254 SACCHAROMYCETES. 



where the means of research are at hand, afford an easy mode 

 of identifying the species of any particular culture by a compari- 

 son of the figures obtained with those indicated by the curves 

 registered on the standard laboratory charts. By a further deve- 

 lopment of the process, the varieties present in a mixed yeast 

 may be separated and determined — always provided that they are 

 amongst those whose temperatures and periods have been ascer- 

 tained experimentally. 



The technical importance of this knowledge to the trades 

 which depend upon fermentation as their chief process can 

 scarcely be over-rated, though it has borne less fruit in this 

 country than on the Continent, owing to the different lines on 

 which fermentation processes are carried on. Its value hinges 

 on the fact that each variety produces special characters in the 

 liquid in which it has developed, and in which it has converted 

 a greater or less part of the hydro-carbon present into alcohol. 

 Thus, S. Pastorianus 11. (Hansen) produces an intense acrid 

 bitterness in the beer in which it multiplies which is especially 

 dreaded by the German brewers. It is said that the accidental 

 presence of this flavour in the beer of the Carlsberg Brewery in 

 Denmark, and the ability of Dr. Hansen to prove to the pro- 

 prietor, Capt. Jacobsen — a name well known in many scientific 

 circles — that it was due to the presence of this objectionable 

 ferment that first led to the practical introduction of pure cul- 

 tures of yeast — or, rather, of suitable varieties of Saccharomyces — 

 into industrial enterprise on the Continent. 



The result of this new departure fully justified the confidence 

 with which the technologists had urged the attempt. The 

 flavours imparted to the saccharine liquids in -which the fermen- 

 tations were carried on were completely controlled by the variety 

 of yeast-cells furnished from the laboratory, and so perfect has 

 the knowledge of working in this respect now become that pure 

 cultures of various species, mixed in such proportions as to suit 

 the requirements of any particular brewery, are now regularly 

 produced in Continental laboratories in quantity sufficient for 

 ordinary working purposes, each variety having been originally 

 grown from a sitigle cell. Several leading manufacturers have 

 made patient efforts to utilise the application in the brewing 



