548 ^^« ^' BUREAU OF FISHERIES 



herring. The latter result may mean that the herring muscle is 

 lacking in it but that the substance is contained in the glandular 

 organs. It is present in turbot roe and is probably found in the 

 reproductive tissues of fish generally, as is true of mammals. 



The most interesting aspect of the investigations of fish products 

 from the food standpoint relates to the pecuhar value of certain 

 fish oils in the prevention and cure of rickets in children and in 

 animals. Rickets is an extremely common disease affecting the 

 skeletal development of children and of certain farm animals. Cod- 

 hver oil is a specific remedy against this disease. It is generally 

 agreed by pediatricians that every child should be given appropriate 

 doses of cod-liver oil from early infancy as a routine measure to 

 safeguard the development of the bones and probably also the 

 teeth. This property is due to the presence in the oil of vitamin D, 

 a substance distinct in its properties from vitamin A. 



Vitamin D is apparently present in considerable amounts in the 



liver oils of fish generally, but the liver oil of the cod is believed to 



be exceptionally potent as a source of it. Cod, shark, and burbot 



liver oils are known to be effective in the cure of rickets. 



I It has long been observed that in regions where fish are regularly 



, eaten in considerable amounts goiter is rare, whereas it is very com- 



I mon in many regions because of lack of iodine. Sea foods such as 



i fish furnish this element in appropriate amounts to supply the needs 



■ of the body. A similar statement may be made concerning rickets in 



children. Even in those parts of the world where the climatic and 



hygienic conditions are such as to favor the development of bone 



defects these are rare among children where fish forms a prominent 



article of diet. The administration of cod-liver oil is an effective 



substitute for the eating of fish for this specific purpose. 



Shellfish, such as oysters, clams, and lobsters, are of great impor- 

 tance. Oysters are so universally liked and their culture has been so 

 much extended that they deserve especial mention in any discussion 

 of the food value of fish. Little attention has been given to the study 

 of the nutritive value of the oyster. Such observations as have been 

 made show that it contains both the vitamins B and C. Since both 

 oysters and clams are frequently eaten in the raw state, they occupy 

 an unique position in that they are the only foods of animal origin 

 which in the temperate regions can take the place, in a measure, of 

 fresh, raw, vegetable foods. It is universally agreed that it is desir- 

 able to take some food daily which is capable of supplying vitamin 

 C, since scurvy will develop after a few weeks of deprivation of this 

 vitamin. There is good reason to believe that at certain times and 

 places oysters and clams have played a special role as antiscorbutic 

 loods in the human dietary. 



' Nothing is known of the vitamin content of the lobster. Crabs, 

 especially soft-shell crabs, are probably comparable to oysters in 

 their vitamin content, but no studies seem to nave been made with 

 them. 



Modern researches on foods and nutrition have brought to light 

 many surprises, both as regards the nutritive needs of the body and 

 the dietary properties of individual foodstuffs, among which the most 

 marked contrasts have been found. In no case have any foods gained 

 more recognition as having unique dietary values than have the prin- 

 cipal fish and shellfish. 



