THEORY OF FERMENTATION 307 



as much of that gas as is necessary to its perfect nutrition, 

 ceases absolutely to be a ferment at all. Nevertheless, 

 yeast formed under these conditions and subsequently 

 brought into the presence of sugar, out of the influence of 

 air, would decompose more in a given time than in any 

 other of its states. The reason is that yeast which has 

 formed in contact with air, having the maximum of free 

 oxygen that it can assimilate is fresher and possessed of 

 greater vital activity than that which has been formed with- 

 out air or with an insufficiency of air. M. Schutzenberger 

 would associate this activity with the notion of time in 

 estimating the power of the ferment; but he forgets to 

 notice that yeast can only manifest this maximum of energy 

 under a radical change of its life conditions; by having no 

 more air at its disposal and breathing no more free oxygen. 

 In other words, when its respiratory power becomes null, ils 

 fermentative power is at its greatest. M. Schutzenberger as- 

 serts exactly the opposite (p. 151 of his work Paris, 1875),' 

 and so gratuitously places himself in opposition to facts. 



In presence of abundant air supply, yeast vegetates with 

 extraordinary activity. We see this in the weight of new 

 yeast, comparatively large, that may be 

 formed in the course of a few hours. 

 The microscope still more clearly shows 

 this activity in the rapidity of budding, 

 and the fresh and active appearance 

 of all the cells. FIG. 6 represents the 

 yeast of our last experiment at the 

 moment when we stopped the fermen- p lo . 



tation. Nothing has been taken from 

 imagination, all the groups have been faithfully sketched as 

 they were." 



In passing it is of interest to note how promptly the 

 preceding results were turned to good account practically. 

 In well-managed distilleries, the custom of aerating the 

 wort and the juices to render them more adapted to fer- 

 mentation, has been introduced. The molasses mixed with 

 water, is permitted to run in thin threads through the 



T Pajre i8a, English edition. 



This figure is on a scale of 300 diameters, mo*t of the figure* in thil 

 work being of 400 diameter*. 



