146 PHYSIOLOGY OF THE BACTERIA. 
According to Pasteur the butyric ferment be- 
longs to his class of anaérobies. 
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°H"O*); 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(C2H20") + 25H2O0 = 12(C2H20%) + 
gum. 
24(CSH#O8) + 12002 + 12H20. 
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, inthis case the increased production of gum 
results from the presence of this second ferment, 
which transforms the sugar only into gum, without 
