126 YEAST IV 



tenable, the fact that the Toridm are alive, and 

 that yeast does not excite fermentation unless it 

 contains living Toridoe., stands fast. Moreover, of 

 late years, the essential participation of living 

 organisms in fermentation other than the alcoholic, 

 has been clearly made out by Pasteur and other 

 chemists. 



However, it may be asked, is there any necessary 

 opposition between the so-called " vital " and the 

 strictly physico-chemical views of fermentation ? 

 It is quite possible that the living Torula may 

 excite fermentation in sugar, because it constantly 

 produces, as an essential part of its vital manifes- 

 tations, some substance which acts upon the sugar, 

 just as the synaptase acts upon the amygdalin. 

 Or it may be, that, without the formation of any 

 such special substance, the physical condition of 

 the living tissue of the yeast plant is sufficient to 

 effect that small disturbance of the equilibrium of 

 the particles of the sugar, which Lavoisier thought 

 sufficient to effect its decomposition. 



Platinum in a very fine state of division — 

 known as platinum black, or noir de platine — has 



circumstantiality worthy of the author of GulUv'rs Travels. 

 As a specimen of the writer's humour, his account of what 

 happens when fermentation comes to an end may suftice. 

 "Sobald namlich die Thiere keinen Zucker mehr vorfinden, so 

 fressen sie sich gegenseitio: selbst auf, was durch eine eigene 

 Manipulation geschieht ; alles wird verdant his auf die Eier, 

 weiche unverandert durch den Darmkanal hineingehen ; man 

 hat zuletzt wieder gahrungsfahige Het'e, namlich den Saamen 

 der Thieie, der iibrig bleibt" 



