Carbon Dioxide. 439 



The inaccuracies in the determination of the water of respiration and perspi- 

 ration and in the method for determining the total nitrogen of the urine and 

 the deficiency in the measurements of oxygen and heat production in the 

 majority of the earlier experiments, are in part at least compensated by 

 reasonably accurate determinations of carbon dioxide. The comparison, there- 

 fore, of the results obtained by different investigators of the carbon dioxide 

 production of fasting men is very much more satisfactory than that of any 

 factor thus far considered in this report. 



The quantitative experiments of Scharling, 116 Andral & Gavarret, 117 Brunner 

 & Valentin U8 gave us at an early date much information regarding the carbon 

 dioxide output of different individuals for short periods, and the rapid advance- 

 ment in the technique of studying the respiratory gases, which followed upon 

 the successful experiments of Speck, U8 Zuntz & Geppert, 1 " Chauveau & Tissot, 121 

 and more recently Magnus-Levy, 122 Loewy, 123 and Durig, 124 leaves but little to 

 be considered regarding the carbon dioxide elimination under normal condi- 

 tions, so far as short periods are concerned. 



Many of these experimenters recognized the importance of determining the 

 carbon dioxide output during inanition, and indeed in the large number of 

 experiments on the effect of muscular work on metabolism, the " base line " 

 may be said to be the value for carbon dioxide production after a short fast. 

 In the very large majority of these experiments, the elimination of this gas was 

 determined for only short periods, rarely an hour, and the length of the fast 

 was seldom over 12 hours. While these results have a definite value for the 

 specific purpose for which the experiments were conducted, they are much less 

 valuable as an indication of the carbon production of fasting man during 24 

 hours. 



The Zuntz-Geppert apparatus has been used for a number of observations 

 on fasting man during short respiration experiments. Zuntz (7) and asso- 

 ciates, in whose hands the method has reached the greatest degree of perfection, 

 made a number of observations on the two fasting men, Cetti and Breithaupt. 

 These observations were confined to short periods, 10 to 20 minutes, of each 

 fasting day. The subjects were lying on a sofa and accordingly the carbon 

 dioxide output represents the elimination during complete rest. In certain 



116 Ann. der Chem. und Pharm. (1843), 45, p. 214. 

 U7 Ann. de Chim. et de Phys. (1843), Ser. 3, 8, p. 129. 



118 Medicinische Vierteljahreschrift Archiv f. physiol. Heilk. von Roser und 

 Wunderlich (1843), 2, p. 373. Abstracted in Pharm. Centrbl. (1843), 14, p. 765. 



119 Schriften zur Beforderung der gesammten Naturwissenschaften zur Marburg 

 (1871), 10. 



120 Archiv f. d. ges. Physiol. (1888), 42, p. 189. 

 m Comptes rendus (1899), 129, p. 249. 



122 Loc. cit. 



123 Archiv f. d. ges. Physiologie (1888), 42, p. 268. 



124 Loc. cit. 



