270 MICRO-ORGANISMS AND FERMENTATION. 



forms, differing indeed but little amongst themselves in shape, 

 but possessing very distinct properties, more especially in 

 respect of the nature of certain minute quantities of secondary 

 products to which they give rise, and which are highly 

 important as giving particular characters to the beers pro- 

 duced. HANSEN has shown how these various kinds of yeast 

 may be grown or cultivated in a state of purity even on the 

 industrial scale, and has in this manner revolutionised the 

 practice of brewing on the continent. For during the past 

 few years these pure yeasts, each endowed with particular 

 properties, have been grown with scrupulous care in labora- 

 tories equipped expressly for this purpose, and these pure 

 growths are thence despatched to breweries in all parts of 

 the world, particular yeasts being provided for the production 

 of particular varieties of beer. In this manner scientific 

 accuracy and the certainty of success are introduced into an 

 industry in which before much was a matter of chance, and 

 in which nearly everything was subordinated to tradition and 

 blind empiricism." 



In top-fermentation the system was founded on the theoretical 

 and practical studies of the author, and has now been intro- 

 duced into all countries. After its adoption by various 

 American and Australian breweries, worked on the English 

 system, W. K. WILSON succeeded (1892) in carrying out this 

 important reform in a London brewery (Messrs Combe & Co.), 

 both primary and secondary fermentation being effected by 

 a single selected species of yeast. According to the reports in 

 English journals numerous breweries in Great Britain have 

 successfully adopted HANSEN'S system of pure cultivated yeast. 



The following is taken from a report by J. C. MACCARTIE of 

 Melbourne : l 



" The Burton yeast 2 yields a mild ' round ' flavoured beer of 

 great brilliancy and stability, and one that is excellently suited 

 for bottling. I now come to a matter that should be of 

 interest to your readers. Mr. DE BAVAY and I read with some 

 astonishment the statements made by certain scientific gentle- 



1 The Brewers' Journal, 1889, No. 291, p. 489. 



2 A " Burton " species obtained in pure cultivation in the author's laboratory 

 from English yeast. 



