322 MICRO-ORGANISMS AND FERMENTATION. 



The attenuation during the primary and secondary fer- 

 mentation with normal wort and in the same brewery is 

 stronger with Race I. than //. 



With regard to the finished beer, similar differences are 

 noted, particularly regarding flavour and resistance to tur- 

 bidity. Most experts prefer //. for flavour, but some difference 

 of opinion exists. It is otherwise regarding the stability of 

 the beer, especially with regard to yeast turbidity. In this 

 respect the difference is very marked. /. gives a quite ex- 

 ceptionally stable beer, and is specially suitable for export 

 beer, which when fermented with this yeast remains unaltered 

 for about a month without any further treatment, and by mild 

 pasteurisation is rendered stable for much longer periods. 

 Race II., although it displays much finer phenomena during 

 the primary fermentation, is unable to produce completely 

 stable beer (about ten days in bottles at room temperature), 

 and it is also noteworthy that this race is much less resistant 

 to wild yeast than /. On account of the rapid clarification 

 and quick fermentation of the liquor this race is adapted for 

 beers which are to be stored for a short time, and are to 

 be consumed immediately. 



In general, it may be stated that the whole of the differences 

 indicated have been observed for years in different breweries, 

 and that they are so sharply defined that every brewer could 

 at once distinguish the two yeasts with certainty when they 

 have been put into the fermenting vessel, and could foretell 

 the nature of primary and secondary fermentation. In fact, 

 no one could be in doubt that we are dealing with two truly 

 distinct races or species. 



In the detailed descriptions of these two races (see Figs. 59 

 and 60), published by Hansen in 1888 (which might equally well 

 have appeared before the author's publications, as will be seen 

 from the preceding historical description), the characteristic 

 distinctions between these two species are further emphasised. 

 Amongst other observations, reference is made to the giant 

 cells, remarkable and abnormal large round cells which suggest 

 the cells of Mucor yeasts. 



In 1908 Hansen described further typical differences, and 

 gave the species the names 8. Carlsbergensis and S. Monacensis. 



