colour of cocoons, piques, and larvce. 213 



a larva iu a gilt box pupated, not on the gilt paper, but 

 on leaves of the food-plant, so that it was not anywhere 

 exposed to the paper ; sometimes, indeed, when practi- 

 cally surrounded by a leaf or leaves, and among these 

 were some of the most golden pupte. Notwithstanding, 

 therefore, the clear evidence that the proximity of 

 brightly illuminated surfaces promotes the production of 

 the metallic appearance in these pupa;, I cannot see 

 that there is any reason to suppose that this is a " pro- 

 tective resemblance," or, indeed, that it is a "resem- 

 blance" at all. 



In his work on this subject, Mr. Poulton, indeed, 

 admits that by reason of their metallic lustre the pupae 

 do not resemble any substance to which they are attached 

 in nature ; but he suggests that perhaps they may have 

 come through a phylogenetic phase in which they did 

 attach themselves to such substances. Though nothing 

 forbids anyone from framing such an hypothesis, it is 

 surely evident that if conjectures of this Idnd are to be 

 admitted as a basis for argument, all zoological science 

 will be thrown into confusion. 



III. Tlie colours of larvoi o/Amphidasys betularia 

 {the Pepper Moth). 



Mr. Poulton was kind enough to send me some newly- 

 hatched larvae of A. betularia, with the suggestion that I 

 should repeat his interesting experiment described in 

 ' The Colours of Animals,' 1890, pp. 152 and 153. 

 Larvae reared among green leaves and green twigs only, 

 were said to be green through life, while larvae reared on 

 leaves amongst which darkly coloured sticks were placed 

 were stated to assume a dark colour. 



My experunent has substantially verified Mr. Poulton's 

 account. When the larvae came to me they were of a 

 kind of medium brownish green colour, being rather 

 more brown than green. They were divided into four 

 lots on the 12th of July. 



Two lots (A) were fed on green leaves {Populus nigra) 

 without black sticks, and two lots (B) were fed on green 

 leaves amongst which black sticks were placed. Care 

 was taken that the leaves given to all were from shoots 

 of similar age. 



