DIGESTIBILITY OF MISCELLANEOUS ANIMAL FATS. 19 
Summary of digestion experiments with ox-marrow fat in a simple 'mixed diet. 
Subject. 
Digestibility of entire ration. 
Esti- 
mated 
Experiment No. 
Protein. 
Fat. 
Carbohy- 
drate. 
Ash. 
digesti- 
bility of 
ox-mar- 
row fat 
alone. 
692 
P. K 
Per cent. 
68.3 
69.2 
31.5 
Per cent. 
91.3 
93.3 
90.9 
89.3 
Per cent. 
97.8 
97.8 
96.9 
97. a 
Per cent. 
71.8 
68.8 
56.1 
50.0 
Per cent. 
93.7 
693 
J. C. M 
95.6 
694 
A. A R 
91.6 
695 
W. E. T 
67.9 
93.1 
Average 
59.2 
91.2 
97.4 
61.7 
93.5 
In the experiments reported above the subjects ate on an average 
21 grams of protein. 89 grams of fat (of which 87 grams were mar- 
row fat), and 340 grams of carbohydrate. This diet furnished ap- 
proximately 2,245 calories of energy daily. It will be noted that in 
experiment No. 695 the subject W. E. T., who did not possess a very 
vigorous ajDpetite, ate only 109 grams of fat during the three-day 
period. The other subjects averaged 104 grams of fat daily. The 
protein supplied by the diet was 59.2 per cent digested, the fat 
91.2 per cent, and the carbohydrate 97.4 per cent. The figure 91.2 
per cent for the digestibility of the total fat of the diet becomes 93.5 
per cent for the digestibility of marrow fat alone when correction is 
applied for the metabolic products and undigested basal-ration fat 
which occurs in the ether extract of the feces. 
The consumption of 100 grams of marrow fat daily for a period of 
three days or more evidently caused digestive disturbances since 
in experiment No. 692, subject P. K. reported : " Health was normal 
when entering on the diet. During the period experienced a slight 
headache and a sickish feeling." In experiment No. 693, subject 
J. C. M. reported : " Felt a severe weakness accompanied by cold 
perspiration." In experiment No. 694, subject A. A. E. reported: 
" Pains in head and abdomen, general feeling of weakness." In ex- 
periment No. 695, subject W. E. T. reported: " Health normal at start 
of diet, during diet headache with general weak feeling." 
On the basis of these experiments alone, it would appear that the 
continued consumption of 100 grams of marrow fat daily is likely to 
be attended with physiological disturbances. The results of the ex- 
periments indicate, however, that this fat is as completely digested as 
the common animal and vegetable fats. 
OX-TAIL FAT. 
Ox-tail fat is separated and marketed as an edible fat to a small 
extent at least in this country. In reply to an inquiry regarding its 
commercial production, one food-packing concern states : " This fat 
