300 SCIENCE PROGRESS. 



condition favourable for the development of the wild fer- 

 ments. An experiment of this kind thus affords no argu- 

 ment against single race yeasts in general. At the same time, 

 however, it cannot be denied that some varieties possess a 

 greater power of resisting infection than others. This has 

 in fact been shown by Hansen to be the case and Van Laer 

 proves that the same holds good for composite yeasts. 



In conclusion, it cannot yet be claimed that the question 

 of the successful application of pure yeast in English 

 breweries has been definitely solved. In view of the dif- 

 ferent character of the beers produced in different parts of 

 the country, no general conclusions can be drawn until pure 

 yeast has been tried in a considerable number of breweries. 

 At the same time the success of single race yeast in a few 

 breweries is undoubtedly of importance, proving its applica- 

 tion for certain classes of beers, and this result should there- 

 fore encourage many brewers to give the Hansen system a 

 fair trial. 



A. K. Miller. 



