THE SKIN AND BATHING 



259 



461. Hair. Extending obliquely nearly through the 

 derma are numerous minute tubes lined with epithelium. 

 Their cells become joined together in a tough string, called 

 a hair, which projects out of the tube. When the hair is 

 pulled out, the epithelium covering the projection in the 

 tube soon produces another hair. A small muscle is 

 attached to the bottom of each hair root. Cold causes 

 the muscles to contract and to pull the hair tubes to an 

 upright position imparting to the skin a roughness called 

 goose flesh. Hair covers almost the entire body. 



462. Sebaceous glands. Near each hair is a gland called 

 a sebaceous gland. It secretes a kind of oil, which softens 

 the skin and keeps the hair glossy. The glands are espe- 

 cially numerous down the center of the face. When their 

 mouths are stopped by - -r-^ : _-_*- ** 

 dirt they often become " T i_~"~ "T-'-^ ~ r & 

 distended and form small, 



black spots called black- 

 heads, which are often 

 mistaken for small worms. 



463. Nails. The epi- 

 dermis upon the backs of 

 the last joint of each finger 

 and toe is hardened into a 

 nail. The nail is formed 

 at its back part and is 

 pushed onward in its 





A nail (X 200). 

 a surface of the nail. 



b body of the nail. 



c epithelial cells just before they are welded 

 into a nail. 



growth. An epithelial cell d papillae. 



- , . ., e growing epithelium. 



remains a part of the nail 



about three months before it is pushed from its root to its 



end. 



464. The complexion. In health the skin has a velvety appear- 

 ance, and a rosy color, and is free from spots or scales. Its moisture is 



