A Search for Vitamin D in the Diatom Nitzschia closterium (W. Sm.)

JAMESON, DRUMMOND and COWARD [1922] showed that the marine diatom Nitzschia closterium (W.Sm.) forma minutissima, grown in sterilised sea-water with the addition of Miquel's nutrient solutions, can synthesise large amounts of fat-soluble vitamin, and they came to the conclusion that the ultimate though indirect source of the fat-soluble vitamin was this and other marine unicellular organisms.In view of the recent differentiation of the fat-soluble vitamins, it was suggested to me by Dr H. Chick that it would be interesting to see whether Nitzschia closterium also contained vitamin D.It has been found that the green land plants examined up to the present contain very little, if any, vitamin D [Goldblatt and Zilva, 1923; McClendon and Shuck, 1923; Zucker and Barnett, 1923; Hess and Weinstock, 1924; Bethke, Kennard and Kik, 1925; Chick and Roscoe, 1926; Boas, 1926; Roscoe, 1927] and it was thought that it would be of interest to ascertain whether the same held for marine unicellular organisms containing chlorophyll.There is good reason to believe that these are the ultimate source, via plankton, copepods and small fish, whence deep-sea fish, such as the cod, indirectly obtain their supplies of vitamin A; but it is not known whether the store of vitamin D, found in the liver oils of the codfish, is obtained in this way.