CLASSIFICATION OF YEASTS 273 



which institution is responsible for the two works mentioned above, 

 on the Httle understood asporogenous yeasts with mycehum, will be 

 available before long. We shall follow, in the main, the classifica- 

 tion of these workers as to the yeasts themselves and that of Mar- 

 tin ^' down to the families. 



ORDERS AND FAMILIES OF HEMIASCOMYCETES 



A. Hyphal cells becoming chlamydospores, each of which germinates to become a 

 single ascus. Parasitic on vascular plants. Order TAPHRINALES 



B. Zygote or single cell transformed into an ascus directly or after proliferation 

 of diploid yeast cells. Order ENDOMYCETALES 



\. Spore sacs (asci?) multispored; gametangia when present sometimes multi- 

 nucleate. Family ASCOIDEACEAE 



2. Asci with eight ascospores or fewer; gametangia when present, always uni- 

 nucleate. Family ENDOMYCETACEAE 



]\Iartin recognizes another family which Stelling-Dekker has com- 

 bined with the Endomycetaceae. To determine the genera and spe- 

 cies of the Endomycetaceae it is necessary to study both morpho- 

 logical and physiological characters. Among these are size and shape" 

 of vegetative cells; nature of cell division — by budding, fission, or a 

 combination of the two; formation of buds at any place on the cell 

 (multipolar) or only at ends of the cell (bipolar) ; formation of true 

 mycelium or pseudomycelium, a condition resulting from bipolar 

 budding cells becoming elongated and remaining attached to one an- 

 other; mode of ascospore formation; number, shape, and size of 

 spores ; appearance of growth in liquid media ; type of growth on agar 

 slants or giant colonies; fermentation of various sugars; utilization 

 of various organic compounds, especially alcohol, as sole source of 

 energy; utilization of various chemicals, especially nitrate, as sole 

 source of nitrogen; dominance of "fermentive" or "oxidative" char- 

 acter. By fermentive Stelling-Dekker means anaerobic production 

 of carbon dioxide and alcohol; by oxidative, she means aerobic pro- 

 duction of carbon dioxide. Methods of studying these characters 

 will be found in Chapter III. Stelling-Dekker's monograph was pub- 

 lished before Winge had published his papers on the sexuality of 

 yeasts, hence the term parthenogenetic, as she uses it, must be un- 

 derstood to include spore formation by yeasts in which the usual 

 growth form is diploid. It will be noted that Stelling-Dekker was 

 compelled to include yeast-like fungi with yeasts as she could find 

 no line of demarcation between organisms which produced mycelium 

 only under exceptional conditions and those which produced it regu- 

 larly. 



