12 
Scientific Proceedings (40). 
After 24 hours 40-70 per cent, of the nitrogen has disappeared, 
presumably by absorption, and of that left, in both stomach and 
intestine, 65-85 per cent, is in solution. The peptone in both 
stomach and intestine is midway between the di- and tripeptid 
stages. It remains at this stage until absorption is complete, which 
occurs in 48-72 hours. After 48 hours, in two cases out of three, 
only 14 per cent, of the ingested nitrogen remained in the tract. 
Urea is constantly present in the intestine. It is excreted 
with the bile, which contained, in the samples analyzed, 1 .7 per cent, 
of urea, in which form over 70 per cent, of the total bile nitrogen 
is found. 
8 (533) 
Absorption and excretion of alimentary nitrogen. 
By DONALD D. VAN SLYKE and GEORGE F. WHITE, 
[From the Laboratories of the Rockefeller Institute and the Laboratory 
of the U. S. Fish Commission at Woods Hole.] 
Beef and different forms of fish flesh were fed to a dog in 
nitrogenous equilibrium, the daily diet containing 3 grams of 
nitrogen, in the form of chopped meat, 65 grams of starch, and 
26-27 grams of fat. The animal was catheterized 3, 6, 9, 12 and 
24 hours after feeding, and the daily feces were separated by 
addition of lamp black to the diet. The rise in the rate of 
nitrogen excretion in the urine was taken as an index of the rate 
of absorption, the excretion of nitrogen in the feces as a measure 
of the completeness of absorption. The significance of the results 
is shown by the following figures: 
Food. 
Boiled Cod. 
Fried Cod. | 
Boiled Beef. 
Boiled Trutog. 
Boiled Eel. 
Boiled 
Weakfish. 
Boiled Mussel. 
Boiled Salt-cod. 
Boiled 
Litorina. 
Nitrogen in urine during first 
9 hrs. after feeding. 
1.50 
1.36 
I.29 
1.28 
I.24 
1.23 
I.23 
I.07 
1. 00 
Nitrogen absorbed in 24 hrs. 
I.98 
1.80 
2.58 
2.55 
I.91 
2.53 
2.40 
2.58 
2.37 
Nitrogen excreted in urine in 
24 hours. 
2.51 
2.48 
2.76 
2.35 
2.20 
2.34 
2.22 
2.29 
1.90 
Nitrogen retained. 
-•S3 
-.68 
-.18 
+ .20 
-.29 
+.18 
+ .18 
+.29 
+•47 
The foods in the table are arranged in rank according to the 
