8-5 



THE YEAST CELL 



and shaken for 48 hours. The suspension of cells from some of 

 the Erlenmeyer flasks was placed in 8 x 1-inch tubes. Tests with 

 Fehling's solution were made to determine when the sugar disap- 

 peared, and sugar was added as soon as a deficiency was indicated. 

 Phosphate was also added, since this is known to increase the de- 

 position of both fat and glycogen. The addition of sugar was con- 

 tinued for four days. 



Timt in Minutes 



Fig. 8-2 Curves Showing the Evolution of CO2 by Three Com- 

 parable Suspensions of Dormant Cells in Different Nutrients over a 

 345-minute Period. 



Three cultures were used, two standard baking yeasts, strains 

 U and R (S. cerevisiae) and a hybrid (S. cerevisiae x S. globosus). 

 Strain U stored both mitochondria and carbohydrate relatively uni- 

 formly as indicated by microscopic examination. Strain R stored 

 carbohydrate well, but the accumulations of mitochondria were ir- 

 regular and the granule -containing culture was discarded. The hy- 

 brid stored mitochondria in large clusters of extremely tiny parti- 

 cles approaching the limits of visibility. The cells appeared to be 



