2 BULLETIN 649, U. S. DEPARTMENT OF AGRICULTURE. 
that the absorption of mineral salts is better on a diet containing 
fresh or salt fish and poorer on a diet containing dried fish than on a 
diet containing beef. Van Slyke and White, 1 using the rate of excre- 
tion of nitrogen in the urine as an index of the rate of protein diges- 
tion, found that boiled cod (fresh) was more rapidly digested than 
boiled beef, boiled weakfish, boiled mussel, and boiled cod (salt). 
Rosenfeld, 2 in a study of the nutritive value of fish (sea pike and sea 
salmon), concludes that fish causes the excretion of a smaller 
amount of uric acid than meat and that fish is equal to beef for 
maintaining nitrogen equilibrium. . In digestion experiments with 
beef and fish, Atwater 3 compared the amounts of protein, fat, and 
ash assimilated, and obtained the same coefficients of digestibility 
for both food materials. 
Studies of the digestibility of canned salmon have been reported 
by Milner, 4 who found in four experiments in which an average of 
401 grams of salmon was eaten daily for three days with a simple 
mixed basal ration consisting of bread, milk, butter, and sugar, that 
96 per cent of the protein and 97 per cent of the fat of the salmon 
were retained by the body. 
A number of other investigators have studied the value of fish flesh 
for food purposes by means of artificial digestion experiments. 
Honigsberg 5 studied the relative digestibility of fish and found that 
pepsin digested whitefish protein more rapidly than raw and less 
rapidly than cooked beef. In a study of the digestibility of fish pro- 
tein by trypsin, White and Crozier 6 found that boiled codfish and 
dogfish digested more readily than boiled beef. Sulima 7 conducted 
experiments to determine whether there were differences in food in 
the raw state and that cooked at a high temperature which would 
affect the digestive process and concluded that gastric digestion was 
much slower with cooked than with uncooked fish (sardines). This 
difference, he believed, was due to the enzyms present in the raw 
fish. Konig and Spittgerber, 8 as a result of determinations of the 
composition, energy value, and constants of fish fat, and a study of 
the digestibility of fish flesh by means of artificial digestion exper- 
iments, concluded that fish flesh is as easily and completely digested 
as meat. 
In the earliest elaborate series of investigations of food materials 
made in this country, Atwater 9 studied the composition of fish, 
and the results of this investigation contributed largely to the gen- 
i Jour. Biol. Chem., 9 (1911), No. 3-4, pp. 219-229. 
2 Zentbl. Inn. Med., 27 (1906), No. 7, pp. 169-176. 
3 Ztschr. Biol., 24 (1888), No. 1, pp. 16-28; abs. in Jahresber. Tier Chem., 17 (1887), p. 418. 
* Connecticut Storrs Sta. Rpt. 1905, p. 142. 
s Wiener Med. BL, 5 (1882), Nos. 19, pp. 582-585; 20, pp. 614-616. 
« Jour. Amer. Chem. Soc., 33 (1911), No. 12, pp. 2042-2048. 
7 Arch. Hyg., 75 (1912), No. 6-7, pp. 235-264. 
8 Landw. Jahrb., 38 (1909), Sup. 4, pp. 1-169. 
9 U. S. Comr. Fish and Fisheries Rpt. 1883, pp. 423-494. 
