ies. There are two kinds of hair on a mammal: (1) 

 the long, coarse, over-hair which is chiefly protective, 

 and (2) the fine, soft, underfur, which serves to pre- 

 serve a normal body temperature. There are also 

 highly specialized hairs, (vibrissae) which are sensory. 

 The "whiskers" located on the face, and the coarse 

 hairs often found above the eyes and on the wrist near 

 the hand, are evidently sensory and aid the senses of 

 smell, touch and hearing. 



The primary purpose of the hair coat is protec- 

 tive. This protection is effected in two ways. In the 

 first place, insulation against low temperatures seems 

 paramount, and secondly, a heavy coat of hair affords 

 protection from serious injury by the teeth of other 

 animals and sheds water, thus preventing the body 

 of the animal from getting wet. Some mammals are 

 born with a fine, silken coat of hair, while others are 

 born hairless. The latter are kept warm by contact 

 with the mother, or by being cuddled together in a well 

 lined nest. These forms are usually born in warm 

 seasons or are produced in deep burrows. 



No single description could account for all of the 

 changes that take place in the hair growth of mammals 

 in general and there are considerable differences 

 among the types of hair of infancy, youth and ma- 

 turity, that of an adult usually being coarser. The dis- 

 tribution of the hair over the body is also variable ac- 

 cording to the kind of mammal, but it is generally long- 

 er and more dense on the dorsal surface of the body. On 

 virtually all forms there are sections of the body which 

 are devoid of hair, such as under the hind legs, around 

 the mammae, etc. 



-*H[ 24 >- 



