IXTRODUCTIOX 647 



I.U. g.; menhaden {Brevoortia tyrannus), 50 I.U./g.; flathead mud cat- 

 fish {Pilodictis olivaris), 20 I.U./'g.; and capelin (Mallotus villosus), 3 

 I.U./g. In the case of the Greenland halil)ut {Reinhardiius hippoglossoi- 

 des), the a^•erage vitamin D content of the ])od3' fat (ol)tained from carcass 

 without Hver) was 30 I.U./g. 



]\Iany factors, such as season, sex, age, food supply, climate, and nutri- 

 tional condition'^- influence the amomit of ^•itamin D in fish liver oils. 

 Liver oil from spa^^'ning, undernourished cod contains considerably more 

 vitamin D than does liver oil from well-nourished cod.^'^- For example, 

 Hess and co-workers ^"^observed that the vitamm D content of the li\'ers of 

 the cod varied in\-ersely with the oil content. Oil from some cod livers 

 studied was as much as 1,000 times as potent as that of others of the same 

 species.^"* A similar phenomenon was noted in the case of livers from the 

 haddock and pollack. According to Bills et al.,"^ the oil content of pooled 

 halibut livers obtained near Seattle in January was at the lowest point, 12%, 

 while the vitamin D content reached its highest value, namely 1400 I.U./g. 

 oil. On the other hand, in August, the oil content of the livers showed its 

 maximum value, namely 25%, coincidentally with the lowest concentration 

 of vitamin D, i.e., 900 I.U./g. Pugsley^''" observed that the vitamin D con- 

 tent of the liver and intestinal oils of the Pacific gray cod {Gadus macro- 

 cephalus) ^'aried inversely with the amount of fat in the livers. The same 

 inverse relationship existed between the fatness of the liver and the vitamin 

 D concentration in the oil of the Atlantic cod (Gadus morrlnm) ."^ On the 

 other hand, the \'itamin D content of the hver oil of this species was found 

 to remain constant when calculated as units per gram of body weight of fish 

 in a given age group, although the vitamin D content of the hver increased 

 with the age of the fish. Bailey^^'^ reported an inverse relationship in the 

 oil jdeld of the whole pilchard {Sardinops caendea), including stomach con- 

 tents, and its vitamin D potency. The vitamin D content of the Nor- 

 wegian cod, which is caught at the time when its nutritional condition 

 is poor, is higher than that of the Newfoundland cod, which is in a much 

 better nutritional state when caught. 



Although the milt and roe of fishes such as the cod were found to con- 



1" E. Poulsson and F. Ender, Skand. Arch. Physiol. 66, 92-96 (1933). 



i'3 A. F. Hess, C. E. Bills, and E. M. Honeywell, /. Am. Med. Assoc, 92, 226-228 

 (1929). 



"^ C. E. Bills, M. Imboden, and J. C. WaUenmeyer, J. Biol. Chem., 105, x (1934). 



»'5 L. I. Pugslev, /. Fisheries Research Board, Can., 4, 405-408 (1939). 



i'6 L. I. Pugslev, C. A. Morrell, and J. T. Kelly, Can. J. Research, F 23, 243-252 (1945). 



"'B. E. Bailey, Canada, Biol. Bd., Pacific Biol. Sta. (Nanaimo, B.C.), and Fisheries 

 Expt. Sta. (Prince Rupert, B.C.), Progress Repts., No. 19, 5-6 (April, 1934). 



