196 " DISEASES" OF BEER, 



been produced under brewery conditions in the fermenting 

 and lager cellars. They were less vigorous than in the pre- 

 vious experiments, and to this I attribute their more feeble 

 action. 



Thus, in the experiments which were undertaken in 

 order to ascertain the effect when the infection occurs at the 

 time of bottling, it was also found that Sacch. ellipsoideus II. 

 was the more vigorous of the two disease yeasts. It was also 

 ascertained that the effect of the infection was more pro- 

 nounced when the yeast consisted of young vigorous cells 

 which had been grown in wort in the course of a few days, 

 than when produced by a protracted fermentation. In order 

 that Sacch. Pastorianus III. may assert its influence it must 

 be introduced into the bottles in quantities which in my opinion 

 are much greater than ever occur in practice. As already men- 

 tioned, the other species behaves somewhat differently. When 

 the yeast of a thin consistency, which was employed for the 

 infection, consisted of young vigorous cells, the introduction of 

 one drop into each bottle was sufficient to cause the beer to 

 become cloudy after fourteen days, whilst the uninfected beer 

 could be kept for about three weeks. A greater degree of 

 infection produced yeast-turbidity more quickly. The species 

 in question is therefore able to cause trouble in practice also at 

 this stage. The development of wild yeasts is promoted by 

 vigorous aeration of the beer whilst it is being drawn off, 

 and also through the bottles being badly corked. Beer which 

 has undergone a feeble fermentation, and which has a high 

 extract, is also more subject to contamination than another 

 beer. This holds good for beer both at the commencement 

 and at the end of the storage period. The slight infection 

 due to atmospheric dust can scarcely acquire any importance 

 in this respect. When beer which has remained sound in the 

 lager casks is attacked by this disease after it has been drawn 

 off, this must accordingly be attributed to the bottles and 

 carnage casks not having been properly cleaned. A slight 



