SA CCHA ROM YCETA CEm 



979 



vegetation as parasites they reproduce by a budding process, hence 

 the name of budding fungi ; when living on artificial media, under 

 unfavourable nutritive conditions, or in the absence of oxygen, they 

 multiply also by formation of endospores or ascospores. Each cel- 

 lular element may become an ascus containing 1-4, sometimes more, 

 up to 12 spores (ascospores). 



The organisms are, as a rule, unicellular plants, but at times the 

 cells elongate, and a rudimentary mycelium may be formed. This 

 occurs, for instance, when the organisms are cultivated in certain 

 fluid culture media — for example, fluid beer -wort. In such cases 

 side-buds, which separate into conidia-like bodies, may also develop 

 on the hyphse. 



Classification. — ^The family contains thirteen genera, of which only 

 two — Saccharomyces Meyen, 1837, and Willia Hansen, 1904 — 

 contain species parasitic on man; while, in regard to Schizosac- 

 charomyces Beyerinck, 1893, it appears doubtful to us whether 

 this really should be placed in this family, as it reproduces by division 

 instead of by budding. The various genera may be recognized 

 as follows : — 



A^. Vegetative cells globose, ovoid, or pyriform, without lemon-shaped 

 extremities : — 

 Bi. Vegetative cells increase by budding : — 



C^. Vegetative cells without large fat globule ; asci 3-4 spored : — • 

 D^. Ascospores globose or ovoid : — 



E^. On germination spores form typical yeast cells: — 

 pi. Ascus formation not preceded by zygosis : — 

 G^. Spore membrane single: — 



H^. Spore membrane verrucosa — Debaryomyces Klocher. 

 H2, Spore membrane verrucose and possessing a superficial 

 elevated linear process, dividing the surface into two 

 unequal portions — Schidnniomyces Klocher, 

 H3, Spore membrane without verrucosities or crest — Sac- 

 charomyces Meyen, 1838. 

 G2. Spore membrane double-^an inner, endosporium, and an 

 outer, exosporium — Saccharomycopsis Schionning. 

 F2. Ascus formation preceded by zygosis: — 



Ascospores have a smooth membrane — Zygosaccharomyces 

 Barker, 1901. 



£2. On germination spores form a poorly developed promycelium, 

 multiplication by a process intermediate between budding 

 and transverse division — Saccharomy codes Hansen, 1904. 

 D2. Ascospores pileiform or limoniform ; costate with bowler-hat shape. 

 No alcoholic formation, but ethers produced, with pleasant 

 fruity odour, in sugar media — Willia Hansen, 1904. 

 D-^ Ascospores spherical, hemispherical, or irregularly shaped. 



Thick pellicle with air-bubbles on sugar liquid media— PicAm 

 Hansen, 1904. 



C2. Vegetative cells large, spherical, each containing a large fat globule 

 as in torula. D. Asci 8-spored — Torulaspora Linder. 

 B2. Vegetative cells increase hy fission : — Asci 8-spored — Schizosaccharomyce 

 Beyerinck, 1893. 



A2. Vegetative cells oval, with one or both extremities lemon-shaped. 



Asci I -spored — Hansenia Linder. 

 A3. Vegetative cells elongate, cyhndrical, spores filiform. 



Asci I -spored — Monospora MetchnikofE. 



Asci 8-spored ; ascospores flagellate — Nematospora PegHon. 



