322 THE MODERN HORSE DOCTOR. 



less, in a draught of air than in a damp stable, where there is no 

 current. 



As no evaporation from the skin can, therefore, take place 

 while the atmosphere is loaded with vapor, and as the perspira- 

 tory glands stiil continue to pour it out on the surface, it must 

 inevitably produce an appearance of profuse sweating. In such 

 cases, the reader will perceive the absurdity of dosing a horse ; for 

 the conditions under which the fluid is poured forth are peculiar 

 to all animals whose skins are not covered with scales or plates. 

 Physiologists teach us that the purpose of this watery exhalation, 

 and of its increase under a high temperature, (for it does increase 

 under the scorching rays of a noonday sun, whether the horse 

 be drawing a load or not,) is evidently to keep the heat of the body 

 as near as possible to a uniform standard. By the evaporation of 

 fluid from the surface of the skin, a considerable quantity of heat 

 is withdrawn from it, becoming latent in the change from fluid to 

 vapor, and this evaporating process lessens the temperature of 

 the whole body. Were it not for this all-wise provision, neither 

 man nor horse could ever endure the rays of a tropical sun ; nei- 

 ther could they sustain any high degree of heat for any great 

 length of time without injury to the vital tissues. Carpenter in- 

 forms us that the perspiration contains a small quantity of solid 

 animal matter, most of which accumulates on the surface : this 

 is — at least should be — removed by the brush and currycomb. 

 Besides, there are other secretions of the skin which are mingled 

 with it ; and there is good reason to think that this excretion is 

 of much importance in carrying off certain substances which 

 would be injurious if allowed to remain in the blood. This re- 

 ceives confirmation from the fact known to all grooms, that hu- 

 mory horses, as they are termed, have an abundance of scurf on 

 their hides, and require constant grooming to keep them any 

 thing like decent. "We here see the circumstances under which 

 evaporation and condensation take place, and have learned 

 something as regards the object of cutaneous exhalation in its 

 normal or healthy aspect. 



"We are now prepared to investigate the causes of abnormal 

 exhalation. And this takes place at various times, subject to the 

 preceding provisions, under several forms of disease ; yet of itself 



