68 PASTEUR : THE HISTORY OF A MIND 



more, of forming several crystalline combinations which 

 do not show any hemihedrism. It was the first exception 

 which Pasteur had encountered in this law of correlation 

 between hemihedrism and the rotary power. Now, ac- 

 cording to the current ideas of the epoch, fermentation 

 was a disintegration: it was the breaking up of a molecule 

 by decay, the debris of which, still voluminous, formed 

 new molecular edifices which were the products of the 

 fermentation. Consequently, by virtue of the theory 

 of Liebig, the edifice of amyl alcohol must form some 

 part of the framework in the molecule of the sugar in 

 order to resist dismemberment, and as it preserves the 

 rotary power its optical action must be derived from that 

 of sugar. 



This idea was repugnant to Pasteur. He had seen, 

 for example, in malic and maleic acids, that the least 

 injury to the structure of the molecule made its rotary 

 power disappear. "Every time," he says, "that we 

 try to follow the rotary power of a body into its deriva- 

 tives we see it promptly disappear. The primitive 

 molecular group must be preserved intact, as it were, 

 in the derivative, in order that the latter may continue 

 to be active, a result which my researches permit me to 

 predict, since the optical property is entirely dependent 

 on a dissymmetrical arrangement of the elementary 

 atoms. But I find that the molecular group of amyl 

 alcohol is too far away from that of sugar, if derived from 

 it, for it to retain therefrom a dissymmetrical arrange- 

 ment of its atoms." 



The origin of this alcohol must, therefore, be more 

 profound, and, recalling the before-mentioned fact that 

 life alone is capable of creating full-fledged new dissym- 

 metries, and thinking that his objection would no longer 

 have a raison d'etre, if between the sugar and the amyl 

 alcohol a living organism were interposed, Pasteur 



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