MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



Technique (b): 



1. Place sections in the sodium hydroxide (Solution C) for 

 three to five minutes. 



2. Mix equal volumes of the ferric sulphate and ferric chloride 

 (Solutions D and E above) in a test-tube or small beaker and heat 

 to boiling. 



3. Immerse sections in the above mixture and leave them therein 

 for five to ten minutes. 



4. Place sections on a slide in a drop of the diluted hydrochloric 

 acid (Solution F above). 



Results: 



A deep blue precipitate (Berlin blue reaction) indicates the 

 presence of hydrocyanic acid which is indicative of amygdalin. 



Amylodextrin 



This product, which is intermediate between maltose and starch, 

 is present in solution in storage organs where starch is hydro- 

 lysed. Its presence is indicated by the red coloration it produces 



with Gram's iodine solution 



Anthocyanin 



This occurs in the petals of the vast majority of blue and red 

 flowers; such flowers owe their colour to anthocyanin 



Solutions required: 



A. Glacial acetic acid. 



B. Ammonia solution. 



Technique: • 



1. Place petals in a little neutral distilled water on slides. 



2. Cover with thick coverslip (No. 2 or No. 3) and press out the 

 coloured liquid. 



3. Run in a drop of glacial acetic acid under the coverslip. 



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