160 



MICRO-ORGANISMS AND FERMENTATION. 



which in the course of fourteen days at the ordinary room- 

 temperature, readily produce 4 to 6 per cent (by volume) 

 of alcohol in beer wort. They are unable to ferment lactose. 



Saccharomyces cerevisice /., is an old English top-fermen- 

 tation yeast, which is employed in breweries in London and 

 Edinburgh. 



The young growth of sedimentary yeast (Fig. 34) developed 

 in wort, consists essentially of large round and oval cells ; 

 really elongated cells do not occur under these conditions. 



FIG. 34. 



Saccharomyces cerevisise I. Hansen. Cell-forms of young sedimentary 

 yeast, after Hansen. 



Ascospore-formation (Figs. 2628, 32, 1) : 1 

 At 37 '5 C. no ascospores are developed. 



3637 

 35 

 33-5 

 30 

 25 

 23 



16-5 

 1112 

 9 



the first indications are seen after 29 hours. 



25 

 23 

 20 

 23 

 27 

 50 

 65 

 10 days. 



no ascospores are developed. 



1 The preparation of the growth of a Saccharomyces species for these 

 investigations must be made in the following manner : After the cells 

 have been cultivated for some time in ordinary wort (about 14 per cent. 



