DISTRIBUTION OF B VITAMINS 25 



sources; (6) for inositol, brewers' yeast and rat carcass are the poorest 

 sources. If the B vitamins are present in any organisms in insignificant 

 amounts, the ones cited above are likely examples; therefore let us con- 

 sider these sources individually. 



In view of Schopfer's extensive work dealing with the importance of 

 thiamine for molds, its indispensable role in these organisms can hardly 

 be questioned. Certainly no one would say that thiamine is insignificant 

 for rats. The fact that seeds are the poorest sources of riboflavin, nicotinic 

 acid and pantothenic acid does not indicate a lack of importance of these 

 vitamins in seed plants, because each increases during germination (at 

 least in blackeyed peas and lima beans) , 5S and there is abundant indirect 

 evidence of a diverse nature that they function in the enzyme systems of 

 seed plants. In view of the importance of biotin as a nutrilite for yeasts, 

 no one could question that it exists in significant amount in brewers' yeast. 

 Wheat has about the same amount, and its significance is undoubted, 

 especially since biotin is relatively abundant in many seed plants. In view 

 of the importance of inositol as a nutrilite for yeasts, the relatively low 

 amount in brewers' yeast cannot be taken as an indication of lack of im- 

 portance. There is no reason to think that inositol is present in rat tissues 

 in insignificantly low amounts, especially in view of the fact that it is 

 unevenly distributed in the various tissues in accordance with a definite 

 pattern, and the total amount present in the carcass of a 200 gram rat is 

 about 40 mg. 



On the basis of these facts we can safely conclude that the B vitamins 

 are present in all organisms in significant amounts. 



The quantitative distribution of the B vitamins in different tissues of 

 the same species is of interest because of the relative uniformity of the 

 amounts present and apparent presence of significant amounts in every 

 tissue and at every stage of development. 



The most complete data available are those obtained by the assay of 

 17 human tissues. In Table 2 is given a summary of the values obtained 

 from the tissues of three persons, two males and one female. An examina- 

 tion of these results shows that in 14 out of the 17 tissues, the absolute 

 amounts of the substances present are in the same order as for the whole 

 biological kingdom, namely inositol (1), nicotinic acid (2), pantothenic 

 acid (3) , riboflavin (4) , thiamine (5) , biotin (6) . In the other three tissues 

 the same order is maintained except that riboflavin slightly exceeds panto- 

 thenic acid in amount (by from 3-10 per cent). 



The variation in content from tissue to tissue is greatest in the case of 

 biotin (see also Table 1) ; liver is about 50 times as rich as seminal duct. 

 The variation is least in the case of nicotinic acid; liver is about seven 

 times as rich as skin. Curiously, when the results in Table 1 are compared 

 with those in Table 2, a striking resemblance is observed. In the latter 



