EXPERIMENTS ON METABOLISM OF ENERGY. ——-125 
From the results obtained in the second night periods in 
these experiments, it would seem that from 65 to 70 calories 
per hour might be not far from representing an average elim- 
ination of heat by a healthy, active man in the time of min- 
imum bodily activity. 
Relation between elimination of heat and of carbon dioxid.— 
The rates of elimination of heat and of carbon dioxid in the 
different periods are nearly parallel, as will be seen by compar- 
ing the figures of Tables 30 and 27. Both these values in the 
two day periods of the work experiments are largely in excess 
of the similar values in the same periods of the rest experi- 
ments. ‘The values for both these factors in the second night 
period of the same experiments, which was one of quiet sleep, 
were small and noticeably uniform. 
INCOME AND OUTGO OF ENERGY. 
Perhaps the most interesting results of these experiments, 
both because of their novelty and because of their bearing 
upon the metabolism and the conservation of energy in the 
living organism, are those which compare the amounts of 
potential energy in the materials actually oxidized in the 
body with the amounts of kinetic energy given off from the 
body either as heat alone in the rest experiments or as heat 
and external muscular work in the work experiments. In the 
rest experiments there was no considerable amount of external 
muscular work. ‘The little that was done would naturally be 
converted into heat, as, for instance, in the impact of the foot 
upon the floor in stepping, or of the body upon the chair or bed 
in sitting or lying down. ‘The heat thus imparted to the floor, 
chair, or bed would naturally find its way to the absorbers, 
and would be carried out with the heat given off as such by 
the body. Roughly speaking, we may say that all the poten- 
tial energy made kinetic in the body by the oxidation of food 
and body material left the body as heat. This is shown by 
the agreement of the amount of heat given off from the body 
with the heat of oxidation of the material oxidized in the body. 
These data are summarized in Table 31. 
