O cO 



224 FAMILY OF SACCHAROMYCETACEAE 



face of which are small elevations, and also provided with a project- 

 ing collar. For germination, one of the halves of the ascospore swells 

 and it is thus that budding is accomplished. 



SCHWANNIOMYCES OCCIDENTALS. Klocker 



This species was found by Klocker l in the same environment as 

 Debaromyces globosus. It has elliptical or spherical cells (5 to 10 ju), 

 but some cells may appear rarely as elongated sausages. After a 

 month's sojourn at room temperature on beer wort 

 C gelatin, the giant colonies appear well developed 



(o/^ with a grayish white appearance. They resemble 



wax and have a glistening appearance. 



Sporulation is easily accomplished on plaster 

 blocks. The limits of temperature for ascospore 

 formation on plaster blocks are: minimum, 10 to 13 

 -p- Q2 _ Schw ^'> max i mu m, 34 to 36 C. The ascs are always 

 occidentalis provided with a projection which gives them the 

 ' r '' appearance of a retort by means of which, during 

 sporulation, they unite two by two. (Fig. 93.) 



Guilliermond 2 has shown that these formations should be re- 

 garded as traces of an ancestral copulation. The cells destined to 

 form ascs retain a little of 

 their sexual attraction and 

 attempt to fuse. Finally, on 

 account of insufficient sexual 

 attraction, the cells are not 

 able to establish an anasto- 

 mosis and develop partheno- 

 genetically. The ascs form 

 usually a single ascospore 

 rarely two. The ascospore has 



the shape of a slightly flat- ^ 93. Formation of the Asc in Schw. 



. . . . , , occidentalis. 



tened bowl. It is surrounded 



by a projecting collar which divides it into two unequal parts. The 

 surface is rendered rugose by many little elevations. In the center 

 is a globule of fat. 



Germination commences by a swelling of the ascospore which lo- 

 calizes itself to the smallest half; this loses its elevations. Finally 

 all of the elevations disappear (Fig. 41). 



1 Klocker, A. Deux nouvelles genres de la famille des Saccharomyces. Comp. 

 Rend, des trav. du lab. de Carlsberg, 8, 1909. 



2 Guilliermond, A. Sur un curieux exemple de parthenogenese observe dans 

 une levure. Comp. Rend. Soc. Biol. 69, 1910; Quelques remarques sur la sexualite 

 des levures. Annales mycologici, 8, 1910. 



