THEORY OF FERMENTATION 317 



point we had taken the precaution on August I5th, 1875, 

 of preparing another flask, exactly similar to the preceding 

 one in every respect, and which gave results identical with 

 those described. We decanted this November 15th, pouring 

 some wort on the deposit of the plant, which remained in 

 the flask. In less than five hours from the time we placed 

 it in the oven, the plant started fermentation in the wort, 

 as we could see by the bubbles of gas rising to form patches 

 on the surface of the liquid. We may add that yeast in 

 the medium which we have been discussing will not de- 

 velop at all without air. 



The importance of these results can escape no one; they 

 prove clearly that the fermentative character is not an 

 invariable phenomenon of yeast-life, they show that yeast 

 is a plant which does not differ from ordinary plants, and 

 which manifests its fermentative power solely in conse- 

 quence of particular conditions under which it is compelled 

 to live. It may carry on its life as a ferment or not, and 

 after having lived without manifesting the slightest symp- 

 tom of fermentative character, it is quite ready to manifest 

 that character when brought under suitable conditions. The 

 fermentative property, therefore, is not a power peculiar 

 to cells of a special nature. It is not a permanent character 

 of a particular structure, like, for instance, the property of 

 acidity or alkalinity. It is a peculiarity dependent on ex- 

 ternal circumstances and on the nutritive conditions of 

 the organism. 



II. FERMENTATION IN SACCHARINE FRUITS IMMERSED IN 

 CARBONIC ACID GAS 



THE theory which we have, step by step, evolved,, on 

 the subject of the cause of the chemical phenomena of 

 fermentation, may claim a character of simplicity and 

 generality that is well worthy of attention. Fermentation 

 is no longer one of those isolated and mysterious phe- 

 nomena which do not admit of explanation. It is the con- 

 sequence of a peculiar vital process of nutrition which 

 occurs under certain conditions, differing from those which 



