SYSTEMATICALLY SELECTED YEASTS. V 19 



r^0/ 



hygienic point of view, pure yeast likewise gives greater 

 security than ordinary impure pitching yeast. 



That my work would in many places be misunderstood 

 and meet with failure was easy to foresee. This also occurred, 

 and I have therefore directed special attention to this side of 

 the question, and have carefully noted every case which came 

 to my knowledge. In the lecture which I delivered on June 

 12, 1887, at the General Meeting of the Austrian Brewers' 

 Union, held at Gratz, I dealt in detail with this matter. The 

 following is an abstract of this lecture, with some additions and 

 a few alterations. We shall thus have to speak of the mis- 

 takes and failures in order if possible to make an end of them. 



It is a mistake to assume that pure yeast can do every- 

 thing. On the contrary, it is necessary to point out that the 

 requirements as regards the preparation of the malt, wort, &c., 

 are the same as formerly. If there are defects here, the beer 

 will also be faulty even though pure yeast has been employed. 

 On the other hand, the doctrine more or less openly expressed 

 by some zymotechnologists, even quite recently, is incorrect, 

 namely, that the fermentation is in the main dependent only 

 on the composition of the wort, so that a good malt always 

 gives satisfactory fermentations, favours the development of 

 the desired species of brewery yeast and checks the disease 

 germs, whilst a bad malt on the contrary favours the develop- 

 ment of the latter. The main result of such a doctrine would 

 be that so long as we take care to have a good wort we do 

 not require to trouble much about the character of the yeast. 

 This, however, like a great deal more that has been written 

 on the manufacture of beer, even by distinguished authors, 

 is only conjecture lacking all foundation. Likewise we must 

 not forget that we have no definite chemical knoivledge as to 

 what we are to understand by a good or an inferior malt, by 

 a good or an inferior wort. 



A pure culture which has once been introduced into a 

 brewery will not for ever remain sufficiently pure. The wort 



C 2 



