SECTION FOUR 



Technique: 



1. A Nitella cell, carefully isolated from the plant, is placed on a 

 piece of filter paper from which it is transferred to a clean dry 

 slide. 



2. The uninjured cell is pricked so that it bursts out its sap and 

 the chloroplasts in effective spread. 



3. Lift the deflated cell with needles and transfer to an adjacent 

 dry region and tear to release more chloroplasts with a small 

 amount of sap. Arrange areas of the cell wall smoothly so that no 

 portion of the cell or its contents are lost in the preparation. By 

 spreading the cell fluid about in this way there is no excess in any 

 region. 



4. Dry rapidly with gentle heat. 



5. Place I ml. of Wright's stain on the dried spread, and leave it 

 to act for one minute ; then add 2 ml. distilled water and rock the 

 slide gently to ensure thorough mixing. 



6. Allow this diluted stain to act for three to five minutes ; then 

 pour off and wash with distilled water until the thin portion of the 

 films appears pink to the naked eye ; then pour off excess stain. 



7. Wash with distilled water and allow the preparation to dry 

 before examining. 



Results: 



Chloroplasts of normal Nitella are basophilic and of marked 

 alveolar structure. Large, homogeneous-appearing vacuole plas- 

 tids which are noted in the streaming of the living cell vacuole 

 are brilliantly eosinophilic. However, they prove to be complex 

 with a central raphe, usually colourless arrangements of both 

 basophilic and eosinophilic granules; and both bilaterally distri- 

 buted lacunae varying according to experimental conditions from 

 colourless to brilliant blue. The staining of Tunicate material is 

 so critical that species differences are readily noted in comparative 

 studies of the same cells. 



Reference: Koehring, Vera (1951), Stain Tech., 26, 29. 



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