508 PKACTICAL BOTANY 



material with ether : the small sections will then be readily found, 

 and collected. 



" Eau de Javelle " is recommended as a clearing agent for 

 growing points, and other merismatic tissues : the cell-contents 

 swell under its action, and the cell-walls which remain may then 

 be easily seen. It is prepared by adding to 2 pints of water 2 

 ounces of chloride of lime, and 4 ounces of carbonate of potash 

 or of soda. Objects treated with it are to be washed with water, 

 then with dilute acetic acid, and should be mounted in 

 glycerine. 



Eosin is used in strong solution in alcohol, or in water, for 

 demonstrating the structure of sieve-tubes (pp. 113, 116). 



Fehling's Fluid is used as a test for grape-sugar (p. 222) : the 

 following directions for its preparation are given in Foster's 

 Practical Physiology : 



a. Dissolve 34'65 grammes of pure crystallized cupric sulphate 

 in about 160 c.c. of distilled water. 



b. Dissolve also 173 grammes of pure crystallized potassic-sodic 

 tartrate in 600 to 700 grammes of sodic hydrate (sp. gr. T12). 



Add (a) to (&), stirring well to cause a thorough mixture, and 

 dilute with distilled water to a litre. 



Fehling's fluid should be fresh made whenever it is required, 

 since it decomposes on keeping ; it will keep some little time 

 if kept in a cool place in the dark, and in completely filled, 

 well-closed bottles (Hoppe-Seyler). 



The solution (ft) may be prepared, and kept for adding to (a) 

 freshly prepared when required. 



Before using a kept solution to test for sugar, always boil a 

 little of it by itself to see if any reduction will take place. 



From 1 c.c. of this solution the copper is completely reduced 

 by 0'005 grammes of grape-sugar. 



Ferrous Sulphate is used in dilute solution in water, to which 

 a drop of nitric acid has been added, as a test for tannin. 



Fuchsin. is used in solution in alcohol, for bringing out the 

 structure of thickened cell-walls, and especially the outer walls of 

 the epidermis (p. 246), and corky walls : the sections should have 

 been previously treated with alcohol. When a section has been 

 stained with fuchsin, and washed in absolute alcohol, the 



