THEORY OF FERMENTATION 331 



ought also to have borne in mind the fact which we have 

 pointed out, that alcoholic yeast is not the only organized 

 ferment which lives in an anaerobian state. It is really a 

 small matter that one more ferment should be placed in 

 a list of exceptions to the generality of living beings, for 

 whom there is a rigid law in their vital economy which 

 requires for continued life a continuous respiration, a con- 

 tinuous supply of free oxygen. Why, for instance, has Dr. 

 Brefeld omitted the facts bearing on the life of the vibrios 

 of butyric fermentation? Doubtless he thought we were 

 equally mistaken in these: a few actual experiments would 

 have put him right. 



These remarks on the criticisms of Dr. Brefeld are 

 also applicable to certain observations of M. Moritz Traube's, 

 although, as regards the principal object of Dr. Bref eld's 

 attack, we are indebted to M. Traube for our defence. 

 This gentleman maintained the exactness of our results 

 before the Chemical Society of Berlin, proving by fresh 

 experiments that yeast is able to live and multiply without 

 the intervention of oxygen. " My researches," he said, 

 " confirm in an indisputable manner M. Pasteur's assertion 

 that the multiplication of yeast can take place in media 

 which contain no trace of free oxygen. . . . M. Bre- 

 feld's assertion to the contrary is erroneous." But im- 

 mediately afterwards M. Traube adds: "Have we here a 

 confirmation of Pasteur's theory? By no means. The 

 results of my experiments demonstrate on the contrary 

 that this theory has no true foundation." What were these 

 results? Whilst proving that yeast could live without air, 

 M. Traube, as we ourselves did, found that it had great 

 difficulty in living under these conditions; indeed he never 

 succeeded in obtaining more than the first stages of true 

 fermentation. This was doubtless for the two following 

 reasons: first, in consequence of the accidental production 

 of secondary and diseased fermentations which frequently 

 prevent the propagation of alcoholic ferment; and, sec- 

 ondly, in consequence of the original exhausted condition 

 of the yeast employed. As long ago as 1861, we pointed 

 out the slowness and difficulty of the vital action of yeast 

 when deprived of air; and a little way back, in the pre- 



