SECTION FOUR 



Results: 



Chromatin is stained deep translucent red, while cytoplasm is 

 unstained. 



Permanent preparations : 



5. Proceeding from Stage 4 (above), immerse the preparation 

 in a Petri dish containing 10% acetic acid until the coverslip 

 becomes loose. 



6. Immerse the slide and the coverslip in a mixture consisting 

 of equal volumes of absolute alcohol and glacial acetic acid, con- 

 tained in another Petri dish. 



7. Transfer to a dish containing a mixture consisting of three 

 volumes of absolute alcohol and one volume of glacial acetic acid. 



8. Transfer to a mixture consisting of one volume of glacial 

 acetic acid and nine volumes of absolute alcohol. 



9. Transfer to absolute alcohol ; then into two changes of xylol. 



10. Refix the coverslip to the slide with a drop of Cristalite. 



METHYL GREEN - ACID FUCHSIN - ERYTHROSIN 

 A cytological stain for plant cells 



Solutions required: 



A. Methyl Green 1% aqueous. 



B. Acid fuchsin 1% aqueous. 



C. Erythrosin 1% aqueous. 



Technique: 



1. Take sections down to distilled water in the usual manner. 



2. Stain for an hour in solution A. 



3. Remove excess stain by washing thoroughly with water. 



4. Stain in the acid fuchsin solution for one minute. 



5. Wash well with distilled water to remove excess stain. 



6. Stain with the er)rthrosin solution for two or three seconds. 



7. Wash well with distilled water and drain and blot off excess 

 water, but do not allow the section to dry. 



305 



