STUDIES ON FERMENTATION. 327 



view I would not willingly abandon, a vital action is a pheno- 

 menon of motion, and, in this double sense of life M. Pasteur's 

 theory agrees with my own, and is not in contradiction with it 

 (page 6)." This is true. Elsewhere Liebig says : — 



" It is possible that the only correlation between the physio- 

 logical act and the phenomenon of fermentation is the production, 

 in the living cell, of the substance which, by some special 

 property analogous to that by which emulsin exerts a decom- 

 posing action on salicin and amygdalin, may bring about the 

 decomposition of sugar into other organic molecules ; the 

 physiological act, in this view, would be necessary for the pro- 

 duction of this substance, but would have nothing else to do 

 with the fermentation (page 10)." To this, again, we have no 

 objection to raise. 



Liebig, however, does not dwell upon these considerations, 

 which he merely notices in passing, because he is well aware 

 that, as far as the defence of his theory is concerned, they would 

 be mere evasions. If he had insisted on them, or based his 

 opposition solel}' upon them, our answer would have been simply 

 this : "If you admit with us that fermentation is correlated 

 with the life and nutrition of the ferment, we agree upon the 

 principal point. So agreeing, let us examine, if you will, the 

 actual cause of fermentation ; — this is a second question, quite 

 distinct from the first. Science is built up of successive solu- 

 tions given to questions of ever-increasing subtlety, approaching 

 nearer and nearer towards the very essence of phenomena. If 

 we proceed to discuss together the question of how living, 

 organized beings act in decomposing fermentable substances, 

 we will be found to fall out once more on your hypothesis of 

 communicated motion, since, according to our ideas, the actual 

 cause of fermentation is to be sought, in most cases, in the 

 fact of life without air, which is the characteristic of many 

 ferments." 



Let us briefly see what Liebig thinks of the experiment in 

 which fermentation is produced by the impregnation of a 

 saccharine mineral medium, a result so greatly at variance with 



