DIGESTIBILITY OF FISH. 5 



ration of the fish loaf was identical for the canned and fresh fish. 

 In each instance a quantity of the fish to be studied sufficient for the 

 entire test period, after being mixed with salt and pepper, was very 

 thoroughly and uniformly mixed and baked for two to three hours 

 in a moderate oven. Whatever crust formed during baking was 

 removed, and the remaining portion was again thoroughly mixed 

 in order to secure a uniform product, after which a sample was 

 taken for analysis. 



NATURE OF THE DIET. 



Inasmuch as experience has shown that in studying the digestibility 

 of a single food it is desirable to supply the food material under con- 

 sideration as a part of a simple mixed diet, a suitable basal ration 

 was served with the fish loaf. It consisted of boiled potatoes, crackers, 

 apple sauce, sugar, tea or coffee, and a little lemon juice as a condi- 

 ment in some cases. In accordance with the usual custom, a sufficient 

 supply of the special food under consideration (fish loaf) and of the 

 other foods was prepared in advance for the whole experimental 

 period. The fish loaf was kept in a refrigerator at 15° C. and remained 

 fresh and in good condition, as did also the potatoes, which were 

 boiled, mashed, and thoroughly mixed to insure uniform composi- 

 tion. The apples, which were eaten raw, were of good grade and 

 pleasant flavor. The crackers or " biscuits" used were taken from 

 a large lot and assumed to be of uniform composition. Though no 

 attempt was made to have all eat like amounts, the subjects were 

 urged to eat liberally of the fish loaf and moderately of the crackers 

 and potatoes, following their individual preferences with respect to 

 the apples and the tea or coffee. 



As a whole, the ration, though it contained no added fat and only 

 moderate amounts of carbohydrates, was reasonably generous as 

 regards protein and energy and was varied enough not to become 

 tiresome. 



The food for each man for each meal was weighed in advance and 

 kept separate. All remaining uneaten was weighed. The difference 

 between the amount furnished and the amount remaining repre- 

 sented the amount eaten. 



Samples of the food were reserved for analysis. The small amount 

 of lemon juice (on an average, 35 grams per day), which was eaten 

 with the butterfish and the Boston mackerel, was disregarded in 

 computing the food value of tne diet. 



The feces were collected, sampled, and analyzed by the methods 

 followed in the department's digestion experiments, of which the 

 present investigation forms a part. 1 



i U. S. Dept. Agr. Bui. 310 (1915), pp. 23. See list on last page. 



