242 PRINCIPLES OF ANIMAL NUTRITION. 
the energy content to be from 6.7 to 8.5 Cals. per gram of nitrogen 
in place of 5.4 Cals. as computed on the assumption that only urea 
was present, while for human urine he has obtained values ranging 
‘from 6.42 Cals. to 8.87 Cals. per gram of nitrogen, and Tangl * 
has reported even higher figures. 
Kellner + has shown that the difference is still greater in the 
urine of an ox receiving only coarse fodder, the actual energy being 
about six times that computed on the above assumption and nearly 
175 per cent. of that computed after allowing for the hippuric acid 
present. In subsequent investigations { he finds that the energy 
content of the urine of cattle is much more nearly proportional to 
its carbon than to its nitrogen, being approximately 10 Cals. per 
gram of carbon. 
In six cases reported by Atwater & Benedict § in the course of 
their investigations with the respiration-calorimeter, the amount of 
energy found in human urine from a mixed diet as compared with 
that computed from the nitrogen reckoned as urea was: 
En . 
Total sie 
Nitrogen, 
Grms. | Actual, | Computed, 
Cals. Cals. 
Experiment No. 5........ cece eeeee 72.43 511 392 
sf SS Gas cakae ye ayenee borders 64.29 504 348 
£6 COON sim seeaen 44 eg SE 70.60 569 382 
bs et. ee eee ere 77.90 658 421 
- TE ID sass seu tebenci sss Mahone Gccie 71.72 597 388 
% BETO sseiesirasstiya aca avons, eratevege’ 77.76 589 421 
Here, too, it is evident that a computation on the basis of the 
urea yields results much below the truth, and later experiments by 
the same authors have fully confirmed this result. 
The Feces——Our knowledge of the proximate principles con- 
tained in the feces is so small that no satisfactory computation of 
their energy content is possible, except perhaps in the case of car- 
nivora on a purely meat diet, where the total amount of feces is 
* Arch, f. (Anat. u.) Physiol., 1899, p. 261. 
¢ Landw. Vers. Stat., 47, 275. 
t Ibid., 58, 437. 
§ U.S. Dept. Agr., Office of Experiment Stations, Bull. 63. 
