PRODUCED BY ALCOHOLIC FERMENTS. . : 201 



those mentioned, and which can also produce Dangerous 

 effects. A careful cleansing of the pipes leading into the 

 lager cellar, and a frequent pitching of the lager casks, is 

 therefore, and always remains, of the greatest importance. 



When the infection was not great, it had no influence on 

 good beer which was bottled in the ordinary way. Indeed, 

 comparatively very large quantities of Sacch. Pastorianus III. 

 could be added to such beer without producing any disease 

 whatever. The addition of one drop of the other species of 

 disease yeast, of a thin consistency, to 350 cc. of lager beer 

 produced faint yeast turbidity, but this was the case only 

 when the yeast consisted of young vigorous cells. 



The main rule is, that both species are dangerous when 

 present at the commencement of the primary fermentation, 

 and, in fact, only at this stage. In all cases, Sacch. ellip- 

 soideus II. was found to be the stronger of the two species. 

 The varying results which the same infection may produce 

 have already been mentioned. 



In recent years the above-mentioned wild yeasts have 

 been observed by Lasche in Chicago, and by Kokosinski in 

 Lille. These investigators have proved that they produce 

 similar ill-effects in the low-fermentation beers of North 

 America and France, as in those of Denmark and Germany. 

 In one of the following chapters we shall become acquainted 

 with other species which also produce yeast turbidity in beer. 

 The two species mentioned in this chapter I regard as 

 especially dangerous in this respect, and this is particularly 

 so in the case of Sacch. ellipsoideus II. 



Saccharomyces exiguus. 



From the above historical survey we perceive that, after 

 the publication of Reess's investigations on the alcoholic 

 ferments, there was a tendency to attribute to Sacch. exigmis 

 the irregularities which can occur in the fermentation, when 



