II. CHEMISTRY 167 



Within any species, however, great variations in potency are noted when 

 the oils of individual livers are assayed. Hess ei al."^ found that the vitamin 

 D potency of the oils from individual cod livers varies inversely with the 

 oil content, and as much as 1000 times. Similar inverse ratios were noted 

 for haddock and pollack. 



Bills et aiy^ investigated the commercial halibut catch of Seattle at 

 weekly intervals. In January the oil content of the pooled livers was at 

 the lowest point, 12 %, and the vitamin D content of the liver oil 

 was highest, 1400 I.U. per gram. In August the oil content reached its 

 highest point, 25%, and the vitamin D potency was lowest, 900 I.U. per 

 gram. Thus, although the decline in vitamin D potency was a little less 

 than can be accounted for by dilution with inactive new oil, it was about 

 what one would expect from dilution with oil containing a little vitamin D. 

 Nevertheless this explanation is not wholly satisfactory, for it was noted 

 that the vitamin A content of the liver oil varied with the vitamin D con- 

 tent, but several times more widely. It declined from 240,000 I.U. per 

 gram in January to 35,000 in August, thus reaching a low point which was 

 much lower than could have resulted merely from dilution. It is possible, 

 of course, that the two vitamins are so different in origin and metabolism 

 that comparisons have no significance. 



Pugsley^^^ observed that the content of both vitamins D and A in the 

 liver oil and intestinal oil of the Alaska cod, Gadus macrocephalus, varied 

 inversely with the fatness of the livers. Pugsley ei al."* found that the vi- 

 tamins D and A of the liver oil of the Atlantic cod, Gadus morrhua, 

 varied inversely with the oil content, but remained constant when figured 

 as units per gram of body weight for fish of a given age group. However, 

 the vitamin content of the liver oil increased with the age of the fish in years. 

 Bailey^^^ reported that the vitamin D potency of commercial pilchard oil, 

 made from the whole fish including stomach contents, varied inversely 

 with the oil yield, and Pugsley^ '^^ noted that the inverse relationship held 

 for both vitamins D and A in this species. 



Hess et aiy^ reported that the milt and roe of cod and other species con- 

 tain vitamin D, but the fry were "practically devoid of this factor, which 

 evidently had been used up in the course of the development of the larvae." 

 Thus it appears that fish begin life with little vitamin D, and as they grow 



»" A. F. Hess, C. E. Bills, and E. M. Honeywell, J. Am. Med. Assoc. 92, 226 (1929). 

 1" C. E. Bills, M. Imboden, and J. C. Wallenmeyer, J. Biol. Chem. 105, Proc. x (1934). 

 1" L. I. Pugsley, J. Fisheries Research Board Can. 4, 405 (1939). 

 "* L. I. Pugsley, C. A. Morrell, and J. T. Kelly, Can. J. Research F23, 243 (1945). 

 "5 B. E. Bailey, Biol. Board Can. Pacific Progr. Repts. 23, 11 (1935). 

 "« A. F. Hess, C. E. Bills, M. Weinstock, E. Honeywell, and H. Rivkin, Proc. Soc. 

 Exptl. Biol. Med. 25, 652 (1928). 



