532 



THE HUMAN BODY 



from the surface. The wrinkles of old persons are due to the ab- 

 sorption of subcutaneous fat and of other soft parts beneath the 

 skin, which, not shrinking itself at the same rate, is thrown into 

 folds. 



Hairs. Each hair is a long filament of epidermis developed on 

 the top of a special dermic papilla, seated at the bottom of a de- 

 pression reaching down from the skin into the tissue beneath, and 



a 



FIG. 143. A section through the skin and subcutaneous areolar tissue, h, 

 horny stratum, and m, deeper more opaque layer of the epidermis; d, dermis passing 

 below into sc, loose areolar tissue, with fat, /, in its meshes; above, dermic papilla? 

 are seen, projecting into the epidermis which is molded on them, o, opening of a 

 sweat-gland; gl, the gland itself. 



called the hair-follicle. The portion of a hair buried in the skin is 

 called its root; this is succeeded by a stem which, in an uncut hair, 

 tapers off to a point . The stem is covered by a single layer of over- 

 lapping scales forming the hair-cuticle; the projecting edges of 

 these scales are directed towards the top of the hair. Beneath the 

 hair-cuticle comes the cortex, made up of greatly elongated cells 

 united to form fibers; and in the center of the shaft there is found, 

 in many hairs; a medulla, made up of more or less rounded cells. 



