CLASSIFICATION OF THE YEASTS 193 



tion of the asc containing 8 ascospores. These two genera, until 

 their relations are better known, merit a place apart. 



Along with the Saccharomycetes we shall make up a family of non- 

 Saccharomycetes or doubtful yeasts all those which do not form 

 spores. Three groups will be made here: First, the Torula, including 

 all yeasts which in liquid media vegetate in the bottom of the culture 

 tube but eventually form a slimy scum with no air bubbles, having 

 all of the other characteristics of the third group with the exception 

 of spore formation. Secondly, the genus Pseudosaccharomyces pro- 

 posed by Klocker for the apiculate yeasts which do not sporulate 

 and the Mycoderma which forms a slimy scum with air bubbles. These 

 correspond, in general, with the fourth group of the Saccharomycetes. 

 Thirdly, the genus Medusomyces (Lindau), characterized by a thick, 

 stratified, gelatinous scum, and the pathenogenic yeasts to which have 

 been given the generic name of Cryptococcus (Vuillemin) .* Below 

 is given a resume* of the classification which we have just outlined. 



Family of Saccharomycetes 



Unicellular fungi, multiplying by budding, sometimes by parti- 

 tion and forming ascs. Each cell may change into an asc in which are 

 formed from 1 to 4, rarely 12, ascospores, each ascospore enclosed in 

 a vegetative cell. 



FIRST GROUP 



Yeasts multiplying by partition. Ascs often derived from a copu- 

 lation, with 4 or 8 ascospores. These are provided with a single mem- 

 brane. 



Genus I. Schizosaccharomyces 

 SECOND GROUP 



Budding yeasts; sexual phenomena, sometimes only in traces, in 

 the formation of the asc. 



1 De Beurmann and Gougerot (Les mycoses dans le nouveau Traite de mede- 

 cine et de therapeutique de A. Gilbert et Thoinot, Bailliere, ed. Paris, 1910) 

 have created the following three genera for pathogenic yeasts which do not sporu- 

 late. 



1. Atelossaccharomyces (areXos = imperfect) which include all well-differenti- 

 ated yeasts which do not sporulate. 



2. Parasaccharomyces which include fungi resembling the yeasts but which 

 offer rudimentary filamentous forms sometimes true filaments. 



3. Zymonema (vjj,rj = levure, J/TJ/ZO, = filament) which include intermediate 

 forms between the yeasts and Endomycetes characterized by a mixture of yeast 

 forms and mycelial formations. 



The pathogenic yeasts are, as stated above, not very well known and the 

 placing of them into genera is difficult. This classification seems premature. 



