THE RELATIONS OF METABOLISM TO FOOD-SUPFLY. 161 
was oxidized in the body. The increase in the amount of oxygen 
consumed is much more marked than in Munk’s experiments, rang- 
ing from 10.4 to 14 per cent. Moreover, as Mallévre points out, in 
the oxidation of sodium acetate about the same volume of oxygen 
is required to produce a unit of heat as in the case of fat. Appar- 
ently, then, while the sodium acetate, like the sodium butyrate in 
Munk’s experiments, must have largely diminished the metabolism 
of the body fat, it also stimulated the total metabolism and was 
substituted for the fat in less than the isodynamic ratio. As in 
Munk’s experiments, a stimulation of the heart action and also an 
increased peristalsis of the intestines was observed. 
It would seem, then, that lactic and butyric acids, when 
introduced into the circulation of the fasting animal, protect 
the body fat from oxidation, and replace other nutrients in 
isodynamic proportions. Acetic acid, on the contrary, seems in- 
ferior to the other two in this respect, and it is of interest to recall 
that according to Weiske & Flechsig (p. 123) it apparently has 
also less effect in diminishing the proteid metabolism. 
Crude Fiber.—As was stated on p. 117, the early experiments 
by v. Kniéeriem * upon the nutritive value of cellulose comprised 
respiration experiments as well as determinations of the proteid 
metabolism. Combining the results for nitrogen. already given with 
those for carbon, we have the following: 
Gain or Loss of 
Period. ee Food per Day. 
Days. Cha Altes) Nitrogen, | Carbon, 
Grms. Grms. 
Te hsieares 9 | Milk and horn dust ................ —0.599 | —4.521 
TD ps acess 10 |Same + 18.63 grms. crude fiber * ...| +0.104 | —0.434 
TIl..... 5 | Milk and horn dust ................ —0.330 | —4.868 
i I seme 4 |Same + 11 grms. cane-sugar.........| —0.318 | —1.673 
Vt 3 «+ 330 CS BEN e hls eee —0.023 | +5.653 
* Water-free. 
+ Results regarded by the author as of doubtful value. 
In addition to its effect in diminishing the proteid metabolism, 
the crude fiber in these experiments seems to have been fully as 
efficient as the cane-sugar as a substitute for body fat. 
* Zeit. f. Biol., 21, 67. 
