202 "DISEASES" OF BEER, 



the beer refuses to clarify, when it becomes cloudy with 

 suspended yeast after storage, or when it acquires a dis- 

 agreeable taste. As stated, no experiments were under- 

 taken, but a simple microscopic examination was made to 

 suffice. The small yeast cells which could be detected in 

 such bad beer were definitely stated to belong to Reess's 

 Sacch. exiguus, and this micro-organism was assumed to be 

 the cause of a whole series of different maladies. At that 

 time it was not known that all, and every one of the Saccharo- 

 mycetes can develop cells which might be regarded as belong- 

 ing to Reess's Sacch. exiguus. 



If, with the knowledge which we now possess, this sys- 

 tematic name is to be still retained, it must be applied to 

 the species which I have described in my treatise 'Action 

 des ferments alcooliques sur les diverses especes de sucre ' 

 (' Compte-rendu des travaux du laboratoire de Carlsberg,' 

 torn. ii. livr. 5, 1888). With this species I carried out some 

 experiments of which the following will serve as examples. 



I. Series of Experiments. Three vessels, A, B and C, in the ferment- 

 ing cellar of the Old Carlsberg brewery were charged with \\ hectoliters 

 of wort of 14*3 percent. Balling. They were the wooden fermenting 

 vessels mentioned in the last section. 



A was pitched with 400 grams of Carlsberg bottom yeast No. 2. 



B 350 ,, No. 2, 



and 75 grams of Sacch. exiguus. 



C ,, 400 grams of Carlsberg bottom yeast No. 2. 



In all cases the yeast was moderately thick and consisted of young 

 vigorous cells which had been grown at about 10 C. The temperature 

 of the wort at pitching was 7 ' 5 C., that of the fermenting cellar during 

 the whole experiment was 8-9 C. After seven days the extract in A 

 was 7*37, in B 7*45, and in C 7*21 per cent. Ball. The beer clarified 

 well in all three vessels, the odour and taste were also faultless and alike 

 in all the beers. 



The beer from each fermenting vessel was run into two similar casks, 

 and into one of those filled with beer from C was introduced 1 5 grams, 

 and into the other 30 grams, of Sacch. exiguus of a thick consistency. 

 All the casks were then placed in the lager cellar, the temperature of 

 which was 0-5-2 "5 C. 



After three months' storage some of the beer from each cask was 



