48 MICRO-ORGANISMS AND FERMENTATION. 



were the yeast-like cells. HOLM did not find any growth of 

 Saccharomycetes ; yet some Torula forms and Mycoderma 

 occurred. 



The number of these germs varied according to the different 

 times of the year, yet did not seem to be dependent on the 

 seasons, the rain-fall, etc., and the condition of the surface 

 water had great influence. As being of practical importance 

 we may mention the discovery of strong contamination 

 injurious to wort and beer, in reservoirs situated near granaries 

 and malt-lofts and not sufficiently protected against the dust. 

 It was also shown that water which had been filtered through 

 charcoal filters contained much larger numbers of wort bacteria 

 than the unfiltered water. 



The water analyses made in the author's laboratory during a 

 period of more than ten years have given the following chief 

 results : The water samples in very few cases were found to 

 contain Saccharomycetes (culture-yeasts or wild yeasts). In one 

 series of analyses species of Saccli. anomalus and S. membranae- 

 faciens were met with. The bacteria noted by HOLM which 

 produced slime-formations or imparted a putrid smell to the 

 wort, occurred very frequently. If a pure yeast was infected 

 with such species and used for pitching hopped wort, these 

 bacteria did not usually develop further. Although, however, 

 the bacteria did not develop during the fermentation, a differ- 

 ence was often observable between the condition of this beer 

 and that of the beer fermented with pure yeast. Acetic acid 

 bacteria were not infrequently found in the analyses, and were 

 usually able to assert themselves in the flasks, even in competi- 

 tion with rival species. In a few cases the experiments with 

 wort showed a growth, and sometimes even an abundant one, of 

 Sarcina forms, which did not occur in the parallel series with 

 sterile beer. They rendered the wort turbid and imparted a 

 peculiar smell to it. Among the moulds the following were 

 the most frequent : Penicillium, Aspergillus, Mucor stolonifer, 

 M. Mucedo, O'idium lactis and Dematium-like forms. In the 

 water conduits of the breweries a coherent layer of Orenothrix 

 was often found. 



It has been proved in many cases that water received a very 

 considerable contingent of its wort and beer organisms in the 



