THE RELATIONS OF METABOLISM TO: FOOD-SUPPLY. 119 
Uncorrected. Corrected. 
3 
ee . Nitro- Com- 
é Ration. : gen Nitro- uted | Nitro- 
ppar- gen A itro en, % 
ently of Gain, gen ee Gain, 
Di- Urine. Di Urine 
gested gested 
Grms. | Grms. | Grms. | Grms. Grms. | Grms, 
I. 500 grms. beans....} 20.51] 20.93 |—0.42] 22.02) 20.93 |+1.09 
490“ 
mide « eed 19.58| 16.82 |+2.76| 21.78] 16.82 | 44.96 
IV. BG . pa 18.81] 17.26 |+1.55] 21.09] 17.26 |+3.83 
Average of II. and IV. +2.16 +4.40 
510 grms_ beans 
.| 1130" “starch bs 20.03] 14.94 |+5.09| 22.16] 14.94 |+7.22 
20 “ sugar 
500 “ beans 
V. 1 90 “ starch }..| 20.64] 17.75 |+2.89| 22.43] 17.75 | +4.68 
10 ‘sugar 
It will be seen that the experiments make substantially the 
same showing for the relative effects of cellulose and starch whether 
we take the uncorrected results or eliminate so far as possible the 
effects of the greater amount of food in the later periods upon the 
excretion of metabolic products in the feces. The addition of starch 
and sugar in Period III produced about twice as great an effect in 
reducing the proteid metabolism as did a somewhat larger amount 
of digestible fiber and nitrogen-free extract from straw in Periods 
II and IV. In Period V the starch added was only equal to the 
digested nitrogen-free extract of the straw in Periods II and IV. 
Since the effect upon the proteid metabolism is substantially the 
same, Weiske concludes that the nitrogen-free extract of the 
straw, which has the elementary composition of starch, is equal to 
it in its effect upon the proteid metabolism, and that the digested 
crude fiber is valueless in this respect. It must be said, however, 
that this latter conclusion is not warranted by the facts, since it 
rests upon the unproved assumption of equality of nutritive value 
(in respect of the proteid metabolism, at least) of starch and the 
nitrogen-free extract of the straw. Weiske also experimented 
with rabbits, finding in one case no effect upon the proteid metab- 
olism and in the second an increase of it, as a result of adding crude 
fiber to a fiber-free ration. 
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