EXPERIMENTS ON METABOLISM OF ENERGY. vTTs 
day. With H. O. this increase is noticeable in all four periods, 
but is especially marked in the first day period, the average in 
that period being three times as great in the work as in the rest 
experiment. In the majority of cases the amount gradually 
fell off during the subsequent periods; but even during the 
last night period the average was nearly 134 times as large for 
the work as for the rest experiments. Of the total daily 
amount 60.3 per cent. was given off during the two day per- 
iods, and 39.7 per cent. during the two night periods. With 
J. F. S. there was an increase in elimination during the day 
periods only, being most noticeable in the second, in which it 
was three times as large in the work as in the rest experiments. 
The elimination during the night periods was practically the 
same in the work as in the rest experiments. Of the total 
daily amount eliminated by this subject in the work experi- 
ments, 75.5 per cent. was given off during the two day periods, 
and 24.5 per cent. during the two night periods. In the aver- 
age of the experiments with the two subjects the amounts for 
the four periods were respectively 107.2, 110.3, 55.1 and 46.0 
PiatioePerinGuls.00 13337, 34,0,.17 23, ald 14.4 per centeonsthe 
total. 
The parallelism between muscular work and increased water 
elimination by the lungs and skin is not close, nor does the in- 
crease, coincide at all exactly with the period of work. The 
‘‘lag’’ in elimination of water, 1. e., the length of time between 
its ingestion in food and drink or its formation by the oxidation 
of hydrogen on the one hand and its elimination by various 
- channels on the other is decided by factors too complex for full 
discussion here, and is reserved for discussion in the light of 
later experiments. 
ELIMINATION OF CARBON DIOXID. 
The carbon dioxid given off from the body is derived wholly 
from the oxidation of the carbon of the food and body material, 
and hence serves asa measure of the amount of that oxidation. 
The quantity given off in the urine and feces is very small in- 
deed. It is here neglected, and that given off by the lungs and 
skin is taken as representing the total elimination. The quan- 
tity eliminated in a given period depends upon a variety of 
conditions, among which are (1) the character of the diet and 
