58 



MICRO-ORGANISMS AND FERMENTATION. 



necessary to start with an absolutely pure culture of a 

 methodically-selected species. The old Orleans process still 

 prevails in France. In this method the wine which is to be 

 converted into vinegar is placed in tuns, to which atmo- 

 spheric air has moderately free access. The formation of 

 acetic acid, as in Pasteur's process, takes place in consequence 

 of the liquid becoming covered with a film consisting of 

 "mother of vinegar." In other countries the German 

 " quick vinegar process " is employed, in which the growth of 

 bacteria, through free access of air and by dividing the liquid 



FIG. 11. 

 Bacterium aceti and Bact. Pasteurianum, after Hansen. 



into small drops, and distributing these over very large 

 surfaces (shavings), comes into intimate contact with the 

 air. The nature of the micro-organisms taking part in this 

 manufacturing process has not yet been investigated. 



Whilst Pasteur, in the above-named work, does not 

 explicitly maintain the theory that the oxidation of alcohol 

 to acetic acid is a purely physiological process, yet Adolf 

 Mayer expresses this opinion, and Hansen emphasises as a 

 certainty the fact that the formation of acetic acid is 

 commonly effected by the action of bacteria. Hanserfs 



