PASTEUR'S WORK ON FERMENTATION 151 



vehicle of the agent, or the agent itself, were not introduced into 

 the organic fluid, or if introduced the agent was not living, then no 

 fermentation occurred. The work of Schwann thus laid the founda- 

 tion of what finally came to be known as the truth respecting 

 fermentation. But his conclusions were not destined to be accepted 

 without protest. Passing over a number of the experiments and 

 counter experiments of Turpin, Helmholtz (1843) and others, we 

 come to the work of Liebig, who viewed the transformation of sugar 

 into alcohol and carbonic acid simply and solely as a non-vital 

 chemical process depending upon the dead yeast communicating 

 its own decomposition to surrounding elements in contact with it. 

 Liebig insisted that all albuminoid bodies were unstable, and if left 

 to themselves would fall to pieces — i.e. ferment — without the aid of 

 living organisms or any initiative force greater than dead yeast cells. 

 It was at this juncture that Pasteur intervened to dispel 

 obscurities, and by new methods of research brought forward con- 

 vincing proofs in support of the vitalistic theory of fermentation. 

 In reply to Liebig's contention as to the natural instability of 

 albuminoids, he abolished albuminoids altogether from his fermen- 

 tations, and in solutions of pure sugar with nothing but mineral 

 additions, he demonstrated that ordinary brewer's yeast grew 

 and multiplied, and that its growth caused the fermentation of 

 the sugar and the production of alcohol and carbonic acid. This 

 is but one example of the work of Pasteur in the elucidation of the 

 process of fermentation. Reference might here be made to his 

 discover}' of the butyric ferment and of anaerobic organisms.^ But 

 we shall have at a later stage occasion to speak of this and of his 

 great contribution in respect .of lactic acid fermentation. In 1863 

 came Pasteur's discoveries in vinous fermentation;- in 1866 his 

 investigations into silkworm disease ; and five years later his work 

 on beer.^ Nor is it too much to say that Pasteur's researches and 

 discoveries in other directions were intimately related to his first 

 work on fermentation in 1857. Out of that came, by his genius, 

 new light upon spontaneous generation, the etiology of virulent 

 diseases, and the cause and prevention of rabies.* Only a small 



^ Nouvel Exemple de Fermentation determinee par des Animalcules infusoires 

 pouvant vivre sans Oxygene Libre (1863). 



- Etudes sur la Vin (1866), and Etudes sur le Vinaxgre (1868). 



' Etudes sur la Biere (1876). 



* For some account of Pasteur's work, see the appreciations by Roux {Agenda 

 du Chimiste, 1896) and Duclaux {Histoire dun Esprit), and also Life of Pasteur^ 

 by Rene Vallery-Radot (2 vols, transl. 1902). 



