THE RELATIONS OF METABOLISM TO FOOD-SUPPLY. ‘15 
Food per Day. 
Urea per Day, 
Meat, Fat, Gre, 
Grms. Grms. 
JULY BL vac seeds gawccoos 1000 0 81.7 
AUG Vv csaedeeyisaiek scans 1000 100 74.5 
. Ee eC ee 1000 300 69.3 
Basins ha wie es Sine eee 1000 0 81.2 
In the whole series of eight experiments with varying amounts 
of meat and fat the decrease in the excretion of urea ranged from 1 
per cent. to 15 per cent. of the amount supplied in the food, averag- 
ing about 7 per cent. With the same amount of fat in the food 
the decrease in the excretion of urea was not, as a rule, greater with 
large than with moderate rations of meat. On the other hand, 
with a small proteid supply in the food the production of urea was 
sometimes increased slightly by the addition of much fat, and the 
same result was observed to a more marked extent when fat alone 
was given to fasting animals. With medium rations of meat, in- 
creasing the fat supply had usually little effect, but with heavy 
meat rations it tended to further diminish the excretion of urea. 
Subsequent investigation has fully established this tendency 
of fat to diminish the proteid metabolism, and the fact is too well 
known to require extended illustration here. As a recent instance 
may be cited the following results obtained by Kellner * in experi- 
ments upon oxen, in which oil was added to a basal ration: 
Nitrogen Digested. Nitrogen in Urine. 
Basal Ration, |Basal Ration + Oil,| Basal Ration, Basal Ration + Oil, 
Grms. Grms. Qrms. Grms. 
C0). B epraearor parece 135.30 134.55 122.54 120.38 
OX Busses ceases 111.67 109.17 106.03 89.27 
OR Gasietccersia oss 86.27 87.08 86.30 79.83 
CaRBonypRraTes.—The effects of the readily soluble hexose 
carbohydrates (starch and the sugars) have been quite fully inves- 
tigated, while as to those of the less soluble carbohydrates, particu- 
larly of the five-carbon series, considerable diversity of opinion 
still prevails. 
* Landw. Vers. Stat., 68, 121 and 210. 
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