STUDIES ON FERMENTATION. 57 



before our experiment, remained as free from change as the 

 flasks of our first series had done. 



Lastly, our fourth series of flasks, containing the drops of 

 juice taken from inside the grapes, remained equally free from 

 change, although we could not be certain of having removed, in 

 every case, without exception, all causes of error which must 

 inevitably occur sometimes in so delicate an experiment. 



These experiments cannot leave the least doubt on our minds : 



That must, if boiled, will never ferment when in contact with 

 air that has been freed from the germs which exist in it in a 

 state of suspension. 



That must may be fermented, after boiling, by introducing 

 into it a very small quantity of water, in which a bunch of 

 grapes has been washed. 



That must will not ferment if we introduce into it some of 

 this same water which has been boiled and afterwards cooled. 



That must will not ferment if we introduce into it a small 

 quantity of the juice contained in a grape.* 



It follows, then, that the ferment which causes grapes to 

 ferment in the vintage tub must come from the exterior, and 

 not the interior of the grapes. Thus, the hypothesis of 

 MM. Trecul and Fremy, according to which albuminous 

 substances transform themselves into grains of yeast by the 

 action of a peculiar vital force, is annihilated ; a fortiori, there 

 can no longer be a question concerning Liebig's theory, on the 



* The experiments that we have described give rise to a useful remark. 

 All the organic liquids, boiled or not, in the course of time must take up 

 oxygen from the air. At the same time, and certainly under this influ- 

 ence, they assume an amber or brownish colour, but this eflfect is only 

 produced when the liquids are placed under conditions of unalterability. 

 Should fermentation or the development of fungoid growths be possible, 

 scai'cely any change of colour will take jDlace. Doubtless this non- 

 coloration may be attributed to the fact that these organisms consume 

 the oxygen necessary for coloration. In these experiments on must, all 

 the unchanged flasks assumed a pale yellowish brown colour ; those 

 which fermented or contained fungoid growths remained colourless, or 

 nearly' so. 



