244 MICRO-ORGANISMS AND FERMENTATION. 



We now return to the epoch-making researches of Pasteur, 

 He proved in the clearest and most unmistakable manner in 

 his Etudes sur la biere what power is possessed by microscopic- 

 life, and he strongly emphasised the fact that bacteria may 

 have a far-reaching influence on the course of alcoholic fer- 

 mentation and on the character of the beer. The budding 

 organisms were dealt with in a similar way. He indicated that 

 certain fungi of this group, which are not described in detail, 

 may react in different ways on the products of fermentation, as 

 Bail had previously experienced. Pasteur's communications r 

 however, only traversed the nebulous views of his predecessors, 

 and his assumptions led to two opposing lines of thought. 

 This is seen, for instance, in his observations on the so-called 

 cheesy and at'robiotic yeast. It is possible that we have to- 

 do in this case with independent and peculiar types of yeast,, 

 but it is also possible that we are dealing with forms which 

 are brought about by a particular treatment of the usual 

 brewery yeast. It should not, however, be overlooked that 

 he himself indicated the direction in which the solution of the 

 question must be sought viz., that it was at the time impos- 

 sible to determine whether one or more species was present ; 

 an exact method for the pure culture of yeast species had not 

 been discovered. Thus a true orientation ' in the world of 

 micro-organisms cannot be found in his work. It was im- 

 possible at any point in Pasteur's thesis to find characters 

 described for the budding fungi that would enable an analysis, 

 to be based upon them. He believed that all budding fungi 

 may to some extent possess the power of bringing about 

 alcoholic fermentation like the Saccharomycetes. It is never 

 possible to tell whether he is referring to true Saccharomycetes 

 or to other budding fungi. Pasteur did not differentiate- 

 between the several kinds of budding fungi (Saccharomycetes, 

 Torula, Dematium, etc.). 



Pasteur took the standpoint that every individual fer- 

 mentation, lactic, butyric, acetic acid, etc., is produced by a 

 particular exciter of fermentation. It was only when the 

 technique of pure cultivation had been further developed that 

 an explanation of the true connection was possible viz., that 

 each one of these processes must be carried out by different 



