320 



THE SKIN 



tation which in turn increases the flow of sweat. The enlarged amount 

 of proteid-katabolism in muscular exercise has little to do with the 

 increase of the sweat, for the kidneys are the glands arranged to take 

 these nitrogenous excreta from the blood. The excretion of the water 

 produced, however, is shared between the two. It is only when the 

 epithelium of the kidneys is thrown out of action or destroyed (as in 

 Bright's disease) that the sweat-glands vicariously take on the excre- 

 tion of considerable amounts of nitrogen in urea, this then soon degen- 

 erating to ammonia. 



FIG. 177 



SWEAT 



SWEAT 



Afferent 

 /Verve 



Efferent 

 A/erve 



Afferent 

 Aferve 



Efferent 

 Merve 



. META 

 HEAT 

 EMOTION 



DRUGS 



VA5O- CON5TR/CT/O/S 



Mechanism of sweat-secretion? On the left side of the picture are represented the mechanism 

 and some of the conditions of an increased production of sweat, and on the right side those of less 

 sweat. In the middle is a diagrammatic sweat-gland delivering its product into the epidermis. 



A high temperature of the skin's environment stimulates the flow of 

 sweat reflexly, and probably through the agency of the minute auto- 

 matic thermostats (heat-corpuscles) scattered throughout the integu- 

 ment. (See Chapter X.) Sweat runs by the liter from the workmen in 

 foundries, glass-works, and rolling-mills, for they sometimes work in 

 temperatures which would be promptly fatal were the air very moist 

 instead of dry and were the skin deprived of its active sweating by any 

 other cause. Excessive heat, internal or external, as well as cold, checks 

 the secretion, and by methods the reader can doubtless readily explain. 



Of the six conditions mentioned as more or less normal states showing 

 an increase of sweat-secretion, five most likely act largely or wholly on 



