THE SKIN. 



345 



Hair Follicles. The hair follicles are the pits in the 

 skin occupied by the roots of the hairs. These pits 

 are placed diagonally to the surface, and in the scalp 

 where the skin is thick they are at least half an inch 

 in length. It is estimated that the normal scalp 

 has about one hundred and twenty thousand of these 

 follicles, or an average of eight hundred to the square 

 inch. Each follicle is really a minute tubular de- 



Longitudinal connective-tissue fibers. 

 Circular fibers. 

 Glassy membrane. 



Outer root sheath. 



Henle's layer. 

 Huxley's layer. 

 Inner root sheath. 



Hair shaft. 



Fig. 244. Cross section of a hair follicle. 



pression or invagination of the skin, and its wall is 

 therefore made up of constituents from both the epi- 

 dermis and the dermis. These layers may be tabu- 

 lated as follows : 



I. Outer tunic. 



1. Connective-tissue fibers arranged longi- 



tudinally. 



2. Connective-tissue fibers, circular. 



3. Glassy membrane. 



