418 



THE HUMAN BODY. 



taneous tissue, where they form little globular masses com- 

 posed of a coiled tube. From the coil a duct (sometimes 

 double) leads to the surface, being 

 usually spirally coiled as it passes 

 through the epidermis. The secret- 

 ing part of the gland consists of a 

 connective-tissue tube, continuous 

 along the duct with the dermis; 

 within this is a basement membrane^ 

 and the fmal secretory lining consists 

 of several layers of gland-cells. A 

 close capillary network intertwines 

 with the coils of the gland. Sweat- 

 glands are found on all regions of the 

 skin, but more closely set in some- 

 places, as the palms of the hands and 

 the brow, than elsewhere. There are 

 altogether about two and a half millions 

 of them opening on the surface of the 

 Body. 



The sebaceous glands nearly always 

 open into hair follicles, and are found 

 wherever there are hairs. Each con- 

 sists of a duct opening near the mouth of a hair follicle and 

 branching at its other end: the final branches lead into globu- 

 lar secreting saccules, which, like the ducts, are lined with 

 epithelium. In the saccules the substance of the cells 

 becomes charged with oil-drops, the protoplasm disappearing; 

 and finally the whole cell falls to pieces, its detritus constitut- 

 ing the secretion. New cells are, meanwhile, formed to take 

 the place of those destroyed. Usually two glands are con- 

 nected with each hair follicle, but there may be three or 

 only one. A pair of sebaceous glands are represented on 

 the sides of each of the hair follicles in Fig. 119. 



The Skin Secretions. The skin besides forming a pro- 

 tective covering and serving as a sense-organ (Chap. 

 XXXIV.) also plays an important part in regulating the 

 temperature of the Body, and, as an excretory organ, in- 

 carrying off certain waste products from it. 



FIG. 120. A sweat 

 gland, d, horny layer of 

 cuticle ; c, Malpighian 

 layer; 6, dermis. The 

 coils of the gland proper, 

 imbedded in the subcu- 

 taneous fat,are seen below 

 the dermis. 



