248 PRESENT POSITION OF 



attention to this difficulty, in the discussion following the 

 reading of the paper, Van Laer was unable to defend his 

 position. Finally, I may also mention here my experiments 

 described above, in which it was shown that there are cases 

 in which low-fermentation yeasts, each of which, when used 

 alone, gives an excellent product ; but which, when mixed, 

 may give rise to diseases in beer. Similar results were 

 obtained by Jorgensen in his experiments with some high 

 fermentation yeasts. On the other hand, it is a universally- 

 known fact that a good product can, in many cases, be ob- 

 tained by means of a mixture of several species of yeast. 

 An intelligent director of a large brewery in Austria told 

 me, some years ago, that he had noticed that he obtained 

 the best beer when the bacteria were not over scarce 

 in his pitching yeast. Before I introduced pure culture, 

 mixtures were, indeed, employed everywhere. The point 

 is, therefore, not whether mixtures can or cannot be used, 

 but whether a single species can effect the desired fermen- 

 tation ; if this should prove to be the case, this method is 

 the most rational, the simplest and the safest ; in this alone 

 lies the real advance. 



The untenable points in Van Laer's arguments were 

 opposed especially by W. R. Wilson, Miller, Hyde and 

 Jorgensen. As early as 1892, Wilson stated ('The Brewers' 

 Journal,' p. 527) that he had obtained the most satisfactory 

 results at Messrs. Combe & Co.'s brewery, London, by the 

 employment of a pure culture of a single selected species. 

 He subsequently stated that pure yeast was employed 

 throughout the whole of the brewery, one species being 

 employed for running ales, porters and stouts, and another 

 species for pale ales. He specially emphasises the fact 

 that a normal after-fermentation was obtained. He cul- 

 tivates his yeast in a propagating apparatus which is con- 

 structed essentially on the model devised by Kiihle and 

 myself, but modified in some respects. The manager of the 



