SYSTEMATICALLY SELECTED YEASTS. 17 



which were raised in England against pure culture in its 

 simple form, Professor Delbriick, of Berlin, was also led to 

 the view that, in the case of the low fermentation beers of 

 Germany, which undergo a vigorous after-fermentation and 

 which have a high reputation for stability, a single species of 

 yeast would not be able to effect the whole fermentation, but 

 that one or more special secondary yeasts would be neces- 

 sary. At his suggestion, Dr. P. Lindner and Dr. Schonfeld 

 undertook to visit various breweries in order to settle this 

 question. " After that," he says, " I had to acknowledge that 

 this question was answered in the negative." His two asso- 

 ciates visited breweries where beers of various ages four 

 weeks, eight weeks, three months, and even six months old 

 were placed at their disposal, and samples were taken at all 

 these different stages in order to ascertain "the point at 

 which the new fungus developes." It was proved, however, 

 that there are breweries where a " pure " after-fermentation 

 occurs in spite of its being prolonged, and where the whole 

 fermentation is effected by the primary yeast. Delbriick 

 concludes his remarks as follows : " The assumption which I 

 made, that eventually we should also have to furnish pure 

 cultures of secondary yeasts, thus falls through at any rate 

 in the case of low-fermentation beer." On a subsequent 

 occasion he stated that single yeast fermentation is also 

 successfully adopted in top fermentation breweries in 

 Germany.* 



It was especially due to Jacobsen's influence that my 

 practical experiments became known in a very short time 

 both in my own country and abroad ; they were, however, 

 for the most part regarded with mistrust, even by intelligent 

 brewers. This opposition would have been sufficient to delay 

 progress for several years had not Aubry worked with vigour 

 and ability from the very commencement. To him is due 

 the honour of having introduced the reform into Germany. 

 * Wochenschrift f. Brauerei, 1894, p. 759, and 1895, p. 2. 



