Sectioning Unennbedded Tissues 97 



Reducing Sugars; Fehling's Solution Test 



Although this is not a microtest. it is included because it is essential for a 

 systematic examination oi the prominent chemical constituents of cells and 

 tissues. 



Solution A 



Water 11. 



Copper sulphate 79.28 g. 



Solution B 



Water 1 1. 



Sodium potassium tartrate 346 g. 



Sodium hydroxide 100 g. 



Mix equal volumes of A and B in a test tube, add a quantity of the finely 

 pulverized materials to be tested, heat to boiling. A brick-red precipitate 

 indicates reducing sugars. 



If a negative or slight test is obtained for reducing sugars, a test for 

 sucrose can be made by first hydrolyzing the sucrose. Add 1 cc. concentrated 

 HCl to 10 cc. of the extract to be tested. Heat in a water bath at 70°C. for 

 5 min. Cool and neiuralize with sodium carbonate, and test for the resulting 

 reducing sugar with Fehling solution. 



Lignin; Phloroglucin Test 



Solution A 

 Phloroglucin, 1% to 2% in 95% alcohol 



Solution B 



Hydrochloric acid (try concentrated acid, as well 



as acid diluted with 1 to 3 volumes of water.) 



Float the sections in a drop of phloroglucin on a slide, and cover with a 

 cover glass. Place a small drop of the acid at one edge of the cover glass. 

 Examine with a microscope. Lignified walls become violet-red. 



Cellulose; Iodine-Sulphuric Acid Test 



Mount sections or crushed fragments in IKI. Observe with the microscope, 

 and locate blue-stained starch. Place a drop of 75 per cent H2SO4 at one side 

 of the cover glass. As the acid diffuses in, note that cellulose walls swell and 

 become blue. 



Cellulose; Chloriodide of Zinc Test 



Water 14 cc. 



Zinc chloride 30 g. 



Potassiimr iodide 5 g. 



Iodine 0-9 g. 



Mount thin sections in a drop of the reagent. Cellulose becomes blue. 



Proteins; Millon's Reagent Test 



Concentrated nitric acid 9 cc. 



Mercury 1 g. 



