ANIMAL AND BIRD MIMICRY AND DISGUISE 



1 



FOR every animal one discovers when observing carefully, 

 there must be ten unseen. This is partly because many 

 animals burrow in the ground or get in underneath 

 things and into dark corners, being what is called cryptozoic or 

 elusive. But it is partly because many animals put on disguise 

 or have in some way acquired a garment of invisibility. This is 

 very common among animals, and it occurs in many forms and 

 degrees. The reason why it is so common is because the struggle 

 for existence is often very keen, and the reasons why the struggle 

 for existence is keen are four. First, there is the tendency to 

 over-population in many animals, especially those of low degree. 

 Second, there is the fact that the scheme of nature involves nu- 

 tritive chains or successive incarnations, one animal depending 

 upon another for food, and all in the long run on plants ; thirdly, 

 every vigorous animal is a bit of a hustler, given to insurgence 

 and sticking out his elbows. There is a fourth great reason for 

 the struggle for existence, namely, the frequent changefulness of 

 the physical environment, which forces animals to answer back or 

 die ; but the first three reasons have most to do with the very com- 

 mon assumption of some sort of disguise. Even when an animal 

 is in no sense a weakling, it may be very advantageous for it to be 

 inconspicuous when it is resting or when it is taking care of its 

 young. Our problem is the evolution of elusiveness, so far at 

 least as that depends on likeness to surroundings, on protective 

 resemblance to other objects, and in its highest reaches on true 

 mimicry. 



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