_ EXPERIMENTS ON METABOLISM OF ENERGY. 129 
to +2.9 per cent. But in the average for the seven experi- 
ments the figures for the net income and outgo are practically 
the same, being 2,268 and 2,259 calories, respectively. In the 
average of the three days of the rest experiment with A. W. S. 
there is a disparity of 1.1 per cent., and in the average of the 
nine days of the three rest experiments with J. F. S. the dif- 
ference is 0.9 percent. ‘Taking the thirty-seven days of the 
eleven rest experiments together, the average income is 2,234 
and the average outgo 2,230 calories; the difference is 0.2 per 
cent. In the average of the eight days of the two work ex- 
periments with EH. O. the net income and outgo are 3,865 and 
3,829 calories, respectively, the difference being 0.9 per cent., 
and in the average of the twelve days of the four work experi- 
ments with J. F. S. the net income and outgo are 3,547 and 
540) calories, Or a ditterence of o:2 per cent. “Taking into 
account the six work experiments with FE. O. and J. F. S. the 
net income is 0.5 per cent. larger than the net outgo. The av- 
erages for the fifty-seven days of the seventeen experiments 
are: Income, 2,740; outgo, 2,731 calories. ‘The difference, 0.3 
per cent., is far within the limits of experimental error and 
physiological uncertainties. 
In experiments of this sort, which represent only the work 
of a period during which experience with new apparatus and 
methods is being accumulated, individual discrepancies, such 
as those above recorded, seem no larger than might naturally 
be expected. The agreement of the average results is much 
closer than we hoped for; indeed, it can hardly be otherwise 
than accidental, and we regard it as by no means certain that 
future averages will show so exact a balance. 
The metabolism of energy in the living organism can be more 
' profitably discussed when data not yet published are available. 
Taking into consideration all the experiments thus far made 
with the respiration calorimeter in which the balance of energy 
has been determined, it may be said that the general result 
scarcely falls short of definite and final demonstration that the 
law of the conservation of energy applies in the living organism. 
