APPENDIX. 395 



Eau de Javelle. To make this reagent, either (a) dissolve 

 some chloride of lime in water, and to the filtered solution add a 

 solution of potassium oxalate as long as a precipitate is formed, and 

 filter; or (ft) to 20 c.c. of 20 per cent, solution of calcium chloride, 

 add 100 c.c. of water, let stand for some hours, then add a solution 

 of 15 grams of potassium carbonate in 100 c.c. of water, and filter 

 if a film forms on the surface of this solution on exposure to the air, 

 add a little more of the potassium carbonate solution and filter off 

 . the precipitate. 



Eau de Javelle is used (1) for clearing growing-points and other 

 dense tissues, by swelling and dissolving the cell contents after 

 treatment with the reagent, wash the sections with water, treat 

 with dilute acetic acid to correct too great transparency, and mount 

 in glycerine ; (2) to extract lignin from sections of woody tissue, 

 the cells then giving cellulose reactions, e.g. violet colour with 

 chlor-zinc-iodine ; (3) to demonstrate starch- grains included in 

 chloroplasts, sections or whole leaves, etc., being treated with the 

 reagent for an hour or more and then with iodine solution. 



Eosin. (1) In dilute aqueous solution, eosin is a good general 

 stain for protoplasmic cell contents and cellulose walls. (2) For 

 staining protein grains, place small bits of tissue, e.g. Castor Oil 

 endosperm, in saturated alcoholic solution of picric acid for a day, 

 rinse in alcohol ; cut sections and stain with clove oil, and mount in 

 balsam the ground substance of the protein grains should be red, 

 the crystalloids yellow, the globoids colourless. 



Fehliiig-'s Solution. To make Solution A, dissolve 35 grams of 

 copper sulphate in 200 c.c. of water. To make Solution B (to be 

 kept in a separate bottle), dissolve 70 grams of Rochelle salt (sodium 

 potassium tartrate) in 200 c.c. of 10 per cent, caustic soda solution. 

 Use equal volumes of Solution A, Solution B, and water. The 

 object of the Rochelle salt is to prevent the precipitation of copper 

 hydroxide by the action of soda on the copper sulphate. 



Fuchsin, Acid. Dissolve 1 gram of fuchsin in 100 c.c. of 50 per 

 cent, alcohol. (1) Fuchsin is a good general stain, the different 

 tissues taking different shades of red. (2) An excellent double 

 stain is obtained with fuchsin and methyl blue. Leave the sections 

 in fuchsin overnight, rinse in water, transfer to methyl blue solution 

 for a few minutes, rinse in weak alcohol, dehydrate with absolute 

 alcohol, treat with clove oil or xylol, and mount in balsam. (3) To 

 stain crystalloids, fix the material in strong alcoholic solution of 

 corrosive sublimate (mercuric chloride), place the sections for a day 

 in fuchsin solution, dehydrate and pass through clove oil or xylol to 

 balsam. (4) To stain crystalloids in leucoplasts, place the sections 

 in fuchsin solution, rinse in strong alcoholic solution of picric acid, 

 dehydrate and pass through clove oil or xylol to balsam. (5) To 

 stain leucoplasts and other plastids, fix the material in strong alco- 

 holic corrosive sublimate for 24 hours, rinse in alcoholic solution of 



