338 MICRO-ORGANISMS AND FERMENTATION. 



The yeast lies rather compact in flask ; violent shaking 

 is required to distribute the cells equally throughout the 

 liquid. 



Film-formation : After 26 days a thin, almost continuous 

 film appears, which in the course of the next five to six days 

 forms a conspicuous covering extending over the whole surface 

 of the liquid. 



The cells of the film have in the main the same shape as 

 those seen during fermentation ; only the youngest generations 

 are elongated and narrow. 



If developed at a low temperature, the spores are medium 

 sized, with no distinct vacuoles. At 11 to 12 C., after nine 

 days, fully developed spores appear ; at 25 C., for forty hours, 

 spores are formed freely. 



When the principal fermentation was broken off, the liquid 

 contained 2-4 per cent, by vol. of alcohol ; during the following 

 two periods 0-95 and 0-00 per cent, by vol. were formed. 



Acid-production : 6-5. 



Agreeable smell and slightly aromatic taste. 



8. (Fig. 66, d, and Fig. 67, d.) 



During fermentation, round, oval, and elongated cells, both 

 free and linked together. 



The yeast lies rather compact in flask ; on violent shaking 

 the cells are distributed equally throughout the liquid. 



Film-formation : After 31 to 32 days very slight isolated 

 patches of a film on the surface, and a slight ring of yeast-cells 

 on the glass, round the edge of the liquid. 



The cells of the film have assumed quite different shapes 

 from those of the fermentation-stage ; they are very much 

 lengthened, mycelial, and irregular. 



If developed at a low temperature, the spores are medium- 

 sized, with no distinct vacuoles. At 11 to 12 C. spores are 

 formed pretty freely on the ninth day ; at 25 C., they are 

 formed freely in forty hours. 



When the principal fermentation was broken off, the liquid 

 contained 2-77 per cent, by vol. of alcohol ; during the fol- 

 lowing two periods 0-98 and 0-00 per cent, by vol. were formed. 



