of potassium iodide and 1.3 parts of iodin are dissolved in 10.5 parts of 

 water. The solution stains the cellulose reddish or bluish violet, the woody 

 portion yellowish or brown and the wall, consisting of pectin substance,, 

 yellow. 



2. Congo red. It is easily soluble in water aud stains the cellulose 



3. Safranin solution. A saturated safranin solution in alcohol is mixed 

 with the same volume of water. It stains the pectin compounds yellowish 

 red. 



4. Ruthenium red. It stains the pectin compounds intensely red. 



5. Methylen blue. It stains the pectin compounds violet. 



0. Millon's reagent. The equal quantities of mercury and nitric acid 

 are mixed and diluted in the same volume of water. It stains protein brick- 

 red iu a short time. 



7. Ammonium copper oxide solution. The solutiou is prepared fresh by 

 pouring the concentrated ammonia over the copper foil or powder and allow- 

 ing to stand for a day. It dissolves the cellulose easily. 



8. Phloroglucin and hydrochloric acid. A few drops of phloroglucin 

 and concentrated hydrochloric acid produces a red color on the cross section 

 of the lignified cell-wall. 



9. Fehliug's solution. Three solutions are prepared separatly, each 

 containing 35 grams of copper sulphate, 173 grams of Seignette salt 

 (potassium sodium tartarate) and 120 grams of caustic soda in a liter of water 

 respectively. Equal volumes of the solutions are mixed and diluted with 2 

 parts of water just before usiug. The sections are put iuto this solution and 

 warmed over a flame until bubbles appear. 



10. Sudan III. Sudan III. is a good coloriug matter for fat. It stains 



11. Osmic acid. It stains fat and protein brown. 



12. Alcanna tincture. It is prepared after Guigard's method in the 

 following manner. 10 grams of alcanna were extracted with 30 c.c. of absolute 

 alcohol. Evaporate the extract and treat the residue with 5 c.c. of acetic 



