80 LOUIS PASTEUR. 



We have thus an ordinary organic infusion exempt 

 from all acidity, and one which could not be better 

 fitted to become the prey of the vibrios of putrefaction 

 or of the aerobic mucors. By these mucors, more- 

 over, which form a film on the surface of the liquid 

 after the mycoderm has fallen, the anaerobic vibrios 

 protected from the action of the air, can come into 

 active existence. Here we find ourselves in presence 

 of one of those double phenomena, of putrefaction in 

 the deeper parts of the liquid, and of combustion at 

 the surface which is in contact with the air. Nothing 

 is more prejudicial to the quality of the vinegar than 

 the setting in of this combustion after the vinegar has 

 been formed, and when it contains no more alcohol. 

 The first materials of the vinegar upon which the 

 oxygen transmitted by the mycoderm fixes are, in fact, 

 the ethereal and aromatic constituents which give to 

 vinegar its chief value. 



Another cause of the deterioration of the quality 

 of vinegar, which is sometimes very annoying to the 

 manufacturer, consists in the frequent presence of 

 little eel-like organisms, very curious when viewed 

 with a strong magnifier. Their bodies are so trans- 

 parent that their internal organs can be easily dis- 

 tinguished. These eel-like creatures multiply with ex- 

 traordinary rapidity. Certainly there is not a single 

 barrel of vinegar manufactured by the Orleans system 

 which does not contain them in alarming numbers. 



