174 "DISEASES" OF BEER, 



statements in connection with the whole of this subject are full 

 of contradictory views, and must be characterised as an 

 exposition of different possibilities. A scientific conclusion 

 was not arrived at at any point. As a rule he only alludes to 

 previous investigators when he wishes to correct some error in 

 their works ; a historical account of the previous development 

 of the science is not found in his book. Pasteur, however, 

 never undertook to give any such account, and it is, therefore, 

 a great mistake which is often committed to look for such 

 in his work. If we wish to acquaint ourselves with the 

 advance made by investigators prior to Pasteur, we must 

 seek this information elsewhere. 



It is on p. 218 that he expresses himself most clearly with 

 regard to beer diseases caused by alcoholic ferments. He 

 mentions here that in some breweries a lager beer is brewed 

 during the winter months, which is intended for consump- 

 tion in August or September of the following year, and that 

 much anxiety is felt lest the beer acquire a vinous flavour 

 during this long storage period. He writes, " From my 

 observations, the cause of this vinous flavour appears to be 

 due in the main to the brewery yeast being mixed with 

 Sacch. Pastorianus or varieties of this species." Pasteur is 

 thus very cautious in expressing his opinion ; he states 

 nothing definite. Against the supposition of Engel that this 

 disease is caused by Sacch. exiguus, he simply brings forward 

 a new supposition, as we have seen, namely, that it may, 

 perhaps, be another species. Neither Engel nor Pasteur 

 attempted to separate this or other micro-organisms which 

 cause disease from the good brewery yeast in order to prepare 

 beer fermented in the one case with the latter species alone, 

 and in the other case with a mixture of this with the supposed 

 disease yeast. This is, however, the only way in which we 

 can determine on the one hand what disease yeast, and on the 

 other hand, what good brewery yeast is. The reason why 

 neither Pasteur nor any of the previous investigators carried 



