SECTION THREE 



4. Take another slide and repeat the process but run in a drop 

 of strong ammonia solution instead of acetic acid. 



Results: 



Anthocyanin is red in acid solution and blue violet to green in 

 alkaline solution. 



Arbutin 



This occurs in Ericacae and Pyrolacae 



Solutions required: 



A. Nitric acid 10% 



B. Ammonia solution. 



C. Ferric chloride 5% aqueous. 



Technique {a): 



1. Place sections in the nitric acid solution. 



2. Cover with a coverslip and examine under the microscope 

 i mmediately. 



Results: 



Cells containing arbutin assume a dark orange colour, which 

 rapidly changes to yellow which slowly disappears altogether. 



Technique (b): 



This depends upon the principle that arbutin is converted, on 

 hydrolysis, to glucose and hydroquinone. 



1 . The dry sections are placed in a drop of water on a slide and 

 heated gently for two or three minutes, when the arbutin sublimes 

 in crystals. 



2. Add a drop of ammonia solution when the arbutin crystals 

 assume a rich brown colour. 



3. Repeat the process adding a drop of ferric chloride solution 

 instead of ammonia : a pale green colour confirms the presence of 

 arbutin. 



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