204 THE SKIN 



themselves. Here, there is a small root from which the 

 hair grows. When a hair is pulled out, the portion 

 which is not alive separates from the living root, which 

 remains and builds a new hair. 



Connected with each canal through which a hair passes 

 are several minute glands, the sebaceous glands, which 

 secrete an oil for making the hair glossy and waterproof. 

 Since the hair tends to collect dust and dirt, it should 

 be washed with warm water and mild soap. The natural 

 oil which is removed in washing can be restored when 

 necessary by rubbing a small amount of vaseline into 

 the roots before the hair is dried. 



Nails. Tha nails, lite the hair, are special modifica- 

 tions of the epidermis. They serve to protect the sensi- 

 tive tips of the fingers and toes, and consist of a trans- 

 lucent horny layer of closely compacted broad cells. 

 They take root in folds of the dermis and epidermis, 

 which dip down through the fatty layer nearly to the 

 bone. The nail is slovly developed and pushed out until 

 it overhangs the end of the finger or toe to which it is 

 attached. When a rail is torn off, a complete new nail 

 is built out from tlie root in about six months, unless 

 the root itself has been destroyed. 



Since the edg3s of the nails afford natural lodging 

 places for all kinds of dirt and microbes, it is important 

 from the standpoint of health as well as of beauty that 

 they should be kept clean. They should be trimmed 

 carefully and the crevies around and under them should 

 be cleaned with a pointed stick rubbed in soap. 



Sweat glands. The iweat glands of the skin have 

 their mouths in the tinj ridges on its surface. Their 

 ducts penetrate in the brm of a spiral through the 

 epidermis and dermis into the subcutaneous fatty layer. 

 Here each duct becomes tested upon itself, and forms 



