168 Metabolism of Healthy Max. 



Obviously, the relatively small number of experiments here reported do not 

 permit of any rigid conclusions in regard to the effect of previous muscular 

 exercise upon the carbon-dioxide production during sleep. They do not accord 

 with the observations of Higley and Bowen * who found an almost immediate 

 return to the normal carbon-dioxide production value on the cessation of work. 

 The latent period was in their experiments but 20 seconds. Marcet 2 also found 

 in experiments on man that the carbon-dioxide production fell to the normal 

 amount in from 6 to 7 minutes after the cessation of work. 



In the experiments of Pettenkofer and Voit, 3 certain results for night periods 

 both after rest and after work are given. In 2 experiments, for the night 

 period following rest, the carbon-dioxide production for the 12 hours of the 

 night was 312 and 316 grams, respectively. In an experiment with work, also 

 without food, while the carbon-dioxide elimination during the day increased 

 some 450 grams over the value at rest, the carbon-dioxide elimination during 

 the night period fell to 257 grams. In a series of experiments with an average 

 diet, the carbon-dioxide production during the night period of 4 experiments 

 averaged about 400 grams. In 1 experiment with work, while the carbon- 

 dioxide production during the day was 360 grams above the resting value, the 

 carbon-dioxide production during the night remained exactly the same as in 

 the experiments after rest. On the other hand, in a second work experiment* 

 while the carbon-dioxide excretion during the day increased about 300 grams 

 over rest, there was a decrease of 100 grams in the carbon-dioxide excretion 

 of the night period. 



An interesting discussion of the after-influence of work on the carbon- 

 dioxide production during rest is taken up by Sonden and Tigerstedt, 4 in which 

 they cite the experiments of Speck, 5 Katzenstein, 8 and Zuntz and Lehmann 7 

 on this point. It is important to bear in mind, however, that the after-results 

 of work in increasing the carbon-dioxide production in the experiments of 

 Speck and Katzenstein usually did not last more than a few minutes ; while in 

 the experiments here reported with A. L. L., the measurement of the carbon- 

 dioxide production did not begin until nearly 45 minutes after the subject 

 was in bed and asleep. 



As will be seen subsequently, the influence of the ingestion of food, the time 

 of day at which the food is taken, and the character of the diet all play im- 

 portant roles in the excretion of carbon dioxide. It is difficult to see how 

 either the previous food or muscular exercise can affect the results during the 

 sleeping period. One would naturally presume that after a day of severe 



1 Higley and Bowen, Amer. Journ. Physiol., 1905, 12, p. 311. 



2 Marcet, Arch, des sci. phys. et nat. Geneve, 1894, 31, p. 21. 

 8 Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2, p. 459. 



4 Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 169, et seq. 



5 Speck, loc. cit., p. 59. 



6 Katzenstein, Archiv f. d. ges. Physiol., 1891, 49, p. 330. 



7 Lehmann and Zuntz, Archiv f. pathol. Anatomie, 1893, 131, supp. bd., p. 70. 



