324 STUDIES ON FERMENTATION. 



barometric pressure on the phenomena of life, has recognized 

 the fact that compressed oxygen is fatal to certain ferments, 

 whilst under similar conditions it does not interfere with the 

 action of those substances classed under the name of soluble 

 ferments, such as diastase (the ferment which inverts cane sugar) 

 emulsin, and others. During their stay in compressed air, 

 ferments proper ceased their activity, nor did they resume it, 

 even after exposure to air at ordinary pressures, provided the 

 access of germs was prevented. 



"We now come to Liebig's principal objection, with which he 

 concludes his ingenious argument, and to which no less than 

 eight or nine pages of the Annales are devoted. 



Our author takes up the question of the possibility of causing 

 yeast to grow in sweetened water, to which a salt of ammonia 

 and some yeast-ash have been added — a fact which is evidently 

 incompatible with his theorj^ that a ferment is always an albu- 

 minous substance on its way to decomposition. In this case 

 the albuminous substance does not exist ; we have only the 

 mineral substances which will serve to produce it. We know 

 that Liebig regarded yeast, and, generally speaking, any fer- 

 ment whatever, as being a nitrogenous, albuminous substance 

 which, in the same wa}^ as emulsin, for example, possesses the 

 power of bringing about certain chemical decompositions. He 

 connected fermentation with the easy decomposition of that allm- 

 minous substance, and imagined that the phenomenon occurred 

 in the following manner : — " The albuminous substance on its 

 way to decomposition possesses the power of communicating to 

 certain other bodies that same state of mobility by which its 

 own atoms are already affected ; and through its contact with 

 other bodies it imparts to them the power of decomposing or of 

 entering into other combinations." Here Liebig failed to per- 

 ceive that the ferment, in its capacity of a living organism, 

 had anything to do with the fermentation. 



This theory dates back as far as 1843. In 1846 Messrs. 

 Boutron and Fremy, in a Memoir on lactic fermentation, pub- 

 lished in the Annales de Chlmie et de Fhysique, strained the 



