io6 



APPLIED PHYSIOLOGY 



forced ahead, and so it grows long and needs to be cut 

 off even with the ends of the fingers, with a sharp knife or 

 scissors. When the nails are bitten off, they are left rough 



__,_<7 an d are likely to catch 



-I_ _~ _r . - " -1 ~_ jtj in the clothing and tear 



away from the flesh. 

 Biting the nails also 

 makes the ends of the 

 fingers soft and sore. 



199. Hangnails.- 

 Sometimes a little tongue 

 of skin at the root of 

 the nail becomes torn up 

 and hangs by one end. 

 This is called a Jiang- 

 nail. They are some- 

 times very sore, and biting 

 them off makes them 

 worse. They should be cut off close to the skin with a 

 sharp knife. Sucking the fingers, or biting the nails, is 

 likely to cause these hangnails. 



Dirt under the ends of the finger nails is not only untidy, 

 but may be poisonous. The nails themselves are not poi- 

 sonous, but the filth which they carry may contain germs 

 of sickness. So we ought to keep our nails clean. 



200. Hair. Little tubes of epithelium from the epi- 

 dermis reach into the derma, and as fast as their cells 

 grow they are matted together into a string called a hair. 

 As new cells are always forming, the old ones are pushed 

 out, and so the hair grows. When a hair is pulled out, 

 the cells lining the tube keep on growing and soon make 

 a new hair. Fine hair covers nearly all the body, but upon 

 the head and upon men's faces, it grows long. 



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. 

 d papilla. 

 e growing epithelium. 



