200 FAMILY OF SACCHAROMYCETACEAE 



Sporulation is accomplished with difficulty on plaster blocks, but 

 is easily observed in hanging drops in which it appears at the end of 

 seven or nine hours. It is easily obtained on slices of carrot at the 

 end of a few hours, in old cultures on gelatin, and in the growth in 

 beer wort after fermentation. Guilliermond 1 has found that the ascs 

 result from an isogarnic copulation. The fusion is always incomplete 

 and results in the formation of two swelled parts united by a narrow 

 canal. The ascospores, always to the number of four, are formed in 

 pairs, two in each swelling. Their dimensions are about 4 ju in diame- 

 ter (Fig. 76). Their walls are covered with a starchy substance which 



is colored blue with iodine. 

 Quite often the ascospores may 

 form at the expense of cells which 

 have not undergone copulation. 

 The ascs reabsorb their mem- 

 branes generally before germina- 

 tion, and thus free the ascospores. 

 Germination is brought about in 

 the following manner: the 

 ascospores swell up and divide 

 by transverse partition like the 

 vegetative cells. 



Beijerinck has noticed as in Sch. octosporus, the existence of a 

 sporogenic variety forming white colonies on gelatin and an asporo- 

 genic variety forming brown colonies on the same medium. 



This yeast forms no scum on beer wort but produces a ring at 

 the end of a month. On gelatin, there develops a compact layer of 

 fine channelings with a liquefaction of this medium. 



Sch. Pombe is a yeast easily attenuated. Fermentation is very active 

 and manifests itself as top fermentation. The optimum temperature for 

 fermentation is situated between 30 and 35 C. This yeast provokes 

 an apparently strong fermentation of beer wort: it ferments maltose, 

 saccharose, dextrose, levulose, raffinose, and a-methylglucoside. On 

 the other hand, it is able to ferment inuline and dextrine. 



SCHIZOSACCHAROMYCES MELLACEI. Jorgensen 2 



This yeast was discovered by Greg 3 from Jamaican molasses used 

 in the manufacture of rum. It has been described by Jorgensen and 

 Holm. It is a species closely related to Schizosaccharomyces Pombe 



1 See references under this subject for Sch. octosporus. 



Jorgensen, A. Die Mikroorganismen der Garungsindustrie, 5th edition P. 

 Parey, Berlin, 1909. 



3 Greg, P. The Jamaica Yeasts. Bulletin of the Botanical Department, 

 Jamaica, Vol. 2, 1895. 



