642 X. VITAMINS D 



grown ill the sunlight. ^^'* The plant provitamins D may under exceptional 

 conditions be transformed to the corresponding vitamins D during proc- 

 essing of the plant. Knapp and Coward '^^ reported a transformation of 

 the provitamin D in the cacao shells {Theobroma cacao) dried in sunlight, 

 while Steenbock and co-workers ^^^ demonstrated a similar transformation in 

 dried hay. Bills and co-workers^"^ and Massengale et al.^^' noted that 

 yeast is relatively devoid of active vitamin D, although the content varies 

 widely for different species. ^"'^ It may be activated to a concentration of 

 10,000 I.U./g. when exposed to sunlight for approximately thirty minutes'*'' 

 under controlled conditions.^ This process is the basis of a patent by 

 Bills. 1S8 



Vitamin D is widely distributed in the animal kingdom, in contrast to 

 its sparse distribution in the plants. Even in the animal world, the species 

 which contain significant amounts of these vitamins are relatively few.'*^ 

 Since the highest concentrations of the D vitamins are to be found in the 

 fish liver oils, it is of considerable interest whether or not the marine plants 

 are rich in this vitamin. In general, most workers have failed to demon- 

 strate any appreciable concentration of vitamin D in the marine vegeta- 

 tion. Thus, Leigh-Clare'®" reported that the pennate, free-floating marine 

 diatom {Nitzschia closterium), failed to s3Tithesize any vitamin D, even 

 when cultured under conditions of maximum insolation. According to 

 Drummond and Gunther,'®''®^ no vitamin D, or only negligible amounts, 

 are to be found in mixed phytoplankton taken from the ocean. Vitamin D 

 was found to be absent from tw^o forms of algae, namely, the green tubular 

 seaweed of the Monterey Pininsula (E titer omorpha intestinalis) and the 

 ruffled brown blade-kelp or "tangle" {Laminaria saccharina). The green 

 rock weed (Fucus vesiculosus) was found to have a slight antirachitic po- 

 tency."'^ Oil from phytoplankton contained some provitainins D but no 

 active vitamin D, except when it was near the surface of the water, and thus 

 exposed to sunlight. In this case small amounts of the vitamin were 



'^5 W. A. Knapp and K. H. Coward, Analyst, 59, 474-478 (1934). 



'56 H. Steenbock, E. B. Hart, C. A. Elvehjem, and S. W. F. Kletzien, J. Biol. Chern., 

 ff^, 425-440(1925). 



i"0. N. Massengale, C. E. Bills, and P. S. Prickett, /. Biol. Chern., 94, 213-219 

 (1931). 



iM C. E. Bills, U. S. Patent No. 1,877,882 (Sept. 13, 1932). 



15' P. A. Coppens and G. A. Metz, Arch, neerland. Physiol. 18, 407-415 (1933); Bio- 

 chem. Z., 266, 169-174 (1933). 



160 J. L. Leigh-Clare, Biochem. J., 21, 368-372 (1927). 



"1 J. C. Drummond and E. R. Gunther, Nature, 126, 398 (19.30). 



162 J. C. Drummond and E. R. Gunther, /. Exptl. Biol. 11, 203-209 (1934). 



163 N. G. Johnson and T. Levring, Svensk. Hydrograf.-Biol. Skrifter, Ser. 3, /, No. 3, 1-7 

 (1947); Chem. Abst., 45, 236 (1951). 



