TORULA NIGRA 329 



tory which formed black yeast bodies and finally a deep green myce- 

 lium. This seemed to be related to Marpmann's yeast. 



Other black yeasts have been mentioned by Marpmann under the 

 name of Schizosaccharomyces niger and Musa. These are not well 

 known and seem to be related to Dematium more than yeasts. They 

 possess a complex mycelium. In all cases they have been improperly 

 called Schizosaccharomyces for they are budding yeasts which possess 

 none of the characteristics of the Schizosaccharomyces. There have 

 been described may species which form a yellow and gray pigment. 

 These are too insufficiently known to be mentioned here. Saccharo- 

 myces sphoericus might be mentioned. Browne has described a Mo- 

 nilia nigra, the characteristics of which are given later in this book. 



In a recent investigation, Will isolated three forms of black yeasts 

 which he regards as varieties of the same species. The three forms 

 have a typical mycelium and a budding mycelium. The mycelium 

 is a little branched and forms conidia which are ellipsoidal or spherical 

 with thick walls. These multiply by budding, forming new yeasts or 

 producing another mycelium. 



In liquid media the three forms of yeast develop on the surface 

 of liquid cultures and on the walls of the container with a typical 

 mycelium. In the bottom of the flask there develops a flocculent 

 sediment made up of yeast cells and mycelium. A ring develops 

 around the side of the container and is cartilaginous, and a deep 

 black in color. The scum is more or less colored a dark green; it is 

 thick and quite tough. The giant colonies are a deep black. They 

 are made up of a mycelium and budding cells. Growth for the three 

 species stops at 35 C. The three varieties are killed in 30 minutes 

 at 48 C. They do not develop in media with 4 per cent of alcohol 

 added. They are slightly resistant to alcohol. No fermentations 

 are induced. 



Form I. The budding cells are ellipsoidal, elongated and some- 

 times apiculate (3. 9-8. 5 /*). Usually they are isolated but may be 

 grouped, three or four cells being in a group. Some of the cells are 

 giant cells. 



Form II. The budding cells are oval, sometimes sausage-shaped 

 (3.9-7. 6 /z). They are sometimes grouped. 



Form III. The budding cells are spherical, sometimes ellipsoidal 

 or sausage-shaped. The mycelial structure is less developed than in 

 the two preceding forms. Will found no relation between these yeasts 

 and Cladosporium herbarum. On the other hand he does recognize 

 relationships between these yeasts and Dematium but they are separated 

 by other characteristics. 



