

FERMENTATION. 45 



own explanation of fermentation was hardly nearer the truth. 

 His conception of fermentation was "life without oxygen." 

 He thought that the microorganisms produce a fermentation 

 only when they grow in a solution with an insufficient amount 

 of oxygen. Under these conditions they extract the oxygen 

 from the molecules of the fermentable compound and this 

 causes the molecule to fall to pieces, like an arch from which 

 the keystone has been removed. This conception of fermenta- 

 tion cannot stand in the light of the fact that many fermenta- 

 tions only take place in the presence of an abundance of oxy- 

 gen (e. g., acetic fermentation). 



The next suggestion came from Nageli who explained the 

 phenomena upon the basis of molecular motion. He assumed 

 that the ferment is endowed with a certain kind of molecular 

 motion and that when in contact with the fermentable body it 

 imparts its own motion to that body. The newly acquired 

 motion then actually causes the fermentable molecule to break 

 to pieces, shakes it to pieces as it were. This suggestion has 

 had no adherents and cannot be regarded as of much signifi- 

 cance, although it may perhaps be the ultimate analysis of the 

 process. 



Lastly there has risen an explanation of the organic fermen- 

 tations which bases them upon the formation of enzymes. This 

 suggestion has been slowly developing for many years and is the 

 view of fermentation most widely accepted at the present time. 

 Inasmuch as this subject has a very close bearing upon a 

 number of the topics which we shall have to consider we must 

 explain it at some little length. 



ENZYMES. 



The relation of the organized and unorganized ferments to 

 each other has been a subject of much study and speculation. 

 The enzymes appear to be very peculiar bodies. They cause 

 certain chemical changes in the material fermented, but the 



