176 MICRO-ORGANISMS AND FERMENTATION. 



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, essentially similar to those of Sacch. exiguus 

 and ellipsoideus. Elongated, sausage-shaped cells, often in 

 colonies, soon appear, however, and if the culture be set aside 

 for some time small mould-like particles are formed, and partly 

 swim in the liquid, and partly settle to the bottom. These 

 particles consist of mycelium-like colonies of essentially the 

 same nature as the film formations of the six species previously 

 described ; they are also built up of cells, which are readily 

 separated at the point of union. The ascospores are kidney- 

 shaped, spherical, or oval. After cultivation for two to three 

 months in wort contained in the two-necked flasks, there 

 were only traces of film-formation with only a few sausage- 

 shaped and oval cells. 



This yeast is one of those species which develop a my- 

 celium under certain conditions of culture on a solid nutritive 

 medium. 



In beer-wort it yields only 1 to 1*3 per cent, (by volume) 

 of alcohol, even after long standing. It does not ferment 

 maltose ; it inverts saccharose ; and in nutritive solutions of 

 the latter, and of dextrose, it yields considerable quantities of 

 alcohol. 



SACCHAROMYCES EXIGUUS (REESS). HANSEN 



develops in wort a growth, the cell-forms of which most closely 

 correspond to the species described by Reess under the above 

 name. It is, however, impossible to determine whether Reess 

 was really dealing with this species, since any Saccharomyces 

 species may, under certain conditions, form a preponderating 

 number of similar small cells. 



This species only gives scanty spore-formation and weak 

 film-formation, but it yields a well-developed yeast-ring. The 

 cells of the film resemble those of the sedimentary yeast, but 

 short sausage-shaped and small cells are more frequent. 



