THE BACTERIA IN DIFFERENT MEDIA. 141 



liquid in which this mycoderma is cultivated should 

 be a little acid, containing one-half per cent of 

 acetic acid, for example. Under these conditions 

 the Mycoderma vini (a species of Saccharomycete), 

 the formation of which should be avoided, finds 

 conditions unfavorable to its existence. Indeed, 

 this second organism, commonly called flowers of 

 wine, has an action quite different from that of 

 the Mycoderma aceti. It consumes the alcohol 

 entirely, transforming it into water and carbonic 

 acid : it also consumes the acetic acid. We must 

 sow the M. aceti, if we do not wish to see the M. 

 vini develop in its place, as the germs of the latter 

 seem more widely diffused in the air. 



In order that the acetification may occur, the 

 oxygen of the air is necessary. Once submerged, 

 the M. aceti develops, but no longer produces 

 acetic acid. It is even probable that it consumes 

 the acetic acid already formed, reducing it to the 

 state of water and carbonic acid. It is the same 

 when, developing upon the surface, it has trans- 

 formed all the alcohol. " In effect, it is not then 

 arrested in its work ; and without changing form 

 or mode of action, it carries the oxygen of the air 

 to the acetic acid which it has produced, transform- 

 ing it into carbonic acid and water. If we add some 

 alcohol to the liquid, the phenomena change : the 

 'acid is respected, and the alcohol is transformed 

 anew into acetic acid " (Duclaux). According to 

 the experiments of Mayer, the maximum of aceti- 

 fying power is obtained between 20° and 30° (68° 

 to 86° Fah.), and this power is lost below 10° (50° 

 Fah.) and above 35° (95° Fah.). 



