174 APPENDIX. 



fermentation they give rise to a pigment in the culture media. 

 They grow upon gelatine which they do not liquefy. 



Saccharomyces Mycoderma. This yeast forms a mould-like 

 growth, a skin, on the surface of fermented liquids, but does not 

 cause any fermentation itself. It forms the common u mould" 

 on wine, preserves, and " sour krout." 



Pathogenic Yeasts. In recent years a number of workers 

 have interested themselves in experiments with yeasts in their 

 relation to disease; and under the name of Blastomycetes, San- 

 felice has grouped yeasts that produce tumors resembling epi- 

 theliomata ; and he has tried to prove that the so-called animal 

 parasites found in malignant growths, and variously known as 

 coccidia and sporozoa, are yeasts. The whole subject is still 

 under discussion. 



Oidium. A form which seems to be the bridge between the 

 yeast and the moulds is the oidium. Sometimes it resembles 

 the yeasts, sometimes the moulds, and often both forms are 

 found in the same culture. Several are pathogenic for man. 



Oidium Lactis. 



Origin. In sour milk and butter. 



.Form. The branches or hyphens break up into short rod-like 

 spores. No sporangium, as in moulds. 



Growth. In milk it appears as a white mould. 



Artificially cultured on gelatine plates, or milk gelatine plates, 

 it forms satin-like, star-shaped colonies, which slowly liquefy. 

 Under microscope the form of the fungus is well seen. 



Agar Stroke Culture. The little stars, very nicely seen at first ; 

 then the culture becomes covered with them, causing a smeared 

 layer to appear over the whole surface, with a sour odor. 



Properties. The milk is not changed in any special way. It 

 is not pathogenic for man or animals. It is found when the 

 milk begins to sour. 



Oidium Albicans. (Soor.) Thrush Fungus. 



Origin. Mucous membrane of the mouth, especially of infants. 



Form. Taken from the surface of the culture, a form like 

 yeasts ; but in the deeper layers, mycelia with hyphens occur. 



Growth. Not liquefying ; snow-white colonies on gelatine 

 plates. 



