86 RESEARCHES ON YEASTS. 



this name are included not one, but several forms, differing both 

 morphologically and physiologically, and to which we are 

 equally justified in applying different specific names, as in the 

 case of numerous other well-characterised micro-organisms. 

 The same holds good of the other species of Reess. With 

 regard to the different species and varieties of wine-yeast 

 (Sacch. ellipsoideus) which have been tested in practice, see 

 Chapter VII. 



I have carried out these experiments in accordance with 

 the above principles with Carlsberg yeasts No. I and No. 2. 

 The first name has been applied to a definite species namely, 

 the first pure cultivated yeast which was introduced into the 

 brewing industry ; the name Carlsberg yeast No. 2, on the 

 other hand, applies to different species which were tried at 

 Old Carlsberg in the course of time, Some zymotechno- 

 logists have completely misunderstood me in thinking that 

 with these names I wished to imply that all low-fermentation 

 brewery yeasts could be grouped around these two types. 

 We have, as yet, no knowledge as to how many groups or 

 types exist ; the number would appear, however, to be con- 

 siderable. Similar analyses of other brewery yeasts were 

 subsequently made by A. Jorgensen, Will, P. Lindner, Holm, 

 Poulsen, Windisch, Kukla, Irmisch, Reinke, Wichmann, 

 Lasche, Prior, Bau, and Olsen, and they have obtained the 

 same main result. In agreement herewith are also the inves- 

 tigations of Borgmann and Amthor.* 



It is seen that some species yield what practical brewers 

 call good fermentations, a well-developed head and satis- 

 factory clarification, whilst other species do not. There are 

 also distinct differences with regard to the attenuation, the 



* The literature here referred to will be found partly in Jb'rgensen's * Micro- 

 organisms and Fermentation,' New Edition, London, F. W. Lyon, 1893 ; partly 

 in ' Compte-rendu des travaux du laboratoire de Carlsberg,' 1882, 1883, 1886 

 and 1888; in the 'Zeitschr. f. d. ges. Brauwesen,' Munich, 1883-95; Fresenius' 

 'Zeitschr. f. analyt. Chemie,' xxv. Heft. iv. 1886; and 'Zeitschr. f. physiolog. 

 Chemie,' xii. 1887. 



