48-t Influence of Inanition on Metabolism. 



the first day of all the experiments was 992 calories. On the second day the 

 average was somewhat higher, 1028 calories, while on the third day, it was 

 noticeably less, 991 calories. The averages for the fourth, fifth, sixth, and 

 seventh days were 938, 885, 857, and 869 calories, respectively. These results 

 show in general a tendency for the heat production per square meter of body 

 surface to diminish after the second day of fasting. The presence of results 

 for food experiments in the calculations (aside from those for experiment No. 

 70) has no material influence on the trend of the averages. While the con- 

 stancy of the heat production per square meter of body surface in all classes 

 of animals has been emphasized in many discussions, it may be observed that 

 even with fasting man at rest, there are marked fluctuations in this factor, and 

 here again variations in internal and external muscular activity may account 

 for these seeming discrepancies in the heat production per square meter of 

 body surface. 



MUSCULAR ACTIVITY. 



This series of experiments was made upon fasting men at muscular rest, 

 and yet as has been repeatedly emphasized in the discussion, there were varying 

 degrees of minor muscular activity during the experiments and it can not be 

 said that the subjects all remained in the same degree of rest. Knowing the 

 marked influence of excessive muscular activity on the heat production as 

 observed in experiments on muscular work, it is important to determine, if 

 possible, to what extent the slight variations in activity observed in these 

 experiments influenced the heat production. 



Method of estimating energy of external muscular activity. Aside from 

 the intermittent strength tests with the dynamometer in some of the experi- 

 ments and the 10-minute exercise period on the bicycle ergometer on the first 

 day of experiment No. 71, no measurement of the muscular activity of the 

 subjects was attempted. Our knowledge regarding the energy required to 

 perform the minor movements of the body, even in a so-called " rest experi- 

 ment " is as yet very meager. But since it was important to estimate as nearly 

 as possible the muscular activity on the different days and with the different 

 subjects, a method for estimating these variations in activity has been put in 

 use, although admittedly based on very uncertain evidence. The muscular 

 activity was in general very slight. The visible muscular activity of the 

 subjects was carefully recorded by the observer outside of the calorimeter 

 chamber, the number of times the food aperture was opened and closed was 

 likewise noted on a sheet provided for the purpose, and from the diary kept 

 by tlic subject, records of certain other movements were obtained. These have 

 been combined as has been shown previously in the " body movement " records 

 for each experiment. From these movements the attempt has been made to 

 estimate the muscular activity, expressed in calories. The material used con- 



