50 PHYSIOLOGY AND TEMPERANCE. 



becomes looser and more open in the deeper parts, so that the 

 whole skin can be pinched up from the flesh. Forming a 

 part of the true skin are the nerves, blood-vessels and to /ands 

 for secreting the sweat and oil. It is the white fibrous tissue 

 forming the body of the true .skin, or dermis, in animals, 

 which is made into leather by action of the tannin contained 

 in the oak bark used by the tanner. The outer surface of 

 the true skin is marked by small elevated points, the papilla. 

 These papillae are well supplied with loops of capillaries, and 

 they have special nerve endings. They are very numerous all 

 over the body, but are more prominent and more thickly set 

 in some parts than in others. On the palmar surface of the 

 hand and fingers, where the sense of touch is most acute, they 

 are very abundant, and are arranged in rows. These- rows 

 are visible to the naked eye. Where these papillae am most 

 densely set, the finest necdlr cannot, penetrate the true skin 

 without causing pain nor without drawing blood. 



4. Glands of the Skin. There are two kinds of glands 

 in the skin, lying cWp down in the' loose tissue. One is the 

 gland for secreting sweat, and the other is the oil gland, 

 found in connection with the hair. The sweat gland consists 

 of a minute tube coiled up below, and running in a zigzag 

 manner to the surface of the skin. These glands are found 

 in all parts of the body. In some places they are more plen- 

 tiful than in others. In the palms of the hands and the soles 

 of the feet they are very thickly set. They are more plentiful 

 on the forehead than on the cheek. The total number in the 

 human body is said to be between two and three millions. 

 The most important duty these glands have to perform is to 

 regulate the heat of the body. Heat is carried off from the 

 body by the process of evaporation. This evaporation is 

 regulated according to the amount of heat the body finds it 

 necessary to get rid of. The sweat poured out on, the skin 

 evaporates and cools the surface. Perspiration is constantly 



