SACCHAROMYCES, HANSENIA, TORULASPORA. 275 



by germination. In addition to yeast cells a few of them produce 

 a membrane with well-defined septse. 



The first sub-group of this genus comprises the species capable 

 of fermenting dextrose, saccharose and maltose, but not lactose. 

 It includes the following species : 



Saccharomyces cerevisiw, E. C. Hansen. Synonyms : /Sacch. 

 cerevisicv /., E. C. Hansen (XII., XVI., XLVI. and XLVIII.) = 

 Sacch. cerevisice, E. C. Hansen (XL1X.) = Sacch. cerevisue 

 (partim), Mayer (I.) = Torula cerevisue (partim), Turpin (!.) = 

 Cryptococcus ferment'm (partim), Kutzing (I.) = Hormiscium 

 cerevisice (partim), Bail (III.) /Sacch. cerevisue (partim), Reess 

 (I.) This species has been drawn by Hansen (XII., XVI., 

 XVII. and XXXII.), also in Figs. 127, 142, 144, and 145 of the 

 present work. The cells of the sedimental yeast are usually 

 large and round; and those of the film vegetation at 6-l5 C. 

 are mostly of the same kind, with but few exceptions. The limits 

 of the budding temperature in wort are 40 C. and i-3 C. The 

 dimensions of the spores vary between 2.5 and 6 /^, the number 

 in each cell being usually 1-4, rarely 5. The limits of sporula- 

 tion temperature on gypsum blocks are 37-37.5 C., and 9-! i C., 

 the optimum temperature being 30 C. For the production of 

 films on wort these limits are 33-34 C. and 6-7 C. The 

 species generally appears as a powerful top -fermentation beer 

 yeast, and was isolated by Hansen (I.) from the pitching yeast of 

 an Edinburgh brewery. Subsequently the same worker detected 

 it in a London brewery. It is one of the many forms previously 

 grouped under the name Sacch. cerevisice. 



Only a small number of the races and species utilised in the 

 brewing industry have been described in the literature, and even 

 then without systematic names, being generally called after the 

 locality or the owner of the brewery where they were discovered, 

 or again bearing merely the number with which they were 

 labelled in the collection (herbarium) of the investigator. The 

 following six may be cited as examples : 



Carlsbery bottom yeast, No. i, E. C. Hansen. One of HANSEN'S 

 (XLIV.) drawings is reproduced in Fig. 130. The cells are 

 usually oval or pointed. Spores are produced with the greatest 

 difficulty, being found in very small number even after a con- 

 siderable time (5-6 days at 25 C.). In the brewery (see p. 187, 

 vol. ii.) this yeast gives imperfect clarification, but high attenua- 

 tion, and the beer is excellent, with good keeping qualities. 



Carlsberg bottom yeast, No. 2, E. C. Hansen. The cells, which 

 are illustrated in Fig. 131, after a drawing by Hansen, are more 

 uniform in shape than the preceding species, and also produce 

 spores rather more readily. The beer obtained with this yeast 

 does not keep so well, but clarifies better. 



Stock 2, H. Will (XXX.). Will's drawing of this species is re- 

 produced in Fig. 139. The cells are round or oval. The limits 



