430 



THE SKIN. 



Sebaceous Glands. Besides the perspiration, the skin 

 Fig. 108.* secretes a peculiar fatty matter, and 



)for this purpose is provided with 

 another set of special organs, termed 

 __L _ ^ sebaceous glands (fig. 108), which, like 



the sudoriparous glands, are abun- 

 dantly distributed over most parts of 

 the body. They are most numerous 

 in parts largely supplied with hair, as 

 the scalp and face, and are thickly 

 distributed about the entrances of the 

 various passages into the body, as the 

 anus, nose, lips, and external ear. 

 They are entirely absent from the 

 palmar surfaces of the hands and the 

 plantar surfaces of the feet. They 

 are minutely lobulated glands, com- 

 posed of an aggregate of small vesi- 

 cles or sacculi filled with opaque 

 white substances, like soft ointment. Minute capillary 

 vessels overspread them ; and their ducts, which have a 

 beaded appearance, as if formed of rows of cells, open 

 either on the surface of the skin, close to a hair, or, which 

 is more usual, directly into the follicle of the hair. In 

 the latter case, there are generally two glands to each hair 

 (fig. 108). 



Structure of Hair and Nails. 

 Hair. A hair is produced by a peculiar growth and 



ceruminous glands ; but they do not much differ in structure from the 

 ordinary sudoriparous glands. 



* Fig. 108. Sebaceous and sudoriparous glands of the skin (after 

 Gurlt) : i, the thin cuticle ; 2, the cutis ; 3, adipose tissue ; 4, a hair, 

 in its follicle (5) ; 6, Sebaceous gland, opening into the follicle of the 

 hair by an efferent duct ; 7, the sudoriparous gland. 



