CHAPTER XVI. 



Conclusions. 



WE have now, more or less fully, examined into the system of 

 colouration in the living world, and have drawn certain 

 inferences from the facts observed. 



It appears that colouration began — perhaps as a product of 

 digestion — by the application of pigment to the organs of trans- 

 parent creatures. Supposing that evolution be true — and, if we may 

 not accept this theory there is no use in induction whatever — it 

 must follow that even the highest animals have in the past been 

 transparent objects. This was admirably illustrated by Prof. Ray 

 Lankester in a lecture on the development of the eyes of certain 

 animals, before the British Association meeting at Sheffield, in which 

 it was shown that the eyes commenced below the surface, and were 

 useful even then, for its " body was full of light." 



Granting this, it follows that the fundamental law of decoration 

 is a structural one. Assuming, as we do, that memory has played a 

 most important part in evolution, it follows that all living matter 

 has a profound experience in decorating its organs — it is knowledge 

 just as anciently acquired, and as perfectly, as the power of 

 digestion. This colour was produced under the influence of light — 

 so it is even in opaque animals. 



With a knowledge so far reaching, we might expect that even in 

 opaque animals the colouring would still follow structural lines, and 

 there should still be traces of this, more or less distinct. 



This is precisely what we do find ; and, moreover, we sometimes 

 get a very fair drawing of the important hidden parts, even where 

 least expected, as in a cat's head, a snake's body, a dragon-fly's 

 thorax, a spider's abdomen, a bird's skull. 



