PROTECTIVE COLORATION 83 



with variations, and the offspring will inherit the instinct 

 unless some vary away from it, in which case they will be 

 eliminated. The origin of the instinct is explicable in the 

 same way. 



The coloration of animals which serves the purpose of 

 rendering them inconspicuous in their usual surroundings, 

 is so well known that it is not necessary to deal with the 

 phenomenon here except in the most general manner. The 

 way in which shadow is eliminated in the bodies of animals, 

 particularly in mammals and birds, has been admirably 

 demonstrated by models. 1 The colour of the back is similar 

 to that of the surroundings, often with markings resembling 

 the usual environment, while the belly shades off into white, 

 thus doing away with the solid appearance which would 

 otherwise make the animal very obvious. 



Insects frequently resemble their surroundings with an 

 accuracy that must be seen to be thoroughly appreciated. 



A remarkable example ot protective coloration is that 

 of the butterfly Kallima, the under surfaces of whose wings 

 resemble dead leaves. One of the most interesting points 

 of resemblance is that on the fore -wing is an oval and 

 transparent patch. Through this the light passes, producing 

 the effect of a hole in what is apparently a dead leaf. On 

 another part of the same wing is a representation of a 

 hole brought about by means of white body-colour, which, 

 though an admirable imitation, is not so exact as the 

 transparent patch. If we examine the transparent patch 

 microscopically, we find that there are numerous opaque 

 white scales scattered upon its surface. The suggestion is 

 very strong that the hole now represented by the transparent 

 patch was formerly represented by an opaque white patch, 

 and that, as we still find some white scales, the process is not 

 quite complete. The process has not yet been started on the 

 other white patch, so probably this patch arose later than 

 that which is now transparent. 2 At any rate it seems almost 



1 By A. H. Thayer, in the Natural History Museum, South Kensington. 



2 Poulton, Essays on Evolution, p. 203. 



