THE EXCRETORY FUNCTION OP THE SKIN. 4:11 



taneous gland in the pig, placed at the posterior inner aspect of 

 the knee and of considerahle size. 



In the sheep, the interungulate 

 gland is an inversion of the integu- 

 ment forming an elongated sac, 

 which is supplied with secreting 

 structures analogous to the seba- 

 ceous glands. The importance of 

 protective structures of this kind 

 in such situations is obvious. 



THE BXORETORT PtTNOTION 

 OF THE SKIN. 



The quantity of matter dis- I'lo- 314. — intenmguiate gland of 



1 T ,T 1 J.1 T . . , sheep (Chauvean). a, inner as- 



charged through the skm is large pect of first phalanx; j, hoof or 

 -greater in man than by the lungs Sli&liflXcf ""' ^"'°''' "' 

 (about as 7 to 11), though the 



amount is very variable, depending on the degree of activ- 

 ity of other related excreting organs, as the lungs and kidneys, 

 and largely upon the temperature as a physical condition ; and 

 so in other animals. 



When the watery vapor is carried off, before it can condense, 

 the perspiration is said to be insensible ; when small droplets 

 become visible, sensible. As to whether the one or the other is 

 predominant will, of coiu-se, depend on the rapidity of renewal 

 of the air, its humidity, and its temperature. Apart from the 

 temperature, the amount of sweat is influenced by the quality 

 and quantity of food and, especially of drink taken, the amount 

 of exercise, and psychic conditions ; not to speak of the effect of 

 drugs, poisons, or disease. 



Perspiration in man is a clear fluid, mostly colorless, with 

 a characteristic odor, devoid of morphological elements (ex- 

 cept epidermal scales), and alkaline in reaction. It may be 

 acid from the admixture of the secretion of the sebaceous 

 glands. 



Its solids (less than 2 per cent) consist of sodium salts, 

 mostly chlorides, cholestenn, neutral fats, and traces of urea. 

 The acids of the sweat belong to the fatty series (acetic, butyric, 

 formic, propionic, caprylic, caprolc, etc.). 



FathologicaL — The sweat may contain blood, proteids, abun- 

 dance of urea (in cholera), uric acid, oxalates, sugar, lactic acid. 



