USES OF THE TRUE SKIN* 37 



a network of blood-vessels and nerves of the finest 

 conceivable texture ; and, taking the vast extent of 

 its whole surface (estimated to exceed in a man of 

 average size 2500 square inches) into account, we 

 can easily understand how these minute ramifi- 

 cations may really constitute a larger mass of ner- 

 vous matter than is contained in the original trunks 

 of the nerves from which they are incorrectly said 

 to arise, and also how so large a proportion of the 

 whole blood may be circulating through the skin at 

 one time. 



To understand the important purposes of the true 

 skin, we must distinguish between its constituent 

 parts, and consider it, in virtue of each of them, 

 1st, As an exhalant of waste matter from the sys- 

 tem ; 2d, As a joint regulator of the heat of the 

 body ; 3d, As an agent of absorption ; and, 4th, As 

 the seat of sensation and touch. 



Besides performing the mechanical office of a 

 shield to the parts beneath, the skin is admirably 

 fitted, by the great supply of blood which it receives, 

 for its use as a secreting and excreting organ. The 

 whole animal system is in a state of constant decay 

 and renovation; and while the stomach and ali- 

 mentary canal take in new materials, the skin forms 

 one of the principal outlets or channels by which 

 the old, altered, or useless particles are eliminated 

 from the body. Every one knows that the skin 

 perspires, and that checked perspiration is a power- 

 ful cause of disease and of death ; but few have any 

 just notion of the real extent and influence of this 

 exhalation, such as we shall attempt to exhibit it. 

 When the body is overheated by exercise in warm 

 weather, a copious sweat soon breaks out, which, 

 by carrying off the superfluous heat, produces an 

 agreeable feeling of coolness and refreshment. This 

 is the higher and more obvious degree of the function 

 of exhalation ; but, in the ordinary state, the skin is 

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