I 5 6 "DISEASES" OF BEER, 



CHAPTER VI. 



INVESTIGATIONS ON THE "DISEASES" OF BEER, 

 PRODUCED BY ALCOHOLIC FERMENTS. 



1892. 



i. INTRODUCTION. 



MY first memoir on this subject was published in the Trans- 

 actions of the Carlsberg Laboratory, vol. ii., No. 2, 1883. 

 The division of my researches on the organisms of fermenta- 

 tion into two series had not then been introduced, and thus 

 it is that this memoir appears amongst my ' Researches sur 

 la physiologic et la morphologic des ferments alcooliques,' 

 although, from the matter which it contains, it belongs rather 

 to the new series which I commenced publishing in 1888 under 

 the title 'Untersuchungen aus der Praxis der Garungsindustrie.' 

 In 1884 I published in the ' Zeitschrift fiirdas ges. Brauwesen ' 

 a short account of some new studies in the direction indicated. 

 This paper, however, contained only the main results of 

 my experiments carried out at that time, and I promised to 

 give a more detailed account later on, and at the same time 

 to discuss the different sides of the question. I have since 

 continued these investigations at intervals, and have carried 

 out more than fifty series of experiments. I believe they are 

 now completed, at least for the present, and in publishing the 

 results I have attempted to fulfil the promises given in the 

 two preliminary communications mentioned. 



Those of my researches which have a direct bearing on 

 the fermentation industry may be grouped around the three 

 main questions, namely : the question of the diseases of beer, 

 the question of the pure cultivation of yeast, and the question of 



