133 
In comparing* the averages of the rest and work experiments with 
both subjects E. O. and J. F. S., it will be observed that while the 
quantity of water in the food and drink was considerably larger in the 
work than in the rest experiments, the amounts of urine and water in 
the urine was larger in the latter than in the former. The differences, 
however, varied with the two subjects. Thus with E. O. the total 
income of water was over 10 per cent larger in the work than in the 
rest experiments, but the outgo in the urine was but little over half as 
large in the former as in the latter. With J. F. S. the total income 
in the work experiments was nearly 20 per cent larger than in the 
rest experiments, but the outgo in the urine was only three-fourths as 
large in the former as in the latter. With both subjects the amount 
of solids in the urine was slightly larger in the work than in the rest 
experiments. • 
Elimination of water by respiration and perspiration. — The differ- 
ences in the elimination of water in the urine in the rest experiments 
as compared with the work experiments find a ready explanation in 
the figures for water in the respiration and perspiration. The amounts 
of water thus eliminated by E. O. averaged 2,275 grams in the work 
experiments as compared with 977 grams in the rest experiments; and 
by J. F. S., 1,670 grams in the work experiments as compared with 
830 grams in the rest experiments. In other words, the water elimi- 
nated by the kidneys depends, of course, upon the ratio of water in 
the food and drink to water of respiration and perspiration. The 
kidneys rid the body of the water not thrown off by the lungs and 
skin. 
It is commonly assumed that the expired air is saturated with mois- 
ture. Supposing this to be a fact, the quantity of water given off 
from the lungs would be proportional to the amount of expired air. 
In times of active muscular exercise the volume of this air is larger than 
in times of, rest, and consequently the amount of water given off from 
the lungs would be larger. Furthermore, the perspiration from the skin 
increases greatly with the muscular activity. With E. O. the amount 
of water excreted per day from the lungs and skin in the work experi- 
ments was 2i times as large as in the rest experiments. With J. F. S. 
it was twice as large in the work as in the rest experiments. 
The balance of income and outgo of water is decided not only by 
the amounts in food and drink on the one hand, and by the kidne} r s, 
lungs, and skin on the other, but also b} T two other factors. One of 
these is the amount of water formed within the body by the oxidation 
of hydrogen. The other is the change in the amount of water in the 
alimentary canal and in the tissues and fluids of the body. The dis- 
cussion of this topic is reserved until additional data, which are being 
accumulated, are available. 
