432 GENERAL PRINCIPLES 



ments would make them conspicuous and invite a second 

 attack. 



865. Mimicry. Many animals are protected in various 

 degree by their stings, poison fangs, malodorous secretions 

 or unpalatable taste. These are naturally avoided by species 

 which would otherwise prey upon them. But this means that 

 the preying species must be able to distinguish between the 

 palatable and unpalatable prey. The unpalatable forms are 

 often conspicuously marked, as if to advertise the fact, and 

 thus prevent an attack which might be disastrous to both 

 pursuer and pursued. Coloring which is regarded as serving 

 such an end is termed warning coloration. It is especially 

 common among insects and protects them from birds. 



866. Where species occur which are protected and warn- 

 ingly colored there are also often other species which are not 

 protected by sting or unpalatable, and yet are very like the 

 protected species in form and color. This is called " mimicry," 

 because the one form is supposed to have acquired a resem- 

 blance to the other for the purpose of protection. If a bird 

 recognizes a certain form and color pattern as belonging to an 

 undesirable insect another insect resembling the first would be 

 spared an attack if the bird failed to discriminate. Upon this 

 ground mimicry is explained by natural selection. A fact of 

 almost conclusive significance is that the mimic and the model 

 are always found associated in the same regions. Mimicry 

 is very common among butterflies, but many cases are known 

 in which bees, bumbleebees and wasps serve as models and are 

 mimicked by flies, beetles and butterflies. Cases in which 

 poisonous snakes are mimicked by harmless ones are also known. 



867. Mimicry also occurs between two species which are 

 both protected. This demands a different explanation from 

 the preceding case. Birds learn that protected species are 

 unpalatable only by experience, and in getting this knowledge, 

 one or more butterflies of the protected species are injured or 



