vi DEFENCES OF INSECTS 205 



More or less complete, concealment is useful to many 

 animals, but to insects it is absolutely essential, and 

 accordingly in insects adaptation to environment is 

 most fully and markedly developed. In the animal 

 world the members eat as they are eaten. To those 

 that live upon others, and to whom activity and 

 energy are denied, compensation in the boon of colour 

 is also important colour such as may best serve the 

 possessor to avoid alarming its prey, either by its 

 presence or its approach. That in this explanation 

 is learned what is the first and most widespread use of 

 colour among animals seems corroborated by the fact, 

 that protective resemblance is apparently possessed 

 by insects in proportion to their sluggish movements 

 or absence of other means of defence. 



This principle of adaptive colouring, though early 

 recognised, found no intelligible exposition until the 

 year 1859, when it met with perfect satisfying solution 

 in Darwin's theory of natural selection, by which he 

 explains how it was that evolution took place. 

 Formerly among a certain section of the community 

 the problem was referred to an originally created 

 specific peculiarity, or the adaptation was understood 

 to be due to the direct action of climate, food, or soil. 

 But while the former interpretation puts an effectual 

 bar to reasonable inquiry, since we cannot get beyond 

 the fact of the adaptation, the second was found to be 

 far from adequate to cope with all the varied phases 

 of this strange phenomenon, and was controverted 

 by some well-known facts. The gradually increasing 

 change of disguised species, from a general harmony 

 with surroundings to precise imitation of particular 



