222 VITAMIN D GROUP 



for future lots of the international standard solution to be made from crys- 

 talline vitamin Da of specified physical constants.*^ The 1949 decision to use 

 crystalline vitamin D3, rather than D2, was prompted by the knowledge 

 that D3, which exhibits approximately the same potency as Do for the rat, 

 has the additional feature of being also effective for chicks. 



The U.S.P. unit of vitamin D, officially adopted^ in 1934, was "equal, in 

 antirachitic potency for the rat, to one International Unit of Vitamin D as 

 defined and adopted by the Conference of (sic) Vitamin Standards of the 

 Permanent Commission on Biological Standardisation of the League of 

 Nations in June of 1931." An official reference cod liver oil of declared 

 potency was issued, and this remained the standard of reference in the 



TABLE IX 



Vitamin D Content of Average Cod Liver Oil in Terms of Various 



Systems of Units. (Adapted from Bills') 



Vaguely defined. 



United States until the new vitamin D reference standard of vitamin D3 in 

 oil became official in 1950.^ 



^ Quart. Bull. Health Organization League Nations 3, extract 15 (1934). 

 ' U.S. Pharmacopeia, 10th revision. Interim Revision Announcement No. 2, 1934. 

 ^ U.S. Pharmacopeia, 14th revision, Easton. 1950. 

 « C. E. Bills, Physiol. Revs. 15, 1 (1935). 

 i» Medical Research Council, Lancet II, 503 (1930). 



11 H. Steenbock, E. B. Hart, F. Hanning, and G. C. Humphrey, /. Biol. Chem. 88, 

 197 (1930). 



12 A. D. Holmes, J. Ayn. Pharm. Assoc. 20, 588 (1931). 



13 E. Poulsson and H. Lovenskiold, Biochem. J. 22, 135 (1928). 



" E. Poulsson and E. Ender, Skand. Arch. Physiol. 66, 92 (1933). 



"A. Scheunert and M. Schieblich, Biochem. Z. 209, 290 (1929); F. Holtz and E. 



Schreiber, Hoppe-Seyler's Z. physiol. Chem. 191, 1 (1930); F. Holtz, F. Laquer, H. 



Kreitmair, and T. Moll, Biochem. Z. 237, 247 (1931). 

 1^ New and Nonofficial Remedies, p. 414. Council on Pharmacy and Chemistrj^, 



American Medical Association, 1931. 



