360 MICRO-ORGANISMS AND FERMENTATION. 



completion of the fermentation, clearly isolated islands of 

 somewhat dense and almost cartilaginous consistency appear 

 on the surface of the wort. It ferments saccharose and 

 maltose, but not lactose. 



Saccharomyces multisporus n.sp. 



is an elliptical wild yeast which was found in a few cases in 

 English top-fermentation yeasts by J. C. Holm. Many very 

 large round cells (giant cells) are found amongst the elliptical, 

 within which nine to eleven spores may form, whilst the 

 elliptical cells occur with two to four spores. The spores are 

 round and strongly refractive. At 25 C. ripe spores are 

 formed in forty hours, at 15 C. in seventy- two hours. The 

 yeast is a bottom-fermentation species, and adheres so closely 

 to the flasks that it can hardly be loosened by shaking. It 

 forms as a thin film, which first covers the bottom, and then 

 the sides of the flask. In ordinary wort it yields about 4 per 

 cent, by weight of alcohol. The taste is strongly bitter. It 

 ferments dextrose, maltose, and saccharose. By preservation 

 both in saccharose and in wort, the giant cells lose their power 

 to produce such an exceptionally large number of spores ; in 

 gypsum-cultures most of these cells did not develop spores, 

 but many vacuoles. 



Saccharomyces mali Risler Kayser 



is found in cider, and imparts to it a uniform flavour. The 

 cells are round, and it does not form a film. At 15 C. spores 

 appear in 96 hours. It is a bottom yeast, which ferments 

 saccharose, dextrose, and maltose. The sedimentary yeast 

 adheres closely to the flask. 



Saccharomyces Marxianus Hansen. 



This species, which was discovered by Marx on grapes, and 

 described by Hansen, develops in beer-wort in the form of 

 small oval cells, similar to those of Sacch. exiguus and ellip- 

 soideus. Elongated, sausage-shaped cells, often in colonies, 

 soon appear, however, and if the culture is allowed to stand 

 for some time, small mould-like particles are formed ; some of 





