MYCODERMA HENNEBERG 333 



per cent of grape must, the colonies are white and round with a plain 

 border. On wine or grape must, there is a scum in the beginning. 

 The yeast gives no fermentation in must. It forms alcohol from wine 

 without noticeably diminishing the acidity. The temperature limits 

 are 2-5 C. and 39 C., the optimum being 32-35 C. Wine is 

 sterilized by heating for 10 hours at 50 C. and 1 hour at 55 C. 

 Direct sunlight in June produced the same results in 10 hours. 



Mycoderma duplex. On grape must or wine, the cells are oval or 

 pear shaped (3-7.2 X 2-3.6/i). After 4 to 8 days, the cells are oval, 

 small, and apiculate with either 1 or 2 refractive granules. Sometimes 

 large oval or globular cells appear (5.4 X 10.2/i). 



On gelatin with grape must, the colonies are round with an entire 

 'edge. On grape must or wine, a white delicate scum is formed at the 

 beginning adhering to the sides of the container. Finally, it breaks 

 away and falls to the bottom as a fine deposit. 



There is no fermentation in must, a slight diminution in the 

 amount of alcohol in wine and a modification of the acidity. It is 

 able to withstand 10 per cent of alcohol and 2 per cent of tartaric 

 acid. The temperature limits are 5-7 C. and 39-40 C., the optimum 

 being 35 C. 



Wine containing this yeast is sterilized by 10 hours' heating at 

 48 C. and 1 hour's heating at 55 C. An exposure of 8 hours to sun- 

 light also destroys it. 



Mycoderma tenax. On grape must or wine, the cells are elliptical 

 (4.8-8 X 2.8-3.8 ju) and solidly united in groups which branch. After 

 3-8 days, the cells are round, or oval, with a large refractive granule. 

 On gelatin or grape must, the colonies are white and round with a 

 plumose edge. On grape must or wine, a delicate scum is formed 

 which clings to the walls of the culture flask but later falls to the 

 bottom of the container. There is no fermentation in must, but a 

 diminution of the alcohol and acid content of wine. It develops in 

 the presence of 4 or 5 per cent of alcohol and 2 or 3 per cent of tar- 

 taric acid. The temperature limits are 12 and 32-35- C. , the opti- 

 mum being 30-32 C. Wine containing this yeast is sterilized by heat- 

 ing for 10 hours at 48 C. or 1 hour at 53 C. Exposure to direct 

 sunlight for 10 hours will kill the yeast. 



MYCODERMA HENNEBERG 



Henneberg l mentioned two species of Mycoderma which he found 

 in brewery yeasts and compressed yeast. These two species differ in 



1 Henneberg, W. Zwei Kahmhefearten an abgepresster Brennereihefe. Zeit. 

 Ges. Brau. 26, 1903. 



