392 CUTANEOUS SECRETIONS. 



under circumstances in which the sweat that was thrown off could 

 not evaporate, and also where water could not easily be given off 

 by the lungs ; Berthold found that after he had remained half an 

 hour in the vapour-bath, he had lost a pound and a half in weight ; 

 since the carbonic acid exhaled from the lungs is nearly replaced 

 by the inspired oxygen, we may fairly assume that an adult man 

 in a vapour-bath loses about 25 grammes of sweat in a minute. 



According to Abernethy, there are about 412 cubic inches of 

 carbonic acid exhaled from the skin of a full-grown man in 

 twenty-four hours. 



Krause calculated that in the course of twenty-four hours there 

 are excreted by the sweat of an adult male 7^1*5 grammes of 

 water, 7*98 of organic and volatile matters, and 2*66 of mineral 

 substances. 



Physiologists have long held different views regarding the 

 sources of the cutaneous transpiration, some maintaining that the 

 whole of the cutaneous transpiration and sweat arise solely from 

 the sudoriparous glands, while others assert that an elastic fluid 

 permeates the epidermis. We shall revert to this subject, in so far 

 as it falls within the scope of our inquiries, when we treat of the 

 mechanical metamorphosis of matter. 



The importance of the cutaneous transpiration is so obvious 

 to every one, that we might readily believe that its objects would 

 be sufficiently manifest; yet the most we can do is to frame 

 hypotheses on the subject. One of the undoubted uses, although 

 not the principal object, of the cutaneous transpiration, is to 

 regulate the temperature of the animal body. Although there is a 

 perfect correspondence of physical laws and physiological experi- 

 ments in so far as this function of the perspiration is concerned, it 

 has in general been somewhat over-estimated ; because, on the one 

 hand, the external temperature is almost always below the tem- 

 perature of the body, and hence the evaporation of fluids is not re- 

 quired to cool the organism from the surface inwards, and because, 

 on the other hand, the activity of the lungs, by which the blood is 

 almost directly cooled, fulfils this object in a far higher degree. 

 It is generally believed that the transpiration is the medium 

 through which certain substances are eliminated, whose retention, 

 in cases of suppressed perspiration, might give rise to various morbid 

 conditions. The most superficial observer cannot fail to perceive 

 the extremely injurious consequences that often follow even a 

 partial suppression of the transpiration, and hence the analysis 

 (which is always imperfect) of the chemical constituents which the 



