264 FKAGMENTS OF SCIENCE. 



could any trace of the ordinary alcoholic leaven be 

 found. As previously proved by Lechartier and Bella- 

 my, the fermentation was the work of the living cells of 

 the fruit itself,, after air had been denied to them. When, 

 moreover, the cells were destroyed by bruising, no fer- 

 mentation ensued. The fermentation was the correla- 

 guished. 

 tive of a vital act, and it ceased when life was extin- 



Liidersdorf was the first to show by this method 

 that yeast acted, not, as Liebig had assumed, in virtue 

 of its organic, but in virtue of its organised character. 

 He destroyed the cells of yeast by rubbing them on a 

 ground glass plate, and found that with the destruc- 

 tion of the organism, though its chemical constituents 

 remained, the power to act as a ferment totally disap- 

 peared. 



One word more in reference to Liebig may find a 

 place here. To the philosophic chemist thoughtfully 

 pondering these phenomena, familiar with the concep- 

 tion of molecular motion, and the changes produced 

 by the interactions of purely chemical forces, nothing 

 could be more natural than to see in the process of 

 fermentation a simple illustration of molecular insta- 

 bility, the ferment propagating to surrounding molec- 

 ular groups the overthrow of its own tottering com- 

 binations. Broadly considered, indeed, there is a cer- 

 tain amount of truth in this theory; but Liebig, who 

 propounded it, missed the very kernel of the phenomena 

 when he overlooked or contemned the part played in 

 fermentation by microscopic life. He looked at the 

 matter too little with the eye of the body, and too 

 much with the spiritual eye. He practically neglected 

 the microscope, and was unmoved by the knowledge 

 which its revelations would have poured in upon his 

 mind. His hypothesis, as I have said, was natural 



