170 CHARACTERIZATION AND IDENTIFICATION 



MAXIMUM, MINIMUM AND OPTIMUM TEMPERATURES FOR THE FORMATION 

 OF ASCOPORES OF SlX VARIETIES STUDIED BY HANSEN 



Maximum Optimum Minimum 



Temperature Temperature Temperature 



Saccharomyces cerevisiae 37-35 30 9-11 



" Pastorianus 29-31.5 27.5 0.5-4 



" intermedius 27-29 25 0.5-4 



validus 27-29 25 4.8-5 



" ellipsoideus 30. 5-32. 5 25 4. 7-5 



turbidans 33-35 29 4-8 



TIMES AT WHICH ASCOSPORES BEGIN TO FORM IN Six VARIETIES 

 STUDIED BY HANSEN 



, r , , 7 Maximum Optimum Minimum 



Name of Yeast m m y 



Temperature Temperature Temperature 



Saccharomyces cerevisiae 29 hours 20 10 



" Pastorianus 30 24 14 



" intermedius 34 27 17 



" validus 35 28 9 



" ellipsoideus 36 21 11 



" turbidans. .31 22 9 



Sexuality: Morphological Characteristics of the Asc and 

 Ascospores. Germination of the Ascospores 



The copulation which precedes the formation of the asc in cer- 

 tain yeasts, the morphological characteristics of the asc and ascospores, 

 and, finally, the mode of germination have great significance in the 

 determination of varieties. Thus, the existence of a copulation served 

 Barker in creating the genus Zygosaccharomyces, characterized only 

 by their sexuality. With the exception of the Schizosaccharomyces 

 which possesses an analogous copulation but in which the form and 

 mode of cellular division do not allow any confusion, all of the 

 yeasts in which the asc results from a copulation fall into the Zygo- 

 saccharomyces. It is true that Klocker has discovered a new variety 

 from which he has made a new genus, Debaromyces globosus and in 

 which he has observed sexual phenomena of the same order. This 

 variety, however, is distinguished from all of the other yeasts by the 

 special shape~t>f its ascospores, upon which Klocker has founded the 

 genus Debaromyces. Therefore if one encounters a yeast which indi- 

 cates sexual processes in the formation of the asc, and if this yeast 

 divides by budding and does not form ascospores with a special form, 

 it may be placed with some certainty with the Zygosaccharomyces. 



In Nematospora coryli and Monospora .cuspidata the ascs arc 

 larger and possess a more elongated form than the vegetative cells. 



