STUDIES ON FERMENTATION. 253 



fact that it had taken twelve hours instead of one. The notion 

 of time has nothing to do with the definition of work. M. 

 Schiitzenberger has not perceived that in introducing the con- 

 sideration of time into the definition of the power of a ferment, 

 he must introduce, at the same time, that of the vital activity of 

 the cells, which is independent of their character as a ferment. 

 Apart from the consideration of the relation existing between 

 the weight of fermentable substance decomposed and that of 

 ferment produced, there is no occasion to speak of fermentations 

 or of ferments. The phenomena of fermentation and of ferments 

 have been placed apart from others, precisely because, in certain 

 chemical actions, that ratio has been out of proportion ; but the 

 time that these phenomena require for their accomplishment 

 has nothing to do either with their existence proper, or with 

 their power. The cells of a ferment may, under some circum- 

 stances, require eight days for revival and propagation, whilst, 

 under other conditions, only a few hours are necessary ; so that, 

 if we introduce the notion of time into our estimate of their 

 power of decomposition, we may be led to conclude that in the 

 first case that power was entirely wanting, and that in the 

 second case it was considerable, although all the time we are 

 dealing with the same organism — the identical ferment. 



M. Schiitzenberger is astonished that fermentation can take 

 place in the presence of free oxygen, if, as we suppose, the 

 decomposition of the sugar is the consequence of the nutrition 

 of the yeast, at the expense of the combined oxygen, which 

 yields itself to the ferment. At all events, he argues, fermen- 

 tation ought to be slower in the presence of free oxygen. But 

 why should it be slower ? We have proved that in the presence 

 of oxygen the vital activity of the cells increases, so that, 

 as far as rapidity of action is concerned, its power cannot be 

 diminished. It might, nevertheless, be weakened as a ferment, 

 and this is precisely what happens. Free oxygen imparts to 

 the yeast an increased vital activity, but at the same time 

 impairs rapidly its power as yeast — quCt yeast, inasmuch as 

 under this condition it approaches the state in which it can carry 



