ACETIC ACID BACTERIA. 103 



Bact. orleanense. The cells vary in shape from spheres to 

 pronounced rod-like forms with all possible transitions. The 

 rods are straight or bent, single or linked in chains, and 

 swollen cells also occur. On wort-gelatine irregular whitish 

 colonies form. On beer - gelatine the older colonies are 

 reddish in colour with a moist glistening surface. The film 

 on liquids adheres firmly, and the liquid, therefore, remains 

 clear. The optimum is at 30 C., and later between 20 and 

 30 C. The species may be used either for the quick vinegar 

 or the wine- vinegar process. 



The same author has described the following special wine- 

 vinegar bacteria (Orleans process). 



Bact. xylinoides occurs both in the form of fully rounded and 

 of short or long rods ; they may be straight, bent, or irregular, 

 and sometimes swollen, single, or in chains. On wort-gelatine 

 the colonies appear like drops of water, and often exhibit 

 a light brownish nucleus. On beer-gelatine they have a moist 

 glistening, pale brownish surface. The film formation on 

 liquids differs greatly. On sugar-yeast-water and on beer it 

 is thick and tough, like Bact. xylinum ; on other liquids it may 

 exhibit every transition from a thin, dry, or smooth, to a thick 

 tough covering. The thick films show the cellulose reaction 

 on treatment with iodine and sulphuric acid, but the thin do 

 not. The optimum for agar-cultures is at 28 C., and later at 

 20-23 C. In wine-vinegar mash the optimum lies nearer 

 to 24 than to 28. The species is found widely distributed 

 throughout wine-vinegar factories. It can be distinguished 

 from Bact. xylinum by the multifarious forms of skin growth. 



Bact. vini acetati has rounded, oval, and seldom moderately 

 elongated cells, single or linked two and three together. In- 

 flated cells also occur. The colonies on wort-gelatine are 

 rounded, clear, have a moist glistening surface, and a whitish 

 precipitate in the middle. The films are not very coherent, 

 and the culture liquid soon turns cloudy. On wort with 3 per 

 cent, alcohol the film has a greasy appearance and pale yellow 

 colour. The optimum is at 28-33. As a nutritive fluid 

 for these different bacteria, dilute vinegar with diluted beer 

 or mash may be used, or diluted vinegar mash. In the 

 vinegar factories, where the useful bacteria are attacked by 



