226 FAMILY OF SACCHAROMYCETACEAE 



tion and, like the Schwanniomyces, are supplied with a projection (Fig. 

 30). Often one may see a union of two of these projections from 

 closely situated cells but no true union takes place on account of the 

 persistence of a wall, and each forms a parthenogenetic asc. 



The giant colonies are flat with small verrucose elevations. This 

 yeast ferments dextrose, levulose, d-mannose, and saccharose and 

 sometimes raffinose, trehalose, and inuline. 



Rose has observed traces of copulation quite similar in a yeast iso- 

 lated by Lindner from the secretions of a tree in the Berlin bo- 

 tanical garden and described in his atlas as Torula sporogene related to 

 Torulaspora Delbruckii. 



SACCHAROMYCES LACTIS 7. Dombrowski 



This yeast isolated by Collau from sour cream butter has been de- 

 scribed by Dombrowski. 1 It possesses no characteristics of the genus 

 Torulaspora. However, as the ascs result from cells which have pre- 

 served a trace of copulation or sexual attrac- 

 tion, it should probably be classed along with 

 the genera Schwanniomyces and Torulaspora, 

 preserving the provisional name of Saccharo- 

 myces lactis (gamma). Perhaps it will be pos- 

 sible to create a new genus for it when it is 

 better known. The cells are oval, sometimes 

 spherical, and, on beer wort, are 5 to 6.5 ju in 



Cells len g th and 5 /* in breadth. 



destined to Form ASCS; 3, Sporulation is easily accomplished on plaster 



Ascs (after Dombrowski). . - . . , . . 



blocks, in old cultures on gelatin, and in the 



moist chamber. They appear in from 72 to 96 hours on plaster blocks 

 at 25 C. The cells destined to sporulate show. the presence of a pro- 

 jection more or less elongated which seems to represent a trace of 

 ancestral copulation (Fig. 95, 2). They contain large fat globules. 

 The ascs contain one or two ascospores, rarely three. (Fig. 95, 3.) 

 The ascospores are shiny and contain a drop of fat in the center. 

 Germination is accomplished by budding, during which the fat dis- 

 appears. 



In cultures on nutrient gelatin in plates, the colonies are round 

 or shaped like a torpedo in which the edge enlarges in old cultures. 

 In gelatin stabs the development is along the line of inoculation and 

 becomes less and less as it progresses into the tube away from the 

 surface. Giant colonies have a raised center and a border composed 

 of concentric rings with slender rays. 



1 Dombrowski, W. Die Hefen in Milch und Milchprodukten. Cent. Bakt. 

 28, 1910. 



