PLANT PRODUCTS 145 



Exercise 22. Test some of this protein with fresh Millon's reagent and 

 note the effect. 



Millon'a reagent. Dissolve mercury in an equal amount (by weight) 

 of nitric acid. Dilute this solution with an equal amount of distilled 

 water. It must be used fresh. Protein treated with this reagent turns 

 brick red. 



Exercise 23. Cut thin sections of wheat grains to show protein. Add 

 a drop of fresh Millon's reagent and note the effect. 



Exercise 24- Treat cotton fibers with chloro-zinc-iodine under cover 

 glass and note the effect. The blue color indicates cellulose. 



Exercise 2o. Cellulose. Cut sections from the interior (endosperm) of 

 a date seed. Note the character of cellulose walls. Treat as in 24. 



Exercise 26. Melt the tip of a stick of sealing wax and attach a flax 

 seed. Cut sections. Examine under the microscope. Add water and note 

 the effect. These cells are mucilaginous. The mucilage is a decomposition 

 product of cellulose. 



Exercise 27. Cut sections of stems or other parts of plants and examine 

 under the microscope. Put a little chloro-zinc-iodine under the cover 

 glass. A blue color indicates that the cell walls are not liquefied 

 or cutinized. 



Chloro-zinc-iodine. Dissolve 25 parts of zinc chloride and 8 parts of 

 potassium iodide in 8y 2 parts of water and add enough iodine to give a 

 dark color. 



Exercise 28. Mount woody sections in aniline chloride and run a few 

 drops of hydrochloric acid under the cover glass. A yellow color indi- 

 cates lignin. 



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