82 THE HAIR. 



mals which inhabit the polar regions are known to become 

 white during the winter season, and among the most remark- 

 able of these is the lemming. Sir John Koss remarks that, 

 finding the lemming, like the polar hares which had been 

 tamed and kept in confinement, preserve its usual colour 

 during the winter, he placed one in the open air, on the first 

 of February, when the thermometer stood at 30 below zero. 

 The next morning, the fur of the cheeks, and a spot upon 

 each shoulder, had become perfectly white. On the follow- 

 ing day the hinder part of the body, and the flanks were of a 

 dirty white hue, and at the end of a week, the animal was 

 entirely white, with the exception of a saddle-shaped patch on 

 the middle of the back. No other change ensued, although 

 the poor animal was kept exposed to the cold until it per- 

 ished. When the skin was examined, the white hairs were 

 found to be much longer than those of the unchanged patch, 

 the blanching being confined to that portion which exceeded 

 in length the natural hairs. So that, when the white ends 

 were cut off, the animal appeared to have regained, with very 

 little alteration, its summer coat, and without any reduction 

 in the length of its fur." 



Kolliker first described the muscles connected with hairs, 

 which had the power of inducing the elevation of these 

 appendages. Mr Lister confirmed this discovery, and the 

 arrangement of these muscles is well shown in the subjoined 

 figure : 



Mr Lister says: The annexed figure "is slightly reduced 

 from a camera lucida sketch of such a section, made in a plane 

 perpendicular to the surface of the scalp, and at the same time 

 parallel to the sloping hairs. I find that such a plane always 

 contains the muscles in their entire length, the reason of which 

 will appear shortly. In this figure d is the corneous, and e 

 the mucous layer of the epithelium; 6, 6, .... are the hair- 



