SECTION THREE 



2. As soon as the ground substance of the aleurone grains appear 

 blue, add a few drops of absolute alcohol, when the globules 

 should be colourless and the crystals a yellowish green. 



3. Remove excess alcohol; clear in clove oil and mount in 

 balsam. 



Results: 



Protein (aleurone) crystals, yellow. Globules, pink. Ground 

 substance, dark red. 



Amygdalin 



This occurs in the seeds of Amygdalus; Pyrus Crataegus and 

 related genera, as well as the leaves of Prunus laurocerasus 



Solutions required: 



A. Picric acid, saturated, aqueous. 



B. Sodium carbonate 10% aqueous. 



C. Potassium hydroxide 4% in 70% alcohol. 



D. Ferrous sulphate 2-5% aqueous (prepared without 



heating). 



E. Ferric chloride 20% aqueous. 



F. Hydrochloric acid, cone. . . i volume 

 Distilled water . . . . • • 4 volumes 



Technique (a): 



1 . Immerse sections in the picric acid solution for half an hour, 

 on slides. 



2. Wash with water ; then add one drop of the sodium carbon- 

 ate to a section. 



Result: 



A red coloration indicates the presence of amygdalin, and this 

 is confirmed by the odour of hydrocyanic acid (almond odour), 

 which is a decomposition product upon which tests for amygdalin 

 are based. 



R 231 



