306 ROMANCE OF LOW LIFE AMONGST PLANTS. 



It is not enough that in one or two cases we find 

 quantities of these bodies present when alcohol or 

 saccharine matter is converted into vinegar ; the 

 question is, are they always present, and do they 

 seem to be the particular agents by which the 

 vinegar-making is carried on ? When vinegar is 

 obtained from a saccharine solution, the cane sugar 

 is converted into grape sugar, the grape sugar into 

 alcohol, and the alcohol into vinegar. Thus the 

 vinegar-plant appears to perform the double function 

 of first alcoholizing and then acetifying the solution. 

 Do the yeast-like cells accomplish one portion of 

 this task, and the bacterium bodies the other? The 

 mycoderm of wine does not in its ordinary state give 

 rise to vinegar. Its own vital processes merely supply 

 the means by which the changes incidental to vinous 

 fermentation take place, but it occasionally happens 

 that brewers are greatly teased by the acetous fei-- 

 mentation of their beer occurring after the alcoholic 

 change has finished. I have heard of several instances 

 this summer in which great annoyance has been 

 experienced from this cause, and it would seem either 

 that spores of the vinegar-plant were diffused to a 

 greater extent than usual, or that portions of yeast 

 remaining in the beer had developed into the vinegar- 

 plant form. M. Pasteur's view of fermentation does 

 not coincide with the common statement that the 

 yeast-plant merely separates sugar into carbonic acid 

 and alcohol — at any rate he does not represent that 

 as the entire process, because he tells us that when 

 experiments were performed in close vessels contain- 

 ing, besides the fermenting liquid, a known quantity 



