INSECTS 231 



must inquire the reason for their occurrence. On the 

 theory that the similarity of habits between the. female and 

 the mimicked species was the cause of the mimicry, the facts 

 at once become intelligible ; on the theory of selection they 

 do not. 



To pursue the investigation further we ought to inquire 

 what in detail are the habits of the female and mimicked 

 species on the one hand, of the male on the other. It is 

 certain that since the males and females copulate they must 

 be in company for a time. But nevertheless they are 

 probably only in company for a brief portion of their lives, 

 and have different habits, as for example in the case of species 

 in which the females are wingless and stationary while the 

 males are winged and active. As to the direct causes of 

 the modifications so far as colour is concerned, I attribute 

 it chiefly to the quality of the light to which the insect is 

 exposed. Light rays of different quality are reflected from 

 different surroundings, and these falling upon the surface of 

 the wings of butterflies most probably produce modifications 

 of colour. That such modifications are produced by the 

 particular exposures of caterpillar and chrysalis, has been 

 sufficiently proved by the experiments of Prof. Poulton. 1 



It follows, of course, that in my opinion all cases of 

 mimicry are simply examples of the similar effect of similar 

 conditions. If the mimicking species were in any instance 

 constantly found to live in situations quite different from 

 those inhabited by the species imitated, this would be a 

 serious objection to my theory. But so far as I can ascertain 

 this is never the case ; disguise and association always go 

 together, and it is therefore reasonable to hold that the 

 association is the cause of the disguise. 



Bates, in his original memoir, 2 considers the question 



1 The Colours of Animals, International Scientific Series, 1890. 

 2 Trans. Linn. Soc, vol. xxiii., 1862. 



