NAILS AXD HATK. 121 



as they advance. Xear the end of the body, as the horny 

 layer becomes thinner, the growth from below is diminished. 



Hairs, varying greatly in size and development, cover 

 nearly every portion of the surface of the body. The only 

 parts in which they are not found are the palms of the 

 hands and soles of the feet, the palmar surface of the fingers 

 and toes, the dorsal surface of the last phalanges of the fin- 

 gers and toes, the lips, the upper eyelids, the lining of the 

 prepuce, and the glans penis. Some of the hairs are long, 

 others are short and stiff, and others are fine and downy. 

 These differences have led to a division of the hairs into 

 three varieties. 



The first variety includes the long, soft hairs, which are 

 found on the head, on the face in the adult male, around the 

 genital organs and under the arms in both the male and the 

 female, and sometimes upon the breast and over the general 

 surface of the body and extremities, particularly in the male. 



The second variety, the short, stiff hairs, is found at the 

 entrance of the nostrils, upon the edges of the eyelids, and 

 upon the eyebrows. 



The third variety, the short, soft, downy hairs, are found 

 on the general surface not occupied by the long hairs, and 

 the caruncula lachrymalis. In early life, and ordinarily in 

 the female at all ages, the trunk and extremities are covered 

 with downy hairs ; but in the adult male, these frequently 

 become developed into long, soft hairs. 



The hairs are usually set obliquely in the skin, and take 

 a definite direction as they lie upon the surface. Upon the 

 head and face, and, indeed, the entire surface of the body, 

 the general course of the hairs may be followed out, and 

 they present currents or sweeps that have nearly always 

 the same direction. These " currents " have been carefully 

 studied by Wilson, and are fully described in his work upon 

 the healthy skin. 1 



1 WILSON, Healthy Skin, Philadelphia, 1854, p. 101, d seq. 



