STUDIES ON FERMENTATION. 207 



or have previously existed in the liquid, and that the reason why 

 this germ multiplied so abundantly was because the liquid in 

 question had been peculiarly adapted to the vitality of the plant. 



In a laboratory where alcoholic fermentations are studied, 

 these germs of my coder ma vini exist in great abundance on the 

 surfaces of different objects. This fact admits of easy proof; 

 we have merely to open in such a laboratory some flasks con- 

 taining yeast- water deprived of air, or yeast- water sweetened, 

 or any natural saccharine medium, or any fermented liquid, 

 which till the moment when our flasks were closed had been 

 kept boiling (Chap. IV.) ; it would be a ver}^ rare thing, 

 indeed, if mycoderma vini did not develop in most of these 

 flasks after the air was readmitted, especially if, shortly before 

 this operation, the dust lying on the surface of the tables or floor 

 of the laboratory had been stirred up by dusting or sweeping. 



This series of experiments, the salient points of which we 

 have just given, conducted with a view to ascertain whether 

 yeast could be transformed into mycoderma, has led the way 

 to certain results of special interest, results which concern 

 all alcoholic ferments, and which in all probability will be 

 found in the long run to apply to all aerobian ferments. 



It being necessary for the conduct of our experiments to 

 preserve our yeast in a state of purity for an indefinite period, 

 often for a great length of time, in contact with pure air, 

 we discovered that yeast was possessed of extraordinary 

 vitality, and that it rarely perished completely throughout, 

 inasmuch as we could almost invariably cause it to revive by 

 bringing it into contact with fresh, fermentable liquid. This 

 revival of the yeast — and it is to this point that we are 

 most anxious to direct the attention of our readers — is effected 

 from two distinct sources : — 



1. By those cells of yeast which have not perished. 



2. By cells of new formation. 



We may give an example to explain this more clearly. 

 In one of our two-necked flasks we cause some pure wort to 

 ferment by employing yeast also in a state of purity. Fer- 



