VARIABLE PROTECTIVE RESEMBLANCE IN INSECTS 155 



the stimulus from the environment falls upon the eye 

 in the one case and probably upon the surface of the 

 skin in the other. 



Variable Protective Resemblance in insects is no 

 explanation of the origin of colour 



Many authorities have believed that, in the results 

 of these experiments upon the colours of insects, we 

 see an explanation of the origin of colour, by the direct 

 influence of environment accumulated through many 

 generations. This is a very tempting conclusion, and 

 one which for a time appeared to me to be satisfactory. 

 But as soon as there was clear evidence that the 

 medium of the nervous system is necessary, the 

 results were seen to be indirect, and to have needed 

 the most astonishing adaptations on the part of the 

 organism before the colour of the environment could 

 exercise any influence upon it. 



It might still be maintained that the existing 

 colours and markings of certain caterpillars are at any 

 rate in part due to the accumulation through heredity 

 of the indirect influence of environment, working by 

 means of the nervous system. To this it msij be 

 replied that the whole use and meaning of the power 

 of adjustment depends upon its freedom during the life 

 of the individual ; any hereditary bias towards the 

 colours of ancestors would at once destroy the utility 

 of the power, which is essentially an adaptation to the 



