232 



FAMILY OF SACCHAROMYCETACEAE 



Fig. 98-A. Chondri- 

 ome in Saccharomyces 

 cerevisiae. 



Fixation in a mixture of 

 Potassium Dichromate and 

 Formalin. Stained with 

 Ferric haematoxyline. 



Temperatures for the formation of ascospores 

 37.5 C. no ascospores are formed 



36-37 first appearances in about 29 hours 



25 " 

 23 

 20 

 23 

 27 

 50 

 65 

 10 days 



35 

 33.5 

 30 

 25 

 23 

 17.5 

 16.5 



11-12 " 

 9 no development 



The ascs enclose from one to four ascospores, sometimes five. The 

 ascospores are very refractive and possess a very distinct wall. (Fig. 

 98.) Their size varies from 2.5 to 6 jit. 



Temperatures of Scum Formation 

 At 38 C. there is no formation of scum. 



33-34 at the end of 9-18 days, very slightly developed 

 26-28 " " " " 7-11 

 20-22 " " " " 7-10 

 13-15 " " " " 15-30 

 6 _ 7 2-3 months " 

 5 no formation of scum. 



The cells in the scum have the following micro- 

 scopic characteristics. At 20-34 C. the cells in the 

 scum are elongated and possess an odd appearance. 

 At 15 to 16 C., most of the cells look like those 

 which were present when the inoculation was made. 

 Some of the cells possess irregular shapes. In old 

 scums all sorts of cells are visible. Some are ex- 

 tremely long, having the appearance of a mycelium. 

 (Fig. 99.) 



Yeasts like S. Cerevisiae 



Numerous races and species of yeasts are known _ 



under the name of S. cerevisiae. Their systematic visiae. Mycelial 

 position is slightly unknown; a few of them will be 

 mentioned here. Hansen) 



