480 VITAMIN Bi2 



TABLE XYII—Concluded 

 Foods As Sources of Vitamin Bu 



Excellent Sources (0.5 y or more per gram of dry matter) 

 Mammalian liver and kidney 

 Oysters 

 Clams 



Good Sources (0.05 to 0.5 y per gram of dry matter) 

 Lean beef Lamb 



Milk Poultry meat 



Veal Salt-water fish 



Poor Sources (in many cases giving no response in the assaj) 

 Cereal grains Leguminous seeds 



Green leaves Yeast 



Vegetables 



Bi2 in the blue-green algae is of great interest." The existence of substantial 

 quantities of the vitamin in this primitive form of life may indicate the 

 source from which marine animals such as clams, oysters, other mollusks, 

 and bony fish accumulate such comparatively large amounts of vitamin 

 Bi2. In terrestrial forms of life, the presence of the vitamin in soil micro- 

 organisms, in earthworms and even in soil itself indicates the sources from 

 which vitamin B12 may reach the tissues of vertebrates. The manner in 

 which i-uminating animals obtain their supply of vitamin B12 is indicated 

 by the role of cobalt in their nutrition. Evidently fermentation in the rumen, 

 in which ingested soil bacteria may well play a part, serves to furnish these 

 animals with the vitamin. 



Robbins has speculated upon the production of vitamin B12 in pond mud 

 by fermentation and its relation to the gro^vth of vitamin Bi2-requiring 

 algal flagellates, typified by Euglena gracilis, m stagnant water." The pos- 

 sible involvement of the vitamin in the growth of marine microorganisms 

 is indicated by Sweeney's^^ observation that Gymnodinium, a marine dino- 

 flagellate associated with "red tides," needs for growth an unidentified 

 organic substance present in soil (? vitamin B12), thus suggesting that 

 "red tides" may be due to the occurrence of vitamin B12 in sea water at 

 levels which favor the growth of Gymnodinium. 



'1 W. J. Robbins, A. Hervey, and M. E. Stebbins, Bull. Torrey Botan. Club 78, 363 



(1951). 

 12 B. M. Sweeney, Am. J. Botany 38, 669 (1951). 

 " W. J. Robbins, A. Hervey, and M. E. Stebbin, Bull. Torrey Botan. Club 77, 423 



(1950). 

 " H. L. A. Tarr, B. A. Southcott, and P. W. Ney, Food Technol. 4, 354 (1950). 

 1^ C. A. Elvehjem, Proc. 2nd Conf. on Research, Am. Meat Inst., rniv. Chlcayu p. 1 



(1950). 

 '* B. S. Schweigert, Personal communication. 



