SCHIZOSACCHAROMYCES MELLACEI 



201 



measure- 



Schizosaccha- 

 romyces Mel- 

 lacei from 

 Cultures on 

 Slices of Car- 

 rot. 



from which it may scarcely be distinguished by its morphological 

 characteristics. The cells have the same shape as those of Sch. 

 Pombe but are generally a little larger (Fig. 78). 



Developing on carrot slants, Guilliermond found the 

 ments to be about 9.5 jit by 5.1 ju; the cells of Sch. 

 Pombe under the same conditions are about 7 // long 

 and 4.5/1 wide (Fig. 77). 



Lepeschkin has noticed in this species as in the 

 former one, the appearance of a true mycelium in 

 deposits at the bottom of the culture flask. 



Sporulation of this yeast is obtained easily at the Fig 77._Vege- 

 end of a few days on beer wort gelatin in hanging tative Cells of 

 drops. The observations of Guilliermond 1 have shown 

 that the ascs result from an isogamic coplation which is 

 accomplished in the same manner as with Sch. Pombe. 

 The ascs have a shape like a dumb bell, both swelled 

 portions being connected by a narrow canal (Fig. 78). 

 The ascospores always to the number of four appear in pairs in each 

 large part of the asc. Cases of parthenogenesis may be often observed 

 in which the ascs result without previous copulation. The ascospores 

 are long and rounded (about 4 JJL in diameter) . They are very refractive, 



and are clothed with a mem- 

 brane impregnated with starchy 

 materials which are stained blue 

 by iodin in potassium iodide. 



This yeast produces no scum 

 on beer wort but forms a ring 

 a ^ the end of four or five months. 



Plate cultures in S elatin and 

 streaks on gelatin offer growths 



which on the surface and in the 

 medium are closely detailed. 

 Sch. mellacei ferments beer wort 

 at 25; there are signs of top 



fermentation with a broken-up deposit, not very compact. During 

 fermentation it liberates an agreeable odor. It ferments dextrose, 

 maltose, levulose, saccharose, raffinose, d-mannose, dextrine, a-methyl- 

 glucosides and inulin; it is distinguished from Sch. Pombe by the fact 

 that it ferments d-mannose on which the latter has no action. 



According to Greg this yeast produces several types which are 

 characterized by the peculiar odor given off during fermentation, or 



1 Guilliermond, A. Rem. sur la copulation du Schizosaccharomyces mellacei. 

 Bull. Soc. Bot. de Lyon, 1903. 



Fig. 78. Formation of the Asc in Schizosac- 

 charomyces Mellacei. 



