1870—1872 215 



He owned that " a few microzoa did fly about here and there," 

 but he called the theory of germs a "ridiculous fiction." 



At the same time Liebig, who, since the interview in July, 

 1870, had had time to recover his health, published a long 

 treatise disputing certain facts put forward by Pasteur. 



Pasteur had declared that, in the process of vinegar-making 

 known as the German process, the chips of beech-wood placed 

 in the barrels were but supports for the mycoderma aceti. 

 Liebig, after having, he said, consulted at Munich the chief 

 of one of the largest vinegar factories, who did not believe in 

 the presence of the mycoderma, affirmed that he himself had 

 not seen a trace of the fungus on chips which had been used 

 in that factory for twenty-five years. 



In order to bring this debate to a conclusion Pasteur sug- 

 gested a very simple experiment, which was to dry some of 

 those chips rapidly in a stove and to send them to Paris, where 

 a commission, selected from the members of the Academie 

 des Sciences, would decide on this conflict. Pasteur under- 

 took to demonstrate to the Commission the presence of the 

 mycoderma on the surface of the chips. Or another means 

 might be used : the Munich vinegar maker would be asked 

 to scald one of his barrels with boiling water and then to make 

 use of it again. "According to Liebig's theory," said 

 Pasteur, "that barrel should work as before, but I affirm that 

 no vinegar will form in it for a long time, not until new myco- 

 derma have grown on the surface of the chips." In effect, 

 the boiling water would destroy the little fungus. With the 

 usual clear directness which increased the interest of the 

 public in this scientific discussion, Pasteur formulated once 

 more his complete theory of acetification : ' The principle is 

 very simple : whenever wine is transformed into vinegar, it is 

 by the action of the layer of mycoderma aceti developed on its 

 surface." Liebig, however, refused the suggested test. 



Immediately after that episode a fresh adversary, M. Fremy, 

 a member of the Academie des Sciences, began with Pasteur 

 a discussion, which was destined to be a long one, on the 

 question of the origin of ferments. M. Fremy alluded to 

 the fact that he had given many years to that subject, having 

 published a notice on lactic fermentation as far back as 1841, 

 "at a time," he said, "when our learned colleague— M. 

 Pasteur— was barely entering into science." . . . 'In the pro- 

 duction of wine," said M. Fremy, " it is the juice of the fruit 



