THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. 109 
proteids. The experiments were conducted with the aid of a respi- 
ration apparatus, the gain or loss of proteids and fat being com- 
puted from the nitrogen and carbon balance in the manner described 
in Chapter ITI. 
The following is a condensed summary of the average results 
of these experiments, as given by the authors,* but includes also 
the average of all the experiments with 1500 grams of meat. On 
Gain (+) or Loss (—) by Animal. 
Number of Meat Eaten per Day, 
Experiments. Grms. 
Flesh. Fat. 
Grms, Grms 
0 —165 —95 
500 — 99 —A7 
1000 — 79 —19 
3T 1500 0 a4 
22 1500 + 18 + 9 
1 1800 + 43 + 1 
2 2000 — 44 +58 
1 2500 — 12 +57 
the smaller rations, which were obviously insufficient for main- 
tenance, the animal lost both flesh and fat. A ration of 1500 
grams of meat per day sufficed approximately to maintain the ani- 
mal as regards flesh and to cause a small gain of fat. On the 
heavier rations the excretion of nitrogen kept pace with the supply 
in the food in the manner illustrated on pp. 94-96 but the excretion 
of carbon fell considerably below the supply, indicating a produc- 
tion of fat. 
It is to be noted that only the last three experiments in the above 
table actually show any very considerable production of fat. The 
insufficient rations naturally do not, and while among the twenty- 
two trials with 1500 grams of meat the majority appear to show a 
formation of fat, the amount is usually comparatively small, and 
in two cases a loss was observed. On the whole, however, the evi- 
dence of this series of experiments has been generally accepted as 
conclusive in favor of the formation of fat from proteids. 
Prutiger’s REcALCULATIONS.—One very important point, how- 
ever, has until recently been overlooked. The evidence is based on 
* Zeitschr. f. Biol., 7, 489. 
+ Series 1 only. 
