326 STUDIES ON FERMENTATION. 



Liebig, who, as well as M. Fremy, was compelled to renounce 

 his original opinions concerning the nature of ferments, devised 

 the following obscure theory (Memoir by Liebig, 1870, already 

 cited) : — 



" There seems to be no doubt as to the part which the vege- 

 table organism plays in the phenomenon of fermentation. It 

 is through it alone that an albuminous substance and sugar are 

 enabled to unite and form this particular combination, this 

 unstable form under which alone, as a component part of the 

 mycoderm, they manifest an action on sugar. Should the 

 mycoderm cease to grow, the bond which unites the constituent 

 parts of the cellular contents is loosened, and it is through the 

 motion produced therein that the cells of yeast bring about a 

 disarrangement or separation of the elements of the sugar into 

 other organic molecules." 



One might easily believe that the translator for the Auna/es 

 lias made some mistake, so great is the obscurity of this 

 passage. 



Whether we take this new form of the theory or the old one, 

 neither can be reconciled at all with the development of yeast 

 and fermentation in a saccharine mineral medium, for in the 

 latter experiment fermentation is correlative to the life of the 

 ferment and to its nutrition, a constant change going on 

 between the ferment and its food-matters, since all the carbon 

 assimilated by the ferment is derived from sugar, its nitrogen 

 from ammonia, and phosphorus from the phosphates in solution. 

 And even all said, what purpose can be served by the gratuitous 

 hypothesis of contact-action or communicated motion ? The 

 experiment of which we are speaking is thus a fundamental 

 one ; indeed, it is its possibility that constitutes the most effec- 

 tive point in the controversy. No doubt Liebig might say, 

 " but it is the motion of life and of nutrition which constitutes 

 your experiment, and this is the communicated motion that m}"- 

 theory requires." Curiously enough, Liebig does endeavour, 

 as a matter of fact, to say this, but he does so timidly and 

 incidentally : " From a chemical point of view, which point of 



