THE STORY OP THE LUNGS, SKIN AND KIDNEYS 91 



spread over the surface of the body. In its structure 

 the skin exhibits a main division into two layers. The 

 outer coating is the epidermis or scarf skin, which 

 possesses neither nerves nor bloodvessels and con- 

 sists of cells perpetually renewed from the upper sur- 

 face of the under skin. The dermis or under skin, 

 lying below the outer layer, contains both nerves and 

 bloodvessels, the ends of the nerves being contained 

 within little projections of this under layer known as 

 papillcs. Below this under layer of the skin we come 

 upon other tissues including fat. 



THE GLANDS OF THE SKIN. The glands of the 

 skin are two in number. The sebaceous glands 

 are small pocket-like organs, the ducts or tubes of 

 which open into the sheaths of the hairs and also 

 frequently pass to the surface of the skin itself. 

 These glands secrete an oily or fatty material, 

 the function of which is to keep the skin pliant 

 and moist, whilst from their relation to the 

 hairs it may be assumed that their secretion may 

 also be held to represent a natural oil or pomade. 

 More important are the sweat glands whose 

 action it is to separate from the fine bloodvessels 

 surrounding them certain waste products constitut- 

 ing the sweat. The sweat consists of a large amount 

 of water, minerals (amongst which common salt is 

 prominent), and certain fatty matters derived from 

 the skin's surface. A certain amount of carbonic 

 acid gas is also given forth from the skin, whilst most 

 physiologists agree that the skin has a limited power 

 of absorbing oxygen. The sweat glands consist each 

 of a minute coiled up tube, the end of which passes 

 upwards to the skin and opens in a. pore. The coiled 

 up part of the tube especially is lined by cells, which 

 are the active agents in taking from the blood the 



