STUDIES ON FEKMENTATJON. 31 



frequently troubled us in our experiments, we might banish it 

 or minimize it by some new arrangement ; but this is unneces- 

 sary. We have suffered no inconvenience from this cause, as 

 there does not exist in the atmosphere anything like a con- 

 tinuous supply of that from which the so-called spontaneous 

 generation arises, as was erroneously believed to be the case 

 before the publication of our Memoir in 1862, to which we 

 have already alluded. 



The following are the results of the experiments conducted 

 in the manner just described. 



The yeast which we sowed, in ever so small a quantity, 

 seemed to acquire vigour, to bud, and to multiply. Soon, that 

 is to say in the course of twent^^-four or forty-eight hours or 

 longer, according to the temperature, and, more especially, the 

 degree of vitality in the globules, we found that the sides of our 

 flasks were covered with a white yeasty deposit, and noticed on 

 the surface of the liquid a fine froth, which at first appeared 

 like little islets formed by groups of bubbles so minute that they 

 would have been imperceptible had they not been joined to- 

 gether. These patches increased in size, and gradually attached 

 themselves to each other, finally forming a thick froth. In the 

 course of two or three days this froth fell, the fermentation pro- 

 ceeded less rapidly, and then ceased completeh'. The beer was 

 finished. This beer might be preserved for an indefinite period 

 in the flask without undergoing any change. The external air 

 passes freely into and out of the flask, as the pressure of the 

 atmosphere and the temperature vary, and the beer in the 

 course of time becomes flat ; it acquires age in much the same 

 manner as wine does, but it never contracts any taste of disease, 

 it never becomes sour, or sharp, or bitter, or putrid ; it does not 

 even become covered with mycoderma vini as is usually the 

 case with all beer exposed to the common air in the course of 

 trade. 



After some weeks, or perhaps months, a white ring may show 

 itself on the surface of the liquid on the glass. This is a crown 

 formed by a mass of young yeast globules, which grow there 



