160 STOAT OR ERMINE. 



summer dress. But in mild winters the hairs re- 

 tain their red colour, and if new hairs come in, they 

 are also red ; if the weather become colder, the new 

 hairs that appear are white, although the old hairs 

 do not vary ; and, if there are alternations of severe 

 cold and temperate weather, the animal becomes 

 mottled. It is certain that the change of season is 

 not regularly attended with a change of colour ; 

 that great cold at any period of winter, if protracted, 

 is accompanied with a change to white ; but there 

 is no evidence that a return of heat produces a re- 

 turn of the red colour in white hairs. The hairs 

 continue to elongate from the end of spring to the 

 beginning of winter, and the fur is certainly not 

 longer in winter than in spring. Perhaps the hairs 

 are renewed at all seasons, and those which grow 

 in mild weather are brown, while those that shoot 

 out in cold weather are red, cold having the effect 

 of changing the structure of growing hairs, or of 

 acting on their bulbs so as to prevent the applica- 

 tion of colouring matter. But there is also reason 

 to believe that sometimes the brown hairs themselves, 

 on the application of intense cold, become whitened 

 for I have seen individuals of a brown colour 

 patched with white, in which the white hairs were 

 of the same length as the brown ; but I have never 

 met with any of which the hairs were partially 

 coloured, or appeared to be changing from brown 

 to white, still less from white to brown. On the 

 whole, therefore, I think that this animal sheds its 

 hair gradually, and in small parcels or patches, all the 



