CELL-CONTENTS AND CELL-WALLS. 69 



microcliemical tests) try the following tests : Dip separate 

 wooden matches into (1) iodine it turns yellow only; 

 (2) chlor- zinc-iodine it turns yellow ; (3) first iodine and 

 then sulphuric acid it turns brownish. 



(e) Cut transverse sections from a wooden match, soak 

 them in alcohol to remove air-bubbles. (1) Mount a 

 section in water, and note the network of walls, which are 

 practically colourless or sometimes very faintly yellow ; 

 (2) add iodine the walls turn yellow ; (3) next add 

 sulphuric acid the walls swell up and turn brownish ; 

 (4) mount another section in chlor- zinc -iodine the walls 

 turn yellow ; (-5) mount another in aniline sulphate the 

 walls turn bright yellow; (6) mount another in phloro- 

 glucin the walls turn bright red ; (7) mount another in 

 carbolic-hydrochloric acid, and expose to the light the 

 walls turn green ; (8) treat another section with potassium 

 permanganate solution, followed by ammonia the walls 

 turn red. 



(/) Note also that lignified membranes are insoluble in 

 cuprammonia, but are swollen and finally dissolved by 

 strong sulphuric acid. After treatment with Schultze 

 maceration fluid ( 80 &), they react like cellulose. 



80. Corky Walls do not give well-defined reactions, 

 except for the relatively great resistance which they offer 

 to the action of strong acids. 



(a) Cut thin sections of an ordinary bottle cork, and 

 soak them in alcohol to remove air-bubbles. (1) Mount a 

 section in water, and note the cork cells, regularly ar- 

 ranged in rows, with thin yellowish walls ; (2) treat with 

 iodine the walls turn more distinctly yellow ; (3) next 

 add sulphuric acid the walls turn deep brown, but they 

 retain their sharp outlines and do not swell ; (4) treat a 

 section with chlor- zinc- iodine the walls either remain 

 unchanged or turn deeper yellow ; (5) treat a section with 

 potash for a few minutes, then add chlor-zinc-iodine the 

 walls turn violet. 



(6) Dissolve crystals of potassium nitrate in strong 

 nitric acid in a test-tube this gives Schultze maceration 



