446 



SCIENCE. 



[N. 3. Vol. VII. No. 170. 



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 

 Euploese. 



The question underlying this is mani- 

 festly 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 experi- 

 ence, aided in some vertebrate groups by 

 parental guidance. So numerous and so 

 marvelous are the instinctive or congenital 

 activities of animals — especially in the in- 

 sect world, where past experience or paren- 

 tal instruction is almost always non-exist- 

 ent — that there has been a very general 

 disposition on the part of naturalists to in- 

 cline to the former view in a matter so all- 

 important as suitable food. Yet, so far as 

 experiment has hitherto gone in this direc- 

 tion, there seems good ground for hold- 

 ing that — at any rate in such specially 

 insectivorous vertebrate 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 Pi'ofessor 

 Poulton's careful and often-repeated experi- 

 ments with lizards and frogs, j but also from 

 Professor Lloyd Morgan's study | of newly- 

 hatched birds of different orders, which in- 

 dicates clearly with what complete want of 

 discrimination every object of suitable size 

 is at first pecked and tasted, but how soon 

 experience tells and is acted upon. Pro- 

 fessor Lloyd Morgan made special trial of 

 these young birds with many distasteful 

 insects and their larvse, and states in con- 

 clusion (I. c, p. 43) that he did not find a 

 single instance of instinctive avoidance, but 



* Report of Intern. Zool. Congress, III. (Leydeu, 

 1895), p. 460. 

 tSeeProo. Zool. Soo. Lond., 1887, pp. 191, etc. 

 i 'Habit and Instinct, ' pp. 39-58. 



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 zoological 

 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 which we 

 may with justice be congratulated, and 

 which should encourage perseverance in the 

 same and kindred lines of inquiry. 



Here, as in many other biological re- 

 searches, it cannot be too strongly insisted 

 on that no result of lasting value can be 

 hoped for without I'esort to the living ani- 

 mals among all the natural conditions and 

 surroundings. It was not a stay-at-home 

 theorist, familiar only with the dried speci- 

 mens 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 syste- 

 matist, which is absolutely indispensable to 

 all intelligible record, and I fully recognize 

 that no naturalist can be properly equipped 

 for his work without a fair amount of sys- 

 tematic training ; but philosophical dis- 

 covery in any direction such as we are now 

 considering can never be truly advanced 

 without unflagging observation and experi- 

 ment among organisms living in their 

 environment. How, but by the closest and 

 most exact attention to the entire life-his- 

 tory 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 dimor- 



