9-14 



THE YEAST CELL 



a Cenco Megavac pump and as soon as the serum boils vigorously 

 enough to flush out the oxygen, the tubes are sealed off with an oxy- 

 gen torch (fig. 9-11). The drying agent removes the remaining water 

 from the yeast cells and the tubes are stored in envelopes. The 

 complete apparatus is shown in fig. 9-12. 



Fig. 9-11 Sealing oif Glass Tube While Under a Vacuum with 

 an Oxygen Torch. 



These cultures are revived by scratching the tube with a file in 

 the center of the cotton plug. The tube is broken, the cotton plug 

 is removed and dropped in one tube of broth medium; the glass beads 

 are fished out with a wire and dropped into a second tube of broth 

 culture medium. After a few days the broth in the tubes becomes 

 cloudy with yeast cells. If only the tube containing the cotton pro- 

 duces growth, a pure culture can be obtained by plating the culture 

 in a petri dish. 



