's theory 
 
 of, 75 ; supported by A. Agas- 
 
 siz, 2 ; confirmed, 45. 
 Cordilleras, 34. 
 Cornhill Mag., 73. 
 cornuta, Disa, 220 n. 1. 
 Cosmodesmus, both sexes of, 
 
 mimetic, 137, 179 ; mimics of 
 
 Pharmacophagus, 137, 177-9 ; 
 
 ofDanainae, &c., 137, 179. 
 Coulter, J. M., on oecology and 
 
 natural selection, x, xi, 143. 
 Courtney, Lord, on Shakespeare, 
 
 Newton, and Darwin, 77. 
 Coventry, A. F., 79. 
 Crassula, mistaken for birds' 
 
 dung by Burchell, 102-3. 
 
 ci'oesus, Ornithoptera, 233 n. 1. 
 Cross and Self Fertilisation in the 
 
 Vegetable Kingdom, C. Darwin, 
 
 228_n. 2. 
 
 Cryptic colouring, see 'Protec- 
 tive Resemblance '. 
 curcatus, Neoclytus, 115. 
 cuttle-fish, variable protective 
 
 resemblance of, 108, 109. 
 Cyllo (Melanitis) leda, Darwin 
 
 and Trimen on, 230 n. 2, 233, 
 
 233 n. 2. 
 Cypripedium, Dai-win's error in 
 
 fertilization of, 224-5, 224 n. 2. 
 
 Dakota, 170. 
 
 Dana, support to Darwin by, 2, 
 
 45. 
 
 Danaida, four of Moore's genera 
 
 sunk in, 158-9, 204 ; Old World 
 
 affinity of, 160-1 ; invasion of 
 
 N. America from Asia, by way 
 
 of N., and of S. America by 
 
 way of N. America, proved 
 
 by mimetic relationships of, 
 
 155, 159-64, 173-7, 204. 
 
 Danaida (Tasitia) lerenice, 154, 
 
 157-9, 162-3, 168-72, 
 
 204-5 ; f. strigosa, 171- 
 
 2, 204-5. 
 
 (Limnas) chrysippus, 156- 
 
 9, 158 n. 3, 160-1. 
 (Salatura) decipiens, 160 ; 
 yenutia, 158-9, 158n. 3, 
 161-2; iiisolata, 160. 
 (Anosia) plexippns, 152 
 n. 1, 154, 158-9, 158 
 n.3, 161-4,168-73, 177, 
 204. 
 
 Danainae, as models, 133, 137-8, 
 178-9, 239 ; relationship be- 
 tween New and Old World 
 species of, 152-9. 
 Danaini, a section of the Da- 
 nainae, q. v., 152 ; mimicry 
 between Euploeini and, 160. 
 Danais, as models, 239. 
 ! ' Danaoid Heliconidae ' of Bates, 
 
 153. 
 
 dardanus (merope), Papilio, 132, 
 139, 236-7, 278.
 
 INDEX 
 
 Darwin, Charles Robert, youth, I 
 4 ; S. American observations, 
 1 (see also ' Beagle ') ; Cam- 
 bridge and, vi, 84-91, 203; ' 
 LL.D. (1877), 90; Oxford and, 
 vi,7,86; D.C.L. offered (1870), 
 90. 
 
 Personality of: vi, 57-77; 
 absolute necessity for work' the 
 explanation of misinterpreted 
 changes described in his own 
 mind, vi, 57-66, 79-83, 216, 
 256-8 ; relation to his family, 
 6, 58-9, 87 ; friends, 4-7, 21- 
 6, 66-7, 70-1 ; opponents, 26- 
 30, 28 n. 2, 68-9, 230 ; readers, 
 69; younger men, 69-70, 107- 
 8,215-17; living things, 72-3. 
 
 Intellectual characteristics 
 of: love of knowledge, 75-6 ; 
 powers of observation, 76, 76 
 . 3; comprehensive view and 
 sure insight, v, x, xi, 18, 45-6, 
 123-4, 123 n. 2, 247-53 ; ima- 
 gination and control, 73-5. 
 
 On Evolution: early 
 thoughts, 1, 4, 5, 53 ; letter to 
 his wife on the 1844 essay, 6, 
 87 ; urged to publish by Lyell, 
 12; publication of joint essay, 
 12-15 ; on the steps of evolution 
 xii-xiv, 49, 49 n. 1, 262 n. 3, 
 272-3, 272 . 1; evolution con- 
 tinuous, 49, 50, 148 ; halts and 
 fresh starts, 48, 267, 272-3, 
 279 ; mutation, xiv, 42-7, 254- 
 6; multiple origins, 46, 247- 
 53 ; causes of variation, 273 ; 
 transmission of acquired char- 
 acters considered and accepted 
 by, 33-7, 273 ; on heredity and 
 memory, 38, 38 n. 1; on adap- 
 tation and natural selection, 
 98-100, 99 n. 1, 262 . 3 (see 
 also 'orchids'); slight effects 
 of climate, 173 ; effect of 
 teachings, 52-6, 213-15, 219. j 
 
 On Sexual Selection :- of 
 special interest to, 103, 139- I 
 41, 236; yet aware that it was j 
 vulnerable, 141 ; on Descent 
 
 of Man, &c., and sexual selec- 
 tion, 230-6, 242-5; on sexual 
 selection and warning colours, 
 lll-12,and markings now con- 
 sidered episematic, 112-13 ; 
 and mimicry, 132-5. 
 
 On Mimicry, Protective Resem- 
 blance, &c.: Bates, Wallace, 
 Fritz Miiller, and Trimen in 
 relation to, 46, 123-9, 132-5, 
 144-5, 236, 240-1; on mimetic 
 Planarians, 122; desert plants, 
 98 ; variable colours of octo- 
 
 ?us, 108-9 ; S. American toad, 
 10-11 ; Bowers and fruit, 113, 
 113 n. 3; protective resem- 
 blance, 103-9 ; recognition 
 marks unknown to, 112-13. 
 
 Correspondence of : ex- 
 tracts from Darwin's pub- 
 lished letters to the following 
 correspondents appear on the 
 quoted pages : Agassiz, L., 
 68-9; Ansted, D. T., 131; 
 Argyll, Duke of, 251-2 ; Ave- 
 bury, Lord, 203 ; Bates, H.W., 
 123-6, 141; Bentham, G., 253; 
 Brunton, Sir Lauder, 73 ; 
 Darwin,Erasmus (his brother), 
 58 n. 2 ; Farrer, Lord, 20-1 ; 
 Fawcett,H.,16-17; Fox.W.D., 
 72, 76, 203 n. 1 ; Gray, Asa, 
 24-5, 27-8, 43, 131, 257 ; Gur- 
 ney, E., 34 ; Haeckel, E., 69, 
 255; Harvey, W. H., 255; 
 Henslow, J. S., 35, 75-6, 108- 
 9; 111, 122; Hooker, Sir 
 Joseph, 12, 15-16, 21-3, 30-1, 
 48, 51 n. 1, 64-7, 70-4, 104, 
 125, 129, 248-9, 254, 257- 
 8; Homer, L., 6, 86; Hux- 
 ley, T. H., 4, 33, 57-8, 67- 
 8, 74, 257 ; Jenyns (Blome- 
 field), L., 22 n. 1, 42 n. 1 ; 
 Lankester, Sir Ray,72 ; Lewes, 
 G. H., 98, 262 n. 3 ; Litchfield, 
 Mrs. (his daughter), 73; Lyell, 
 Sir Charles, 11 n, 1, 44, 47, 
 173,250-1, 254 ; Masters, Max- 
 well, 254; Meehan, T., 93; 
 Meldola, R., 255 ; Muller, F.,
 
 INDEX 
 
 287 
 
 38 n. 1, 122, 127 n.2; Romanes, 
 G. J., 38, 258 ; Scott, J.,18-19, 
 53 . 1,70, 74; Thiselton-Dyer, 
 Sir W., 100; Wallace, A. R., 
 104-5, 112, 129 n. 3, 133-4, 
 134 . 1, 140, 255; Weir, 
 J. Jenner, 112 ; Weismann, A., 
 127. 
 
 Twenty -two of Darwin's let- 
 ters first published in these 
 addresses were written to the 
 following correspondents : 
 Hope, F. W., 202-3 ; Trimen, 
 Roland, 63, 213-46; Weir, 
 J. Jenner, 32 ; Wilson, E. B., 
 107; Wallace, A. R., 106 (see 
 also vii). 
 
 Autobiography of: 51, 58 
 . 2, 59, 60, 63-4, 66, 74-6, 
 75 n. 2, 85 n. 1, 99 n. 1, 100, 
 103, 123 n. 2, 140. 
 
 Darwin, Mrs. Charles, 58, 58 
 n. 2 ; letter from Darwin to 
 on 1844 essay, 6, 87 ; letters 
 signed by Charles Darwin writ- 
 ten by, 227-9, 234; letter 
 written on behalf of Charles 
 Darwin by, 216, 231, 245. 
 
 Darwin, Dr. Erasmus (grand- 
 father of Charles Darwin), 
 Lamarck and, 3, 4; A. R. 
 Wallace on, 15 ; on protective 
 and aggressive resemblances, 
 101-2. 
 
 Darwin, Erasmus Alvey (brother 
 of Charles Darwin), letter to, 
 58 n. 2. 
 
 Darwin, Francis, permission to 
 publish Darwin's letters 
 granted by, vii, 31, 106, 201, 
 213; to reprint Section IV, 
 ix ; assistance in editing let- 
 ters, &c., rendered by, 215, 
 224 n. 2, 245 n. 1, 273 ; pre- 
 sent at Oxford centenary, 78; 
 speech at, 79; che debt to, 90-1; 
 on the conditions of Darwin's 
 health and work, 58, 61-3, 61 
 
 . n. 1 ; Darwin's attitude to- 
 wards his readers, 69; Dar- 
 win's control, 75 n. 1 ; tele- 
 
 ology and natural selection, 
 100-1 ; transmission of ac- 
 quired characters, 38-42 ; an 
 orange-piercingmoth,224. 1. 
 
 Darwin, Sir George, permission 
 to reprint Section IV granted 
 by, ix ; on discontinuity in 
 rate of evolution, 50-1 ; pre- 
 sent at Oxford centenary, 78; 
 speech at, 79 ; writer of 
 letter signed by Charles Dar- 
 win, 244-5. 
 
 Darwin, Major Leonard, present 
 at Oxford centenary, 78. 
 
 Darwin, William E, present at 
 Oxford centenary, 78 ; speech 
 at Cambridge centenary, 79. 
 
 Darwin and modern science, Se- 
 ward, Ed., viii, ix, 92, 260. 
 
 Darwin celebration of the 
 American Assoc.for Adv. Sci. t 
 viii, 1, 57. 
 
 Darwin centenary at Cambridge, 
 
 Darwin centenary at Oxford, 78. 
 
 Darwin-Wallace celebration of 
 the Linnean Society. 12-15, 26, 
 52, 71. 
 
 Darwin-Wallace essay, publica- 
 tion of, (July 1, 1858), 12-15, 
 23, 144; effect of, 52; pro- 
 tective resemblance described 
 in Wallace's section, 103; 
 sexual selection in Darwin's, 
 103, 139-40. 
 
 Darwin - Wallace hypothesis, 
 xiv, xy, 8, 9; see also 'natural 
 selection'. 
 
 ' Darwinism versus Wallaceism', 
 Hubrecht, 269. 
 
 Davenport, C. B., 185; on de 
 Vries's ' fluctuations ', 269-70. 
 
 Dawson, Sir William, on the 
 Origin, 15-16. 
 
 de Vries, on the variations in- 
 cluded in ' fluctuations ', 49, 
 49 n. 1, 263; Bateson's, Pun- 
 nett's, and Shipley's ' fluctua- 
 tions ' differ from those of, xi, 
 xii, 49 n. 1, 258-80; the mu- 
 tation hypothesis of, xi-xiv,
 
 INDEX 
 
 47, 265, 276; on the trans- 
 mission of acquired charac- 
 ters, 261-2, 270, 276 ; errone- 
 ously holds that Darwin's 
 views were consistent with his 
 own, xii, xiii, 265 ; difference 
 between Darwin's views and 
 those of, xii, xiii, 43-4, 254-6. 
 
 decipiens, Danaida, 160. 
 
 deer, keen scent of, 242. 
 
 Descent of Man, &c., C. Darwin, 
 93, 104-5, 111, 113, 124, 126, 
 135, 140, 230, 230 n. 2, 231 
 . 2, 283 n. 1,2, and 3, 234 
 n. 4, 235 n. I and 2, 242 n. 2, 
 244, 245 n. 2. 
 
 desert plants, defences of, 96-8, 
 102-3 (see also 262 n. 3). 
 
 Detroit, 154. 
 
 Development and Evolution, Bald- 
 win, 48. 
 
 diana, Argynnis, 189-90, 207. 
 
 Diaposematism, 196-8, 208. 
 
 Different Forms of Flowers, &c., 
 C. Darwin, 226 n. 1. 
 
 Diptera, of the Beagle at Oxford, 
 202 ; as mimics of Lycidae, 
 121; orchids and, 219,223; 
 captured by Apocyneae, 225. 
 
 Disa, 220 n. 1 and 2, 222-4, 227. 
 bartata, 220 . 1. 
 cornuta, 220 n. 1. 
 grandiflora,H. Trimen on, 
 217-18, 219 n. 1, 222. 
 
 Discontinuity : see ' continuous 
 or discontinuous, &c.' 
 
 Distnorphia, Belt on, 135 ; fe- 
 males of , better mimics than 
 males, 139. 
 
 Disperis, 218-19, 221. 
 
 Dixey, F. A., on butterflies' 
 scents, 141-2 ; on mimicry of 
 L. astyanax by A. diana, 189. 
 
 dogs, Darwin on humour in, 244. 
 
 Dolichonyx oryziwrus, Beebe's 
 experiments on, 142. 
 
 d'Orbigny, A., Darwin on, 6. 
 
 dorippus, f. Danaida chrysippus, 
 157. 
 
 Doubleday, H., on sexes of 
 butterflies, 242. 
 
 Duncan, J. S., 95-6. 
 Duncan, P. B., 95-6. 
 
 Eastern States, 211. 
 
 Edinburgh, 245. 
 
 Edinburgh Review, 27, 28 n. 2, 
 
 230. 
 Egybolis vaillantina, piercing 
 
 peaches, 224 n. 1. 
 Eigenmann, C. H., 201 n. 1. 
 Eltringham, H., 237, 239. 
 Elwes, H. J., 209. 
 Elymniinae, 161. 
 Emperor moth, 233 n. 3. 
 Encycl. of Anat. and Physiol., 
 
 109. 
 Entomological Society of America, 
 
 anniversary address to, 144- 
 
 212. 
 Entomological Society of London, 
 
 202, 203 n. 1 ; Proceedings of, 
 
 128, 141 ; Transactions of, 
 
 116, 120, 141, 152 w.l; 158 
 
 n. 3, 159 . 1, 160 n. 1, 164- 
 
 6, 169, 172, 183, 189, 195, 
 
 237, 242 n. 1. 
 Entomologists Monthly Mag., 
 
 237. 
 
 Epigamic characters, 139-43. 
 Episematic characters, 112-13. 
 Erebia, 130. 
 
 Eresia, females of, better mi- 
 mics than males, 139. 
 eros = floridensis, f.of L. archip- 
 
 pus, q.v. 
 Erycinidae, mimicking Adelpha, 
 
 176. 
 
 erythromelas, Piranga, 142. 
 Essays on Evolution, Poulton, 93, 
 
 125 n. 4, 155, 232 n. 1, 237 
 
 n. l,274w. 1,279. 
 Euclid, 100. 
 Eulophia, 218. 
 Euploea, 158 n. 3. 
 Euploea asyllus, 160. 
 
 brenchleyi, 160. 
 Euploeini, as models, 152 ; 
 
 mimicry between Danaini 
 
 and, 160. 
 Euralia, as mimics, 138.
 
 INDEX 
 
 289 
 
 Euripus, as mimics, 133. 
 
 Eutresis imitatrix, a mimic, 153. 
 
 Evans, Sir John, on Archaeo- 
 pteryx, 30. 
 
 Evening Primroses, de Vries 
 and, xi, 276. 
 
 Evidences of Christianity, Paley, 
 Darwin and, 100. 
 
 Evolution, rate of, 46-7, 50, 51 ; 
 continuous or discontinuous, 
 43-4, 48-51, 138-9, 200, 208, 
 254-6 (see also ' Mutation ') ; 
 mimicry and, 145-9, 200, 203, 
 208. 
 
 Examinations, evils of, 88-9. 
 
 Exotic Butterflies, Hewitson, 237. 
 
 ' External causes ', as interpreta- 
 tion of mimicry, 148 ; nega- 
 tived by the facts, 173-4, 
 205-6. 
 
 Eye-spots on butterflies' wings, 
 attractive to enemies, 231-2; 
 seasonal development of, 231- 
 2 ; Darwin and Trimen on 
 sexual selection and, 230 n. 
 2, 231-4, 233 n. 2 and . 3. 
 
 Farmer, J. B., at Oxford cen- 
 tenary, 78. 
 
 Farrer, Lord, Darwin to, 20, 21. 
 
 Father and Son, 9, 10. 
 
 Fawcett, H., defence of Darwin 
 by, 2, 16-17, 32-3. 
 
 feelings of the sublime, 34-7. 
 
 Felton, S., 101. 
 
 Female mimicry, 132-9, 240. 
 
 Fertilisation of Orchids, C. Dar- 
 win, 217, 219 . 1, 224 n. 1 
 and n. 2, 229 n. 1. 
 
 fertilization, bearing of Men- 
 delian research on, 277-8. 
 
 Fifty years of Darwinism, New 
 York, 1909, viii, xi. 3, 50 . 1, 
 143, 201, 269, 270, 276. 
 
 ' Fifty years of Darwinism', Sec- 
 tion I, 1-56. 
 
 Fiji, 155. 
 
 fish, sea-weed like, 107. 
 
 Fiske, J., evolution in America 
 and, 2. 
 
 Fitton, W. H., 13. 
 
 Fitz-Roy, 61, at Brit. Ass., Ox- 
 ford (I860), meeting, 66 n. 1. 
 Flora of Middlesex, Thiselton- 
 
 Dyer and H. Trimen, 234 n. 2. 
 Florida, 157, 168-70, 205. 
 floridensis, f. of L. archippus, 
 
 168-71, 205. 
 
 flowers, bright colours of, 113. 
 ' fluctuations ',de Vries, Bateson, 
 
 and Punnett on, xi, xii, 258- 
 
 80. 
 ' Fluted swallow-tails ' = ' Pa- 
 
 pilio ', cj.v. 
 
 Fly, as mimic of Lycidae, 121. 
 Forbes, E., 45 : anticipated by 
 
 Darwin, 45, 123, 123 n. 2. 
 Forms of Flowers, C. Darwin, 25. 
 Fortnightly Review, 73. 
 Fossorial wasps, as models, 114- 
 
 16 ; Asclepiad pollen-masses 
 
 on true wasps and, 225 n. 2. 
 Foundations of the Origin of 
 
 Species, F. Darwin, Edr., 273. 
 Fox, W. D., Darwin to, 72, 76, 
 
 203 n. 1. 
 fresh-water, ancestral forms in, 
 
 47. 
 
 frog, warning colours of a, 111. 
 From the Greeks to Darwin, Os- 
 
 born, 3, 4, 8. 
 fruits, bright colours of, 113, 
 
 113n. 3. 
 
 fullonica, Ophideres, 224 n. 1. 
 fur, thicker in north, 273. 
 
 Galapagos Islands, 251 ; Darwin 
 on colours of animals in, 127. 
 
 Galileo, effect of teachings of, 
 55-6. 
 
 Galton, Sir Francis, on heredity, 
 recession, and transilience, 
 xii, 266, 271, 273-4, 276 ; on 
 freedom conferred by the 
 Origin, 52. 
 
 Ganoid fishes, ancestral, 47. 
 
 Gardener's Chronicle, 224, 227. 
 
 Gartner, Darwin on, 53, 58 n. 1. 
 
 Genesis of Species, St. G. Mivart, 
 31. 
 
 genutia, Danaida (Salatura), 
 158-9, 158 n. 3, 161-2.
 
 290 
 
 INDEX 
 
 Geranium spinosum, defence of, 
 98. 
 
 glandulosa, Clematis, 71. 
 
 Glaucus, group of 'Papilio', 
 182-3. 
 
 glaucus, Pap., 182-5, 188, 206. 
 
 Godman, Dr. F. D., 209. 
 
 Godman-Salvin Coll., 195. 
 
 Gosse, Philip, 9-11. 
 
 Gower, H., 221. 
 
 Grand Canyon of the Colorado, 
 37. 
 
 </mnd(/7om,Z>isa,217,21 9 n.1,222. 
 
 Grapta (Polygonia), 175. 
 
 Gray, Asa, sure insight of, x ; 
 Darwin and, 1, 2, 22-5 ; ex- 
 tracts from Darwin's letter to, 
 published in joint essay, 23 ; 
 on the Origin, 23 ; on Cypri- 
 pedium, 224, 224 n. 2; on 
 Habenaria, 228-9. Darwin to, 
 24-5, 27-8, 43, 131, 257. To 
 Darwin from, 23. 
 
 Gray, G. E., 214. 
 
 Greenland, 46. 
 
 Griffith, George, on Oxford Brit. 
 Ass. (1860) meeting, 66 n. 2. 
 
 grossuloriata, Abraxas, 242 n. 1. 
 
 Grove, Dr., on Tennyson and the 
 Origin, 9. 
 
 Gryllus (Acridian), resembling 
 stone, 96-S. 
 
 Guatemala, 192, 208 n. 1. 
 
 Guerrero, 182. 
 
 Guiana rock-thrush, 140. 
 
 Gulf of Mexico, 176, 186. 
 
 Gunther, Dr. A., 107. 
 
 Gurney, E., on vivisection, 73 ; 
 Darwin to, 34. 
 
 Gynanisa isis, 230 n. 2, 233, 
 233 n. 3. 
 
 Haase, E., 137, 177-8, 181, 189. 
 
 Habenaria, 229. 
 
 Haeckel, E., on memory and 
 heredity, 38 ; on transparency 
 of oceanic forms, 105 ; Dar- 
 win to, 69, 255. 
 
 hahneli, Pharm., 179. 
 
 Hall, American Palaeontology 
 and, 3. 
 
 Hallett, on improvement of 
 wheat, 48. 
 
 Halley, Newton and, 86. 
 
 Hamadryas, 152. 
 
 Harcourt, A. G. Vernon, 66 n. 2. 
 
 Hardwick, 234. 
 
 hare, concealment of, 113. 
 
 Haredene, Darwin's residence 
 at, 245, 245 n. 1. 
 
 Harvey, W. H., 218, 220, 220 
 n. 1 and n. 2, 254-5. 
 
 health, work essential for Dar- 
 win's, 59-66, 216, 256-8. 
 
 'Heliconidae ', 239. 
 
 Heliconinae, 153, 239. 
 
 Hemiptera as mimics. 116-18, 
 120. 
 
 Henfrey, A., 13. 
 
 Henslow, J. S., and Darwin, 4, 5, 
 85-6, 88 ; Darwin to, 35, 75-6, 
 108-11, 122. 
 
 Heredity, J. A. Thomson, 271. 
 
 heredity, bearing of Mendelian 
 research on, 277-8 : see also 
 ' acquired characters ' and 
 ' fluctuations '. 
 
 Bering on memory and heredity, 
 38. 
 
 Herschelia, 222. 
 
 Hestia, 152. 
 
 heterostyled Oxalis, 226, 226 
 n. 1, 227. 
 
 Hewitson on mimicry, 237-40. 
 
 History and arrangement of Ash- 
 molean Museum, P. B. Dun- 
 can, 95-6. 
 
 Hobart Town, 202. 
 
 Holland, W. J., 171, 211-12. 
 
 Homer, 280. 
 
 Hong-Kong, 155, 156. 
 
 Hooke, Newton and, 85. 
 
 Hooker, Sir Joseph,45; Darwin's 
 great friendship with, and 
 help received from, 1, 2, 
 12-13, 21-2, 25, 64-7, 70-1, 
 123 n. 2, 124, 221. 
 
 Darwin to, 12, 15-16, 21-3, 
 30-1, 38 n. 1, 48, 51 . 1, 
 64-7, 70-4, 104, 125, 129, 
 248-9, 254, 257-8. 
 
 Hooker, Sir William, 36.
 
 INDEX 
 
 291 
 
 Hope Department, Oxford, Dar- 
 win's letters in, 31-2, 201-3 ; 
 will help in work upon N. 
 American mimicry, 210. 
 
 Hope, F. W., Darwin and, 201-3, 
 203 n. 1 ; Darwin to, 202-3, 
 first published in Section V. 
 
 Homer, L., Darwin to, 6, 86. 
 
 Horsfield, T., 178. 
 
 Hubrecht, A. A. W., xii, xiii ; 
 on de Vriea's ' fluctuations ' 
 hereditary, 267-9. 
 
 Hudson, N. T., stripeless L. 
 archippus at, 211. 
 
 Hudson's Bay, 176. 
 
 'Hugo de Vries's Theory of 
 Mutations ', Hubrecht, 267. 
 
 hulsti, f. of L. archippus, 167, 
 171-2, 205. 
 
 humble-bee found dead on As- 
 clepias flower, 225 n. 2. 
 
 Humboldt, Darwin on, 35. 
 
 humour in dogs, Darwin on, 244. 
 
 Huxley, Julian, 78. 
 
 Huxley, T. H., 38 n. 1, 61,61 n. 2 ; 
 defence of Darwin by, and 
 Darwin's friendship with, 25- 
 6, 53-4, 66-8, 89, 124, 255 ; on 
 Lyell, 5 ; influence on teach- 
 ing of, 53 ; on teleology, 97 
 n. 1 ; Darwin to, 4, 33, 57-8, 
 67-8, 74, 257. 
 
 Huxley, Mrs. T. H., 243. 
 
 Hyatt, A., 2 ; American Palae- 
 ontology, and, 3. 
 
 Hymenoptera, as mimics, 120; 
 orchids and, 223 ; Asclepiad 
 pollen-masses on, 225-6, 225 
 n. 2. 
 
 Hypolimnas, as mimics, 138. 
 
 Hypolimnas misippus, as mimic, 
 161. 
 
 hypothesis, Darwin on value of, 
 126. 
 
 Iliad, 280. 
 
 imitatrix, Eutresis, 153. 
 
 incidental colours, Darwin on, 
 
 93. 
 individual adjustment, power of, 
 
 41-2, 143. 
 
 individual differences claimed 
 as mutations, 270-80 : see 
 also ' fluctuations '. 
 
 In Memoriam, 8, 9. 
 
 insolata, Danaida, 160. 
 
 ' internal causes ', as interpreta- 
 tion of mimicry, 148. 
 
 Introduction to Entomology, 
 Kirby and Spence, 118: see 
 also 99. 
 
 isis, Gynanisa. 230 n. 2, 233, 
 233 n. 3. 
 
 isolation, ancestral forms pre- 
 served by, 46-7. 
 
 Ithomiinae, as models, 153-4, 
 239. 
 
 Ituna, F. Miiller's theory and, 
 153-4. 
 
 Ituna phenarete, as model and 
 mimic, 153. 
 
 James, William, on Psychology 
 and natural selection, 3. 
 
 Japan, 156. 
 
 Java, 156. 
 
 Jen. Zeit., 141. 
 
 Jenyns, L. (Blomefield), Darwin 
 to, 22 n. 1, 42 . 1. 
 
 johnstoni, Acraea, 130. 
 
 Joint essay of Darwin and 
 Wallace: see ' Darwin- Wai- 
 
 Jordan, Karl, on the genera in- 
 cluded in ' Danaida ', 152 n. 1, 
 158-9, 158 n. 3, 159 n. 1 : see 
 also 'Rothschild and', 178, 
 181. 
 
 Journal of Researches, &c., C. 
 Darwin, 109, 111. 
 
 Judd, J. W., on debt to science 
 felt by Darwin, 65 ; present 
 at Oxford centenary, 78. 
 
 Kerner, 219 n. 1. 
 
 Kew, 221. 
 
 Kidd, Dr., 95. 
 
 Kilimanjaro, 130. 
 
 King George's Sound, 202. 
 
 King's College Chapel, 37 . 1. 
 
 Kingsley, C., on Omphalos, 10, 
 
 U 2
 
 292 
 
 INDEX 
 
 Kirby and Spence, teleology 
 
 and, 99, 118. 
 ' Kite swallow-tails ' = cosmo- 
 
 desmus, q. v. 
 
 klugii, f. of D. chrysippus, 157. 
 K5lreuter, Darwin on, 53. 
 Kosmos, 128. 
 Krefft, Dr. G., 106. 
 Kiinckel, on Oph. fullonica, 224 
 
 n. 1. 
 
 Lagriidae, as mimics, 120. 
 
 Lamarck, Erasmus Darwin and, 
 3,4. 
 
 Lamarckian evolution, xiii ; ac- 
 quired characters and, 33-42, 
 275 (see also xiv, xv). 
 
 Lamellicorn, sexes of, 233 n. I. 
 
 Landor, W. S., 61, 61 n. 2. 
 
 Lankester, Sir Ray, on T. H. 
 Huxley, 26; on Lyell, 86; 
 Darwin to, 72. 
 
 Lasiocampa quercus, males of 
 'assembling', 230 n. 2, 235, 
 235 n. 1, 242, 242 w. 1. 
 
 leda, Melanitis (Cyllo), 230 n. 2, 
 233, 233 n. 2. 
 
 Leibnitz, 129. 
 
 Leidy, J., American Palaeonto- 
 logy and, 2. 
 
 Lepidoptera, orchids and, 223; 
 captured by Physianthus, 225 
 n. 1. 
 
 Lepidosiren, 47. 
 
 lerna, Adelpha, 192. 
 
 levana, Araschnia, 176. 
 
 Lewes, G. H., review of Animals 
 and Plants by, 68 ; Darwin to, 
 98, 262 n. 3. 
 
 Life and Letters of Charles Dar- 
 win, F. Darwin, Edr., 5, et 
 passim. 
 
 Life and Letters of Sir Charles 
 Lyell, Mrs. Lyell, Edr., 249 n.2. 
 
 Life and Letters of T. H. Huxley, 
 L. Huxley, 27, 97 n. 1. 
 
 Light, Darwin on birds and 
 moths attracted by, 243. 
 
 Limenitis, 152 n. 1 ; evolution and 
 theories of mimicry in relation 
 to, 174-6, 205; relationship 
 
 to Adelpha of, 192-3 ; recent 
 changes in mimetic, 199. 
 Limenitis archippus, evolution 
 from L. arthemis 
 of, 137-8, 164-8, 
 172, 186-8, 204-5 ; 
 continuous evolu- 
 tion of, 165-8 ; 
 floridensis derived 
 from, 168-71,205; 
 hulsti derived from, 
 171-2, 205 ; stripe- 
 less form of, at 
 Albany, 166 n. 2, 
 211-12: see also 
 155, 161, 199. 
 
 arthemis, archippus 
 derived from, 137- 
 8, 164-8, 172, 186- 
 8, 204-5 ; astya- 
 nax derived from, 
 172,186-8,205,207. 
 
 astyanax, evolution 
 from L, arthemis 
 of, 172, 186-8,205, 
 207 ; female Arg. 
 diana a mimic of, 
 189-91, 207 ; phi- 
 lenor and its ' Pa- 
 pilio ' mimics, mi- 
 micked by, 186-91, 
 207 : see also 199. 
 
 bredowi, a S. f. of 
 califomica, has a 
 greater likeness to 
 Adelpha, 192-3, 
 197, 207-8. 
 
 califomica, resem- 
 blances between 
 lorquini and, 191- 
 200, 208. 
 
 floridensis, derived 
 from archippus, 
 168-71, 205. 
 
 hulsti, derived from 
 archippus, 171-2, 
 205: see also 167. 
 
 lorquini, resemb- 
 lances between 
 califomica and, di- 
 minishing N. of
 
 INDEX 
 
 293 
 
 Limenitislorquini (continued): 
 their overlap, 191- 
 200, 208 ; as a pos- 
 sible standard of rate 
 of specific change, 
 210. 
 
 populi, 193. 
 sybilla, 164. 
 weidermeyeri, 196. 
 
 Limnas, 156-8, 158 n. 3, 204 : 
 see also 'Danaida '. 
 
 Lingula, 47. 
 
 Linnean Society of London, 217, 
 219, 222, 253; Trimen's 
 paper on mimicry read 
 at, 241 ; Journ. Proc. Bot., 
 222 n. 2, 227, 229, 229 n. 1 ; 
 Journ. Proc. Zool, 103, 110, 
 139, 246 n. 2 ; Trans., 122, 
 225-6, 236 : see also ' Darwin- 
 Wallace Celebration, &c.' 
 
 Linum, 223. 
 
 Linum perenne, 224. 
 
 Litchfield, Mrs., Darwin to, 73. 
 
 ' Literature and Science ', in 
 Times Lit. Suppl., protest 
 against, 79-83. 
 
 Livingstone, D., 98. 
 
 Lizard, attracted by butterfly's 
 'eye-spots', 231, 232. 
 
 Lock, R. H., on de Vries's ' fluc- 
 tuations ', 262, 270, 271. 
 
 Locust idae as ant mimics, 116. 
 
 Long Island, 186. 
 
 Longicorn beetles as mimics, 
 114, 115, 120-2; sexes of, 
 233, 233 n. 1. 
 
 Longstaff, G. B,, on chameleon, 
 109 ; on scents of butterflies, 
 141. 
 
 lorquini,Limeiiitis. 191-200, 208, 
 210. 
 
 Lubbock, Sir John, see 'Ave- 
 bury'. 
 
 Luteva macrophthalma, Burchell 
 on mimicry in, 117-18. 
 
 Lycid beetles as models, 118-21. 
 
 Li/coraeini, ancient S. American 
 Danaines, both mimics and 
 models, 153-4. 
 
 Lycorea, 153. 
 
 Lyell, Sir Charles, 10, 15, 24-5, 
 28, 45, 61, 88, 243 ; Darwin's 
 debt to, 4-7, 86-7 ; Darwin 
 urged to publish by, 12 ; part 
 in the publication of joint 
 essay taken by, 13 ; on single 
 centres of creation, 249-53 ; 
 Darwin to, 11 n. 1, 44, 47, 
 173, 250-1, 254 ; to Darwin, 7 ; 
 to Hooker, 249. 
 
 Lysander group of section 
 ' Pharmacophagus ', 178. 
 
 Macdonell, A. A., 264. 
 
 MacGibbon, J., 227. 
 
 machaon, a type of section 
 ' Papilio ', 177 ; and type of a 
 group of that section, 182-3. 
 
 Macmillan's Magazine, 16. 
 
 macrophthalma, Luteva, 117. 
 
 Madagascar, 177. 
 
 Magpie moth, 242 n. 1. 
 
 Malay archipelago, 156. 
 
 Malayan Swallow-tails, Wallace 
 on, 132, 236, 238-9. 
 
 male butterflies, scents of, 141-2. 
 
 Malvern, 224. 
 
 Mantis, 117. 
 
 Mars, 251. 
 
 Marsh, 0. C., American Palaeon- 
 tology and, 2 ; on Archaeo- 
 pteryx, 29, 30. 
 
 Marshall, G. A. K., on S. 
 African ant mimics, 116; on 
 S. African mimics ot Lycidae, 
 118-21 ; on use of butterflies' 
 eye-spots, 232. 
 
 Massachusetts, 211. 
 
 Masters, Maxwell, Darwin to, 
 254. 
 
 ' Meadow Brown ' butterfly, 
 eye-spots of, 232. 
 
 Meehan, T., Darwin to, 93. 
 
 inelanic forms and mimicry, 
 136, 138, 184, 206-7. 
 
 Melanitis (Cylloi) leda, Darwin 
 and Trimen on, 230 n. 2, 
 233, 233 n. 2. 
 
 mtlasina, f. of Pap. polyxenes 
 americus, 184. 
 
 Meldola, R., at Oxford cen-
 
 294 
 
 INDEX 
 
 tenary, 78 ; notes on mimicry, 
 &c., sent by Darwin to, 106, 
 126-9 ; Miillerian mimicry 
 introduced by, 128-9; on 
 butterflies' 'eye-spots', 231; 
 on ' acquired characters ' dis- 
 cussed in Origin, 273 ; Darwin 
 to, 127, 129, 255. 
 
 Melyridae, as mimics, 120. 
 
 Memory, heredity and, 38, 38 n. 
 1,40; adaptation evident in, 40. 
 
 Mendel, Gregor, effect on evo- 
 lutionary thought of, 276-9. 
 
 Mendelism, Pimnett, 258, 259, 
 262, 279. 
 
 Mendelism, xiii, xiv ; ' acquired 
 characters' and, 3, 39, 275; 
 N.American butterflies favour- 
 able for experiments in, xiv n. 
 1, 185-6, 188, 208-9. 
 
 Menders Principles of Heredity 
 (1909), Bateson, 259. 
 
 Mendel's Principles of Heredity : 
 A Defence (1902), Bateson, 52. j 
 
 Mesembri/anthemum, Burchell on 
 S. African stone-like species 
 of, 96-8 ; truncatum, 96 ; tur- 
 biniforme, 96. 
 
 Messiah, 257. 
 
 Metamorphoses, Moeurs et In- 
 stincts des Insectes, Blan chard, 
 235 n, 1. 
 
 Methods and Scope of Genetics, 
 Bateson, 277. 
 
 Mexico, 180, 182, 186 n. 1, 192. 
 
 Mill, J.S., on the logical method 
 of the Origin, 17. 
 
 Milton, 60, 77, 111. 
 
 Mimicry, vii ; definition of, 145 ; 
 protective resemblances and, i 
 145-7, 174-5 ; Batesian and ! 
 Mullerian defined, 149-50 (see \ 
 also 118-21) ; Bates's memoir i 
 on, 122-6, 236, 238-40 ; Wai- ; 
 lace's memoir, 236, 238-9; i 
 Trimen's memoir, 230 n. 2, 
 231, 236-il ; Mulled paper, 
 126-9, 240 ; Darwin's interest 
 in memoirs, 123-9, 144-5, 240- 
 1 ; Darwin's anticipation of I 
 Bates, 46, 123-4; reciprocal i 
 
 mimicry, 197, 208 ; secondary, 
 182-3, 188, 190-1, 207 ; ter- 
 tiary, &.C., 207 ; melanic forms 
 and, 136-8, 184, 206-7; initial 
 resemblances and, 180 ; evo- 
 lution (continuity, mutation) 
 and, 138, 145-9, 200, 203 ; na- 
 tural selection and, 123-4, 131- 
 2, 148-9; sex, sexual selection 
 and, 127-8, 132-9, 148, 149 n. 1, 
 182-3, 238, 240; 'external 
 causes'suggestedfor,148,173- 
 4, 205-6; 'internal causes' 
 suggested for, 148 ; the bear- 
 ing of N. American butter- 
 flies on theories of, 144-212 ; 
 examples of, observed by 
 Burchell, 114-22 ; prejudice 
 against, 130. 
 
 ' Mimetic North American 
 species of the Genus Limeni- 
 tis, &c.', Poulton, 152 n. 1. 
 
 misippus, Hypolimnas, 161. 
 
 Mississippi Valley, 170, 181, 186. 
 
 Mitchell, P. C., at Oxford cen- 
 tenary, 78. 
 
 Mivart, St. G., attacks of, 30-2 ; 
 Darwin's replies to, 104, 255. 
 
 monad, 47. 
 
 monstrosities, see ' mutation '. 
 
 Moore, Aubrey, on argument of 
 Omphalos, 11. 
 
 Moore, F., Danaine genera of, 
 154, 156, 158, 159. 
 
 Moral Philosophy, Paley, 100. 
 
 More Letters of Charles Darwin, 
 F. Darwin and Seward, Edrs., 
 4, et passim. 
 
 Morgan, Lloyd, on Organic Selec- 
 tion, 3, 48 ; on chameleon 
 and snake, 97. 
 
 Morse, E. S., on colours of shells, 
 105. 
 
 Moseley, H., 78. 
 
 Moseley, H. N., 79. 
 
 Moths, mimics of 'Papilio\ 180; 
 fruit pierced by, 217, 224, 224 
 H.I, 227; orchids and, 219; 
 brightly coloured beneath, 
 230 n. 2 ; light and, 243. 
 
 Moulton, J. C., on mimicry be-
 
 INDEX 
 
 295 
 
 tween Euploeini and Danaini, 
 160 n. 1. 
 
 Mailer, F., 151, 164; help to 
 Darwin by, 2 ; on butterflies' 
 scents, 141 ; on sexual selec- 
 tion and mimicry, 127-8, 238 ; 
 Darwin to, 38 n. 1, 122, 127 
 
 . a 
 
 Mullerian Mimicry, defined, 
 149-50, see also 1 14-32, 153-4 ; 
 warning colours and, 175-6; 
 African Lycid mimics and, 
 118-21 ; N. American Dana- 
 ine mimics and, 174-7, 205 ; 
 N. American Ph. philenor 
 mimics and, 189-91, 207; 
 Darwin's interest in, 126-9, 
 144-5 ; strong opposition to, 
 129 ; reason for slow accep- 
 tance of, 129. 
 
 Multiple origins, 3 ; Darwin on, 
 46, 247-53. 
 
 Murray A., on an alternative to 
 natural selection, 19 ; on dis- 
 tribution of beetles, 246 n. 2. 
 
 Murray, John, 31. 
 
 music, the thrill of, 37 ; Darwin 
 and, 37 n. 1, 60. 
 
 Mutation, xiii-xiv, 3, 39, 259-60, 
 265 ; de Vries's theory of evo- 
 lution by, xi, xiii, 276 ; Dar- 
 win's disbelief in evolution by, 
 v, xii-xiv, 42-7,254-6; certain 
 facts of mimicry opposed to, 
 147-8,164-8, 166 n. 2,200,208, 
 211-12; Darwin's individual 
 differences sometimes claimed 
 as, 49 . 1,279-80. 
 
 Mtitationstheorie, de Vries, xii, 
 xiii, 262-5, 263 . 1. 
 
 mutilation, Darwin on non- 
 inheritance of (1844), 273. 
 
 Mylothris (Perrhybris) pyrrha, 
 Darwin and Wallace on mi- 
 micry in female of, 134 n. 1. 
 
 N. America, butterflies of, speci- 
 ally advantageous as intro- 
 duction to study of mimicry 
 and its bearing on evolution 
 and past history and lines of 
 
 migration, vii, 144-212 ; also 
 for testing Mendel's law in 
 nature, xiv n. 1, 170, 185-6, 
 188, 208-9 ; insects of, held 
 by Asclepiad flowers and bear- 
 ing pollen-masses of, 225-6. 
 225 n. 2. 
 
 N. Australia, 224 n. 1. 
 
 N. Wales. Darwin's trip to with 
 Hope, 203 n. 1. 
 
 Nageli, C. Darwin on, 20-1. 
 
 Najas: see Limenitis lorquini 
 and populi. 
 
 Natural History Revieiv, 125-6, 
 228, 228 n. 1. 
 
 natural selection, at first mis- 
 understood by naturalists, 
 32-3, 129-31 ; individual sus- 
 ceptibility and, 42, 143 ; adap- 
 tation and, 99-101 ; mimicry 
 and, 123-4, 131-2, 148-9, 
 200-1 : see also ' Darwin- Wal- 
 lace essay '. 
 
 Natural Selection, Essays on, 
 A. R. Wallace, 111, 112. 
 
 Natural Theology, Paley, 95. 
 
 natural versus artificial selec- 
 tion, 278-9. 
 
 Naturalist in Nicaragua, Belt, 
 111. 
 
 Naturalist on the Amazons, Bates, 
 225. 
 
 Nature, 252, 255, 256. 
 
 nectarine and peach, 251. 
 
 Neoclytuscurvatus, as mimic, 115. 
 
 Neo-Lamarckism, 3. 
 
 Nevada, 192-3. 
 
 New England, 211. 
 
 New Mexico, 176. 
 
 Newton, Darwin and, 55-6, 77, 
 90 ; nearly lost to science, 57, 
 85-6 ; Hooke and, 85 ; Halley 
 and, 86 ; Leibnitz and, 129. 
 
 Newton, A., 30, 89. 
 
 nigricans, Phryniscus, 110, 111. 
 
 niphe, Argynnis, 161. 
 
 Nomenclature of colours, Werner, 
 111. 
 
 North American Review, 31. 
 
 North-West Territory, Canada, 
 185.
 
 INDEX 
 
 'Notes on Fertilisation of Or- 
 chids ', C. Darwin, 229 n. 1. 
 
 ' Notes on the Geographical 
 Distribution and Dispersion 
 of Insects, &c.', R. Trimen, 
 246 n. 2. 
 
 Novitates Zoologicae, 152 n. 1, 
 158, 178. 
 
 'Oak Eggar 1 moth, 235 n. 1, 
 242, 242 n. 1. 
 
 Ocellated spots on butterflies' 
 wings, Darwin and Trimen on, 
 230 n. 2, 231, 232, 233, 233 n. 2 
 andn. 3, 234. 
 
 Octopus, Darwin on variable 
 protective resemblance of, 
 108, 109. 
 
 Oecology and natural selection, 
 xiii, 143. 
 
 01iver,D., on tendrils, 74; present 
 at reading of joint essay, 13. 
 
 Omphalos, P. Gosse, 9-12. 
 
 'On some remarkable Mimetic 
 Analogies among African 
 Butterflies ', R. Trimen, 236. 
 
 ' On the Geographical relations 
 of the chief Coleopterous 
 Faunae ', A Murray, 246 n. 2. 
 
 ' On the Phenomena of Varia- 
 tion and Geographical Dis- 
 tribution as illustrated by the 
 Papilionidce of the Malayan 
 Region ', A. R. Wallace, 236. 
 
 On Variation, Bateson, 274. 
 
 Ophideres fullonica, piercing 
 oranges, 224 n. 1. 
 
 Orange River, 96. 
 
 oranges pierced by moth, 224 n. 1. 
 
 orchids, Darwin and Trimen on 
 fertilization and structure of, 
 217-29, 232. 
 
 Oregon, 192-4. 
 
 organic selection, 3, 48. 
 
 Oriental Region, butterfly 
 models and mimicry in, 
 152-3, 156, 160-1, 177, 179-80. 
 
 Origin, C. Darwin, v, ix, xiv, 2, 
 et passim ; Owen criticized in 
 the, 28 ; effect of the, 51-6 ; 
 adaptation and the, 99 n. 1 ; 
 
 Paley quoted in the, 100; 
 ' individual differences ' the 
 steps of evolution in the, 272 
 n. 1, transmission of acquired 
 characters considered in the, 
 273. 
 
 Omithoptera, 179. 
 
 Ornithoptera croesus, sexes of, 
 233 n. 1. 
 
 Ornithorhynchus, 47. 
 
 Orthoptera, as mimics, 116. 
 
 oryzivorus, Dolichonyx, 142. 
 
 Osborn, H. F., American Palae- 
 ontology and, 2 ; on organic 
 selection, 3, 48 ; on Erasmus 
 Darwin and Lamarck, 3-4 ; on 
 In Memoriam, 8. 
 
 Owen, Sir Richard, 15 ; Darwin 
 and, 26-30, 28 n. 2, 230. 
 
 Oxalis, Darwin and R. Trimen 
 on, 217, 223-4, 226-7, 229. 
 
 Oxford, Buckland, Lyell, Darwin 
 and, 6-7, 86-7; Brit. Ass. 
 Meeting (1860) at, 66-8 ; Dar- 
 win Centenary at, 78-83. 
 
 Pacific States, 207-8. 
 
 Palaearctic Region, mimicry in 
 W. section of, 150; in E. sec- 
 tion of, 151. 
 
 palamedes, Pap., 183, 206. 
 
 Paley, influence on natural his- 
 tory of, 95-8, 100-1 ; quoted 
 in Origin, 100. 
 
 Pall Mall Gazette, 68. 
 
 pamphilus, Coenonympha, 231-2. 
 
 Pangenesis, 33-4, 38-9, 38 n. 1. 
 
 l Pai)ilio* or 'Fluted Swallow- 
 tails ', one of the three sections 
 ofPapilionidae, 137, 177-8, 206; 
 'Anchisiades ', ' glaucm ', ' ma- 
 chaon', and 'troilus' groups of, 
 182-3 ; as mimics ofPharmaco- 
 phagus, 137, 177-91, 206-7 ; of 
 Pharm. philenor in N. America, 
 181-91, 206-7 ; of Danainae, 
 &c., 137, 179 ; secondary mimi- 
 cry between, mimetic, 182-3, 
 207 ; females of, especially mi- 
 metic, 132, 137, 139, 179, 182- 
 5, 206, 236-7, 278; Oriental
 
 INDEX 
 
 297 
 
 species of, greatly mimicked, 
 179-80. 
 
 'Papilio ' polyxenes americus, 184. 
 polyxenes asterius, 182- 
 
 5, 188, 206. 
 
 sarpedon choredon, 106. 
 dardanus (merope) , 132, 
 
 139, 236-7, 278. 
 glaucusglaucus( turmts) , 
 
 182-5, 188, 206. 
 palamedes, 183, 206. 
 troilus troilus, 182-5, 
 
 188, 206. 
 
 Papilionidae, see ' Cosmodesmtis', 
 'Papilio', and ' Pharmacopha- 
 gus'. 
 Patagonia, Darwin on colours of 
 
 animals in, 127. 
 peach, moths piercing, 217, 224, 
 224 n. 1, 227 ; nectarine and, 
 251. 
 Peacock, butterflies' ' eye-spots ' 
 
 and tail of, 231, 234. 
 Peckham, Dr. and Mrs. G. W., 
 on mimicry in Attid spiders, 
 116-17. 
 Pelargonium, defence of desert 
 
 species of, 98. 
 perenne, Linum, 224. 
 Perrhybris (Mylothris) pyrrha, 
 Darwin and Wallace on mi- 
 micry and sex in, 134 n. 1. 
 Peru, 184. 
 
 ' Pharmacophagus ' or ' Aristo- 
 lochia swallow-tails ', one of 
 the three sections of Papili- 
 onidae, 177-8 ; as models, 137, 
 177-91, 206-7 ; distribution of, 
 177-80 ; New World species 
 of a distinct group, 180-1, 
 206 ; ' tailed ' forms of primi- 
 tive, 181; females of S. Ameri- 
 can species mimicked, very 
 rarely males, 178-9. 
 1 Pharmacophagus ' philenor, a 
 model of N.Ameri- 
 can species of 'Pa- 
 pilio', &c., 180- 
 91, 206-7; special 
 protection of, 181. 
 polydamas, 180. 
 
 phenarete, Ituna, 153. 
 philenor, Ph., see ' Pharmaco- 
 phagus philenor '. 
 Philosophic Zoologique, Lamarck, 
 
 Phyllotettix, leaf-like, 101. 
 
 Physianthus albens, 217 ; Dar- 
 win and R. Trimen on in- 
 sects captured by, 225, 225 
 n. 1. 
 
 Physiology and vivisection, Dar- 
 win on, 72-3. 
 
 Phytophagous beetles as mimics, 
 120-1. 
 
 Pierinae, 134 n. 1, 135, 139; 
 Pharmacophagusmimickedi by, 
 179. 
 
 Piranga erythromelas, Beebe's 
 experiments on, 142. 
 
 Planaria, Darwin on mimetic 
 species of, 122. 
 
 Planema, as model, 238. 
 
 Plateau, F., on taste of Magpie 
 moth, 242 n. 1. 
 
 plexippus, Danaida (Anosia), 
 152 n. 1, 154, 158-9, 158 . 3, 
 161-i, 168-73, 177, 204. 
 
 Pneumora, 230 n. 2. 
 
 Pocock, R. I., on mimicry in 
 Attid spider, 117. 
 
 podalirius, a type of ' Cosmodes- 
 mus ', 178. 
 
 poetry, Darwin and, 60: see 
 also vi, 57-66, 79-83, 216, 
 256-8. 
 
 polydamus, Pharm., 180. 
 
 Polygonia (Grapta), 175. 
 
 polyphyletic, see multiple 
 origin. 
 
 Popular Science Monthly, 267. 
 
 populi, Limenitis, 193. 
 
 Poulton, E. B., 78 ; on ' eye-spot ' 
 of butterfly, 231-2; on ac- 
 quired characters, 274 n. 1. 
 
 Poulton, E. P., 79. 
 
 Prieska, 96. 
 
 Primula, 229. 
 
 Principles of Geology, Lyell, 5, 
 6, 9 n. 1, 86. 
 
 Proc. Am. Acad., 24. 
 
 Promeces viridis as mimic, 114.
 
 INDEX 
 
 proserpina, a probable hybrid 
 between Lim. arthemis and 
 astyatiax, 186. 
 
 protective resemblance, aggres- 
 sive and, 101-10; mimicry 
 and, 101, 145-7, 174-5. 
 
 Pseudacram, a mimetic genus, 
 238. 
 
 pseudodorippus, f. of Lim. archip- 
 pus, 211. 
 
 Punnett, R. C., on de Vries's 
 ' fluctuations ' non-transmis- 
 sible, xi, 258-80; individual 
 differences claimed as ' muta- 
 tions ' by, 279-80. 
 
 purpurata, Radena, 158 . 3. 
 
 pyrrha, Perrhubris (Mylothris), 
 134 n. 1. 
 
 Quart. Joum. Micr. Sci., 224 
 
 n. 1. 
 Quarterly Revieic, xiv, 13 n. 2, 
 
 16 n. 4, 28 n. 2, 30, 44, 47, 
 
 254, 260, 280 n. 1. 
 qitercus, Lasiocampa, 230 n. 2, 
 
 235, 235 n. 1, 242, 242 n. 1. 
 
 Rabbit, Darwin on white tail of, 
 
 113. 
 
 Radena purpurata, 158 n. 3. 
 Rambles of a Naturalist. &c., 
 
 Collingwood, 124. 
 Reader, 228. 
 Reciprocal mimicry, a probable 
 
 example of, 196-8, 208. 
 recognition markings, 112-13. 
 red cabbage, 249. 
 Regeneration, Darwin and 
 
 others on, 38 n. 1. 
 reginae, Strelitzia,211 ', 228-9, 228 
 
 n.2. 
 Researches on Mimicry. Haase, 
 
 178. 
 reversion, Bateson on causes of, 
 
 277. 
 
 Rhodesia, S.E., 130. 
 Rhopalocera Africae Australia, 
 
 R. Trimen, 228 n. 1. 
 
 Riley, C. V., on variable protec- 
 tive resemblance, 109. 
 
 Rio de Janeiro, 35. 
 
 Rio Macao, 35. 
 
 rock-thrush of Guiana, 140. 
 
 Romanes, G. J., on Darwin's ex- 
 periences of ' the sublime ', 
 34 ; Darwin to, 38, 258. 
 
 Rothschild and Jordan, on 
 two Danaine genera, 158 ; on 
 synonymy of Papilionidae, 
 152 . 1, 182 n. 1 ; on classi- 
 fication of Papilionidae, 178 ; 
 on structural distinction of 
 American Pharmacophagus, 
 181. 
 
 Rowe, Arthur W., on 'continu- 
 ous 1 evolution in the white 
 chalk, 280 n. 1. 
 
 Royal Institution, 67. 
 
 Royal Society of Edinburgh, Proc. 
 of, 19, 44. 
 
 Royal Society, Phil Trans, of, 
 101. 
 
 Rugby School Nat. Hist. Soc., 109. 
 
 S. America, Darwin and Wallace 
 in, 1 ; thorn-bearing plants of, 
 98 ; N. forms in S. of, 46 ; 
 butterfly models of, 153-4 ; 
 invaded by Danaida from N., 
 163-4, 204. 
 
 Salatura, see Danaida decipiens, 
 
 genutia, and insolata. 
 1 Salisbury Lord, D.C.L. offered to 
 
 Darwin in 1870 by, 90. 
 I Sargassum resembled by Scyllaea, 
 
 107, 108. 
 
 | Saturnidae eye-spot in S. African 
 species of, 233. 
 
 Satyrine mimics of l Papilio\ 
 180. 
 
 Satyrium, 220-1, 220 n. 2, 229. 
 
 Scarlet tanager, 142. 
 
 Scent of butterflies, 141-2, ap- 
 preciation of, by insects, 235, 
 235 n. 1, 242, 242 n. 1 ; and 
 deer, 242.
 
 INDEX 
 
 299 
 
 Scotsman, 44. 
 
 Scott, D. H., at the Oxford 
 centenary, 78. 
 
 Scott, J., help given by Darwin 
 to, 53, 70 ; Dai-win to, 18-19, 
 53 n. 1, 70, 74. 
 
 Scott, W. B., American Palaeon- 
 tology and, 2. 
 
 Scudder, S. H., on N. American 
 butterflies, 152 n. 1, 165, 169 
 n. 1, 172, 176, 186, 188, 189- 
 90, 193. 
 
 Scyllaea, a sea- weed-like mollusc, 
 107-8. 
 
 sea-sickness, probably not 
 cause of Darwin's ill-health, 
 58 n. 2. 
 
 season, ' eye-spots ' developed in 
 wet, 231-2. 
 
 secondary and tertiary mimicry 
 in N. American butterflies, 
 182-3, 188, 190-1, 207. 
 
 Sedgwick, A., Darwin taught by, 
 85 ; on Origin in review, 16 
 n. 4 ; and in letter to Darwin, 
 16, 18, 89. 
 
 Seeley, H. G., on Archaeo- 
 pteryx, 30. 
 
 segregation of varieties, 125. 
 
 Semnopsyche, see ' Argynnis 
 diana '. 
 
 Semon, R., on memory and here- 
 dity, 38. 
 
 Seward, A. C., 4 . 1, 92. 
 
 sex, mimicry and, 132-9, 182-3, 
 240. 
 
 sexes, relative numbers of, in 
 butterflies, 233-5, 233 n. 1, 
 234 n. 4, 242. 
 
 sexual selection, 139-43; Dai-win's 
 great interest in and descrip- 
 tion of, in joint essay, 103, 111, 
 113, 125-8, 139-40 ; the origin 
 of species and, 125; mimicry 
 and, 127-8, U8, 149 n. 1,238, 
 240 ; sounds and scents of in- 
 sects as evidence of, 141-2; 
 Darwin on, in letters to Tri- 
 men, 230-6, 242-4. 
 
 Shakespeare, 62, 77, 80, 90. 
 
 Shipley, A. E., on de Vries's 
 ' fluctuations ' non-transmis- 
 sible, 49 n. 1, 258-9, 265. 
 
 shorthorn cattle, 249. 
 
 Silurian, 47. 
 
 ' single centres of creation ', 
 Darwin and Lyell on, 248-9, 
 253. 
 
 ' Small Heath ' butterfly, value 
 of eye-spots of, 231-2. 
 
 Smith, Geoffrey, 79. 
 
 Solomon Islands, mimicry in, 
 160. 
 
 Sound-producing organs as 
 evidence of sexual selection, 
 141. 
 
 Species and Varieties; their 
 Origin by Mutation, de Vries, 
 49 n. 1, 259, 265-7. 
 
 speciosa, Bonatea, 217, 228, 229, 
 229 n. 1. 
 
 Spectator, 9 n. 1, 16 n. 4. 
 
 Spencer, Herbert, 2 ; acquired 
 characters and the theories 
 of, 33-7. 
 
 Sphex, as model, 114, 118. 
 
 Spiders, as mimics, 116-17; mi- 
 metic males of, 133. 
 
 spines and thorns, 98, 262 
 n. 3. 
 
 St. Helena, 71. 
 
 St. Jago, 6, 108. 
 
 Stainton, T. H., 235. 
 
 Strecker, 168, 211. 
 
 Strelitzia reginae, fertilized by 
 sun-bird, 217, 228-9, 228 
 n.2. 
 
 strigosa, f. of Danaida berenice, 
 154, 162-4, 171-2, 204-5. 
 
 struggle for existence, the 
 essential feature of Dar- 
 winism, 8, 9; rate of evolu- 
 tion determined by, 46-7 ; 
 adaptation, natural selection 
 and, 94-101. 
 
 sublime, feelings of the, 
 34-7. 
 
 Sugar-bird, see ' sun-bird '. 
 
 Sun-bird, Strelitzia fertilized by, 
 228-9, 228 n. 2.
 
 300 
 
 INDEX 
 
 Sybilla, Limenitis, 164. 
 Sydney, 202. 
 
 ' Tails ' of Pharmacophagus, 
 primitive, 181. 
 
 tanager, scarlet, 142. 
 
 Tasitia, see ' Danaida berenice ' 
 and ' D. strigosa '. 
 
 Tasmanian insects of Beagle, 
 202. 
 
 Teleology and adaptation, 
 94-8. 
 
 Telephoridae as mimics, 120. 
 
 Tendrils, Darwin on origin of, 
 73-4. 
 
 Tennyson, natural selection 
 and, 8, 9. 
 
 Thackeray, F. St. J., on Tenny- 
 son and evolution, 9 n. 1. 
 
 Thayer, A. H., on white under 
 sides of animals, 109, 110. 
 
 Thiselton-Dyer, Sir William, 
 234 n. 2; at Oxford cen- 
 tenary, 78 ; on protective 
 adaptations of plants, 97 n. 1, 
 102 . 2 ; on origin from a 
 single pair, 252-3; Darwin 
 to, 100. 
 
 Thomson, J. Arthur, on de 
 Vries's ' fluctuations ', 271. 
 
 Thomson, Sir Wyville, 256. 
 
 thorns and spines, value of, 98 ; 
 origin of, 262 n. 3. 
 
 Thyridia, F. Muller on Ituna 
 and, 153-4. 
 
 tiger, Darwin on the stripes of, 
 104. 
 
 Times, 49 n. 1, 68, 79. 
 
 toad, warning colours of a, 
 110, 111. 
 
 transilience, 274, 276. 
 
 transmission of acquired char- 
 acters, Weismann on the, xv, 
 3, 33-42, 274-5; F. Darwin 
 on the, 38-42 ; de Vries on 
 the, 261-2, 270, 276 ; C. Dar- 
 win on the, 273 ; Poulton on 
 the, 274 n. 1. 
 
 Travels in the Interior of Southern 
 Africa, Burchell, 96-7. 
 
 tree-frog, Darwin on the, 99 
 w.l. 
 
 Tres Marias Islands, 181. 
 
 Trichius, sexes of, 233 n. 1. 
 
 Trigonia, 47. 
 
 Trimen, Henry, 234 n. 2. 
 
 Trimen, Roland, first meeting 
 between Darwin and, 213- 
 14, 219 ; on Dai-win and 
 Owen, 28 n. 2, 230 ; on Dar- 
 win's help to younger men, 
 215 ; contributions to Descent 
 of Man by, 230 n. 2 ; on fruit- 
 piercing moths, 224, 224 . 1, 
 227 ; Oxalis sent to Darwin 
 by, 226-7, 226 n. 1 ; on fer- 
 tilization of Strelitzia, 228 n. 
 2 ; on ' eye-spots ' of Melanitis 
 leda, &c., 230 n. 2, 231, 233, 
 233 n. 2 and 3 ; on sexes of 
 African butterflies, 234 n. 4 ; 
 papers on Disa and Bonatea 
 by, 217-18, 222, 224, 228-9, 
 229 n. 1 ; on distribution of 
 beetles by, 231, 246, 246 n. 2 ; 
 memoir on mimicry by, 231, 
 236-41 ; 18 unpublished let- 
 ters (1863-71) from Darwin 
 to, vii, 63, 213-46, 256 ; from 
 Mrs. Darwin to, 216, 245. 
 
 trirnorphic Oxalis, 226, 226 n. 1. 
 
 Troilm, group of ' Papilio ', 
 182-3. 
 
 troilus, Papilio, 182-5, 188, 
 206. 
 
 tropical forest, feelings excited 
 by, 34-7. 
 
 turkeys, white moths rejected 
 by, 112, 112 n. 3. 
 
 Turner, H. H., on Newton, 57, 
 85-6. 
 
 turnus, mimetic female f. of 
 Pap. glaucus, 182-3, 185. 
 
 Tyndall, J., Belfast address of, 
 54-5. 
 
 Uitenhage, Lycidae and mimetic 
 Longicorn found together by 
 Burchell at, 121.
 
 INDEX 
 
 801 
 
 'unit character', Castle's defi- 
 nition of, 276, 278. 
 Ursula, see 'Limenitis astyanax '. 
 
 vaillantina, Egybolis, 224 n. 1. 
 
 value of colour in struggle for 
 life, 92-143. 
 
 Vancouver Island, 193, 196. 
 
 Variable protective resem- 
 blance, 108-10. 
 
 variation, Bateson on causes of, 
 277. 
 
 Variation, Heredity, and Evolu- 
 tion, Lock, 262, 270. 
 
 Venezuela, 184. 
 
 Verhandl. d. V. Intemat. Zool. 
 Congr. z. Berlin (1901), 155. 
 
 Vestiges of the Natural History 
 of Creation, E. Chambers, 28, 
 249. 
 
 Vine-tendrils, 73-4. 
 
 Vines, S. H., at Oxford cen- 
 tenary, 78. 
 
 viridis, Promeces, 114. 
 
 Vivisection, defended by Dar- 
 win, 72-3. 
 
 Walcott, C. D., American Palae- 
 ontology and, 3. 
 
 Walker, F., 202, 203 n. 1. 
 
 Wallace, Dr. A., of Colchester, 
 235, 235 n. 2. 
 
 Wallace, A. R., 45, 92, 256; 
 dedication to,iii ; S. American 
 observations of, 1 ; theory of 
 Darwin and, xiv, xv, 8, 9; 
 publication of theory of Dar- 
 win and, 12-15 ; individual 
 differences the steps of evo- 
 lution for Darwin and, 265, 
 272-3; on Darwin, 14-15; 
 on protective resemblance, 
 103-5 ; on warning colours 
 of insects, 111-12; on sexes 
 of Ornithoptera croesus, 233 
 n. 1, 234; inscription in 
 memoir given by Bates to, 
 123 ; term mimicry restricted 
 . by, 101, 145 ; memoir on 
 mimicry by, 132, 236, 238-9 ; 
 
 on female mimicry, 132-5, 
 138 ; on movements of mi- 
 metic Longicorns, 115; Dar- 
 win to, 104-5, 112, 129 n. 3, 
 133-4, 134 n. 1, 140, 255, 106, 
 the latter first published in 
 Section V. 
 
 Walsingham, Lord, 209. 
 
 Wanderings in the Great Forests 
 of Borneo, Beccari, 19. 
 
 Warner, C. D., 37. 
 
 Warning Colours, 110-12. 
 
 Wasps, as models, 114-16 ; Fos- 
 sors and, held by Asclepias 
 flowers, 225 n. 2. 
 
 Waterhouse, G. R., 202, 203 . 1. 
 
 Watson and Cook, lanthanis 
 var. of Lim. archippus named 
 by, 212. 
 
 Wedgwood. Miss Elizabeth, 
 241 n. 1. 
 
 weidermeyeri, Limenitis, 196. 
 
 Weir, J. Jenner, on distasteful- 
 ness of conspicuous larvae, 
 112 ; Darwin to, 112, 32, the 
 latter first published in ad- 
 dress I. 
 
 Weismann, A., 49 n. 1 ; on the 
 non-transmission of acquired 
 characters, xv, 3, 33-42, 274- 
 5 ; Darwin to, 127. 
 
 Werner on colours, 111. 
 
 Westwood,,!. O., Darwinism and, 
 15, 89, 90. 
 
 wheat, Darwin on limit to im- 
 provement of, 48. 
 
 Whewell, Dr., and the Origin, 
 15, 89. 
 
 White, Adam, 214. 
 
 ' White Admiral ' butterfly, 
 164-5. 
 
 white moth, rejected by turkeys, 
 112, 112 n. 3. 
 
 Wilberforce, Huxley and, 66-8, 
 89. 
 
 Wilson, E. B., on resemblance 
 of Scyllaea to Sargassum, 107, 
 108; Darwin to, 107, first pub- 
 lishedin SectionV(see also 70). 
 
 Wollnaton, 46.
 
 302 
 
 INDEX 
 
 woodpecker, Darwin on the, 
 
 99 n. 1. 
 Worlds in the Making, Arrhenius, 
 
 Wright, Dr., on Archaeopteryx, 
 
 30. 
 Wright, Chauncey, defence of 
 
 Darwin by, 2, 31-2. 
 
 York, Owen on Archaeopteryx 
 at (1881), 29. 
 
 Zool Soc. Proc., 107, 158. 
 Zoologica: N.Y. Zool. Soc., 110. 
 Zoonomia, Erasmus Darwin, 3. 4. 
 
 102. 
 Zygaenidae, as mimics, 121. 
 
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