PREVIOUS INVESTIGATIONS. 



31 



TABLE 6. Average diurnal variations in 

 carbon-dioxide production after food and 

 during fast (Johansson and associates). 

 (Values in grams.) 



In a discussion of the results the authors consider the total metabo- 

 lism per kilogram on the fifth fasting day as equal to 100, and state 

 that the metabolism during the food days is 128.4, 122.0, and 117.8 

 per cent of the basal value respectively. They recognize that the low 

 values found during fasting may perhaps be ascribed to decreased 

 muscular movement due to the weakened condition of the subject. 

 They also point out that this decrease in the carbon-dioxide production 

 is observed during sleep, for on the food days the average carbon- 

 dioxide production per kilogram in sleep is 35.4 per cent greater than 

 the corresponding average value on the fifth day of fasting, while the 

 minimum value is 43.4 per cent greater than the corresponding mini- 

 mum value during the fifth day of fasting. In discussing the bearing 

 of these experiments upon the problem of the dynamics of digestion 

 the authors state: 



"In wie fern dies, wie es sich Lehmann und Zuntz vorstellen, von der Ver- 

 dauungsarbeit herriihrt oder ob die Zufuhr von Nahrung in der That den 

 Stoff wechsel erhoht, dariiber giebt uns der vorliegende Versuch keine bestimmten 

 Anhaltspunkte." 1 



Basing the discussion of the 

 energy transformations wholly upon 

 the carbon-dioxide production is of 

 course open to the serious objection 

 that in many instances we may 

 have a simple protein-fat kata- 

 bolism replaced by a katabolism 

 consisting essentially of carbohyd- 

 rate, thus increasing enormously 

 the carbon-dioxide production 

 without a corresponding increase in 

 the total energy transformations. 

 Nevertheless it is clear that in these 

 experiments there was a great 

 increase in the metabolism on the 

 food days. 



Laschtschenko, 1898. To study the influence of water-drinking upon 

 the carbon-dioxide output of the body in man, Laschtschenko, 2 working 

 in Rubner's Institute in Berlin and employing the Rubner modification 

 of the Pettenkofer-Voit chamber, made a series of experiments on 

 himself as subject. Each experiment lasted about 5 hours, during 

 which the subject read but was otherwise in complete muscular repose. 

 Water was taken in 250 c.c. portions at regular intervals to the amount 

 of 2 liters, the last portion being drunk an hour before the end of the 



1 Obtained during sloop. 



'Johansson, Landergren, Sonden, and Tigerstedt, Skand. Arch. f. Physiol., 1897, 7, p. 61. 

 'Laschtschenko, Arch. f. Hyg., 1898, 33, p. 145. 



