MICROBES, OR BACTERIA. 103 



This ferment may be destroyed by tannin (15 

 grammes to a hogshead), which has the effect of pre- 

 cipitating it. Very ripe sorbs, which have been crushed, 

 may also be used for this purpose, as well as gall- 

 nuts and grape-seeds which have been ground to 

 powder ; all substances rich in tannin. The precipitate 

 thus formed should be separated from the wine by 

 refining. 



Wines affected by Bitterness. This disease affects 

 red wines, especially those of the choicest vintages 

 of Burgundy. Pasteur writes that "at its outset 

 the wine assumes a peculiar smell, its colour is less 

 vivid, and its taste becomes insipid. Soon the wine 

 becomes bitter, and there is a slight taste of fermen- 

 tation, due to the presence of carbonic acid gas. 

 Finally, the disease becomes more aggravated, the 

 colouring matter is completely changed, and the wine 

 is no longer drinkable." 



The microbe which is the essential cause of this 

 disease is seen under the microscope in the form of 

 articulated filaments, curled back or bent, and it may, 

 or may not, be invested with the colouring matter of 

 the wine. It is reproduced by fission, not by bud- 

 ding. It is probably a bacillus (Fig. 56). 



This ferment must not be confounded with that 

 of wine affected by pousse, of which the filaments are 

 much more slender, the articulations are hardly apparent, 

 and they are not incrusted with colouring matter. 

 Pousse is readily developed in wines of inferior quality, 



