82 Plant Tissue Culture 



thin flat bottom. The cover slip carrying the cul- 

 ture is then inverted over the chamber. This 

 chamber is optically flat. It can be opened either 

 by removal of the culture or, if access to the cul- 

 ture is desired without disturbing it, as for micro- 

 manipulation, the chamber can be opened from 

 below by sliding out the first cover glass. Because 

 of the cemented-on strips at the ends of the slides, 

 they can be stacked one on top of another or used 

 freely on the microscope platform without danger 

 of deranging the cultures. Pierced slides for this 

 purpose can be obtained for about 30 cents apiece 

 (Fig. 27). 



A special burette for filling flasks has been 

 found useful. This will be discussed in the chap- 

 ter on the preparation of nutrients. 



Implements. Scalpels, scissors, needles, for- 

 ceps, platinum loops, etc., are standard equipment. 

 For severing roots in the flasks, Bobbins uses a 

 long-handled scalpel made by spot-welding a chip 

 of razor blade to a wire held in a transfer loop 

 handle. A surgeon's nasal scissors of the Gruene- 

 wald or Heymann type is, for many types of dis- 

 section, still more satisfactory. It is of just the 

 right length to reach to the bottom of a 125 ml. 

 Erlenmeyer flask, does not require a wide space 

 for manipulation as do iridectomy scissors, 

 will cut cleanly even against considerable resis- 



