THE INTEGUMENT, OR SKIN 



59 



glands. These glands are little rounded sacs, usually connected 

 with the hair-bulbs; and upon these bulbs they empty their 

 product of oil, which acts as a natural dressing for the hair 

 (Fig. 18). A portion of the sebaceous matter passes out upon 

 the surface, and prevents the cuticle from becoming dry and 

 hard. The glands situated upon the face and forehead open 

 directly upon the skin. In these, the sebaceous matter is 

 liable to collect, and become too hard to flow off naturally. 



13. These glands on the face and forehead frequently appear 

 on the faces of the young as small, black points, which are 

 incorrectly called "worms." It is true, that 



occasionally living animalcules are found in 

 this thickened sebaceous matter, but they can 

 only be detected by the aid of the micro- 

 scope. This sebaceous matter acts not only 

 to keep the skin flexible, and furnish for 

 the hair an oily dressing, but it especially 

 serves to protect the skin and hair from the 

 acridity arising from the perspiration. 



14. The Perspiratory Glands. The chief 

 product of the skin's action is the perspira- 

 tion. For the formation of this, there are 

 furnished countless numbers of little sweat- 

 glands in the true skin. They consist of fine 

 tubes, with globe-like coils at their deeper 

 extremity. Their mouths or openings may 

 be seen with an ordinary magnifying-glass, 

 upon the fine ridges which mark the fingers. 



These tubes, if uncoiled, measure about one- a, the gland surrounded 



tenth of an inch in length. In diameter 



they are about one three-hundredth of an 



inch, and upon parts of the body there are 



not far from three thousand of these glands through the upper epi - 



[G. 20. MAGNIFIED 

 VIEW OF A SWEAT- 

 GLAND, WITH ITS 



by fat-cells ; &, the duct 

 passing through the 

 dermis ; c, its continu- 

 ation through the rete 

 inucosum, and d, 



dermis 



to the square inch. Their whole number in 



the body is, therefore, very great ; and it is computed, if they 



13. Black points, called worms ? Animalcules ? Service performed by sebaceous matter ? 



14. Perspiration ? Sweat glands ? Of what do they consist ? Dimension of the tubes ? 



