STRUCTURE OF THE HAIR. 241 



methods in the skin. On the one hand they run horizontally, 

 and form either an anastomosing plexus (Kolliker), as in the 

 scrotum (Tunica dartos) and prepuce, or circular fasciculi, as 

 in the area of the nipple and in the nipple itself. 



On the other hand they traverse the corium obliquely in 

 the form of single fasciculi, with a diameter of O045 0*22 of a 

 millimeter, and are in immediate relation with the hair follicles 

 (constituting the muscles of the hair follicles of Kolliker, or 

 Erector 'es pili of Eylandt). They arise in the upper part of 

 the corium, and run obliquely in immediate proximity to the 

 sebaceous glands, to the hair follicle, into the inner sheath of 

 which they are inserted just below the sebaceous gland. 

 Many hairs possess two muscles, that decussate over the 

 sebaceous gland, and encircle it crescentically. As the hairs 

 are inserted obliquely in the skin, forming a moderately acute 

 angle with the surface, whilst the muscular fasciculus lies in 

 the plane of the corresponding obtuse angle, the contraction 

 of the latter must obviously cause the hair to become more 

 erect (goose-skin). 



Neumann describes oblique muscular fasciculi as existing in 

 the skin that have no connection with the hairs. 



B. HAIRS PILI. 



Hairs are cylindrical horny structures, inserted into tubular 

 depressions of the skin the hair follicles, from a papilla at 

 the bottom of which the hair papilla their development 

 proceeds. 



In describing the hair we must therefore consider (1) The 

 structure of the hair follicle and hair papilla; and (2) the 

 hair ; and in the latter again the part including the papilla, or 

 hair-root, and the part projecting beyond the skin, or hair- 

 shaft. 



HAIR FOLLICLE. The hair follicle is a depression of the 

 surface of the corium, that exhibits a blind inferior extremity 

 (fig. 201 c), the so-called dilatation of the hair follicle and a 

 tree funnel-shaped and dilated excretory duct (a). 



Below the excretory duct the hair follicle is contracted, 

 VOL. n. R 



