652 THE CLOUDING OF WHITE WINE, 



vigorous cultures of these fresh plates of peptone-glucose-gelatine* 

 were prepared. The examination of the colonies that developed 

 upon th»se plates made it evident that there were two varieties of 

 yeast. As passage through a solid medium tends to alter the 

 characters of the yeast, the two kinds were isolated by the 

 dilution method from a vigorous culture in Hansen's peptone- 

 glucose fluid. 



Pure cultures of the two yeasts obtained in this way showed 

 that they both belonged to the group which has for its type 

 Saccharomyces rnembranifaciens. The first of these yeasts con- 

 sisted of round, oval or sausage-shaped cells, containing one or 

 two refractile granules. In wine must it formed a strong 

 crumpled film and a slight flocculent precipitate. Many 

 cells of the film contained two, and occasionally three, round or 

 flattened spores. The second of the yeasts formed in wine must 

 a slight transparent film and a bulky white sediment. The cells 

 were chiefly oval, indistinctly vacuolated, and contained one or 

 two refractile granules. Only a few of the film cells contained 

 two spores. Neither of the yeasts induced a visible fermentation. 



I was informed that the turbidity which arises in the wine 

 would probably not be found to have a bacterial origin since 

 the cloudiness is never so pronounced as when the wine 

 is attacked by bacterial diseases. From this it was to be 

 inferred that the exciting agents would be yeasts, and of the two 

 yeasts separated, one would probably be found to bring about a 

 turbidity in experimental wine. For the purposes of experiment 

 I had sent to the laboratory a few bottles of wine siphoned 

 directly from the 750-gallon storage casks into sterilised bottles 

 and closed with sterilised corks. The wine had been allowed to 

 run for some time in order to clean the siphon. A portion of 

 this wine was filled into small bottles and pasteurised at 75° C. 

 for a quarter of an hour. These small experimental bottles were 

 infected with the pure yeasts separately and together. At the 



* Gelatine 10% added to Hansen's peptone-glucose fluid and neutralised to 

 faint acidity with potassium hydrate. 



