WHAT IS THE PURE YEAST OF PASTEURf, 155 



to purify the brewery yeast (purification des levures), not, 

 however, to prepare a true pure culture from it. 



From my standpoint, on the other hand, the alcoholic 

 ferments play a chief part. Since I showed, in 1883, that 

 some of the commonest and most dangerous diseases of low- 

 fermentation beer are not caused by bacteria, but by certain 

 species of the Saccharomycetes t it followed that a purifica- 

 tion of the yeast, such as that proposed by Pasteur, would 

 not lead to the end in view, but that a true pure culture was 

 necessary. And since a careful study of the Saccharomycetes 

 led me to the conclusion that the views of my predecessors 

 in this field were incorrect, and that, for instance, the 

 systematic name Sacch. cerevisice included a whole series of 

 species and races of high and low yeasts differing widely in 

 their action, it followed further that it did not merely suffice 

 to prepare a pure culture, but that, in order to satisfy the 

 different conditions required in the manufacture of the various 

 kinds of beer and wine, and also of spirit and bakers' yeast, 

 a systematic selection of the most suitable species or race 

 must be made. In this way I was led to introduce into the 

 fermentation industries the same principles which have long 

 been adopted in horticulture and agriculttire for the cultivation 

 of the higher plants. 



Starting as I did from a different point of view and with 

 different methods from those of my famous predecessor, the 

 results were of necessity also different. In my writings, I 

 have often emphasised the great importance of Pasteur's 

 1 Etudes sur la biere ' in relation to my researches, and I again 

 gratefully acknowledge it. On the other hand, I cannot help 

 protesting against the attempts made in France to check 

 development, and to bring everything back to the standpoint 

 of 1876, for this is antagonistic to all progress. If the famous 

 teacher of my opponents had continued his studies in this 

 field, he would himself have carried them much further. 



