STUDIES ON FERMENTATION. 199 



itself have been a distinct one, differing from others, especially 

 those which we have been considering in this chapter. 

 Fig. 43 represents the rejuvenescence of this ferment. 



Fig. 43. 



Comparing this figure with Fig. 42, we see that this ferment 

 presents a considerable resemblance to " low " yeast in dimen- 

 sions, method of budding, and oval shape ; but the feature 

 which distinguishes it essentially from " low " yeast is that it 

 rises to the surface, like " high " yeast. Buoyed up by the 

 gas during fermentation, it forms a layer of yeast on the 

 surface of the fermenting liquid, where it remains after the 

 head has fallen. Some of this head of yeast likewise adheres to 

 the sides of the vessel above the level of the liquid. 



In short, by the greater regularity of its forms and the 

 uniform dimensions of its cells, this ferment is to be easily 

 distinguished from saccharoiuyces pastorianus ; its aspect, which 

 is oval instead of spherical, and the ramified form of its chains 

 of cells, which is less marked than in the case of " high " 

 yeast, also prevent our confounding it with the latter ferment ; 

 in its rising character it differs absolutely from " low " yeast ; 

 lastly, it may be distinguished from all other ferments by the 

 flavour of the beer that it produces. 



The ferment which we discovered in this accidental way may 

 be utilized. Indeed, we may ask, is it not to be found already 

 in our beer ? We are inclined to believe that it is. After the 

 war of 1870, some Viennese traders established at Maisons- 

 AUort, near Paris, a manufactory of yeast for bakers. They 

 saccharified by means of malt a mixture of the meals of rye, 



