BACILLUS AOETI 191 



with on plants. F. Winkler and Von Schr otter found 

 the Staphylococcus pyogenes aureus in rotten portions of 

 apples, and the Bacillus melochloros in the excreta of cater- 

 pillars in worm-eaten specimens of the same fruit. 



Bacillus aceti. — As early as 1864 Pasteur brought for- 

 ward proof that the oxidation of alcohol and its alteration 

 into acetic acid are connected with the vinegar ferment, 

 which could only develop in the presence of oxygen. 

 This ferment consists of short thick rods often uniting in 

 curved chains, and forming a mass of zooglcea which 

 is thick and glutinous, the [so-called] ' mother of vine- 

 gar.' 



Mace found another bacterium of vinegar, the zooglcea 

 mass of which is thick, white or slightly rose-tinted, never 

 wrinkled, and feels almost like cartilage. Numerous rods, 

 sometimes isolated, sometimes joined in pairs or in threes, 

 lie in a colourless interstitial substance ; they are without 

 movement in the membrane, but when free in fluids possess 

 a slow motility. Gelatine is not liquefied, and a thick, 

 undulating, rather hard layer develops on its surface. A 

 less hard, but smooth and non-undulating, layer forms 

 upon agar. 



The bacteria of vinegar are very widely diffused through 

 nature, according to Duclaux, who assigns an important 

 part in transmission of the ferment to a kind of fly, the 

 Musca cellaris, which is met with everywhere. 



Bacillus indigogenus was found by Alvarez in infusion of 

 indigo leaves. It consists of short motile rods surrounded 

 by an envelope, and has the property of causing the ap- 

 pearance of blue indigo in decoctions of the leaves of the 

 Indigofera. Surface cultures on agar cause cleavage of the 

 medium, with development of gas. 



Pediococcus cerevisise.^Balcke found the Pediococciis 

 cerevisim in beer, in breweries, and in the washings from 



