﻿IX, B, 4 



Barber: The Pipette Method 



323 



and the blunt end of the tube is slipped through the cork. If the 

 tube is too small to fit well, a piece of paper may be rolled around 

 it. The rubber tube is now adjusted and passed under a clip of 

 the stage of the dissecting microscope, so that any slight move- 

 ment of the tube will not disturb the pipette. 



The low power of the microscope is now focused on the free 

 edge of the cover, then lowered somewhat as in the first method. 



Fig. 7. A dissectinsr microscope used as a pipette holder. 



The compound microscope is slipped along the table until the 

 center of the free edge of the moist chamber is near the tip of 

 the pipette ; then the pipette is raised or lowered until it is about 

 midway in the center of the opening. By sighting along the 

 edge of the cover and adjusting the movable arm of the simple 

 microscope, one can bring the tip of the pipette into such a posi- 

 tion that it can be found with the low power. In case it is not 



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