222 THE LIFE OF PASTEUR 



discussions entered into by his scientific adversaries; but 

 those discussions certainly brought out and evidenced many 

 guiding facts which are now undisputed, as for instance the 

 following — 1. Ferments are living beings. 2. There is a 

 special ferment corresponding to each kind of fermentation. 

 3. Ferments are not born spontaneously. 



Liebig and his partisans had looked upon fermentation as a 

 phenomenon of death; they had thought that beer yeast, and 

 in general all animal and vegetable matter in a state of putre- 

 faction, extended to other bodies its own state of decomposition. 



Pasteur, on the contrary, had seen in fermentation a 

 phenomenon correlative with life; he had provoked the com- 

 plete fermentation of a sweet liquid which contained mineral 

 substances only, by introducing into it a trace of yeast, which, 

 instead of dying, lived, flourished and developed. 



To those who, believing in spontaneous generation, saw in 

 fermentations but a question of chance, Pasteur by a series of 

 experimental proofs had sho\^Ti the origin of their delusion by 

 indicating the door open to germs coming from outside. He 

 had moreover taught the method of pure cultures. Finally, 

 in those recent renewals of old quarrels on the transformations 

 into each other of microscopic species, Pasteur, obliged by the 

 raycoderma vini to study closely its alleged transformation, 

 which he had himself believed possible, had thrown ample 

 light on the only dark spot of his luminous domain. 



*'It is enough to think," writes M. Duclaux concerning that 

 long discussion, ''we have but to remember that those who 

 denied the specific nature of the germ would now deny the 

 specific nature of disease, in order to understand the darkness 

 in which such opinions would have confined microbian 

 patholog}^; it was therefore important that they should be 

 uprooted from every mind.' 



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