STUDIES ON FERMENTATIOX. 61 



alcoliolic fermentation often takes place in liquids that are not 

 exposed to contact with air ; but we sliall prove by experiment 

 that, notwithstanding what may happen duinng fermentation, 

 oxygen has the greatest influence on the readiness with which 

 ferment develops itself, and that this gas is indispensable to the 

 revival of withered cells, and still more so to the germination of 

 special cells, which we may consider to be the true germs of the 

 little plant. 



The advocates of the doctrine of spo7iianeous generation 

 have based most of the objections which they vainly urge 

 against their opponents upon erroneous interpretations of certain 

 facts relating to tlie spontaneous impregnation of organic 

 infusions. Taking a very wrong view of the essential condi- 

 tions of the phenomena, they require that the assertors of the 

 diffusion of the germs of microscopic organisms should be com- 

 pelled to place at any one point of space, so to say, all the 

 germs of the products of infusions ; a demand which really borders 

 on absurdity. They believe, or feign to believe, that we are 

 bound to admit the existence of germs of must in all places and 

 at all times, on the banks of rivers and on the loftiest moun- 

 tains, and so on. " Fermentations," said one of these gentle- 

 men one day, before the Academy, " cannot depend upon chance 

 particles of atmospheric dust. How is it possible that germs of 

 yeast can be present everywhere throughout the universe, ever 

 ready to fall upon must ? " It is an established fact that grapes 

 crushed in any part of the globe whatsoever, even on a glacier or 

 at the highest elevations, can set up a fermentation. The expla- 

 nation of this pretended impossibility is most simple, for we 

 know, from the facts related in the preceding paragraph, that 

 grapes carry on their skins the germs of their own ferments. 



In experiments relating to the kind of organisms which we are 

 discussing we must never fail to take into account the action of 

 the particles of dust spread over the articles that are used. Very 

 often an effect that should be attributed to gferms adhei'lng: to 

 the vessels and utensils used in experiments, the origin of which 

 may be altogether special, is erroneously imputed to the dust- 



