300 NON-SACCHAROMYCETES OR DOUBTFUL YEASTS 



mentation is accomplished slowly and only ends after eight months 

 at 20 C. They ferment sucrose without giving products which reduce 

 Fehling's solution, although an inversion of the saccharose is brought 

 about. According to Schionning, these types may be distinguished 

 in these ways. Torula A may be distinguished from Torula B by its 

 action towards sugars and also by the temperature limits for budding. 



Torula A. The cells are ellipsoidal while some are sausage shaped 

 or in the form of a mycelium. Others present odd, irregular shapes. 

 The size of the cells is variable. Giant cells are found with a very 

 refractive protoplasm, showing vacuoles scarcely visible in which a 

 mobile granule is often found. The temperature limits for budding 

 are 5-7 C. and 40-40.5 C. The races of type A produce, in old liquid 

 cultures, a loose scum in which the cells are filamentous, resembling a 

 mycelium. It ferments dextrose, levulose, saccharose and maltose 

 (saccharose more actively and maltose less actively than type B). 

 It has no action on lactose and dextrine. 



Torula B. The cells resemble somewhat those of Torula A. They 

 are often sausage shaped. Long mycelial structures are found among 

 them. The temperature limits for budding are 3-4 C. and 39-39.5 C. 

 In old liquid cultures, the races of type B form a scum identical with 

 that of Torula A. They ferment saccharose, maltose, dextrose, levu- 

 lose and lactose but do not act on dextrose. 



BEIJERINCK'S TORULA 



Beijerinck l has isolated three yeasts which do not sporulate and 

 which ought to be classed among the Torula. They are: 



Saccharomyces fragrans, Beijerinck. According to Beijerinck, this 

 yeast is a contamination in compressed yeast. It has been insuffi- 

 ciently described. 



Saccharomyces muciparus, Beijerinck. Related to the preceding 

 species, this is also incompletely known. It is characterized by a 

 very evident polymorphism. In old cultures, it presents filamentous 

 and yeast forms. 



Saccharomyces curvatus, Beijerinck. This yeast was isolated by 

 Beijerinck from an impure culture of S. muciparus. It seems to 

 correspond to the cheesy yeast described by Pasteur. The shape is 

 much like that of Saccharomyces Pastorianus. It is curved, however, 

 whence the name S. curvatus. This yeast has the characteristic, as 

 Pasteur found, of not being broken up in water. It settles to the 

 bottom of the culture flask as a curd leaving the supernatant liquid 



1 Beijerinck, M. W. Die Erscheinung des Flokenbildung oder Agglutination 

 bei Alkoholhefen. Cent. Bakt. 20, 1908. 



