202 



THE VITAMINES 



showed no influence on yeast growth; this was also true of vitamines 

 A and C (after vitamine B had been completely removed by adsorp- 

 tion with fuller's earth). The active substance was found also out- 

 side of the wheat and corn germ, though in smaller amounts. The 

 substance influencing the growth of yeast was very resistant towards 

 heat; it could be diazotized, oxidized and reduced without loss of 

 activity. With this method as a control, a fractionation of yeast 

 was undertaken; partial results have already been published (Funk 

 and Dubin (I.e. 511) ) but the work is not yet completed. 



Mm. 

 35 



30 

 25 

 20 

 15 

 10 



7 



t 





0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 

 Cc. of autolyzed yeast 



FIG. 50. VITAMINE ACTIVITY SHOWN BY INCREASING AMOUNTS OP ATJTOLYZED 

 YEAST (FUNK-DUBIN) 



The use of these methods was criticized by de Souza and McCollum 

 (529). They employed the first method of Williams, slightly 

 modified, for their investigations and found, as a rule, that with 

 increasing amounts of vitamine B, the growth of yeast is favorably 

 affected. They believed, however, that the method could hardly be 

 applied to the determination of vitamine B, because glucose and 

 amino-acids also show a growth-promoting action. Despite this, if 

 we examine their findings more closely we see that the addition of a 

 10 per cent glucose solution had no more influence during the first 

 24 hours, as compared with the controls; it was only after 48 hours 



