120 T O R R E Y A 



stated that yeast neither grew nor fermented sugar under the conditions de- 

 fined by Pasteur. This criticism was so keenly felt that in 1872 Pasteur de- 

 clared he was so sure of his results that he was prepared to perform the 

 experiment in the presence of Liebig himself. The demonstration never took 

 place, Liebig died in 1873, and the nutritional requirements of yeast as defined 

 by Pasteur remained unchallenged for many years. 



In 1901 Wildiers of Belgium reported that yeast would not grow under 

 the conditions defined by Pasteur if the amount of yeast used in the seeding 

 was small. He found that small amounts of a thermostable organic material 

 were necessary for the growth of yeast and gave to this chemically undefined 

 material the name, bios. Bios was a concentrate prepared from the yeast itself. 

 Wildiers suggested that Pasteur obtained his results because he had used a 

 large quantity of yeast for the seeding, and this large seeding had carried with 

 it sufficient bios to permit growth. 



Wildiers' proposal that minute traces of organic material in addition to 

 minerals, ammonium salts and sugar were necessary for yeast growth was 

 roughly handled by some of his contemporaries, including Fernbach (1902) 

 Windisch (1902) and Pringsheim (1906). Various students in Wildiers's 

 laboratory supported his proposal but since no one could identify bios chemi- 

 cally, it remained for 20 years before the bar of science with the verdict, pro- 

 posed but unproven. 



In 1921 ]\IacDonald and McCollum reported that yeast would grow in a 

 solution of cane sugar and inorganic salts, but 2 years later Funk and Fried- 

 man demonstrated that ordinary cane sugar may contain a growth activator 

 of organic character which required for its removal three crystallizations of 

 the sugar from alcohol. And so after 60 years the dispute between Pasteur and \ 

 Liebig was still unsettled. However, a decision was rapidly approaching. In^ 

 1921 Copping reported that .wild yeasts would grow in a solution of minerals 

 and sugar while cultivated yeasts required the addition of bios for normal 

 growth, and in 1924 Lash Miller and Lucas of Toronto showed that there 

 was a difference between races of yeast in their response to bios. It seems^ 

 reasonable now to suggest that the conflict in the results obtained 60 years 

 before by Pasteur and Liebig may have been the result of differences in the 

 strains of yeast they used. 



However, although the burden of evidence seemed tipping the scales ii 

 favor of the reality of bios its chemical nature remained unknov/n. From 1919-1 

 1928 various unsuccessful attempts were made to identify bios with the anti- 

 beri beri vitamin of Eijkman and with the coenzyme of Harden and Younj 

 and to isolate it in crystalline form. However, Fulmer in 1923 demonstratec 

 that bios w^as not a single substance, and Lash-]\Iiller's laboratory in Toronto 

 separated it into two fractions. Bios I and Bios II. In 1928 Eastcott showec 



