STUDIES IN FERMENTATION 67 



substance to another. Through the labors of 

 Lavoisier, Gay-Lussac, Thenard, and others, a good 

 deal had been learned of the chemical changes that 

 occur during the fermentation of sugar into alcohol 

 and the transformation of the latter into vinegar. 

 The part played by yeast in converting sugar into 

 alcohol and carbon dioxide seemed quite* mysterious. 

 An important step was taken when Cagniard-Latour 

 showed that yeast consisted of small oval or 

 rounded bodies which had the power of growth and 

 multiplication by budding and fission. This ob- 

 server and the German biologist Schwann held that 

 fermentation is produced by the growth and activi- 

 ties of these small organisms, and Schwann gave 

 reasons for believing that these organisms are of 

 vegetable origin. But the chemists, as a rule, were 

 averse to attributing fermentation to the influence 

 of living forms; they sought for a purely chemical 

 explanation of the process and regarded the asso- 

 ciation of fermentation with the mysterious vital 

 activities of the living organism as a backward step 

 calculated to obscure rather than to elucidate the 

 phenomenon. 



The illustrious Liebig who called attention to the 

 fact that sugar can be caused to undergo alcoholic 

 fermentation by adding to it almost any decom- 



