^12 Mr. W. Bateson on Variation in the 



they are wetted. Of the physiology of these phenomena 

 I have gleaned no hint at all. 



The whole question touching the putative utility of 

 these colours as a protection, seems to me an unprofitable 

 field for study. As to the enemies of these creatures, 

 other than insect-parasites, there is almost no evidence, 

 and as to the senses by means of which these parasites 

 seek their prey, there is still less. Of enemies to any of 

 these forms in the pupal state, there is, so far as I know, 

 no direct evidence at all. The jmpal state is very short, 

 lasting about a fortnight or three weeks, according to the 

 weather, and the view that these peculiar colours have 

 been developed by these creatures to conceal them from 

 imaginary enemies during that brief time is, in my 

 judgment, quite unsupported by fact. This view is 

 applied to the case of these pupa3 by an indiscriminate 

 extension of deductions made in other cases fairly 

 enough, as, for example, in that of the larvae of A. betii- 

 laria (v. infra). 



After experience of these pupae, the doubt whether the 

 metallic colour can in any way lead to their concealment 

 is stronger than it was. The gilded pupae, so far as I 

 can see, do not by reason of their gilding approximate 

 to the appearance of any natural substance, either of 

 flakes of mica, or to the dried slime left by slugs, or to 

 any other bright objects to which they have been com- 

 pared by ingenious persons. If Mr. Poulton had spoken 

 of this gilding as a " warning coloration," I should have 

 been less surprised. 



One thing more may be said. In the case of the sole, 

 in the case of the larvae of A. hetularia, and the like, 

 there can be no doubt that the change of colour repre- 

 sents an " attempt " on the part of the animal to ap- 

 proximate to the colour of its surroundings. Now, in the 

 case of these gilt pupae, do we really know that the 

 change represents any such effort at approximation ? I 

 confess that, though as regards the deposit of pigment 

 this may be so regarded, the change in the degree of 

 metallic colouring does not seem to me to be an approxi- 

 mation of this kind at all. It is true that gilt paper 

 makes some aiijiroach to the look of these pupae, but the 

 yellow paper, and silver or white papers, do not in 

 the least. In this connexion a circumstance, which I 

 saw several times, may be mentioned. In several cases 



