MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



hydroxide solution in a stoppered jar and leave in the dark until 

 the chlorophyll is extracted. 



2. Remove the sections from the jar and wash them for ten 

 hours in running water. 



3. Transfer to a large volume of distilled water and leave therein 

 for an hour, afterwards transferring to a fresh lot of distilled water 

 for a further period of one hour. 



4. Transfer to slides ; mount in glycerine. 



Results: 



Carotin, if present, appears as orange-red crystals. Xanthophyll 

 will appear after two or three days as yellow crystals. 



Cellulose 



Solutions required: 



A. Gram's iodine. 



B. Sulphuric acid 75%. 



Technique: 



1. Place sections in a drop of Gram's iodine solution on a slide. 



2. Cover with a coverslip; examine under the microscope, 

 taking careful note of the location of the blue coloration. 



3. Place a drop of the sulphuric acid solution along the edge of 

 the coverslip and observe the swelling of the cellulose membranes 

 as the sulphuric acid seeps under the coverslip, hydrolysing the 

 cellulose to a colloid substance known as hydrocellulose. 



Note: As certain other plant substances give a blue colour 

 reaction with iodine it is important to note the locality of any blue 

 colour which appears prior to the hydrolysation with the sul- 

 phuric acid. 



Chitin 



This is said to occur principally in the higher fungi. 



Solution required: 



A. Potassium hydroxide . . . . 78 gm. 



Distilled water . . . . . . 68 ml. 



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