THE SKIN 



231 



procedure is called skin grafting and in modern surgery is a 

 common practice of dealing with slowly healing wounds, 

 especially wounds from burns. 



Hair. To the naked eye hair appears unlike any other part 

 of the skin. Throughout most of its length, hair is dead 

 and shows little structure; but* near the root where still 

 alive it is made of cells like all other organic material. If a 



Hair 



HairPapilla 



FIG. 113. SEC- 

 TION THROUGH 

 THE BASE OF A 

 HAIR 



Showing its differ- 

 ent layers, the 

 papilla upon which 

 it grows and the 

 blood vessel that 

 nourishes it. 



~J*eaf Gland 

 FIG. 114. SECTION THROUGH THE SKIN 



Showing the various organs in the dermis and 

 epidermis. 



hair were split and examined under the microscope, its appear- 

 ance would be something as in Figure 113. In the center is 

 a kind of pith called the medulla of the hair; next this is a 

 horny layer, the so-called cortex, in the cells of which is the 

 pigment determining its color. Outside the cortical layer is 

 the cuticle of the hair, a transversely arranged series of horny 

 cells, each upper row overlapping the one below it like the 

 shingles of a roof. Each hair comes out of a sac, or hair 



