INFLUENCE OF CUTANEOUS TRANSPIRATION. 375 



acid; the ratio of the absorbed oxygen to that in the carbonic 

 acid is as 100 : 77*5. 



As in all these experiments on animals, the cutaneous perspi- 

 ration has been investigated at the same time with \\\Qpulmonary 

 exhalation, it might be supposed that no very exact result could be 

 obtained for the latter, but the above numerical values are correct 

 enough for the higher animals, as mammals and birds ; for the 

 inexactness is here so slight, that it generally falls short of the 

 fluctuations in the errors of observation and other irremediable or 

 incalculable conditions. In the case of rabbits, dogs, and hens, 

 Regnault and Reiset have, indeed, adopted two methods for the 

 more accurate determination of that portion of the gaseous 

 excretion of the animal body which escapes through the skin ; in 

 both cases the animals were inserted in an air-tight bag, and 

 their mouths alone were allowed to come in contact with the atmo- 

 sphere ; in one case the air within the bag was changed ; in the 

 other it was left undisturbed. In the first mode of experiment 

 hens yielded only from 0*0047 to 0*18 of the carbonic acid re- 

 sulting from the whole perspiration, rabbits only from 0*0102 to 

 0*017.3, and dogs from 0*0035 to 0*0041. The second method 

 also showed that the influence of cutaneous perspiration and in- 

 testinal exhalation is very unimportant when compared with the 

 pulmonary function in the warm-blooded animals. 



The relation between cutaneous transpiration and pulmonary 

 exhalation must not, however, be considered so unimportant as it 

 might appear from these experiments on thick haired and densely 

 feathered animals. The gaseous exhalations from the skin in man 

 have scarcely been examined, but the quantitative investigations 

 hitherto made, as for instance, those of Valentin, prove that the 

 human skin takes a very considerable part in the separation of 

 aqueous vapour from the body. This fact had already been ren- 

 dered very probable by certain dietetic and other observations, and 

 seemed to derive confirmation from Magendie's method of making 

 the skin of animals wholly impermeable by means of glue, paste, 

 varnish, &c. ; and although the death of the animals thus experi- 

 mented upon cannot be referred solely to the retention of gaseous 

 fluids, the latter, although inconsiderable in quantity, are not devoid 

 of importance in a physiological point of view. There are indeed 

 many questions which still demand our earnest attention in refer- 

 ence to this subject ; and even if the life of an animal of higher 

 organization could continue to exist in a relatively normal 

 state for any length of time after cutaneous exhalation had been 



