146 PHYSIOLOGY OF THE BACTERIA. 



According to Pasteur the butyric ferment be- 

 longs to his class of anaerobies. 



This fermentation resembles putrefaction in a 

 great many particulars. Indeed some authors in- 

 clude it under the same head. 



3. Viscous Fermentation. — Wines often change 

 so that they contain a mucilaginous substance and 

 mannite. This viscous matter has the same com- 

 position as gum or dextrine (C 6 H 10 O 5 ) ; at the 

 same time it disengages carbonic acid. 



In the fermenting liquid, we find an organism 

 which is not yet sufficiently studied. " There are 

 chaplets of little spherical bodies, of which the di- 

 ameter varies sensibly, according to the kind of 

 wine attacked by this malady (Pasteur). 



Pasteur has proposed the following formula : — 



25(C 12 H 22 O n ) + 25H 2 = 12(C 12 H 20 O 10 ) + 



gum. 



24(C 6 H"0 6 ) + 12C0 2 + 12H 2 0. 



mannite. 



which represents the phenomena well enough as it 

 usually occurs. There is produced in the vicinity 

 of 51.09 of mannite and 45.5 of gum for one hun- 

 dred parts of sugar. But sometimes the gum ex- 

 ceeds the mannite in quantity. In this case, 

 according to Pasteur, we can always verify in the 

 liquid the presence of a larger ferment of a differ- 

 ent nature ; and the same author adds that, per- 

 haps, in this case the increased production of gum 

 results from the presence of this second ferment, 

 which transforms the sugar only into gum, without 



