SKIN

forms a protective coating over the whole Nf It is popularly thought to consist of three layers, but really only consists of two:—the cuticle, scarf-skin, or epidermis above, and the true skin or dermis beneath. The epidermis is devoid of nerves and blood-ve els, so that it stands wear and tear without bleeding or causing pain. In order to withstand the constant wear to which it is exposed, it is formed of several layers of scales, which are renewed beneath as fast as ey are rubbed off at the surface. The greater the friction the greater the scale formation; hence erise the “ horny hand of toil,” corns, ete. The dermis or true skin is richly supplied with blood-ve els and nerves. To the latter the sense of touch isdue. Deep in the dermis are the sweat glands, which pour the sweat into canals or ducts that open on the surface of the skin; the pees of these ducts are tho pores of the skin, which are visible through a strong magnifying gla . The chief purpose served by the sweat gland is to aid in regulating tho temperature of the body. As the body becomes heated the formation of sweat is much increased, and this in the course of evaporation chills the skin and the blood flowing through it. Tho skin contains hairs. The so grow in little pits in the skin called hair-follicles. As soon as & hair has attained a certain ee ea varies with the individual, it is cast off and rep by a young hair that grows up beneath it. From disease or advancing age tho follicles may cease to produce new hairs, and batineas results. Opening into the follicle are two oil glands, the sebaceous glands, the pu of which is to oil the hair and the surface of tho ae Attached to each folliclo is a emall muscle, which, under the influence of cold or fright, makes the hair stand on end. The condition termed goose-flesh is thus produced. If dirt is allowed to collect on the surface, the mouth of the sweat glands and the sebaceous glands become blocked, and their secretions are pent up. 1. [s. 409]