194 



ANATOMY FOB, NURSES. [CHAP. XVIL 



keeps it soft and flexible. An accumulation of this sebaceous 

 matter upon the skin of the foetus furnishes the thick, cheesy r 

 oily substance, called the vernix caseosa. 



The sudoriferous or sweat-glands, All over the surface of the 

 skin are minute openings or pores. These pores are the open- 

 ings through which the sweat-glands pour their secretions upon 

 the surface of the body. The sweat-glands are tubular glands 

 with their blind ends coiled into little balls which are lodged 

 in the true skin or subcutaneous tissue ; from the ball the tube 

 is continued as the excretory duct of the gland up through 

 the true skin and epidermis, and finally opens on the surface 

 by a slightly widened orifice. Each tube is lined by a secreting 



epithelium continuous 

 with the epidermis. The 

 coiled end is closely in- 

 vested by a mesh work of 

 capillaries, and the blood 

 in the capillaries is only 

 separated from the cav- 

 ity of the glandular tube 

 by the thin membranes 

 which form their respec- 

 tive walls. The secre- 

 tory apparatus in the 

 skin is somewhat simi- 



FIG. 114. COILED END OF A SWEAT-GLAND, lar to that which obtains 

 a, the coiled end ; b, the duct ; c, network of capil- i n the kidnev ' in the 

 laries, inside which the sweat-gland lies. J ' 



one case the blood- 

 vessels are coiled up within the tube, while in the other the 

 tube is coiled up within the meshwork of blood-vessels. 



The sweat-glands are abundant over the whole skin, but 

 they are most numerous on the palm of the hand and on the sole 

 of the foot; in the groin, and especially in the axilla, they are 

 larger than in other parts of the body. At a rough estimate, 

 the whole skin probably possesses from two to two and a half 

 millions of these glands, and their combined secreting power is 

 therefore very great. 



Perspiration or sweat. The sweat is a transparent colourless 

 fluid, of a distinctly salt taste and with a strong, distinctive odour. 

 When the secretion is scanty it has an acid reaction, but when 



