CUTANEOUS SYSTEM OR SKIN. 189 



without the offensive effluvia of the dissecting-room, and at all 

 seasons. This great improvement constitutes a new era in favor of 

 MEDICAL REFORM, and must be identified with it, and must be car- 

 ried out as soon as circumstances permit. 



CHAPTER XII. 



CUTANEOUS SYSTEM OR SKIN. 



THE glands which are disposed in the substance of the skin, and 

 in the walls of the intestinal canal, although individually minute, 

 make up by their aggregation an excreting apparatus of no mean 

 importance. The skin is the seat of two processes in particular ; 

 one of which is destined to free the blood of a large quantity of 

 fluid ; and the other to draw off a considerable amount of solid 

 matter. To effect these processes, we meet w r ith two distinct 

 classes of glands in its substance ; the sudoriparous or sweat-glands, 

 and the sebaceous or oil-glands. They are both formed, however, 

 upon the same simple plan ; and can frequently be distinguished 

 only by the nature of their secreted product. 



The perspiratory form small oval or globular masses, situated 

 just beneath the skin, in almost every part of the surface of the 

 body. Each is formed by the convolution of a single tube; 

 which thence runs towards the surface as the efferent duct, 

 making numerous spiral turns in its passage through the skin, and 

 penetrating the^ epidermis rather obliquely, so that its orifice is 

 covered by a sort of little valve of scarf-skin, which is lifted up as 

 the fluid issues from it. The convoluted knot, of which the gland 

 consists, is copiously supplied with blood-vessels. On the palm of 

 the hand, the sole of the foot, and the extremities of the fingers, 

 the apertures of the perspiratory ducts are visible to the naked eye, 

 being situated at regular distances along the little ridges of papillae, 

 and giving to the latter the appearance of being crossed by trans- 

 verse lines. According to Wilson, as many as 3528 of these glands 

 exist in a square inch of surface on the palm of the hand ; and as 

 every tube, when straightened out, is about a quarter of an inch in 

 length, it follows that in a square inch of skin from the palm of the 



