482 Influence of Inanition on Metabolism. 



movements that any intelligent comparison can be made. In fasting experi- 

 ments such as those here reported, in which the subjects were distinctly 

 inactive, the proportions of the total heat for 24 hours are about evenly 

 divided among the periods. The average of all the fasting experiments shows 

 that 28 per cent of the heat was produced between 7 a. m. and 1 p. m., 26.2 

 per cent between 1 and 7 p. m., 24 per cent from 7 p. m. to 1 a. m., and 21.8 

 per cent from 1 to 7 a. m. 



When these men were asleep the heat production per hour averaged 70 

 calories. Considerable variations in the quantities produced per hour may be 

 observed, not only with different subjects, but with the same subjects in 

 different experiments. The unusually large production of 115 calories of 

 heat per hour during the first period of the first day of experiment No. 71 is 

 due to the fact that during this period the subject rode for 10 minutes on the 

 bicycle ergometer. In no other period with this subject did the heat pro- 

 duction rise to over 98 calories per hour. The lowest heat production recorded 

 in any experiment was 56 calories per hour. This small amount was produced 

 in the last period of the last day of the two longest experiments, Nos. 73 

 and 75. In explanation of these irregularities reference must be made to the 

 notes in the diaries of the subjects and records of body movements previously 

 recorded and to the estimates of muscular activity given beyond. 



Heat production per kilogram of body-weight and per square meter of body 

 surface. The irregularities in the heat production noted in the fasting experi- 

 ments reported herewith may be accounted for in several ways: First, there 

 may be marked differences in muscular activity. This factor receives special 

 discussion elsewhere (see p. 484). Second, there may be a difference in size 

 of the different subjects and consequently the total heat production per kilo- 

 gram of body-weight is of value in comparing the different experiments. For 

 other comparisons commonly made by physiologists, the production per square 

 meter of body surface is likewise of value. 



The heat produced per kilogram of body-weight and per square meter of 

 body surface has been computed for all of these fasting experiments and is 

 recorded in table 233. The results for the food experiments Nos. 70, 72, 74, 

 and 76 are also included in the table. 



The average heat production per kilogram of body-weight for the first day 

 of the 18 experiments with and without food was 30.7 calories. The range 

 is from 26.6 to 34.6 calories, but the results in the large majority of the experi- 

 ments were very close to the general average. On the second day the average 

 is over 1 calorie greater, i. e., 31.8. The fluctuations range from 28.6 to 

 36.9 calories. The average heat production per kilogram of body-weight on 

 the third day is 31.0 calories and on the fourth, fifth, sixth, and seventh days, 

 the averages are 29.6, 28.5, 27.5, and 28.0 calories, respectively. There is, 

 then, a distinct tendency for the heat (per kilogram of body-weight) to 

 decrease after the second day. 



