THEORY OF FERMENTATION 389 



M. Paul Bert, in his remarkable studies on the influence 

 of barometric pressure on the phenomena of life, has recog- 

 nized the fact that compressed oxygen is fatal to certain 

 ferments, whilst under similar conditions it does not inter- 

 fere 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 theory that a fer- 

 ment is always an albuminous substance on its way to decom- 

 position. 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 ferment whatever, as being a nitro- 

 genous, albuminous substance which, in the same way as 

 emulsin, for example, possesses the power of bringing about 

 certain chemical decompositions. He connected fermentation 

 with the easy decomposition of that albuminous substance, 

 and imagined that the phenomenon occurred in the follow- 

 ing manner: "The albuminous substance on its way to 

 decomposition possesses the power of communicating to cer- 

 tain 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 perceive that the ferment, in its capacity of a living organ- 

 ism, 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, 

 published in the Annales de Chimie et de Physique, strained 

 the conclusions deducible from it to a most unjustifiable 

 extent They asserted that one and the same nitrogenous 



