118 ANIMAL COLORATION. 



from a considerable heis'ht. Which of these two models does 

 the insect most resemble ? Perhaps it will be said that the 

 summit of a chalk cutting, where the white chalk is beginning to 

 commingle with the brown earth lying above it, is a still more 

 likely model. Now, if we accept " natural selection," it is 

 quite evident that the main principle upon which Nature works 

 is economy: a new organ is not made for the performance of a 

 new function when an old one a little altered will do as well. 

 Accepting the analogy, we might be led into forgetting the 

 difference between this kind of economy and the more human ; 

 and into believing that the colour of the insect was brought 

 about in order that it might resemble as many " environments" 

 as possible. It might be urged that only one of these different 

 models was successfully imitated by the moth, the likeness to 

 the others being accidental ; in fact, this is the only possible 

 view that could be taken. But if the resemblance is accidental 

 in the one case, why not in the other ? The fact is, that with 

 a varied environment — such as a wood for instance — we may 

 easily get a large number of examples of coloration among its 

 insect inhabitants that are purely accidental. After all, the 

 same colours occur among animals as among plants, even 

 amounting in a few cases to an identity in the pigments 

 (e.g. chlorophyll, and carotin — which has been found by Prof. 

 Blanchard in a crustacean). Among moths, for instance, yellow, 

 browns, greys and white, are the i>revailing colours ; and these 

 are just the colours which predominate upon the tree trunks 

 and decaying vegetation at roots of trees, where moths 

 chiefly pat-s the day. To assume that the second is the reason 

 for the first is to assume too much. It is not the pigments 

 themselves which are supposed to be produced by the action 

 of natural selection, but their distribution; it is not the colour, 

 but the coloration of animals, which forms the subject of 



