45 
Table 28. — Income and outgo of nitrogen. 
Ex- 
peri- 
ment 
No. 
389 
396 
398 
401 
403 
405 
406 
Kind of food. 
Grapes, assorted , whole period (4 days) 
Average for 1 day 
Grapes, Brazil nuts, -whole period (4 days) 
Average for 1 day 
Grapes. Brazil nuts, granose, whole period (4 days) 
Average for 1 day 
Grapes, walnuts, granose, whole period (4 days) . . 
Average for 1 day 
Persimmons, peanuts (milk, 227 grains), whole 
period (4 days) 
Average for 1 day . . 
Pears, walnuts (milk, 227 grams; granose, 113 
grams) , whole period (4 days) 
Average for 1 day , 
Pears, cocoanut, whole period (4 days) 
Average for 1 day 
Dried rigs, apples, walnuts, whole period (4 days) 
Average for 1 day 
Apples, dates, peanuts, whole period (4 days) 
Average for 1 day 
Apples, dates, pecans, whole period (4 days) 
Average for 1 day 
Apples, raisins, walnuts, whole period (4 days) . . . 
Average for 1 day 
Nitrogen. 
In food. 
drain*. 
8.80 
2.20 
33. 99 
8.50 
42.64 
10.66 
34.49 
8.62 
60.00 
15.00 
45. 85 
11.46 
22. 71 
5.68 
41.08 
10. 27 
49.49 
12.37 
30.41 
7.60 
43. 83 
10.96 
In urine. 
Grams. 
18.69 
4.67 
18.77 
4.69 
21.88 
5.47 
22.34 
5.59 
29. 58 
7.40 
21.55 
5.39 
23.37 
5.84 
23. 94 
5.99 
29. 64 
7.41 
23.33 
5.83 
22.57 
5.64 
In feces. 
Grains. 
4.89 
1.22 
5. 39 
1.35 
6.21 
1.55 
6.98 
1.74 
7.93 
1.98 
7.29 
1.82 
5.64 
1.41 
12.01 
3.00 
10. 82 
2. 70 
7. 26 
1.81 
8. 46 
2.12 
Gain ( + ) 
or loss ( — ). 
Grams. 
-14. 78 
- 3.69 
+ 9.83 
+ 2.46 
+14.55 
+ 3.64 
+ 5.17 
+ 1.29 
+22.49 
+ 5.62 
+17.01 
+ 4.25 
- 6.30 
- 1.57 
+ 5.13 
+ 1.28 
+ 9.03 
+ 2.26 
- .18 
- .05 
+12. 80 
+ 3.20 
In considering these and the succeeding digestion experiments it 
must be remembered that the digestibility of the food, and therefore 
the coefficients of digestibility, depend on mam T factors. The point has 
been so freely discussed in previous publications of this Office a that in 
this present instance it is not necessary to treat the matter in detail. 
It might not be out of place, however, to call to mind some of Praus- 
nitz's & obseryations in this connection. He points out that there are 
three possibilities — either (1) each food digests as if it were used alone, 
or (2) one is hindered or (3) is helped in digestion by the presence of 
others. For the experiments under discussion the question is an 
exceedingly important one. 
It appears from an examination of the data in Table 32 that in the 
first experiment, No. 3S8, in which the diet consisted entirely of grapes, 
the coefficients of availability for protein are extremely low. This 
may be accounted for in several wa} T s. The protein of the grape may 
contain considerable amid nitrogen, although an examination of the 
data for the urine and feces would tend to an opposite view. The total 
amount of protein supplied by the food during the experimental period 
was 55 grams, while the feces contained 30.55 grams, or oyer 60 per 
cent, implying either a large amount of undigested protein or an 
unusual excretion of nitrogen in the so-called metabolic products. A 
reference, howeyer, to Table 55, page 73, showing the metabolic nitro- 
gen of the feces, indicates that for the experiment the feces contained 
about 1.3 grams of nitrogen in the so-called metabolic products, while 
the average of the 11 experiments is 1.35 grams. Whether the low 
«U. S. Dept. Agr., Office of Experiment Stations Bui. 21, pp. 53-80. See also 
Konig's Chemie der menschlichen Nahrungs- und Genussmittel, 1889, p. 46. 
& Arch. Hyg., 1893, p. 626. 
