CHAP. XIV.] FUNCTIONS OF THE SKIN. 427 



The skin combines the opposite functions of absorption and secre- 

 tion. Its lymphatic network, and the capillaries, are both concerned 

 in the former, which, under certain conditions, is very actively 

 performed. 



Secretion may be said to be carried on at every point of the sur- 

 face of the cutis, since the cuticle is a deciduous product, constantly 

 in course of separation from it. But the principal seat of this func- 

 tion are those glandular offsets from the skin that lie scattered in 

 numberless multitudes beneath it. It may be safely said, that the 

 secreting membrane they comprise far exceeds, in extent, the surface 

 of the whole body. By the involutions of the sweat-glands, the 

 surface is multiplied, for the sole purpose of secretion, and the 

 quantity of material capable of being thus eliminated is enormous. 

 There is one peculiarity connected with this great glandular sur- 

 face, which results from its not being made up into a solid organ, 

 but disseminated in detached points under the integument, viz., 

 that it is more than all others subject to the influence of external 

 temperature, acting upon the cutaneous blood-vessels ; but an 

 apparatus for adjusting the irregularities hence resulting is pro- 

 vided in the kidneys, as will be hereafter explained. 



The sebaceous glands are another great system, chiefly subser- 

 vient to the protection and health of the skin itself, but resembling 

 the sweat-glands in their disseminated arrangement. They are 

 extremely numerous, and yield an oily material for the lubrication 

 of the surface of the cuticle. On most parts of the body they are 

 as abundant as the hairs themselves. They are an important 

 accessory organ for the elimination of hydro-carbonous matters 

 from the system. Thus the skin is a superficial emunctory of great 

 extent and importance, and will demand subsequent consideration 

 in that character. 



We may now consider the function of the skin as the organ of 

 touch. One of the distinguishing characteristics of this sense is its 

 universal diffusion over the exterior of the body, by which its sphere 

 of action as a recipient of impressions, and as a criterion of locality, 

 is rendered more extensive than that of any other. The contact of 

 foreign bodies is perceived as occurring at the point at which they 

 actually strike the organ of touch, whether that point be within the 

 sphere of operation of any other sense or not. The precision with 

 which this is effected depends very much on the degree of develop- 

 ment of the papillary tissue in the several regions of the body. 



We have already seen that the papillae present great varieties in 

 different parts. These varieties will be found to correspond very 



