208 PASTEUR: THE HISTORY OF A MIND 



subject of the non-existence of spontaneous genera- 

 tions, and on the subject of the role and multiplica- 

 tion of the ferment in fermentations. Bernard was very 

 respectful when face to face with facts, but when he 

 reflected on them he gave himself, as he had every right 

 to do, a great liberty of interpretation. Not because 

 one salutes another is he obliged to think well of him. 

 Now, on reflection, Bernard came to approach, little by 

 little, the stand taken by Liebig, and asked himself, 

 for it was still only the period of hypotheses and of brain- 

 work which preceded that of laboratory work in his case, 

 asked himself, I say, whether, perchance, it was not 

 in virtue of the second mechanism which he predicated, 

 that is to say by disassociation and destruction, that the 

 microbes caused the destruction of organic matter. 



Unquestionably a mind like his had the right to put 

 these questions since it was in his power to solve them. 

 If he could show that the best-known phenomena of 

 organic destruction, the transformation of sugar into 

 alcohol and carbonic acid, could be produced entirely 

 without the intervention of yeast or even of living cells, 

 by the natural play of forces exterior to the cell, and 

 subject only to the laws of physics and chemistry, what a 

 precious confirmation of his preconceived ideas! These 

 physico-chemical forces could not, it is true, be common 

 forces taken by chance from the ambient nature. Pas- 

 teur had shown too clearly, apropos of spontaneous 

 generations, that, reduced to these forces alone, the trans- 

 formation of dead matter was a very slow process. But 

 if living cells are needed to accelerate this transformation 

 why should these cells not act by manufacturing and 

 secreting, on the vital side of their organization, sub- 

 stances capable then of acting outside of the cell, and in 

 a physico-chemical way? The yeast secretes a diastase 

 which, outside the cell, can invert cane-sugar. Why 



