SECTION THREE 



Technique: 



1. Sections are placed directly into a drop of the cupric acetate 

 solution on a slide and left therein for about ten minutes. 



2. Examine under the microscope and if calcium oxalate crystals 

 are present they will have dissolved and the oxalic acid diffused 

 into the intracellular spaces where cupric oxalate is formed. 



3. To test for the dissolved oxalate, add a few drops of the ferric 

 sulphate (solution B) and examine under the microscope. The 

 appearance of yellow ferrous sulphate crystals confirms the pres- 

 ence of calcium oxalate, in the tissue. 



Callose 



Solution required: 



Lacmoid I % alcoholic .. .. o-i ml. 



Distilled water . . . . 25 ml. 



Technique: 



1. Immerse sections in the lacmoid solution for about fifteen 

 minutes, when callose, if present, is stained a brilliant blue. 



2. Mount in a drop of glycerine on a slide and examine under the 

 microscope. 



The following solubility tests may be employed to distinguish 

 callose from other membrane substances: 



{a) Soluble in copper oxide ammonia, while cellulose and hemi- 

 celluloses are insoluble. 



{b) Swells but is insoluble in solutions of ammonia, sodium 

 carbonate, potassium carbonate, whilst pectic acid is soluble in 

 these reagents. 



{c) Soluble in glycerine at 280° C. whilst cellulose and chitin are 

 insoluble. 



Carotin 



Solution required: 

 Potassium hydroxide 20% in absolute alcohol. 



Technique: 



I . Place sections of fresh young green leaves in the potassium 



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