THE SKIN. 



545 



F[ g. m.- A section of skin from the 

 fi"9 er > showing the vascular net- 

 work of papillcs, at the surface of 



the **<, 



amount of solid matter. To effect these processes, we 



meet with two distinct classes 



of glandulae in its substance: 



the sudoriferous, or sweat 



glands; and the sebaceous, 



or oil glands. They are both 



formed, however, upon the 



same simple plan, and can fre- 



quently be distinguished only 



by the nature of their secreted 



product. 



The sudoriferous or perspi- 

 ratory glands form small OVal 



Or globular masses, Situated 

 , ^ ,-iJi , 



just beneath the cutis, in 

 almost every part of the sur- 

 face of the body. Each is 

 formed by the convolution of 

 a single tube, which thence 

 runs towards the surface, as 

 the efferent duct, making nu- 

 merous spiral turns in its pas- 

 sage through the skin, and pene- 



trating the epidermis rather Fig. 282. Capillary network and dis- 

 Obliquely; SO that its Orifice is tribution of papilla; over the tongue. 



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



lifted up as the fluid issues from it. Mr. Erasmus Wilson 



says: "To arrive 



at something like 



an estimate of the 



value of the perspi- 



ratory system, in 



relation to the rest 



of the organism, I 



counted the perspi- 



ratory pores on the 



palm of the hand, Fig 283 _ Distrihution of the tactile nerves at the ex . 



and. lOUnd 3,528 tremity of the fingers, as seen in a thin perpendicular 



in a square inch. Action of the skin. 



Now, each of these pores being the aperture of a little 



tube of about a quarter of an inch long, it follows that in 



N N 



