ALCOHOLIC FERMENTS. 233 



The spores, if developed at a low temperature, are medium- 

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

 formed pretty freely on the ninth day; at 25 C., for 40 hours, 

 they are formed freely. 



When the principal fermentation was broken off, the liquid 

 contained 2*77 per cent, (by vol.) of alcohol; during the 

 following two periods 0*98 and O'OO per cent, (by vol.) were 

 formed. 



Acid-production: 6*5. 



Odour good, but bitter, adherent taste. 



9. Fig. 72, 9 and Fig. 74, 9. 



During fermentation a very uniform growth of big, round 

 and oval cells. 



The yeast lies rather loose in flask ; on violent shaking the 

 cells are distributed equally throughout the liquid. 



Film-formation : In 31-32 days very slight, isolated indica- 

 tions of film-formation on the surface, and a slender ring of 

 yeast-cells on the glass, round the edge of the liquid. 



The cells of the film differ but little from those of the 

 fermentation. 



The spores, if developed at a low temperature, are medium in 

 size and granulated. At 11-12 C. spore-formation sets in on 

 the ninth day; at 25 C., for 40 hours, a not very abundant 

 spore-formation takes place, accompanied by a considerable 

 formation of net-work. 



When the principal fermentation was broken off, the liquid 

 contained 2'96 per cent, (by vol.) of alcohol; during the 

 following two periods 1*19 and O'OO per cent, (by vol.) were 

 formed. 



Acid-production : 7*0. 



Odour good, markedly vinous taste. 



A preliminary grouping for practical purposes of the different 

 species or races of bottom- and top-fermentation beer-yeasts which 

 have been prepared in pure culture by HANSEN'S method in 

 the author's laboratory, is as follows : 



