434 CAUSES OF THE N^'IRIETIES 



the winter coat is of a lighter colour than the smoother 

 covering- vvliich succeeds it in the spring. The difference is 

 much more considerable in wild animals. I have shewn 

 instances of it in two kinds of antelope (saiga and guttu- 

 rosa), in the musk animal (moschus moschifer), and in the 

 equus hemionus. The Siberian roe, which is red in sum- 

 mer, becomes of a grayish white in winter ; wolves and the 

 deer kind, particularly the elk and the rein-deer, become 

 light in the winter ; the sable (m. zibellina), and the martin 

 (m. martes), are browner in summer than in winter*." 



Although these phenomena seem obviously connected 

 with the state of atmospherical temperature, and hence the 

 change of colour, which the squirrel and the mustela ni- 

 valis undergo in Siberia and Russia, does not take place in 

 Germany f ; we do not understand the exact nature of the 

 process by which it is effected ; and cold certainly appears 

 not to be the direct cause. For the varying hare, though 

 kept in warm rooms during the winter, gets its white winter 

 covering only a little later than usual J ; and in all the 

 animals, In which this kind of change takes place, the 

 winter coat, which is more copious, close, and downy, as 

 well as lighter coloured, is found already far advanced in 

 the autumn, before the cold sets In §. 



The coverings of animals, as well as their colour, seem 

 to be modified in many cases by climate ; but, as the body is 

 naked In the human subject, and as the hair of the head 

 cannot be regarded in the same light as the fur, wool, or hair 

 which covers the bodies of animals generally, the analogies 

 offered by the latter are not very directly applicable to the 

 present subject. 



In cold regions the fur and feathers are thicker, and more 

 copious, so as to form a much more effectual defence against 



* NovcE Species Quadrupedum, p. 7. 



+ Ibid. p. 6, note h. The ermine changes its colour in the winter in Ger- 

 many ; but Pallas states, on the faith of sufficient testimony, that it does not 

 undergo this change in the more southern districts of Asia and Persia. 



:{: Nova: Species Quadrupedum, p. 7. 



^ Ibid. p. 9. 



