60 AXIMAL COLORATIUX. 



moisture may affect the formation and deposition of pigment 

 in one animal, temperature in another, while a third may be 

 entirely uninfluenced by either cause, but will yield to some other 

 environmental influence. Until all these matters have been 

 more thoroughly investigated than they have at present, the 

 theories of modification of colour by selection or elimination 

 rest upon a basis which is manifestly insecure. 



The colour of the wings of the beautiful Indian Moon moth 

 (Aciias selene) is very susceptible to drj^ness and moisture; the 

 normal colour is a delicate pale green; pieces of the wing of 

 a specimen chloroformed for the purpose of this experiment, 

 became very soon straw-coloured in dry air of a temperature of 

 a little under 60° centigrade ; when the same fragments were 

 floated in a saucer containing cold water they rapidly recovered 

 their green colour, which was even intensified. I am not at 

 present concerned with the chemical or physical reasons for 

 their change ; it is sufiicient that it occurs. On the other hand, 

 the green colour of an Emerald moth (^Hemithea thymiario^, 

 though bleached when heated and dried, was not restored by 

 moisture. 



It is at least possible that the tawny colours of desert animals, 

 which have been so often brought forward as an instance of 

 adaptation to the hues of their environment, may be due to a 

 similar cause. 



Mr. Wallace has justly pointed out that the older theory, 

 that colour was dependent for its development upon light and 

 heat, is upset by the colour characteristics of the inhabitants of 

 sandy and dry localities ; on this theory colour should be most 

 intense and varied where light and heat are at a maximimi. 



But any one who will take the trouble to inspect a most 

 interesting case of stuffed animals in the central hall of the 

 Natural History Museum, will be convinced that the contrary 



