[L,. fermentation A change which many organic liquids are capable of undergoing in the presence of certain substances termed ferments. The decompositions which take place are different from ordinary chemical actions, and the resulting products vary with the nature of the fermented body and with the kind of ferment used. There are two distinct kinds of ferments-(i) organized, and (2) non-organized, or soluble ferments. The former consist of minute vegetable organisms. One is yeast, which gives rise to the alcoholic fermentation, producing chiefly alcohol and carbonic acid; another, called bacterium lactis-a rod-like form-is the cause of the fermentation in milk, or lactic fermentation, the chief product of which is lactic acid ; a third produces acetous fermentation, giving rise to acetic acid, and there are many others.