\D\I'M 207 



| hat thei i tin- whole, the Hi, c and Bates is 



supported by the ' lailrd in tin- ;m<l my former paper-, - ' 



deal with bird- land with the die mammal U P lessor 



Pnulton' ion that animal- may be forced by : <) eat Un- 



palatable form- i- also more than conlinncd, as the unpalatable forms 

 i nmmonly eaten without the -timulus of a< tual hunger generally, 

 al-o, I may add, without di-like." 



Though insects ha\'e many vertebrate and arthropod C1 

 probable that the evolution of mimetie re-emblance, implying warning 

 coloration, has been brought about chiefly by in.-e< t ivorou.- bird-. 



Neglecting papers of minor importance, we may pass at once to the 

 mo-t important contribution upon this subject the voluminous work 

 of Mar-hall and Poulton upon mimicry and warning colors in S 



an insects. These investigators have found that birds are to be 

 counted as the principal enemies of butterflies; that the Danaime and 

 inie, which are noted as models, are particularly immune from de- 

 struction, while unprotected forms suffer; and that mimicking, though 

 palatable, species share the freedom of their models. The same is true 

 of beetles of which Coccinellidae, Malacodermidae (notably Lye us > 

 Cantharidae and many Chrysomelidae serve as models for many other 

 Coleoptera, being " conspicuous and constantly refused by insect- 

 -." In short, the splendid work of Marshall and Poulton tends to 

 place the theory of Batesian and Miillerian mimicry upon a substantial 

 foundation of observational and experimental evidence. 



In regard to the important question do birds avoid unpalatable 

 insects instinctively or only as the result of experience the evidence is 

 all one way. Several investigators, including Lloyd Morgan, have 

 found that newly-hatched birds have no instinctive aversions as regards 

 food, but test everything, and (except for some little parental guidance) 

 are obliged to learn for themselves what is good to eat and what is not. 

 This experimental evidence that the discrimination of food by birds is 

 due solely to experience, was evidently highly necessary to place the 

 theory of mimicry especially the Miillerian theory upon a sound 

 basis. 



Though butterflies as a group are much subject to the attacks of 

 birds in the tropics, it has been asserted that butterflies in temperate 

 regions are as a whole almost exempt from the attacks of birds, and that 

 consequently the mimicry of the monarch (Fig. 247) by the viceroy is 

 of no advantage. In answer to this assertion Marshall has published a 

 long list of references showing that butterflies are attacked by birds 



