22 THE BIOCHEMISTRY OF B VITAMINS 



evidence is available) are present in significant amounts in this organism. 

 The requirement of vitamin C for the growth of certain protozoa (Tricho- 

 monads) has been reported, 40 but not enough information is given to rule 

 out the effect on the oxidation-reduction potential as an important factor. 

 The definite absence of ascorbic acid from Paramecium caudatum, P. 

 bursaria, Stentor coeruleus, Opalina and Nictoterus has also been re- 

 ported, 41 and in the same study it was found that intestinal trypanosomes 

 in the guinea pig may or may not contain ascorbic acid, depending upon 

 whether or not the guinea pig diet is deficient. 



So far as vitamin C is concerned, it appears to belong definitely in a 

 different category from the B vitamins in that it is not universally dis- 

 tributed, being absent from eggs and seeds, from certain embryonic organs 

 and in general from bacteria, yeast and protozoa. 



Vitamin A in its various forms occurs widely in nature, but shows a 

 marked contrast to the B vitamins inasmuch as it does not appear to be 

 present in all mammalian tissues, 42 and has been found to be absent 

 during the entire life cycle of cockroaches. 43 Its distribution in numerous 

 lower forms has apparently not been ascertained, but the two facts cited 

 above are sufficient to show that its distribution shows a marked contrast 

 to that of the B vitamins. It is interesting that in plants there is some 

 relationship between the distribution of the carotenoids and ascorbic 

 acid. 44 



Vitamins D. Information regarding the distribution of the D vitamins, 

 except for relatively rich sources, is scanty. 45 The fact that they are prac- 

 tically absent from plant foods and that they appear to be unimportant 

 for microorganisms indicates that they are not universal. Yeasts, fungi, 

 and other lower forms contain sterols which may be converted to D vita- 

 mins by ultraviolet light, but since many of these organisms can live 

 entirely in the dark, there is no reason to think that D vitamins function 

 in their physiology. How the D vitamins are distributed in animal organs 

 and tissues is unknown. 



Vitamins E. Comparatively little quantitative information is avail- 

 able regarding the distribution of tocopherols (E vitamins) in mammalian 

 tissues, 46, 47 though it appears to be generally present. Still less is known 

 about its presence in lower animals. Its principal known sources are seed 

 germ oils and certain plants (lettuce, alfalfa) . The mold Phy ' corny ces 

 appears to contain none at all. 48 Yeast evidently contains none because 

 it is included in vitamin E-deficient diets which are fed to rats. "Royal 

 jelly," which is fed to the bee larvae that are to become fertile queens, is 

 devoid of any significant amount of vitamin E. 49 In contrast, royal jelly 

 is a relatively rich source of most of the B vitamins and is even richer in 

 pantothenic acid than beef liver. 50 Sea-urchin eggs are a rich source of 



