SECRETION. 



425 



quantity, lowers the amount of casein and butter, but augments the 

 proportion of sugar of milk. A diet rich in fats does not augment 

 the quantity of butter, but if kept up too long it diminishes it. 

 Atropine and potassium iodide dry up the milk secretion; antipyrin 

 is said to have a similar effect. Jaborandi increases it. Alcohol, 

 frequently given in the shape of porter, increases the secretion of 

 milk. 



THE SWEAT=GLANDS. 



The sweat-glands are the organs 

 which furnish the means for the elimina- 

 tion of a large portion of the aqueous and 

 gaseous materials excreted by the skin. 

 They are found in almost every part of the 

 integument, being particularly numerous 

 where hairs are absent, as upon the palms 

 and soles. Krause found the smallest 

 number of them (400 for each square inch) 

 upon the back and buttocks; the greatest 

 number (2800 per square inch) on the sur- 

 face of the palm of the hand and the sole 

 of the foot. By this observer it was cal- 

 culated that the total number of them is 

 2,400,000. These glands may become hy- 

 pertrophic (in elephantiasis), thereby pro- 

 ducing sudoriparous tumors upon the 

 cheek. Atrophy also occurs. 



In structure the sweat-glands are 

 small, lobular, reddish bodies. Each con- 

 sists of a single, convoluted tube, from 

 which mass the efferent duct proceeds up- 

 ward through the corium and cuticle. It 

 is somewhat dilated at its extremity and 

 opens upon the surface of the cuticle by 

 an oblique valvelike aperture. The effer- 

 ent portion of the duct in its course through the skin presents a 

 corkscrew arrangement in those places where the epidermis is thick. 



The convoluted or coiled portion of the tube is the place where 

 secretion takes place, and is usually known as the secretory part of 

 the sweat-apparatus. Here the tube is lined by a single layer of 

 clear, nucleated, cylindrical epithelium. Smooth muscular fibers in 



Fig. 159. Sweat Gland. 

 (HEDON.) 



I, Bpiderm. 2, Malpighian 

 layer. 3, Derm. 4, Papilla. 

 5, Gland folded on itself. 6, 

 Duct of gland. 8, Opening of 

 duct. 9, Subcutaneous tissue. 



