DISTRIBUTION OF B VITAMINS 21 



min, it will be well to examine critically the available information regard- 

 ing the distribution of those vitamins which are not considered within 

 this group. 



Ascorbic Acid. Of the vitamins not considered in the B group probably 

 ascorbic acid is most widespread. Certainly, there is no question but that 

 it is generally, and probably universally, present in the tissues of mature 

 higher animals. 24 Extremely interesting in this connection, however, is 

 the fact that it is absent from unincubated hen eggs and only appears on 

 incubation, when the amount increases during the first two weeks. 25 Dur- 

 ing embryonic development, as judged by the acid silver nitrate staining 

 technique, it does not appear in all of the chick tissues. It disappears from 

 the liver after the tenth day and does not appear in the adrenals until 

 the twelfth day. 26 These results are in striking contrast to those observed 

 in connection with the B vitamins. All of these are present in eggs from 

 the start, even when they are synthesized (e. g., nicotinic acid) by the 

 chick tissues during incubation. 27 Certainly, the B vitamins do not appear 

 to be absent from any actively growing tissue. 



Ascorbic acid likewise is widespread in higher plants. Unlike B vitamins, 

 however, it is practically absent from typical seeds but is produced during 

 embryonic development. 



It also seems clear that ascorbic acid is present in the tissues of many 

 lower organisms: earthworms, six molluscs, sea urchins, crustaceans, 28 

 crabs, 29 thirteen marine invertebrates, seven marine plants, 30 cock- 

 roaches, 31 and mushrooms. 32, 33 It is also produced by Aspergillus niger?^ 

 In many of these organisms its distribution in the various organs strongly 

 suggests that it is of functional importance. The fact that cockroaches 

 synthesize it and maintain it at about the same level whether or not it 

 is present in the diet, as do rats, points to the same conclusion. 



When we consider the monocellular organisms, bacteria, yeasts and 

 protozoa, however, we find that the preponderance of evidence indicates 

 that in these organisms ascorbic acid is generally absent and nonfunc- 

 tional. Although ascorbic acid has been reported repeatedly to promote 

 the growth of specific bacteria, 35, 36 this effect has always been inter- 

 pretable as due to the change in the oxidation-reduction potential of the 

 medium rather than to its action as a specific nutrilite. Though the forma- 

 tion of vitamin C by bacteria has been reported, 36, 37 there is no clear-cut 

 proof that it is actually ascorbic acid and not some other highly reducing 

 substance that is produced. There is no doubt that intestinal bacteria 

 utilize ascorbic acid, 38, 39 but in these cases it is probably serving simply 

 as an energy source. The fact that no one has ever identified ascorbic acid, 

 either chemically or biologically as a constituent of yeast places it in 

 striking contrast to the B vitamins, all of which (for which adequate. 



