130 PRINCIPLES OF ANIMAL NUTRITION. 
5 Eaten per Day. Protein Protein 
& Date Digested pe rig 
5 - F er Day, er Day, 
2 eft: ea Parma. ‘i Grms. 
| Z Grms. 
1 | May 23-29............ 1500 100 111.6 66.6 
2| June 6-12............ 1450 150 125.0 79.4 
3 £f 20-26) wien eee xs 1400 200 132.2 90.6 
4| July 4-10............ 1350 250 150.9 90.1 
5 SY 20-8 Lanes siaie cage tae 1250 350 170.5 101.6. 
6 | Aug. 8-14........ ie a 1100 500 193.8 117.9 
7 enya. 950 650 221.4 143.1 
8 | Sept 5-l1............ 800 800 257 .2 173.7 
9 OE NGS sina eae guts 1600 0 92.9 56.3 
10: |) Oct: 8-95 cas eee eas 1600 0 74.1 41.9 
A full compilation of these earlier results has been made by 
v. Wolff,t and the fact is now so well established that further cita- 
tions would be superfluous. 
Rare or Nitrogen Excretion.—Some interesting hints as to 
the manner in which the non-nitrogenous nutrients produce the 
effect upon the proteid metabolism which has just been described 
are afforded by a consideration of the rate of nitrogen excretion 
under their influence. 
It was shown in the preceding section that the effect of a meal 
of proteids was a sudden, almost explosive, increase in the nitrogen 
cleavage and excretion, reaching its maximum within a few hours. 
after the meal. If, however, non-nitrogenous nutrients are given 
along with the proteids, the character of the curve is essentially 
altered, the maximum rate of excretion being less and being reached 
somewhat later, while the fall from this maximum is less rapid. 
In other words, the rate of excretion becomes more uniform—the 
curve is flattened out. The influence of fat in this respect is clearly 
shown in the experiments of Panum { and of Feder { cited pre- 
viously, and appears evident also in those of Graffenberger.§ In 
the latter experiments the nitrogenous substances to be tested were 
added to a mixed diet. The results show a distinct maximum, but 
the rate of decrease after the maximum was reached was not rapid, 
* Exclusive of the protein of the milk. 
{ Erniihrung Landw. Nutzthiere, pp. 285-309 
t Thier. Chem. Ber., 12, 402. 
§ Zeit. f. Biol., 28, 818. 
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