72 ANIMAL COLOEATION. 



alteration in the insect would preserve its harmony in colour 

 with the environment. It has even been suggested that the 

 colour change is the same as that which occurs in leaves, — that 

 the insect owes its coloration to chlorophyll, — but this has 

 been disproved by Kriikenberg. 



The colour of the grasshopper is caused by several different 

 substances in the skin, which can be separated by treatment 

 with different reagents. If a green or brownish individual be 

 treated with ether, the fluid is stained yellow, and the insect 

 remains of a cochineal red. This effect is produced by the 

 removal of the green pigment, a red colouring matter being left 

 behind. 



In Locusta viricUssima, the green colour is relieved here and 

 there by reddish spots ; these alone remain when the green 

 pigment is dissolved away by ether or alcohol. 



Dr. Kriikenberg was able to prove that the green colouring 

 matter is affected by light : a piece of paper was thoroughly 

 soaked in, until it became dyed by, the green extract ; one half 

 of this was exposed to the light, and the other half covered by 

 a slip of metal ; the light was found to partially destroy the 

 colour. It is concluded, therefore, that light may effect a 

 change under ordinary conditions during the life of the insect. 



Seasonal Change in a Beetle. 



Besides these Orthoptera, something like a seasonal change 

 of colour occurs in beetles. The green colour of some of these 

 insects changes in the autumn to a brownish tint ; here .again 

 we have what appears at first sight to be an excellent instance 

 of adaptability to environmental colour. This case, however, 

 is a little different from that of the grasshoppers ; in those 

 insects the colours are due to pigments ; but in the Beetle 

 {Carabus auratus) the structure of the chitinous wino-cases 



