80 THE LIFE OF PASTEUR 



from that small laboratory were about to inundate the world, 

 and in order to take account of the effort necessitated to obtain 

 the triumph of a theory which was to become a doctrine, it is 

 necessary to go back to the teachings of that time upon the 

 subject of fermentations. All was darkness, pierced in 1836 

 by a momentary ray of light. The physicist Cagniard-Latour, 

 studying the. ferment of beer called yeast, had observed that 

 that ferment was composed of cells " susceptible of reproduc- 

 tion by a sort of budding, and probably acting on sugar 

 through some effect of their vegetation." Almost at the same 

 time the German doctor Schwann was making analogous 

 observations. However, as the fact seemed isolated, nothing 

 similar being met with elsewhere, Cagniard-Latour's remark 

 was but a curious parenthesis in the history of fermentations. 



When such men as J. B. Dumas said that perhaps there 

 might be a sequel to Cagniard-Latour's statement, they 

 emitted the idea so timidly that, in a book On Contagion 

 published at Montpellier in 1853, Anglada, the well known 

 author, expressed himself thus — 



' M. Dumas, who is an authority, looks upon the act of 

 fermentation as strange and obscure ; he declares that it gives 

 rise to phenomena the knowledge of which is only tentative at 

 present. Such a competent affirmation is of a nature to dis- 

 courage those who claim to unravel the mysteries of contagion 

 by the comparative study of fermentation. What is the 

 advantage of explaining one through the other since both are 

 equally mysterious! " This word, obscure, was to be found 

 everywhere. Claude Bernard used the same epithet at the 

 College de France in March, 1850, to qualify those phenomena. 



Four months before the request of the Lille manufacturer, 

 Pasteur himself, preparing on a loose sheet of paper a lesson 

 on fermentation, had written these words : " What does fer- 

 mentation consist of? — Mysterious character of the phe- 

 nomenon. — A word on lactic acid." Did he speak in that 

 lesson of his ideas of future experiments? Did he insist upon 

 the mystery he intended to unveil? With his powers of con- 

 centration it is probable that he restrained himself and decided 

 to wait another year. 



The theories of Berzelius and of Liebig then reigned 

 supreme. To the mind of Berzelius, the Swedish chemist, 

 fermentation was due to contact. It was said that there 

 was a catalytic force. In his opinion, what Cagniard-Latour 



