190 



MICRO-ORGANISMS AND FERMENTATION. 



Microscopic appearance of the cells in the films : 



At 2 0-34 C. : Colonies frequent; sausage-shaped and 

 curiously formed cells occur. 



At 15-6 C. (Fig. 49): The greater number of the cells 

 resemble the original cells ; isolated cells of different form 

 occur. 



In old cultures of films all forms occur, including greatly 

 elongated mycelium-like cells (Fig. 49). 



SACCHAROMYCES PASTORIANUS I. (HANSEN). (Figs. 50, 51.) 



Bottom-fermentation yeast. 



Sedimentary forms grown in wort : Mainly elongated, 



FIG. 50. Saccharomyces Pastorianus I. (HANSEN). Cell-forms of young sedimentary, 

 yeast (after HANSEN). 



sausage-shaped cells, but also large and small, round and oval 

 cells (Fig. 50). 



It frequently occurs in the air of fermenting-rooms. It 

 imparts to beer a disagreeable bitter taste and unpleasant 

 odour; it may also produce turbidity, and interfere with the 

 clarification of beer in the fermenting vessel. 



According to investigations of MACH and PORTELE, this 

 species may also be successfully used in wine fermenta- 

 tion. 



