434: EESPIRATTON. 



variation did not depend upon the time of day, inde- 

 pendently of the digestive process, he made a comparison at 

 12 M., at 1 and at 2 p. M., without taking food, which showed 

 no notable variation, either in the pulse, number of respira- 

 tions, volume of expired air, or quantity of carbonic acid 

 exhaled. 1 



It is unnecessary to cite other observations on this point, 

 unless we mention those of Prout and Coathupe, which 

 seemed to show a diminution in the exhalation of carbonic 

 acid during digestion. Dr. John Reid, in the Cyclopaedia 

 of Anatomy and Physiology, points out the source of error 

 in these observations. 2 Prout did not estimate the actual 

 quantity of gas exhaled, but only its proportion in the ex- 

 pired air ; and it has been demonstrated that in digestion the 

 volume of the expirations is notably increased. Coathupe, 

 in the observations on his own person, took a pint of wine 

 with his dinner. As it has been shown by experiment that 

 alcohol has the effect of rapidly reducing the exhalation of 

 carbonic acid, this observation does not represent the simple 

 influence of digestion. 



There can be no doubt, then, that the exhalation of car- 

 bonic acid is notably increased during the functional activity 

 of the digestive system. 



The effect of inanition is to gradually diminish the exha- 

 lation of carbonic acid. This fact was long since demon- 

 strated by Spallanzani on caterpillars, and Marchand on 

 frogs; but observations on the warm-blooded animals are 

 more applicable to the human subject. Bidder and Schmidt 

 noted the daily production of carbonic acid in a cat which 

 was subjected to eighteen days of inanition, at the end of 

 which time it died. The quantity diminished gradually from 

 day to day, until just before death it was reduced a little 

 more than one-half. Dr. Smith 8 noted in his own person 



1 Cyclopcedia of Anatomy and Physiology, vol. iv., part i., pp. 34 G, 347. 



2 Ibid., article Respiration. 

 9 Op. dl, p. 696. 



