STUDIES ON FERMENTATION. 25 



The resemblance between these fihiments and those which, in 

 considerably smaller proportion, accompanied the globules of 

 alcoholic ferment in our preceding observations, the change 

 in the beer, which was almost as bad as beer could possibly be, 

 along with an abundance of filaments, and the change, to 

 a minor extent, in that beer which only jaresented a few 

 filaments in a field of the microscope, impressed those managers 

 of the brewery who were present with an entire belief in the 

 theory which we had been endeavouring to impress on their 

 minds concerninsr the causes of the badness of their beer. 

 Some eight days afterwards we paid another visit to this same 

 brewery, and learnt that the directors had lost no time in 

 acquiring a microscope, and in procuring changes of yeast for 

 all the varieties of beer, which they had put in working since 

 our first visit. 



There are some periods of the year — early spring, summer, 

 and autumn, for instance — when the working of a brewery 

 is a matter of great difiiculty. The preservation of yeast 

 becomes a subject requiring the most delicate treatment, in 

 consequence of the increase in the temperature. In the early 

 part of autumn the most important ingredients used in brewing 

 are of inferior quality ; the deteriorating influences which have 

 been at work have covered them with a variety of parasites. 

 All these circumstances contribute to facilitate the development 

 of diseased ferments. 



i:^ II. — The Absence of Change in Wout and Beer Coincides 

 WITH the Absence of Foreign Organisms. 



The method which we have just pursued in demonstrating 

 the existence of a relation between the diseases of beer and 

 certain microscopic organisms can scarcely leave a doubt, it 

 seems to us, as to the correctness of the principles which we are 

 advocating. In every case where the microscope reveals in a 

 yeast, especiall}^ a yeast which is in a state of activity, products 



