PRODUCED BY ALCOHOLIC FERMENTS. 205 



In addition to the Sacch. exigtms which I have mentioned 

 above, there are, as I have pointed out on different occasions, 

 several other species of wild yeasts which can grow freely in 

 wort, but which produce no disease in beer. The same holds 

 good also for several bacteria. 



My experiments described above were carried out with re- 

 ference only to the practical points in question, and, regarded 

 from this point of view, they show that the addition of Sacch. 

 exiguus is without influence. If we were to follow out the 

 question of competition from a theoretical standpoint, we 

 should find, however, that Sacch. exigmis is not absolutely 

 without effect. In several experiments, for instance, I noticed 

 that the addition of this species in larger proportion had a 

 retarding influence on the attenuation during the early stages 

 of the fermentation, as compared with the result when the 

 brewery yeasts are alone present. 



Disagreeable Odour and Taste prodiiced in Beer by 

 Sacch. Pastorianus I. 



The main result indicated in the above heading was pub- 

 lished very briefly in the * Zeitschriffc fur das ges. Brauwesen,' 

 in 1884, and I then promised a more detailed account of my 

 investigations. This will be given in the following pages, 

 together with an account of some more recent experiments. 



In the preliminary notice mentioned I stated that, in 

 1883, the beer of the Old Carlsberg brewery was attacked by 

 a disease which communicated a disagreeable bitter taste and 

 an unpleasant odour to it. Some beer experts designated 

 the taste and odour as smoky ; all agreed that the beer had 

 suffered. By separating the yeast into its constituent species, 

 I succeeded in isolating four. In the experiments which I 

 made with these in flasks of wort, only one of them gave a 

 beer of good taste and odour ; this was the species to which I 

 gave the name Carlsberg bottom yeast No. i, and which 



