188 STUDIES ON FERMENTATION. 



that these ferments become intermixed, that their morphological 

 differences are merely a question of medium, and that the 

 transition of one to the other is a simple matter. The follow- 

 ing facts seem to contradict such statements. 



" High" Ferment. — Fig. e39 represents some "high " yeast 



^^§@©# 



450 



Fig. 39. 



taken from a deposit after fermentation, and Fig. 40 the same 

 yeast in course of propagation in some aerated wort. In com- 

 paring " high " yeast with other alcoholic ferments at the same 

 stage of development, there are three points which are especially 

 striking : the diameter of its cells is relatively large, their 

 general aspect is rounder, and when they are undergoing pro- 

 pagation their mode of budding produces a markedly ramified 

 appearance, so that the cells always occur in clusters and 

 branches. Fig. 40 gives a very exact idea of these characters. 

 To investigate satisfactorily the branching habit of growth 

 peculiar to this ferment we should examine it during the first 

 few hours of its propagation, when, under the influence of the 

 oxygen dissolved in the fermentable liquid, its vital activity is 

 greatest. Later on, often on the day following the sowing, 

 the groups become disconnected, and at the end of the fermen- 

 tation the cells have quite separated from each other, not 

 more than 2 or 3 per cent, remaining united, and even these 

 in groups of not more than two cells together. This is 

 represented in Fig. 39. 



To give an idea of the rapidity with which this ferment 

 multiplies, we may state that our sketch (Fig. 40) was made 

 under the following conditions : — On April 28th, 1874, we 

 caused a flask of wort to ferment by means of a trace of 

 " high " yeast. On the morning of the next day, that is 



