28 U. S. BUREAU OF FISHERIES 
Medical College, Charleston, S. C., and Mr. Coulson, which was sub- 
mitted to Dr. Hunter for inclusion as a chapter in a book to be pub- 
lished by the American Public Health Association, entitled, “Standard 
Methods for the Examination of Shellfish.”’ 
CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF FISH PROTEINS 
This investigation, begun during the latter part of 1935, has con- 
sisted of a detailed study of fish proteins. Because of their importance 
in nutrition as constituents of these proteins, the amounts of the amino 
acids, cystine, tryptophane, arginine, histidine, and lysine were deter- 
mined in the following species of fish and shellfish: Boston mackerel, 
Spanish mackerel, cod, shad, shrimp, croaker, halibut, red snapper, 
oysters, clams, and haddock. Also the same amino acid determina- 
tions, except cystine, were made on casein, a protein which is generally 
used as the standard or control protein in all determinations of this 
character. 
Studies of the metabolism or biological value of some of these fish 
proteins were carried on in our nutrition laboratory by the use of 
albino rats. Casein was used as the control protein in making these 
feeding tests. At the present time, these studies have progressed far 
enough to indicate the relative biological value of the protein in three 
species of fish. The protein of Boston mackerel, Spanish mackerel, 
and haddock were compared with respect to each other and with 
reference to casein as to their value in growth promotion, mainte- 
nance of body weight and digestibility. Synthetic diets containing 
9 percent of fish protein produced approximately the same gain in 
weight per gram of protein eaten for each of the above-named species 
of fish. All three of them proved superior to casein. However, in 
diets containing 18 percent of protein, the fish proteins produced 
about equal growth to that of casein. The data on maintenance of 
body weight indicated that all three of the fish proteins were superior 
to casein and Boston mackerel probably was the best of the lot. 
Haddock was the most completely digested fish protein and was closely 
followed by Spanish and Boston mackerel in this respect. 
MINERAL CONSTITUENTS OF FISHERY PRODUCTS AND BYPRODUCTS 
Studies of the mineral constituents of fishery products and byprod- 
ucts were continued by E. J. Coulson, assistant pharmacologist of the 
Bureau’s technological staff, stationed in the laboratories of the State 
Medical College, Charleston, S. C., with special reference to the role 
of these mineral constituents in nutrition. Chemical determinations 
of the amount of calcium, phosphorous, magnesium, iron, copper, 
sulphur, iodine, and arsenic were made in the principal commercial 
species of fish and shellfish during the past year. With the resignation 
of Mr. Coulson, this work is being continued by another investigator. 
The principal mineral nutrients of value to man and animal are 
calcium, phosphorus, iron, copper, iodine, and sulphur. It has been 
known for a long time that most fishery products are exceptionally 
good sources of these minerals and the above described studies further 
verify and amplify this information. 
