56 DARWINISM AND THE PROBLEMS OF LIFE 



colour were to come from another locality, it would 

 either be soon destroyed, or those of its offspring would 

 have most chance of surviving which had most greenish- 

 brown in their coats. In favourable circumstances the 

 species might be acted on by natural selection, and 

 "adapted" more and more, until at last its colour was 

 in harmony with its environment. 



Where other colours are found at the limits of a 

 country, the animals are affected by these. Our winter 

 is usually so short that hares are not exposed for too 

 long a period to attacks through the contrast of their 

 colour with the snow, besides that the grey tones of the 

 field and wood rarely disappear. It is otherwise in the 

 high Alps. Here, during the long winter, a broad 

 unbroken sheet of snow covers the earth, and a brown 

 hare could not long escape detection. We can 

 understand, therefore, why the Alpine hares are white 

 in winter. In fact, this very species shows clearly how 

 natural selection modifies an animal. The Alpine hare 

 is also found further north in the Arctic hare. While it 

 remains brown throughout the winter in the south of- 

 Sweden, further north it assumes a white coat at this 

 season. And the further north we go, the longer does 

 the white coat last, always in proportion to the number 

 of cold months. In the extreme north, where the snow 

 never melts, and where no trees break the dazzling 

 white surface, the Polar hare is white at all seasons, like 

 almost all the other Arctic animals, the Polar bear, fox, 

 owl, and so on. 



These adaptations to the winter have clearly been 

 brought about by natural selection. Just as amongst 



