SACCHAROMYCES. 361 



these swim in the liquid, others settle to the bottom. These 

 particle's consist of mycelial colonies of practically the same 

 character as the film-formations of Hansen's six species ; they 

 are also built up of cells, which are readily separated at the 

 point of union. When S. Marxianus is cultivated in wort 

 near the maximum temperature for growth, the vegetation 

 consists of round and oval cells. The ascospores are kidney- 

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

 months in wort contained in two-necked flasks, there were only 

 traces of film-formation with few sausage-shaped and oval cells. 



This yeast is one of those species which develop a mycelium 

 under certain conditions of culture on a yeast- water gelatine. 



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. The temperature limits for budding in wort are 

 46-47 C. and 0-5 C. 



The maximum temperature for spore-formation lies between 

 32 and 34 C., the minimum between 4 and 8 C., the optimum 

 between 22 and 25 C. The growth yields quicker and more 

 abundant spore-formation if cultivated in yeast-water, or wort 

 with 10 per cent, dextrose (Klocker). 



In agreement with his theory that maltose is split up by a 

 particular enzyme differing from invertase, and only subse- 

 quently fermented, Emil Fischer found that an aqueous 

 extract of the pulverised growth of this yeast decomposed 

 saccharose, but not maltose. 



Saccharomyces exiguus (Reess) Hansen 



develops a growth in wort, 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 



