264 PHYSIOLOGY: ARMSBY, FRIES AND BRA MAN Proc. N. A. S. 
lively. A comparison of these shows a somewhat smaller ratio in the lying 
than in the standing position. 
Carbon Dioxide; : Hbat Ratio op Catti^e; 
STANDING 
LYING 
Range 
1.8600 to 2.9400 
1.6900 to 2.5700 
Mean value 
2.5129 ^ 0.0185 
2.2529 ± 0.0149 
Standard deviation 
0.196 ± 0.013 
0.158 ±0.011 
Median 
2 . 5020 
2.2713 
Theoretical mode 
2.4802 
2.3081 
Error of single variate 
±0.13 
±0.11 
Coefficient of variability 
7.80% 
7.01% 
A further study of the results indicated that the rather wide range in 
the single values of the CO2 : heat ratio was caused in large degree by 
variations in the amount of feed consumed, the ratio tending to decrease 
as the amount of feed increased. This is what would have been expected 
for two reasons. F'irst, the CO2 : heat ratio for the methane fermenta- 
tion, although not very satisfactorily determined, is undoubtedly much 
lower than that due to the tissue metabolism of the animal and as the 
feed is increased this constitutes an increasing proportion of the total 
elimination. Second, it is clear that the formation of fat from carbohy- 
drates which takes place on a heavy ration would tend to lower the ratio ; 
while, on the other hand, the oxidation of body fat on an insufficient 
ration would tend to increase the ratio. It should be noted also that our 
subjects were performing no external work and while not absolutely at 
rest were for the most part standing or lying quietly. Any considerable 
muscular exertion would doubtless have materially increased the ratio. 
In 99 48-hour experiments, the factor of the varying size of the sub- 
jects being eliminated by computing all the results per kilogram of live 
weight, it appeared from a graph in which the abscissas represented the 
total weights of feed consumed and the ordinates, respectively, the grams 
of carbon dioxide excreted, the calories of heat measured and the ratio 
Heat/C02, that the individual results grouped themselves quite closely 
about three straight lines which could be represented by the three follow- 
ing linear equations, in which 
% = Air-dry weight of feed in grams per kilogram of live weight 
yi = Calories of measured heat per kilogram live weight 
y2 = Grams of CO2 per kilogram live weight 
Heat yi 
yz = = . 
CO2 :v2 
(1) = 0.869:x: -f 14.176 
(2) y^ = -h 4.365 
(3) y, = —0.0226:^ -h 2.802. 
