MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



6. Examine again after an hour when the precipitate will re- 

 appear in crystalline form. 



Chlorophyll 



Solutions required: 



A. Potassium hydroxide 20% in pure 

 methyl alcohol. 



Technique: 



1 . Place sections directly onto a slide and add two or three drops 

 of ether. 



2. Add a few drops of the potassium hydroxide solution. 



Results: 



Chlorophyll immediately turns brown, afterwards changing 

 back to green again. 



Formic Acid 



Solutions required: 



A. Mercuric chloride 1% aqueous. 



B. Hydrochloric acid, cone. 



C. Potassium hydroxide 1% aqueous. 



Technique: 



1. Place fresh sections on slides; flood with the mercuric 

 chloride solution and heat on a water bath for an hour. 



2. Pour off excess mercuric chloride solution and wash with dis- 

 tilled water which has been acidified by the addition of i ml. hydro- 

 chloric acid cone, per 100 ml. 



3. Place sections on slides; add one drop of 1% potassium 

 hydroxide, and examine. 



Results: 

 Where formic acid is present, the cells are blackened. 



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