THE VITAMINES IN THE VEGETABLE KINGDOM 51 



The subject of this chapter serves merely as a suggestion of the 

 important role of the vitamines in plant life, without which knowledge 

 of the vitamines can never be complete. The very few facts 

 mentioned here should serve to stimulate further work in this 

 direction. 



YEAST 



Since the discovery of its curative influence on beriberi by Schau- 

 mann (I.e. 2), yeast appears to be the best material available for the 

 chemical study of the vitamines. Of all natural products, it seems 

 to be the one most rich in vitamine B and therefore is worthy of 

 special attention. One could be tempted to assume that since yeast 

 cells are so rich in vitamines and possess such an energetic metab- 

 olism of their own, they should be able to prepare their own 

 vitamines. This is, however, only partially the case, as has been 

 already shown in some older neglected work which has recently 

 been repeated, and confirmed. Pasteur (112) made the obser- 

 vation in 1871 that the capacity of yeast-cell growth depended 

 very much upon the size of the inoculation. He found also that 

 addition of certain organic substances accelerates the fermenta- 

 tion of certain types of yeasts. It was Wildiers (113) who correctly 

 understood Pasteur's observation and developed it further. It may 

 well be said that Wildiers foresaw the existence of the vitamines 

 as far back as 1901. His important studies have demonstrated 

 that upon the addition of a small quantity of sterile yeast extract 

 to a nutritive solution, containing an ammonium salt as its sole 

 source of nitrogen, a small inoculation is sufficient; the growth 

 of the cells being measured in this case by the CO 2 evolved. - He 

 recognized that this growth stimulus could not be attributed to 

 the presence of the hitherto known factors, and named this new 

 substance "bios." Its characteristics were not so far different 

 from that which we have come to know as B-vitamine. It was 

 soluble in water and also in 80 per cent alcohol, and insoluble in 

 ether. It was dialyzable and could not be precipitated by the well- 

 known precipitants, phosphotungstic acid included. The substance 

 was found to be stable in acid medium but on heating for a short 

 time with alkali it was destroyed. The investigation of the resistant 

 qualities of this substance gave no clear results. The presence of 

 bios was never shown in the decomposition products of egg albumin 



