THE COLOURS OF ANIMALS AND PLANTS 117 



the Malay Archipelago, &c, where man is almost 

 unknown and wholly unwelcome. Again, man is a 

 comparatively recent arrival on the earth, and the 

 exquisite shapes and mouldings of many fossil shells 

 show us that at any rate beauty of form existed in 

 rare perfection long before his advent. This is a 

 subject worth inquiring into, and one which has 

 attracted the attention of many men, especially 

 Wallace. The result of these inquiries is to show 

 that colour is no mere accidental attribute of animals 

 and plants, but has a very definite reason for its 

 existence, and that in various ways and for divers 

 reasons it may contribute materially to the welfare 

 of its possessor. 



The colours of animals in a state of nature are 

 constant, or nearly so. Tame rabbits vary greatly, 

 but wild ones are all very much alike ; each kind 

 of animal having a particular colouring, which does 

 not vary very greatly, save in exceptional cases. 

 Not merely in the individuals of a given species, but 

 in genera or even in entire families a certain con- 

 stancy of colouring may be noticed. For instance, 

 the "blue" family of butterflies are characterised, 

 not only by their blue colour, but more markedly 

 still by the eye-spots on the under-surface of the 

 wings. The mottled under-surface of the wings of 

 VanessidK, and the silvering of the wings of Fritil- 

 laries, are other examples. 



Colour cannot be explained as due to the direct 

 action of light or heat ; for although it is true that 

 there is an immensely greater number of richly- 

 coloured birds and insects in tropical than in tem- 



