KATABOLISM. 



437 



epithelium consists of only a few layers of living cells, 

 which are constantly dying, shedding, dissolving, and 

 forming the slimy mucus which covers the interior sur- 

 face and again renew- 

 ing; while in the epi- 

 dermis the lower layer 

 in contact with the 

 dermis consists also 

 of living nucleated 

 cells, which are also 

 constantly dying and 

 renewing; but the dy- 

 ing cells, instead of 

 dissolving and form- 

 ing slime and leav- 

 ing the surface still 

 composed of living 

 cells, gradually dry 



Up, mummify, flatten Fig. 304.— Section through the skin, show- 



mnrp anH mnrp and in S its structure: ep, epidermis, and m, 



more ana more, ana ;ts Malpighian layer ;d, dermis ; sg, sweat 



finally pass off as gland ; joT, sweat duct ;#, sense papilla: ; 



J h, hair ; bv, blood vessels. 



scales of the scarf 



skin. Thus, besides the lower layer {Malpighian layer) 

 of living cells, there are many layers in various stages 

 of dying and mummification. This mummified part is 

 the cuticle. The color of the skin is in the lower living 

 layer. A blister is a lifting of the epiderm from the 

 derm and an accumulation of lymph beneath. 



Sudorific Glands. — Scattered in great numbers over 

 the surface of the skin are found pores formed by the 

 infolding of the living or Malpighian layer of the epi- 

 derm, forming tubes (sd, Fig. 304) opening on the sur- 

 face. They pass through the dermis into the subcutane- 

 ous connective tissue, and are there convoluted into a 

 pellet, sg. These are the sudorific glands. The num- 



