Relations between Factors of Metabolism. 



323 



nation of oxygen are eliminated, and consequently the results can be considered 

 as satisfactory. The variations in the 24-hour experiments, therefore, are con- 

 sidered as well within the limits of the error of experimenting, the lowest value 

 being 3.27 calories, and the highest, 3.48 calories. The variation above or 

 below the average, 3.37 calories, is but about 3 per cent. It is evident, there- 

 fore, that in experiments of 24 hours' duration, where the oxygen consumption 

 is accurately determined, the heat production of individuals subsisting on an 

 ordinary mixed diet can be computed with an accuracy inside of 3 per cent. 



Table 93. Calorific equivalents of oxygen consumed and carbon 

 dioxide eliminated during sleep, during waking hours, 

 and for total 2>i hours in rest experiments. 



The calorific equivalent of carbon dioxide during the waking hours varied 

 from 2.80 to 3.29 calories, averaging 2.97 calories. As is to be expected, with 

 marked changes in diet or absence of food in certain cases, the fluctuations in 

 the calorific output per gram of carbon dioxide would be larger than the corre- 

 sponding fluctuations obtained on the measurements of the oxygen, and the 

 values here reported may be considered as normal fluctuations. During sleep, 

 the fluctuations vary from 2.70 to 3.27 calories, averaging 3.08 calories. The 

 value 2.70 calories found for J. F. S. needs especial explanation. As has been 

 pointed out in this table, the periods of sleep are taken immediately after the 

 day period and do not represent all the periods of sleep with these different 

 individuals, such as the sleep of the preliminary night. As a matter of fact, in 

 the experiments with J. F. S., 12 experiments supplied the values from which 

 the day value was drawn and the 12 following nights were used for the night 

 period. Apparently with this subject there is normally a low carbon-dioxide 

 calorific equivalent during the night, for in table 91 it is seen that this subject, 

 J. F. S., showed a carbon-dioxide calorific equivalent of 2.83 calories, which was 



