MIMICRY 209 



schemes. There is the naturalist who acknowledges 

 the resemblances but makes no attempt to account 

 for them ; that type of naturalist is fortunately becoming 

 extinct. There is also the naturalist who can detect 

 flaws in the theory when it is applied to particular 

 cases a few of which we will examine later on : mean- 

 while we will only say that this sort of argument is 

 perfectly valid, only it must be remembered that when 

 a great majority of observed facts support a theory, 

 while a few do not, it is more reasonable to suppose 

 that the few are capable of another interpretation than 

 that they subvert the theory. 



Thus it is no argument against mimicry that birds 

 have been seen to capture and devour distasteful 

 species of insects ; not only are some birds e.g. the 

 cuckoos catholic enough in their tastes to devour 

 every kind of insect, nauseous or otherwise, but 

 we may be certain that if young and inexperienced 

 birds and birds with strong palates or with very 

 hungry appetites did not from time to time devour 

 butterflies of all sorts, there would be no mimicry at 

 all : it is the severity of the struggle for existence which 

 has brought about the present state of mimetic per- 

 fection. Some suppose that mimetic resemblances are 

 due to parallelism in development induced by simi- 

 larity of environment, but such an argument will not 

 bear examination ; far more often than not the two 

 creatures, model and mimic, differ widely in their life- 

 histories. For example, in Borneo and elsewhere cer- 

 tain Pierine butterflies are closely mimicked by moths 

 of the sub-family Chalcosiince, yet the caterpillars are 

 widely different and feed on different plants. Again, 

 there occurs in Borneo a wonderful locust which 



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