176 Metabolism of Healthy Man. 



The other direct method mentioned above is that used first by Begnault 

 and Eeiset 1 on small animals, which was subsequently elaborated and modified 

 by Hoppe-Seyler 2 for use with man. More recently Zuntz and Oppenheimer 3 

 have constructed an apparatus on this principle for use with small animals or 

 with infants. The apparatus has already been used in studying the metabolism 

 of infants/ The principle is the basis of the method employed in the experi- 

 ments here reported. In these experiments the subjects lived in a chamber 

 through which a current of air was continually passed, the carbon dioxide and 

 water-vapor given off being absorbed, and the air returned to the respiration 

 chamber after the deficiency in oxygen had been made up by admitting pure 

 oxygen from a cylinder of the compressed gas. 



The methods employing the special mouthpiece or nosepiece or, indeed, the 

 helmet, are hardly applicable to experiments of long duration. The apparatus 

 of Jaquet, involving as it does the analysis of the incoming and outgoing air, 

 is extremely practical and should find more extended use especially in hospital 

 clinics. It is open to the objection that the deficiency in oxygen is usually but 

 a few tenths of a per cent, for example, 20.92 20.16 = 0.76 per cent, and 

 hence an error in analysis, even when using the extremely delicate Pettersson 

 apparatus, may involve an error of 2 to 5 per cent in the oxygen determination. 



EARLIER INVESTIGATIONS. 



Of the early researches on the consumption of oxygen by man, none antedate 

 those of Lavoisier and Seguin. 5 In their remarkable memoir of 1789 they 

 quote experiments to show that when a man is fasting and in a state of repose 

 at a temperature of 26 E. he consumes per hour 1210 "cubic pouces " (24 

 liters) of oxygen. This is increased by cold, as under the same conditions of 

 fast and rest, but with a temperature of 12 E. he consumes 1344 cubic pouces 

 (26.7 liters) of oxygen per hour. During digestion this is increased from 

 1800 to 1900 cubic pouces (37.7 liters) per hour. Muscular exercise also 

 increases it ; thus Seguin, fasting and performing work, raised his oxygen con- 

 sumption to 3200 cubic pouces (63.5 liters) per hour. The same exercise 

 during digestion raised the oxygen consumption to 4600 cubic pouces (91.2 

 liters) per hour. The conversion of the old French values, cubic pouces, to 

 liters was made by Gavarret. The values are also given by Sonden and 

 Tigerstedt. 7 



1 Regnault and Reiset, Ann. de Chimie et de Physique (3), 1849, 26. 



2 Hoppe-Seyler, Zeit. physiol. Cheni. 1894, 19, p. 574. 



3 Zuntz and Oppenheimer, Englemann's Archiv fur Physiol. Abt. 1905, Suppl. band, 

 p. 431. 



4 Schlossmann, Oppenheimer and Mursehhauser, Bioehemische Zeitschrift, 1908, 

 14, p. 385. 



5 Lavoisier and Seguin, loc. cit. 



6 Gavarret, Physique Medicale, Paris, 1855, p. 330. 



7 Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 165. 



