ALCOHOLIC FERMENTS. 



157 



film-formations of nearly all species. An ordinary microscopic 

 examination of the pitching-yeast in a brewery does not 

 show this formation ; with the help of staining, however, its 

 presence can be readily detected (Fig. B). When the yeast 

 was repeatedly washed, it was no longer possible to detect the 



,a 



FIG. 33. 



Yeast cells with gelatinous network, after Hansen : A, network obtained by 

 partial drying ; 1, portion formed of threads, from which the cells have 

 become detached ; 2 and 3 show that the network can also form complete 

 walls ; such a formation is seen between a and b ; a is a vegetative 

 cell, b is a cell with two spores ; 4, shows three cells, a, imbedded 

 in the network. , network with yeast cells; the latter were stained 

 by methyl-violet ; the network is not stained. Some of the yeast 

 cells are still in the meshes, but most have become detached. 



network by staining ; but if the water was removed, and the 

 yeast set aside for a time, the gelatinous masses could after 

 suitable treatment be readily seen. By varying the conditions 

 of nourishment of the cells, the development could be pro- 

 moted or hindered, and the chemical composition modified. 



