ACID FERMENTATION 147 



unstable, and water is eliminated with formation of the 

 aldehyde group. 



+ H^O 



Further addition of oxygen gives rise to an acid, thus : — 

 H ^OH 



-C + = -C 



^0 % 



If the oxidation is carried still further, hydrocarbons and 

 carbon dioxide (COg) generally result. E.g., calcium acetate 

 undergoes fermentation with formation of calcium carbonate 

 and marsh gas, thus :— 



CHg 



I + HgO = CaCOg + 2CH^ + CO^ 

 /Ca 



CH3 



Up to the present no specific enzymes have been discovered 

 capable of bringing about separate and defined reactions of 

 any of these types ; few, if any, of the reactions are confined 

 to specific bacteria, consequently the oxidation of an alcohol 

 through the intervention of the hving organism is a highly 

 complex process, generally resulting in the production of a 

 number of secondary products. The action of an organismj 

 as has been frequently stated, may be broadly described as 

 respiratory and fermentative. It consumes a certain amount 

 of the medium for building up its own structure ; in such a 



