THE UTILIZATION OF ENERGY. 453 
having been made on the same individual as Experiment V, the 
result of the latter is used directly. 
In Experiments I and I the ration consisted of rice, in Experi- 
ment III of barley, and in Experiment IV of rice, flesh-meal, and 
whey. In all cases large amounts of food were consumed and a 
rapid production of fat was observed. The digestibility of the food 
was determined. Its metabolizable energy has been computed by 
the writer from the results of the digestion experiments by the use 
of the following factors: * 
1 gram digestible protein................ 4.1 Cals, 
1 “ m nitrogen-free extract... 4.2 “ 
rT * - crude fiber............ B35 
LS a ether extract.......... 8.8 “ 
No attempt was made in these experiments to determine the 
methane, if any existed, in the respiratory products. The results 
per day and head were as follows: 
Tem- Live ompatee eae E tin 
. . as triti 
Experiment. earch Weight, Metabolism, Tneray, Gain, als. Ratio. 
Tigi scat 18.0 140 2607 7157 3464 1:15.4 
EDs sate actions 18.5 70 1621 7167 4048 1:14.1 
i renee 19.3 125 2386 5125 + 1774 1: 9.3 
TV a se a exten 16.7 104 2111 6129 2556 1: 2.4 
No determinations were made of the actual requirements for 
maintenance as distinguished from the fasting metabolism, and 
hence the data are lacking for a computation of the net availability 
of the metabolizable energy of the food on the one hand and the 
percentage utilization of the excess food on the other. Cooke’s re- 
sults mentioned on p. 438, however, seem to give some indication 
that the maintenance demand of swine may not be greatly in excess 
of the fasting metabolism. If in these experiments we assume the 
same net availability as that just assumed in the case of man, viz., 
91 per cent., we obtain the following figures: 
* Compare p. 332. 
+ In this experiment the ether extract of the feces exceeded that of the 
food by 23.95 grms. This excess has been assumed to have a heat value 
of 4.2 Cals. per grm. and a corresponding amount deducted from the com~- 
puted energy of the other digested nutrients. 
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