147 
0.9 per cent, and in the average of the 12 days of the 4 work experi- 
ments with J! F. S. the net income and outgo are 3,547 and 3.540 
calories, or a difference of 0.2 per cent. Taking into account the 6 
work experiments with E. O. and J. F. S., the net income is 0.5 per 
cent larger than the net outgo. The averages for the 65 days of the 
19 experiments are: Income, 2,691; outgo. 2.682 calories. The dif- 
ference, 0.3 per cent, is far within the limits of experimental error 
and physiological uncertainty. 
In experiments of this kind, 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 was hoped for, 
and we regard it as by no means certain that future averages will show 
so exact a balance. 
At the same time it is to be noted that when, to the results of the 19 
experiments here summarized, those of the 11 others above referred 
to as published elsewhere are added, the agreement is almost absolute. 
The 30 experiments covered, all told, 93 days. The average daily 
income was 2,719 calories and the outgo 2.716 calories. It thus 
appears that, with increase in the number of experiments, the differ- 
ences due to unavoidable errors more and more nearly counterbalance 
one another. 
The general subject of metabolism of energy in the living organism 
will be more profitably discussed when data not yet published are 
available. Meanwhile it is safe to say that the results thus far obtained 
fall very little short of definite demonstration of the action of the law 
of the conservation of energy in the living organism. 
O 
