SACCHAROMYCETACEAE 307 



to distinguish spores from the large oil globules found in many yeasts. Spores 

 are usually much more uniform in size and do not stain readily with Sudan 

 III or osmic acid. 



The method of IMoeller (Hufschmitt, Sartory & Meyer 1931) is also sug- 

 gested : Treat for 10 seconds to 5 minutes in 1% sulphuric acid, wash, stain 

 with carbolfuchsin, heating for 1 minute, differentiate with 5% sulphuric acid 

 for 5 seconds ; wash, counterstain with aqueous methylene blue for 3 minutes. 

 Also the method of Schumacher (Buschke & Harry 1923) : Fix, stain for 1 

 minute in carbol-methylene blue, rinse with distilled water, stain 1% minutes 

 with slow movement or slide with 1% phosphin (diamidophenylacridin). 

 Spores also stain with Ziehl-Neelsen acid-fast procedure if the sulphuric acid 

 is replaced by 1% nitric acid in alcohol. Fatty acids may be stained blue and 

 neutral fats red by the technic of Smith (1907). For further methods see 

 Shrewsbury (1930). 



The germination of the ascospores should be noted, if possible, especially 

 whether there is copulation between them. 



Many species form very characteristic giant colonies, while others do not. 

 Some also produce rather characteristic liquefactions of gelatin. 



Among the pathogenic yeasts, Fontoynont reports very good results in 

 dressing the lesions with methylene blue ; he also recommends 0.1 gm. methy- 

 lene blue per diem administered per os, stating that it is tolerated for several 

 months at a time. 



Key to Genera 



Cells dividing by septa, sprouting absent or rare, asci usually 4-8-spored. 



„„,..,. , ,. ^ , , Schizosaccharomyces. 



Cells dividing by sprouting, septa absent. 



Spores rough-walled, copulation usually lieterogamic. 



Ascus sprouting from the zygote, cell division sometimes suggesting that of Schizo- 



saccharomyces. Nadsonia. 



Ascus developing directly in the zygote. Debaryomyces. 



Spores smooth, copulation usually isogamic or absent. 



Ascospores thick-walled with a double membrane. Saccharomycopsis. 



Ascospores thin-walled without a double membrane. 



Copulation between vegetative cells prior to ascosporc formation, parthen- 

 ogenesis rare. Zygosaccharomyces. 

 Copulation produced but usually not functional, ascospores commonly resulting 



from parthenogenesis. Torulaspora. 



Copulation absent. Soccharomyces. 



Copulation between ascospores while still in the ascus. Saccharomy codes. 



SCHIZOSACCHAROMYCES 



Schizosaccharomyces Lindner, Woch. Brauerei 10: 1298, 1893. 

 The type species is Schizosaccharomyces Pomhe Lindner. 

 Cells cylindric or elongate ellipsoid; vegetative division by fission not by 

 sprouting; asci arise after isogamous copulation; spores spherical or ovoid 



