ALCOHOLIC FERMENTS. 185 



washed with water the cell-contents long remain clear, and 

 only slightly granular, and if the yeast be kept for a long 

 time in this way only very few dead cells will be found. 



The gelatine cultures of both species form colonies, having 

 the ordinary appearance of the Saccharomycetes. 



On gypsum blocks the species No. 2 develops spores much 

 more quickly and abundantly than No. 1 species. 



The fermentation phenomena also differ. No. 2 gives 

 thick, high foam and a dense, firm layer on the surface ; No. 1 

 gives a low foam and the liquor is often exposed in places. 

 No. 2 clarifies comparatively quickly ; No. 1 clarifies slowly. 

 No. 2 forms a firm layer at the bottom of the fermenting- 

 vessel, whilst No. 1 gives a fluid sediment. In the primary 

 and secondary fermentations No. 2 gives a more feeble 

 fermentation than No. 1. 



The finished beer obtained with the two yeasts in the 

 same brewery shows marked differences. With regard to 

 taste, the beer obtained with No. 2 yeast is preferred by most; 

 but this is a matter of opinion ; at all events the taste is 

 different in the two cases. Finally the two species give very 

 different results as to the stability of the beers with regard 

 to yeast turbidity. The beer prepared with the No. 1 yeast 

 is decidedly more stable in this respect than that prepared 

 with No. 2 yeast. Consequently No. 1 is especially suited 

 for lager and export beers, and No. 2 for running beers. 

 These characteristics have always been found to remain 

 unchanged for years. 



From the above description of the microscopic relation- 

 ships of these two types of bottom-yeast it must on no 

 account be assumed that we are able, by means of a micro- 

 scopic examination of an unknown species of yeast, to 

 determine whether it will give a high or a low attenuation, or 

 whether it will clarify slowly or quickly, etc., etc. Hansen's 

 investigations have, on the contrary, proved that it is 

 impossible to establish any general rule by this means, since 

 species which give a high attenuation may have the same 



