Energy. 48 1 



From the above data the estimates given in table 234 were obtained. They 

 are shown both in units and in calories. It must be understood, however, 

 that in obtaining the figures in this table no attempt has been made to estimate 

 the minor involuntary movements, hence the figures obtained give nearer the 

 minimum than the maximum. 



The figures recorded in column b of table 234 are admittedly but approxi- 

 mate estimations. Perhaps the most striking feature of the table is the fact 

 that the differences between the experimental days when computed on the 

 basis of calories are, relatively speaking, so small. The maximum difference 

 observed in any fasting experiment is that of experiment No. 77, where there 

 were 60 calories for the second day and 40 calories on the third, and yet the 

 difference here recorded, 20 calories, is barely over 1 per cent of the average 

 total heat production per day of this experiment. A comparison of the varia- 

 tions in muscular activity as expressed in calories given in this table with the 

 total heat production on the succeeding days of each experiment shows that, 

 while the fluctuations in the estimated energy of the external muscular activity 

 are very small, they generally follow those appearing in the total heat produc- 

 tion. That the differences in the heat production noted from day to day in 

 the different fasts, however, can be directly caused by variations in visible exter- 

 nal muscular activity is very completely disproven. A careful revision of the 

 estimates given in this table has been made and it is certain that although there 

 may be errors in the apportionment and the estimate of value of the activity, 

 the error can certainly not be over 100 per cent and it is probably very much 

 less. Assuming that an error of 100 per cent exists and that the error is 

 always in the same direction, so as to increase the apparent differences on 

 different days, the amounts even then are far too small to account for the 

 absolute differences in the total heat production. It is clear, therefore, that 

 while the variations in muscular activity are proportional to the variations in 

 the total heat produced, some factor other than external muscular activity 

 must account for the wide variations in the total heat production. 



Relations of internal muscular activity to total heat production. Aside 

 from the external muscular activity, there is a considerable amount of muscular 

 work which can be conveniently termed " internal " muscular work, typified 

 perhaps by the work of respiration and circulation. 



Estimates, which for the most part are based on the respiratory exchange, 

 have been made of the energy required for circulation and respiration. Eecently 

 Loewy & v. Schrotter 163 have made an extensive study of these factors of 

 internal work in man. From the results of their experiments they conclude 

 that the total energy required for circulation is 3.6 per cent of the total energy 

 transformation of a man at rest. The work of respiration is 2.4 times that 

 of circulation, and the work of respiration and circulation combined amounts 

 to about 13 per cent of the total energy output for the day. 



163 Zeit. f. exper. Path. u. Therapie (1905), 1, p. 197. 



