PRODUCED BY ALCOHOLIC FERMENTS. 209 



and E, the latter species alone ; they had in all cases gone through a 

 primary fermentation in the fermenting cellar. The conditions were, 

 therefore, similar to those obtaining in practice. 



When this beer had been two and a quarter months in the lager cellar 

 a considerable number of bottles were filled from each cask. The beer 

 was bright in each case, and contained no sediment. Experts who tasted 

 the samples were generally inclined to pronounce the beer from all the 

 casks as faultless ; only in the case of the bottles containing the beer 

 from C, in which the infection consisted entirely of Sacch. Pastorianus I., 

 was a faint disagreeable bitter taste noticed by most. The infection had, 

 therefore, in this respect little or no effect, and the same holds good for the 

 stability of the beer. After the bottles had stood at the ordinary room-tem- 

 perature for twenty-one hours, there were still no signs of yeast turbidity. 



IV. Series of Experiments. The method adopted was the same as 

 in the last series of experiments. The beer was of the same character, 

 and was taken at the same stage, namely, at commencement of storage. 

 In this case, however, to each quantity of seventeen liters was added 

 10 cc. of yeast of fairly thin consistency, and which consisted of a vigorous 

 growth of Sacch. Pastorianus I. produced by twenty-four hours' cultiva- 

 tion in wort. The temperature of the lager cellar was 2*5 C. 



After about three months' storage, and after the beer had been bottled, 

 both the infected and the uninfected were bright and free from sediment ; 

 the taste and odour were good in both cases, and also as regards stability 

 no difference could be detected; after standing fourteen days under the 

 conditions mentioned above, no signs of yeast turbidity were perceptible. 



The following examples will serve to illustrate the experi- 

 ments which were carried out with a view to ascertain the 

 effect of infection occurring at the end of the storage period. 



V. Series of Experiments. Nine bottles of lager beer were infected 

 with Sacch. Pastorianus /., as follows : three of them with one drop each 

 of the yeast, two with three drops, and four with I cc. each. The yeast 

 consisted of a young vigorous growth cultivated in wort, and was of a 

 very thin consistency. Three uninfected bottles served as a control. In 

 other respects the method was the same as before. 



The bottles which had been infected with one and with three drops 

 showed no signs of yeast turbidity after fourteen days, and the taste and 

 odour of the beer was as good as at the commencement of the experiment; 

 the beer, in fact, was the same as that in the control bottles. The four 

 bottles which had been very strongly infected, namely, with i cc. of the 

 yeast, were cloudy after only four days; the beer, however, had only 

 acquired a faint indication of the bitter taste. 



VI. Series of Experiments. After the beer of the second series of 

 experiments was drawn off from the casks, which had been about two 



P 



