VAEIABLE PEOTECTIVE EESEMBLANCE IN INSECTS 143 



spun in white surroundings in a strong light (see 

 fig. 82). 1 



In this case it seems almost impossible for the 

 surrounding colours to influence directly the colour of 

 the cocoon. It is necessary to assume the existence 



Pig. 31.— The cocoon of Emperor Moth 

 (S. carpini), spun in a black calico 

 bag ; natural size, although an excep- 

 tionally small cocoon. 



Fig. 32.— The cocoon of Emperor Moth, 

 spun on a white surface in strong 

 light ; natural size. 



of a complex nervous circle as a medium through 

 which the stimulus of colour can make itself felt. If 

 this conclusion be correct it is probable that the 

 colours of the pupa and larva are adjusted in the 

 same manner. 



The observation upon S. carpini has been con- 



' Proc. Boy. Soc. vol. xlii. p. 108. I have since found that the 

 fact must have been known previously, for it is quoted in Mr. A. E. 

 Wallace's Tropical Nature. I do not yet know the name of the 

 naturalist who made the observation. 



