AND PHYSIOLOGY. 



307 



and Nerves — Amount of Waste Escaping from the Skin. 

 : — In the corium, or internal layer of the skin, resides the vi- 

 tality. Here the arteries terminate in the capillaries and the 

 nerves double upon themselves, producing the highest sensi- 

 bility to external impressions. So that when any function of 

 the skin is spoken of, reference is usually made to this inner 

 layer. And we see that the skin is not only useful as a pro- 

 tection and covering to the body, but is of great value as an 

 excretory apparatus. And in this office the skin is pecu- 

 liarly valuable, since it removes a great amount of matter 

 from the system that the lungs cannot remove. The actual 

 amount of waste matter escaping daily from the skin is given 

 variously by different writers. All, however, make out an 

 average of from thirty , to forty ounces, or if condensed to 

 water, about two pints. A proof that the vapor of water es- 

 capes in the form of insensible perspiration is had by placing 

 the dry hand upon a cold glass or polished metallic substance, 

 when moisture in a few seconds condenses on the surface. 



539. Uses of the Oil Glands— Renders the Hair Soft 

 — Softens the Skin — Protects the Eye — Guards the 

 Mem bran a Tympani.— The function of the sebaceous, or oil 

 glands of the skin seems to be the secretion of substances pro- 

 tective to the skin. These are mainly oily products, and are 

 given off at the roots of the hair, so as to give it flexibility, 

 that by its stiffness it may not irritate the skin. The oil tubes 

 are most abundant on those parts of the body which are most 

 exposed, and especially the face and neck. The design of the 

 secretion seems to be to give flexibility to the skin, to prevent 

 the heat and air from drying it so that it would crack in many 

 places, and also to lubricate it when brought into contact with 

 foreign substances, as is the case so frequently with the hands. 

 The oil of the skin also prevents moisture from adhering to it, 

 and thus its functions can be more perfectly carried on, and 



50S. Whore lies the vitality of the skin ? Wheat other use than a protection is the 

 skin? How much waste matter escapes daily from the skin? How many pints ? 539. 

 What is the use of the oil glands? How does it affect the hair? What value does it 

 impart to the skin ? 



