276 CLASSIFICATION OF SACCHAROMYCETACE^E. 



of speculation temperature on gypsum blocks are 31 C. and 1 1 C., 

 the optimum temperature being 2^-26 C. For the production 

 of films on wort these limits are 2S-3i C. and 7-io C. This 

 species is a high-attenuation bottom yeast. 



Stock 6, H. Will (XXX.). The cells are round or oval. Limits 

 of sporulation temperature on gypsum blocks, 31 C. and 11 C., 

 optimum 28 C. For the production of films on wort the limits 

 are 25-3i C. and 7-io C. A bottom yeast with medium 

 attenuation. 



Stock 1,11. Will (XXX.). Cells round or oval; giant cells 

 of regular occurrence. Limits of sporulation temperature on 

 gypsum blocks, 30 C. and 13 C., optimum 2^-26 C. ; for the 

 production of films on wort the limits are 25-28 C. and 4-7 C. 

 The species is a low-attenuation bottom yeast. 



/Stock 93, II. Will (XXX.), is illustrated, from a drawing by 

 Will, in Fig. 137. Cells round or oval. Limits of sporulation 

 temperature on gypsum blocks, 30 C. and 10 C., optimum 

 28 C. Limits of temperature for the production of films on 

 wort, 30-3i C. and 4-7 C. A high-attenuation bottom yeast. 



Although imperfectly described from the standpoint of botanical 

 classification, mention may be made of three other beer yeasts, 

 which bulk largely in discussions between fermentation techno- 

 logists, and in treatises by fermentation physiologists, and are 

 also mentioned frequently in the present Handbook, namely, 

 Saaz yeast, Frohberg yeast, and Logos yeast. The former two 

 were isolated by LINDNER (XXXI.) at the Institute for Fermen- 

 tation Industries, Berlin : one for the pitching yeast used at the 

 municipal brewery in Saaz (Bohemia), the other from the yeast 

 from Frohberg's brewery at Grim ma (Saxony). Both have been 

 carefully investigated by DELBRUCK (IX.), IRMISCH (II.), LIND- 

 NER (XXXI.), REINKE (IV.), and others. Logos yeast was isolated 

 by H. VAN LAER and DENAMUR (I.) from the pitching yeast 

 employed at Logos and Co.'s brewery in Rio de Janeiro (Brazil). 

 Its origin is unknown, but was probably the sugar-cane. On 

 chemico-physiological grounds A. BAU (VI.) proposed to divide 

 the old collective name Sacch. cerevisice into four types : Sacch. 

 cerevisice Frohberg, top fermentation ; Sacch. cerevisice Saaz, top 

 fermentation ; Sacch. cerevisice Saaz, bottom fermentation ; and 

 Sacch. cerevisice Frohberg, bottom fermentation. In this manner 

 the names Saaz and Frohberg originally applied to two different 

 species of yeast are used to denote types. Various other top- 

 f ermentation beer yeasts have also been described by H. van Laer, 

 A Jorgensen, Greg, &c. 



The top yeasts also include the well-known distillery yeasts 

 Race XI. and Race XII. (the latter also cultivated in the manufac- 

 ture of pressed yeast), both of which were isolated at the Institute 

 of Fermentation Industries, Berlin. Compare p. 113, vol. ii., and 

 HENNEBERG (I.). 



