FERMENTATION 21 



into a resting stage, and while in this condition will withstand con- 

 ditions which quickly kill them in the vegetative stage. Eleven 

 years later Cohn of Breslau carefully investigated organisms in this 

 resting or spore stage, and today forms of microorganisms are known 

 which will withstand boiling water for sixteen hours without being 

 killed, and others resistant enough even to endure for many hours a 

 10 per cent, solution of carbolic acid. 



Fermentation. Since the dawn of history man has been interested 

 in that wonderful process known as fermentation, and although 

 many an ingenious theory has been formulated to explain it, little 

 more than theory existed until the classic w r ork of Pasteur on fer- 

 mentation appeared about 1837. Pasteur claimed that all forms of 

 fermentation were due to the action of microscopic organized cells. 

 An idea such as this, even at this late date, did not go unchallenged, 

 for we find no less illustrious workers than Helmholtz and Liebig 

 opposing it. Liebig scoffed at such an idea, writing: "Those who 

 pretend to explain the putrefaction of animal substance by the 

 presence of microorganisms reason very much like a child who 

 would explain the rapidity of the Rhine by attributing it to the 

 violent motions imparted to it in the direction of Burgen by the 

 numerous wheels of the mills of Venice." 



However, Pasteur's carefully planned experiments soon demon- 

 strated that without the microorganisms there would be no fermen- 

 tation, no putrefaction, no decay of any tissue, except by the slow 

 process of oxidation. The care with which his experiments were 

 planned and executed are well shown in the experiments with grape 

 sugar, concerning which he wrote: "I prepared forty flasks of a 

 capacity of from two hundred and fifty to three hundred cubic 

 centimeters and filled them half full with filtered grape-must, per- 

 fectly clear, and which, as is the case of all acidulated liquids that 

 have been boiled for a few seconds, remains uncontarninated, 

 although the curved neck of the flask containing them remains 

 constantly open during several months or years. 



" In a small quantity of water, I washed a part of a bunch of 

 grapes, the grapes and the stalks together, and the stalks separately. 

 This washing was easily done by means of a small barber's hair- 

 brush. The washing- water collected the dust upon the surface of the 

 grapes and the stalks and it was easily shown under the microscope 

 that this water held in suspension a multitude of minute organisms 

 closely resembling either fungoid spores or those of alcoholic yeast, 

 or those of Mycoderma rini, etc. This being done, ten of the forty 

 flasks were preserved for reference; in ten of the remainder, through 

 the straight tube attached to each, some drops of the washing-water 

 were introduced; in a third series of ten flasks a few drops of the 

 same liquid were placed after it had been boiled; and finally in the 

 ten remaining flasks were placed some drops of grape-juice taken 



