9-10 



THE YEAST CELL 



is drawn up into the tube again. About 3 drops of this suspension 

 of yeast cells in blood serum is introduced into a sterilized cotton- 

 plugged, 7 mm. pyrex tube (fig. 9-8). The tube is made by sealing 

 one end of a 7 mm. glass tube, six inches long, in an oxygen flame. 

 It contains two single -hole glass beads. After adding the yeast sus- 

 pension, the tube is plugged and the cotton is burnt off at the end of 



Fig. 9-7 Dropping the blood serum from a pipette on the 

 surface of an agar slant covered with a growth ol yeast cells, 



the tube and shoved down into the tube to about one inch above the 

 yeast cell suspension. The tube is now filled with a drying agent 

 above the cotton plug (fig. 9-9). We use a patented drying agent 

 called Hydralo, but dehydrated CaCla will probably serve as well. 

 A second cotton plug is now added above the drying agent and shoved 

 down into the tube. The tubes are connected with rubber tubing to 

 a vacuum dessicator with a hollow center (fig. 9-10) .in which CaCl2 

 and ice are placed to condense the water. Vacuum is applied with 



