January i^, i^qSJ 



NATURE 



;o7 



as to the manifest avoidance or disgust with which such species 

 are left untouched, or thrown aside after tasting, when offered 

 to domesticated or captive vertebrate animals that devour 

 ordinary insects with avidity. The numerous experiments 

 of this kind recorded by Butler, Jenner Weir, Weismann, 

 Poulton, and Lloyd-Morgan, as regards both larvK and imagos 

 of European species, are supported by a few made by Belt with 

 HeliconiinK in Central America, by D'Url^an and myself with 

 Danainie and Acrsinc-e in South Africa, and by Haase with 

 Danainie in Singapore. 



It is manifest, of course, that even the most distasteful forms 

 cannot enjoy complete immunity from persecution ; in ordinary 

 circumstances they are doubtless mainly kept down by parasitic 

 insects, and during any scarcity of more palatable prey it is cer- 

 tain that they will be devoured faiite de mietix by vertebrates 

 and invertebrates alike. 



((/) Losses due to Inexperience of Enemies. 



As regards the important point whether the protected forms 

 have to suffer a certain percentage of loss from the attacks of 

 young and inexperienced birds and other animals, it must be 

 admitted that the evidence at present forthcoming is exceedingly 

 scanty ; and I have long felt considerable doubt as to the 

 sufficiency of this factor to account for the mimetic resemblances, 

 often remarkably close, between members of associated pro- 

 tective groups. But on reviewing carefully the recorded observa- 

 tions which appear to bear on the question, I have found reason 

 to think that there is enough support to justify the provisional 

 acceptance of the Mullerian explanation. We have in the first 

 place Fritz Miiller's own capture of Heliconii and Acrreinze with 

 a notched piece bitten out of the wings, and Distant's {i.e., p. 65) 

 of a Danais chrysippiis whose wings had been bitten unsym- 

 metrically, apparently by a bird. Then there is the significant 

 record of Skertchley, who, among twenty-three species of 

 Bornean butterflies taken with both hindwings mutilated in the 

 same manner, notes no less than four Danainae, viz. Hestia 

 lynceus, H. lettconoe, Ideopsis daos, and Etiplcca viidamiis. 

 Moreover, it is very remarkable that several of those ento- 

 1 mologists who have specially emphasised the small part played 

 f by birds in attacking butterflies mention, among the few cases of 

 such attack as they witnessed, instances of protected forms being 

 assailed. Sir G. Hampson remarking that in South India the 

 EuplcEse and Danaids were caught as often as any others, and 

 M. Piepers that in two of the four cases which he had seen in 

 Sumatra and Java, the species seized were Euploeae. 



The question underlying this is manifestly whether insect- 

 eating animals have an instinctive inherited discernment of what 

 species are unfit for food, or whether, on the contrary, each 

 individual has to acquire this necessary knowledge by personal 

 experience, aided in some vertebrate groups by parental guid- 

 ance. So numerous and so marvellous are the instinctive or 

 congenital activities of animals — especially in the insect world, 

 where past experience or parental instruction is almost always 

 non-existent — that there has been a very general disposition on 

 the part of naturalists to incline to the former view in a matter 

 so all-important as suitable food. Yet, as far as experiment has 

 hitherto gone in this direction, there seems good ground for 

 holding that — at any rate in such specially insectivorous verte- 

 brate groups as birds, lizards, and frogs — the young possess no 

 such hereditary faculty of discrimination, but have to discover 

 individually what to avoid. This appears not only from Mr. 

 Jenner Weir's and especially Prof. Poulton's careful and often- 

 repeated experiments with lizards and frogs, but also from Prof. 

 Lloyd-Morgan's study of newly-hatched birds of different orders, 

 which indicates clearly with what complete want of discrimina- 

 tion every object of suitable size is at first pecked at and tasted, 

 but how soon experiehce tells and is acted upon. Prof. Lloyd- 

 Morgan made special trial of these young birds with many dis- 

 tasteful insects and their larvae, and states in conclusion that he 

 did not find a single instance of instinctive avoidance, but that 

 the result of his observations is that "-in the absence of parental 

 guidance, the young birds have to learn for themselves what is 

 good to eat and what is distasteful, and have no instinctive 

 aversions. " 



In concluding what I feel to be a very incomplete outline of 

 what has been done in this most important branch of zoolc^ical 

 research, I cannot refrain from expressing the gratification I 

 find in noting how by far the chief part in the investigations 

 pursued and in the deductions derived from them has from the 

 outset been borne by Fellows of this Society. It is work on 



NO. 1474, VOL. 57] 



which we may with justice be congratulated, and which should 

 encourage perseverance in the same and kindred lines of 

 inquiry. 



Need of Observations of Living Organisms. 



Here, as in many other biological researches, it cannot be too 

 strongly insisted on that no result of lasting value can be hoped 

 for without resort to the living animals among all the natural 

 conditions and surroundings. It was not a stay-at-home theorist, 

 familiar only with the dried specimens of the cabinet, that 

 detected the meaning of mimicry and gave to science a rational 

 explanation of the mystery, but an ardent explorer and naturalist, 

 who devoted many of the best years of his life to field-work in 

 tropical lands. I am the last to undervalue the knowledge of the 

 systematist, which is absolutely indispensable to all intelligible 

 record, and I fully recognise that no naturalist can be properly 

 equipped for his work without a fair amount of systematic 

 training ; but philosophical discovery in any direction such as 

 we are now considering can never be truly advanced without 

 unflagging observation and experiment among organisms living 

 in their natural environment. How but by the closest and most 

 exact attention to the entire life-history of animals in their native 

 haunts can we expect to deal satisfactorily with such questions as 

 this of mimicry, of protective resemblances generally, of seasonal 

 dimorphism, sexual selection, local variation, and the like? 

 Admitting gratefully the good work of this kind which has been 

 carried on in Europe, and especially in our own country, one 

 cannot but regret that from tropical regions, where alone the 

 abundance, complexity, and incessant activity of life afford full 

 prospect of the adequate reward of such research, we have little 

 more than isolated notes and unconnected and incomplete 

 observations, mere indications — precious as they are — of the 

 rich harvest that lies unreaped for lack of resident workers 

 devoted to the task. 



It is on this account that I earnestly renew the plea put 

 forward from this chair on May 5 last, for the establishment, in 

 tropical countries, of biological stations for the study of the 

 terrestrial fauna ; where, as in the existing marine biological 

 stations, naturalists could follow, during a succession of seasons, 

 special lines of observation and experiment under favourable 

 conditions of laboratory and other equipment, free from the 

 hindrances and distractions of ordinary collecting travel, and 

 with all the advantages of mutual help and encouragement. 

 The living expenses, for men of the simple tastes of the naturalist, 

 would not be great ; and I feel certain that, with the increasing 

 facilities for swift transport, it would not be long before many 

 students of biology would embrace the opportunity so provided 

 for the effectual prosecution of researches of the utmost value to 

 science. 



UNIVERSIT V A ND ED UCA TIONA L 

 INTELLIGENCE. 



Oxford. — The usual courses in the Scientific and Medical 

 Departments are being continued this term. Prof. Ray Lan- 

 kester is lecturing on the "Structure and Classification of 

 Fishes," and Prof. E. B. Poulton on the " Natural History and 

 Classification of Insects." Prof. Tylor purposes to lecture on 

 "Ancient and Barbaric Stages of Culture compared with 

 Advanced Civilisation." The Regius Professor of Medicine 

 (Prof. J. Burdon-Sanderson) proposes to continue his Patho- 

 logical Lectures of last term by discussing the " Nature and 

 Causes of Tuberculosis." 



The examination for the Radcliffe Travelling Fellowship will 

 begin on March i. Candidates must have passed all the ex- 

 aminations for B.A. and B.M. in the University, and must 

 either have been placed in one of the First Class in one of the 

 Final Honour Schools, or have taken some University prize 

 op)en to all. 



Cambridge. — Mr. R. H. Biffen, of Caius, has been appointed 

 Demonstrator of Botany ; Mr. F. C. Kempson, also of 

 Caius, Demonstrator of Anatomy ; and Mr. H. W. Pearson, of 

 Christ's, Assistant Curator of the Herbarium. 



The honorary degree of M.A. has been conferred on Dr. 

 H. A. Giles, Professor of Chinese, and on Dr. W. H. R. Rivers, 

 of St. John's, Lecturer in Experimental Psychology. 



Two Shuttleworth Scholarships in Botany and Comparative 

 Anatomy will be awarded at Caius College in March. Candi- 



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