THE SKIN AND ITS ADNEXA. 2^1 



SEBACEOUS GLANDS. 



These are racemose glands, whose excretory ducts 

 are lined with polyhedral and somewhat flattened 

 cells. The alveoli, bounded by a membrana pro- 

 pria, are lined with granular polygonal epithelium, 

 and the cavity is more or less filled with larger 

 polyhedral cells, crowded with fat-droplets. The 

 sebaceous glands, as a rule, either open into a hair- 

 follicle near the surface of the skin, or their excre- 

 tory ducts are pierced near the surface by the shaft 

 of a hair. 



The hair-follicle, as above mentioned, is placed 

 cbliquely in the skin, and at the side at which it 

 forms an oblique angle with the surface, a bundle 

 of smooth muscle-cells is placed. This is attached 

 to the connective-tissue sheath of the follicle in its 

 lower third, and, passing obliquely upward, is in- 

 serted into the upper portion of the corium at some 

 distance from the opening of the follicle. A con- 

 traction of the muscle thus placed will, of course, 

 draw the hair-follicle, and with it the shaft, into a 

 position more nearly perpendicular to the surface of 

 the skin, and hence it is called the erector pilce. As 

 a rule, the sebaceous follicle lies above the erector 

 muscle in the angle which it forms with the upper 

 portion of the hair-follicle, and is moved with the 

 hair when the muscle contracts, and may even be 

 pressed upon by it, when, as is frequently the case, 

 it runs closely over the surface of the gland. This 



