266 MICRO-ORGANISMS AND FERMENTATION. 



use of this knowledge, and only employ pitching-yeasts 

 which do not show the characteristics mentioned above for 

 injurious species which so frequently and actively exert a 

 disturbing influence in the brewery. This, .however, will 

 only be possible when yeast-cells endowed with the properties 

 of normal bottom-yeast are isolated from the ordinary brew- 

 ing yeast, and further cultivated with the exclusion of every 

 contamination ; in other words, when only pure cultivated yeast 

 is employed in the brewery. HANSEN is entitled to the 

 greatest praise in this particular direction, since he has 

 pointed out a way and devised a method which enabled him 

 to attain the desired end. The far-reaching results which 

 were obtained in Old Carlsberg with pure cultivated yeast 

 have already caused many other breweries to employ only pure 

 cultivated yeast, and the results in general have given satis- 

 faction when varieties of normal bottom-yeast were chosen 

 which corresponded with the requirements as regards attenua- 

 tion and taste. 



" It is to be hoped, therefore, that the value of pure cul- 

 tivated yeast may be recognised in ever-increasing circles, 

 and many old prejudices regarding the yeast overcome ; also 

 that the smaller breweries, which have besides many difficulties 

 to contend with, will not resist the conviction that a number 

 of calamities may be avoided by the introduction of pure culti- 

 vated yeast into an otherwise well-conducted brewery. The 

 amount expended will yield a liberal interest." 



Dr. REINKE, who is at the head of the experimental brewing 

 station of the Royal Agricultural College in Berlin, made the 

 following significant statement of the situation in 1888: l 



" Without the exact study of HANSEN'S pioneer investiga- 

 tions, and without their utilisation, no one at the present time 

 is able to permanently survive the competition in the brewing 

 industry. HANSEN'S researches have brought about a revolu- 

 tion in the brewery, especially with regard to the treatment of 

 the yeast." 



Professor BELOHOUBECK, of the Bohemian Polytechnic at 

 Prague, says in his well-known biography of Hansen, 1889: 2 



1 Chemilcer-Zeitung, 29 Dec., 1888, p. 1749. 

 *Zeitschrift f. d. ges. Brauw., Munich, 1889, p. 505. 



