STUDIES ON FERMENTATION. 211 



again show the remarkable extent to which the forms of a 

 particular organism may be varied by changes in composition 

 of the nutritive medium : — 



On August 6th, 1873, we took some of the ferment 

 saccharomyces pastoriamis from a flask of wort that had under- 

 gone fermentation, and sowed a scarcely perceptible quantity 

 of it in another flask containing a saline medium, composed as 

 follows : — 



Water containing about 10 per 



cent, of sugar-candy . . . . 150 c.c. (5j fl. oz.) 



Ash of yeast . . . . . . 0'5 gramme (8 grs.) 



Ammonic bitartrate . . . . 0'2 „ (3 grs.) 



Ammonic sulphate . . . . 0*2 „ (3 grs.) 



In the course of the following days the ferment began to 

 develop, although with difiiculty, the fermentation revealing 

 itself by collections of bubbles appearing here and there on 

 the surface of the liquid. We left the flask undisturbed till 

 the 25th of November following. On that day we found a very 

 white deposit of ferment covering the yeast-ash that had not 

 been taken into solution, and a ring of aerobian ferment on a 

 level with the surface of liquid ; all the sugar had disappeared ; 

 the liquid contained 5 '2 per cent, of alcohol, by volume, at a 

 temperature of 15° C. (59° F.) ; and, lastly, in consequence of 

 the purity of the materials employed, there was no trace of the 

 formation of fungoid growths, whether of mycoderma vini or of 

 mycoderma cerevisiw, on the surface of the liquid, or of vibrios or 

 lactic-ferment below the surface. 



Thus then we see — and several other examples throughout 

 this work confirm the fact — that saccharine liquids holding 

 mineral salts in solution are as capable of complete fermentation 

 as any media of natural composition. It is true that ferment 

 develops slowly and with dijficulty in them, and at times takes 

 on rather curious forms, but, nevertheless, it does develop in 

 the media and carry on a fermentation in which not the 



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