GAY PLUMES AND DULL 



zero, it began to change to white in a single night, 

 and at the end of a week was almost entirely so. 

 It is said that in Siberia domestic cattle and horses 

 become lighter-colored in the winter, and Darwin 

 says he has known brown ponies in England to 

 become white during the same season. 



Only one of our weasels, the ermine, becomes 

 white in winter; the others keep their brown coats 

 through the year. Is this adaptive color any ad- 

 vantage to the ermine? and are the other weasels 

 handicapped by their brown tints? 



The marten, the sable, and the fisher do not turn 

 white in the cold season, nor the musk ox, nor the 

 reindeer. The latter animals are gregarious, and 

 the social spirit seems to oppose local color. 



Apart from the intense cold, the long Arctic 

 nights no doubt have much to do with the white of 

 Arctic animals. " Absence of light leads to diminu- 

 tion or even total abolition of pigmentation, while 

 its presence leads to an increase in some degree 

 proportionate to the intensity of the light."* 



When the variable northern hare is removed to 

 a milder climate, in the course of a few years it 

 ceases to turn white in winter. 



The more local an animal is, the more does it 



incline to take on the colors of its surroundings, 



as may be seen in the case of the toads, the frogs, 



the snakes, and many insects. It seems reasonable 



' Vernon on Variation in Animals and Plants. 



65 



