378 



MICRO-ORGANISMS AND FERMENTATION. 



at 25 C. This development is much more vigorous on the 

 surface of nutrient gelatines, such as wort-gelatine (Fig. 85), 

 where it forms round, waxy, and raised colonies with a de- 

 pression in the centre. The cells grow shorter and more 

 rounded after developing for some days at the temperature of 

 the room, and the ascus-formation, according to Schionning's 

 observations in the Carlsberg laboratory, now takes place as 

 follows (Fig. 84) : 



The rounded cell lengthens; a partition - wall appears, 

 which splits off, after which the two new cells merely touch or 

 connect at one point. They then, again, coalesce (compare 

 the fusions observed by Hansen in S. Ludivigii), and at last 



Fig. S3.Saccharomyees octospont*. Young growth after cultivation for twenty-four 

 hours in beer-wort, at 25" C. (after Schiouning). 



form a lengthened, ellipsoidal, hour-glass shaped or irregular 

 cell, which gradually increases in bulk (frequently 14 to 20 jj. 

 long). In these cells eight spores form, as a rule, but frequently 

 only four, and less frequently from two to seven. By degrees 

 the wall of the mother-cell dissolves, and the spores now lie 

 embedded in slime, which subsequently disappears. The spores 

 are often oval, and, according to Lindner, their membrane is 

 coloured blue by a solution of iodine in potassium iodide. 

 According to Guilliermond, the ascus - formation may also 

 proceed in this way. Two cells which have not been derived 

 from one and the same cell fuse together, or again an ascus 

 may be formed without the fusion of two cells. 



