26 THE HUMAN BODY. 



limits, according as the cellular tissue which it carries with 

 it is more or less relaxed, and as it is itself thick or thin. 

 Thus it is movable on the back of the hand and top of 

 the foot, on the front of the neck and on the surface of the 

 joints; it is almost immovable on the cranium, on the palm 

 of the hand, and on the sole of the foot. 



Elastic, very extensible, and very resistant, it sustains, 

 without being torn, violent shocks and great compression; as 

 in certain wounds by firearms, for instance, the projectile 

 will penetrate the clothing to the skin, and injure the organs 

 which it covers without itself being broken. 



The skin is the organ of feeling, its surface is endowed 

 with a sensibility which becomes extremely delicate at several 

 points. Being constantly in more or less intimate contact 

 with the atmosphere, it transmits to the economy the influ- 

 ence of external agents ; and it is partly by its tissues that the 

 fluids and gases are eliminated, which have done their office, 

 and are to be thrown off as the ultimate and abandoned 

 products of nutrition. 



This function of continual exhalation makes the skin the 

 regulator of the temperature of the body. When the tern-, 

 perature of the organism is elevated either by motion or any 

 other internal or external cause, the sweat immediately 

 appears, and the cooling or loss of heat caused by its evapo- 

 ration reduces the temperature to its normal standard. 

 Lavoisier was the first who clearly explained this function, 

 so important from its utility, and from the serious conse- 

 quences which result from its disturbance. 



Almost entirely deprived of the covering which nature has 

 given to animals, the colour of the human skin exhibits the 

 richest and greatest variety of shades. This colour is inces- 

 santly modified by the sensations, the movements, by moral 

 or physical emotions; and the transparency of its tissues 

 give as much delicacy as vigour to the tones which animate 

 it; it is not, as in the plumage of birds or in the shells of 

 molluscs, an assemblage of brilliant colours, often without 

 transition, but it is a blending at once the most harmonious 

 and the most striking; it is light in its softest changes, w 

 its most dazzling splendour. 



