STRUCTUEE OF THE HAIR-FOLLICLES. 



221 



it swells out at its lower end into a bulbous enlargement or knob 

 (fiir. 147 c), and is received into a recess of tlie skin named the Jiair- 

 foilicle, which, when the hair is of considerable size, reaches down 

 into the subcutaneous fat. 



The follicle, which receives near its mouth the opening ducts of one 

 or more sebaceous glands (/', Jc), is somewhat dilated at the bottom, to 

 correspond with the bulging of the root ; it consists of an outer coat 

 continuous with the corium "(fig. 147, h; 148, d, d), and an epidermic 



Fi-. 147. 



148. 





Fi 



147. — ^Iedium-sized Hair 

 IN ITS Follicle, maonified 

 50 Diameters from (KoUiker). 



a, stem cut short ; 6, root ; c, 

 knob ; d, hair-cuticle ; c, internal 

 and/, external root-sheath ; g,Ji, 

 dermic coat of follicle ; /, papilla ; 

 Ic, h, ducts of sebaceous glands ; I, 

 corium ; in, mucous layer, and n, 

 horny layer of epidermis ; o, upper 

 limit of internal root-sheath (from 

 Kollikcr). 



Fis. 148. 



—Magnified View of the Root op 

 a Hair (after Kohlrausch). 



a stem or shaft of hair cut across ; h, inner, 

 and c, outer layer of the epidermic lining of the 

 hair-follicle, called also the inner and outer root- 

 sheath ; d, dermic or external coat of the hair- 

 follicle, shown in part ; c, imbricated scales about 

 to form a cortical layer on the surface of the hair. 

 The adjacent cuticle of the root-sheath is not repre- 

 sented, and the papilla is hidden in the lower 

 part of the knob where that is represented lighter. 



lining (fig. 147, e,fx 148, h, c), con- 

 tinuous with the cuticle. 



The outer or dermic coat of the fol- 

 licle (fig. 149, 1 in tranvsverse section) 

 is thin'but firm, and consists of three 

 layers. The most external (fig. 149, a) 

 is'formed of connective tissue in longi- 

 tudinal bundles, without any elastic 

 fibres, but with numerous corpuscles. 

 It is highly vascular, and provided with nerves. It is intimately con- 

 nected above with the corium, and dei?ermines the form of the follicle. 

 The most internal layer {ItijaUne layer, Ivulliker) (fig. 140, d) is a 



