The Oidia 41 



given the name Parasaccharomyces. Both authors regard it as 

 the cause of the tropical diarrhoea known as "Sprue." 



KEY TO THE GENERA OF BUDDING FUNGI * 



I. Ascospores known: 



Vegetative cells single or attached in irregular colonies, my- 

 celium not developed, ascospores formed within 



isolated vegetative cells (Saccharomycetaceae.*) 



* This genus, which does not bud, and the relatively unimportant genera, 

 Monospora and Nematospora, are not included in this key. 

 Spores globose or ovoid: 



Spores on germination forming typical yeast cells: 

 Ascus formation preceded by the conjugation of 



gametes i. Zygosaccharomyces. 



Ascus formation not preceded by the conjugation of 

 gametes: • • 



Spore membrane single 2. Saccharomyces. 



Spore membrane double 3. Saccharomycopsis. 



Spores on germination forming a poorly developed pro- 

 mycelium 4. Saccharomycodes. 



Spores pileiform or limoniform, costate 5. Willia. 



Spores hemispheric, angular or irregular in form, on 



germination forming an extended promycelium. . . 6. Pichia. 

 Vegetative, cells produced predominantly by budding, but 

 forming a mycefium under some conditions, asci 

 terminal or intercalary, .differentiated from the 



mycelium 7. Endomyces. 



II. Ascospores not known, i.e., Fungi imperfecti: 



Heavy dry pellicle formed on Hquid mediums 8. Mycoderma. 



No distinct pellicle formed: 



Vegetative cells forming a septate mycelium under excep- 

 tional conditions but predominently budding. 



g. Parasaccharomyces. 

 Vegetative cells formed only by budding: 



Cells apiculate, limoniform 10. Pseudosaccharomyces. 



Cells frequently elongate into narrow non-septate 



hyphal threads 11. Pseudomonilia. 



Cells typically yeast-like 12. Cryptococcus. 



THE OiDIA 



These organisms seem to occupy a place intermediate between the 

 yeasts and the molds — the Blastomycetes and the Hjrphomycetes. 

 In certain stages they appear as oval cells which multiply by gem- 

 mation, but instead of becoming separated, hang together. At a 

 later stage of development they grow into long filamentous forma- 

 tions suggesting the myceha of molds, but being less regular. 

 Certain cells also develop as reproductive organs. 



They are common micro-organisms of the air an.d appear as 

 frequent causes of contamination in culture-media, upon all forms 

 of which they grow readily, producing hquefaction where possible. 

 They engage in but few pathogenic processes, the most familiar 

 being that brought about by Oidium albicans, which causes the 

 common disease of childhood known as thrush {q. v.). 



* Anderson, "Jour. Infectious Diseases," xxt. No. 4, p. 376, 1917. 



