THE WHITE HARE. 81 



within eight days. During the whole of this remark- 

 able change in the fur, no hair falls from the animal; 

 hence it appears that the hair actually changes its 

 colour, and that there is no removal of it. The fur 

 retains its white colour until the month of March, or 

 even later, depending on the temperature of the atmos- 

 phere ; and, by the middle of May, it has again a grey 

 colour. But the spring change is different from the 

 winter, as the hair is completely shed." 



This seasonal change of the fur of the alpine hare 

 (and it is not confined to that animal) answers several 

 important purposes. One of these is safety from 

 enemies. The summer colour approaches that of the 

 grey stones and lichen among which it lives, while its 

 winter hair is that of the snow, which then completely 

 covers the mountains. Another advantage of the 

 change of colour is even more important : it tempers 

 them to the weather. White is much more difficult 

 both to heat and to cool than black, and thus the white 

 colour preserves the natural heat of the animal in 

 winter ; and the dark colour in summer raises the tem- 

 perature of the surface, and makes the animal perspire, 

 the evaporation of which is a source of cold. The 

 adaptation of the colour to the temperature is much 

 more obvious than the protection. The animals that 

 prey upon the alpine hares are a part of creation as 

 well as they, and their preservation is just as essential ; 

 so that we may suppose that the increased mode of 

 concealment on the part of the one, is counteracted by 

 an increased vigilance on the part of the other. But 

 the protection of the animal from the weather counter- 

 acts no part of the economy of nature, and there we 



