THE BACTERIA IN DIFFERENT MEDIA. 147 
any correlative formation of mannite. But this 
ferment has never been isolated. M. Monoyer has 
explained the variation in the proportion of gum 
in another manner (see his thesis for the doctorate 
in medicine, Strasburg, 1862). 
White wines are more subject than red wines to 
this fermentation, called graisse des vins. Accord- 
ing to M. Francois, the absence of tannin in the 
white wines is the cause of this disease, and it 
may be prevented by adding this substance. This 
remedy is even very highly appreciated in cham- 
pagne, according to Pasteur. What is the exact 
action of the tannin upon the gummy ferment? 
The only means of knowing is by cultivating this 
ferment in a state of purity and treating it with 
this agent. 
We have united together the lactic, butyric, and 
viscous ferments, because all three manifest them- 
selves in the same liquids,—wines, beer, sweetened 
water, etc.; and because they have for effect the 
transformation of glucose. We ought to say a 
word here of some other inferior organisms, per- 
haps bacteria, observed also in the same liquids, 
but which have not been as well studied. Not 
only are they not known systematically, but we 
do not know precisely what is their chemical ac- 
tion upon the elements of the medium which 
nourishes them. I shall only enumerate them. 
1. Ferment of Turned Beer (Pasteur). — “These 
are rods or filaments, simple or articulated into 
chains of variable length, of about 1 » diameter. 
