24 THE BIOCHEMISTRY OF B VITAMINS 



flavin, (5) thiamine, (6) biotin. Only the following exceptions may be 

 noted: In five cases (including the 3 seeds) the thiamine content exceeds 

 that of the riboflavin; in two cases, riboflavin exceeds pantothenic acid; 

 and in one case pantothenic acid exceeds nicotinic acid. Otherwise the 

 order of their occurrences falls into the same pattern, and the regularity 

 observed in the diverse forms is remarkable. 



Among the sources given, the values vary least in the case of inositol — 

 protozoa are 12 times richer than brewers' yeast — and most in the case 



Table 1. Relative Abundance of B Vitamins in Whole Organisms (dry wt.).* 



* Too much reliance should not be placed upon the exact numerical values, since incomplete extractions 

 and other limitations are involved in connection with the methods used. The material given represents 

 the only data on the subject that are available. 



of biotin — P. fluorescens is 120 times as rich as wheat seed. Sixty per cent 

 of the values given in Table 1, however, do not differ from the mean 

 value for that vitamin by more than a factor of two. 



Since microbiological methods are extremely sensitive and can be used 

 to determine infinitesimally minute amounts, the question may be raised 

 whether the mere finding of measurable amounts of the various B vitamins 

 in all organisms is really significant. If we select the lowest values for 

 each of the vitamins in Table 1 we find that they correspond to the fol- 

 lowing sources: (1) for thiamine the mold is poorest and the whole rat 

 a poor second; (2) for riboflavin the three seeds are lowest; (3) for 

 nicotinic acid again the seeds are lowest; (4) the same is true for panto- 

 thenic acid; (5) for biotin, wheat and brewers' yeast are the poorest 



