STKUCTUKE OF THE ^KIN. 6 



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termed eud-organs; some of the nerves may even penetrate the 

 epidermis to germinate there. So the corium is a highly-sensi- 

 tive structure, and forms the seat of the sense of touch. In the 

 corium certain glands are present, such as the sweat glands, 

 which are long, tubular, highly-convoluted glands, opening upon 

 the surface of the epidermis, either alone or with a hair. These 

 glands are lined by an epithelium that is directly continuous 

 with the stratum malpighii of the epidermis. Imbedded in 

 the corium are the roots of the hairs. If a hair, its sheath, and 

 the papilla, as the small conical elevation of the corium at the 

 bottom of the pit is called, be examined, it will be found that 

 cells also derived from the stratum malpighii cover this papilla, 

 and from the proliferation of these cells the hair is formed, 

 moving from off the papilla like a cast. As the cells continue 

 to grow and multiply, more additions are made to the newly- 

 formed hair below, so that eventually it projects from the level 

 of the epidermis. It continues to increase in length for a time, 

 but soon growth ceases and the hair dies, but provision is made 

 for a new hair in the same sheath by a process of budding and 

 the formation of a new papilla by the corium, which continues 

 the function of the first one. The cells lining the hair sheath 

 and covering the papilla are continuous with the stratum 

 malpighii, and thus hair is as truly a derivative of epidermis 

 as scurf. Growing out, also, from the cells lining the hair- 

 sheath and into the corium at several points, we have masses of 

 cells arranged to form glands, which provide an oily secretion 

 that is poured into the root sheath of the hair. These glands 

 are the sebaceous glands, are mostly associated with hairs, and 

 provide the secretion that renders the skin unctuous, smooth 

 and silky to the touch, and less liable to crack. 



The lioof derived from the epidermis. — The epidermis 

 covering the corium of the foot provides the horn that forms 

 the hoof. The epidermis covering all the corium below the 

 line where the hair terminates has this function. In other 

 words, from the epidermis covering the corium of the perioplic 

 ring, the coronary band, the sensitive laminae, sensitive frog, 

 and sensitive sole horn grows, and hoof is developed. 



The corium is not smooth : if the epidermis is removed it 

 will be found to be covered with minute projections stickino- 

 apparently into the epidermis. In certain regions, e.g., the 



