THEORY OF FERMENTATION 361 



consciously or by accident, in a mineral medium free from 

 organic and nitrogenous matters other than ammonia, in 

 which medium the fermentable matter alone is adapted to 

 provide the ferment with whatever carbon enters into its 

 composition, from that time forward the theories of Liebig, 

 as well of Berzelius, which M. Robin formerly defended, 

 have had to give place to others more in harmony with 

 facts. We trust that the day will come when M. Robin 

 will likewise acknowledge that he has been in error on the 

 subject of the doctrine of spontaneous generation, which 

 he continues to affirm, without adducing any direct proofs 

 in support of it, at the end of the article to which we 

 have been here replying. 



We have devoted the greater part of this chapter to the 

 establishing with all possible exactness the extremely im- 

 portant physiological fact of life without air, and its cor- 

 relation to the phenomena of fermentations properly so- 

 called that is to say, of those which are due to the pres- 

 ence of microscopic cellular organisms. This is the chief 

 basis of the new theory that we propose for the explana- 

 tion of these phenomena. The details into which we have 

 entered were indispensable on account of the novelty of the 

 subject no less than on account of the necessity we were 

 under of combating the criticisms of the two German nat- 

 uralists, Drs. Oscar Brefeld and Traube, whose works had 

 cast some doubts on the correctness of the facts upon which 

 we had based the preceding propositions. We have much 

 pleasure in adding that at the very moment we were re- 

 vising the proofs of this chapter, we received from M. Bre- 

 feld an essay, dated Berlin, January, 1876, in which, after 

 describing his later experimental researches, he owns with 

 praiseworthy frankness that Dr. Traube and he were both 

 of them mistaken. Life without air is now a proposition 

 which he accepts as perfectly demonstrated. He has wit- 

 nessed it in the case of mucor racemosus and has also veri- 

 fied it in the case of yeast. "If," he says, "after the re- 

 sults of my previous researches, which I conducted with 

 all possible exactness, I was inclined to consider Pasteur's 

 assertion as inaccurate and to attack them, I have no lu-^i 

 tation now in recognizing them as true, and in proclaiming 



