THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. 123 
gain of nitrogen as the total non-nitrogenous matter digested from the 
hay, and the author follows Weiske in concluding that the digested 
crude fiber producd but little effect on the proteid metabolism. 
The same author also reports experiments upon a rabbit similar 
to those of v. Knieriem, crude fiber prepared from hay being added 
to a basal ration of peas, with the following results, which show 
practically no effect of the crude fiber upon the proteid metabolism: 
Nitrogen Nitrogen Excreted. Gain of 
Food. of Food, Nitrogen. 
Grms. Urine, | Feces, | Total, | Grms. 
Grms. Grms. Grms, 
PEAS a ct etinnes Be be ee ae es 0.845 | 0.855 | 0.016 | 0.871 |—0.026 
“and 5 grams. crude fiber....| 0.857 | 0.821 | 0.120 | 0.941 |—0.084 
Ont Onsss sugar... ..... 0.845 | 0.701 | 0.080 | 0.781 |+0.064 
fe 6.5 crude fiber....| 0.860 | 0.899 | 0.170 | 1.069 |—0.209 
While it is obviously unsafe to draw any positive conclusions 
regarding the relative effect of cellulose and the more soluble carbo- 
hydrates from the various experiments cited above, the balance 
of evidence seems clearly to show that their influence upon the pro- 
teid metabolism is qualitatively the same, while it appears on the 
whole probable that digested cellulose is at least not greatly in- 
ferior quantitatively to digested starch. 
Organic Acids.—Certain methods of preparing or preserving 
fodder, notably ensilage, result in the formation of not inconsider- 
able amounts of organic acids. Moreover, it appears that these acids 
are normally produced in considerable quantities in the herbivora 
by the fermentation of cellulose and other carbohydrates, and that 
fact naturally leads to a consideration of their effects upon meta- 
bolism as compared with the latter substances. 
We have seen (p. 27) that the organic acids are oxidized in the 
body, and it therefore seems natural to suppose that they may 
influence the proteid metabolism. This question has been investi- 
gated by Weiske & Flechsig.* After some only partially success- 
ful experiments on a rabbit, they fed a sheep with a basal ration 
(of hay, starch, cane-sugar and peanut cake) containing a liberal 
supply of protein and having a nutritive ratio of 1:3.4. To this 
ration there was added in succeeding periods lactic acid as calcium 
lactate, acetic acid as sodium acetate, and for comparison. dextrose. 
* Jour. f. Landw., 37, 199. 
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