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 /i, diameter. 



