216 THE LOSS OF COLOUR IN RED WINES. 



simply be a matter of technique. The acetic bacteria are the 

 oxidising bacteria ^ja?* excellence, and they must do their work by 

 means of oxidases which they produce and possibly excrete. 

 Since acetic bacteria were the only bacteria detected in the wines 

 under investigation, there is every reason to believe that they 

 were responsible for the loss of colour. 



The only objection to this claim is that experimentally the 

 sudden formation of a powder}'- deposit was not obtained. In 

 place of it a slow precipitation occurred concomitantly with the 

 sedimentation of the bacteria. The difference is probably merely 

 one in the time through which the phenomenon extended, and 

 might be explained by the difference between the natural and the 

 experimental conditions. 



Attempts were made to produce the sudden precipitation of 

 the colouring matter of the wine by subjecting infected 

 samples of wine to various anaerobic and partly anaerobic con- 

 ditions during times varying from a week to a month, but without 

 success. When the cultures were again exposed to the air no 

 change occurred. This does not necessarily mean that the 

 bacteria cannot produce the phenomenon, but it means that they 

 cannot do so under laborator}' conditions. Under natural con- 

 ditions, such as the infection of the wine in bulk and storage for 

 a year or more, another result might have been obtained. 



The bacterium appears to be a race of Bad. ascendens, 

 Henneberg. It forms a delicate film which creeps high up the 

 sides of the culture flasks; it is easily broken and falls to the 

 bottom of the wine as a flocculent precipitate. The cells are 

 not stained by iodine, they are non-motile and are not arranged 

 in threads, but occur singly, in pairs and in masses. The white 

 opalescence upon the medium around the colonies on nutrient 

 glucose gelatine was not observed, but this is not enough to con- 

 stitute it as a new species. When contained in wine it is killed 

 by an exposure to 43° C. for ten minutes. 



[Printed off August 2nd, 1904.] 



