350 



ANATOMY FOR NURSES [Chap. XVIII 



the surface of the skin. An accumulation of this sebaceous matter 

 upon the skin of the foetus furnishes the thick, cheesy, oily sub- 

 stance called the vemix caseosa. 



Ceruminous glands. — The skin lining the external auditory 

 canal contains modified sweat glands called ceruminous glands. 

 They secrete a yellow, pasty substance resembling wax which is 

 called cerumen. 



Sweat-glands. — The sweat-glands are simple, convoluted, tubu- 

 lar glands with the blind ends coiled into little balls which are 



lodgetl in the true skin or 

 subcutaneous tissue ; from 

 the ball the tube is con- 

 tinued 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 

 called a pore. Each tube 

 is lined by a secreting epi- 

 thelium continuous with 

 the epidermis. The coiled 

 end is closely invested by 

 a meshwork of capillaries, 

 and the blood in the cap- 

 illaries is only separated from the cavity of the glandular tube by 

 the thin membranes which form their respective walls. The secre- 

 tory apparatus in the skin is somewhat similar to that which 

 obtains in the kidneys; in the 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 largest and most numerous in the axillae, the palms of the 

 hands, soles of the feet, and the forehead. 



Perspiration, or sweat. — The sweat is a watery, colorless 

 liquid, slightly turbid, of a salty taste, with a strong, distinctive 

 odor and an acid reaction. It is an excrement, the chief normal 

 constituents of which are water, salts, fatty acids, a small 

 quantity of carbon dioxide, and a slight amount of urea. In vari- 



FiG. 174. — Coiled End of a Sweat-gland. 

 a, the coiled end ; b, the duct ; c, network of 

 capillaries, inside which the sweat-gland lies. 



