The Colours of Animals. 77 



the light of the sky. Those fishes which live deep 

 down in the depths of the ocean present no such 

 contrast between the upper and under surface. 

 Many of the smaller animals which live in the sea 

 are as transparent as glass, and are consequently 

 very difficult to distinguish. 



5. It is sometimes said that if animals were 

 really coloured with reference to concealment, 

 sheep would be green, like grass. This, however, 

 is quite mistake. If they were green they would 

 really be more easy to see. In the grey of the morn- 

 ing and the evening twilight, just the time when wild 

 animals generally feed, grey and stone colours are 

 most difficult to distinguish. Sheep were originally 

 mountain animals, and everyone who has ever been 

 on a mountain-side knows how difficult it is to 

 distinguish a sheep, at some distance, from a mass 

 of stone or rock. 



6. It is, again, a great advantage to the rabbit 

 and hare to be coloured like earth ; black or white 

 rabbits are more easy to see, and consequently 

 more likely to be killed. This, however, does not 

 apply to those which are kept in captivity, and we 

 know that tame rabbits are often black and white. 

 Again, in the far north, where for months together 

 the ground is covered with snow, the white colour, 

 which would be a danger here, becomes an advan- 

 tage ; and many arctic animals, like the polar bear 

 and polar hare, are white, while others, such as the 

 mountain hare and ptarmigan, change their 



