REAGENTS AND MOUNTING MEDIA. 481 



E. 



Eau de Javelle (Potassium hypochlorite). Eau de Labarraque (Sodium 



hypochlorite). 



I give potassium hypochlorite the preference, though the two differ 

 little in their action. Eau de Javelle can be prepared by stirring 

 20 parts of the officinal (25 per cent.) chloride of lime with 100 

 parts water, allowing it to stand some time, and adding a solution 

 of 15 parts pure potash in 100 parts water. After allowing it to 

 stand for one or several hours the mixture is filtered, and the 

 filtrate used. Should lime still remain in the solution, and as a 

 result the drops brought into use form in the air a skin of crystal- 

 line carbonate of lime, this is easy to remove by adding a few 

 drops of potash solution and filtering off the precipitate. Used to 

 delignify wood sections, and as a clearing reagent for growing 

 points. 



Egg, White of. Used, diluted with water, and with the addition of a little 

 camphor, lor observations in the embryology of Gymnosperms. See 

 p. 374. 

 Ehrlich's Aniline-water fuchsin. To prepare and use, see p. 273. An 



admirable stain for Bacteria and their spores. 



Enclosing (or mounting) Fluid for Alyw, in order to preserve the natural 

 colour and form of Desmids, Volvox, and other Algae, can be prepared 

 by dissolving 1 gramme acetate of copper in a mixture of 130 

 grammes camphor water, 130 grammes distilled water, and 20 drops 

 glacial acetic acid. To this is added 260 grammes glycerine, or, in 

 cases, more or less, and the solution is filtered. 



Enclosing (or mounting) Jluid. Hoyer's, for Aniline preparations. A tal) 

 glass vessel with a wide neck is filled up to two-thirds with gum- 

 arabic, in selected clear pieces. The vessel is then filled up to the 

 neck with a solution of 50 per cent, acetate of potash, or with a 

 watery solution of acetate of ammonia containing, to each 30 grammes, 

 10 grammes of caustic ammonia neutralised by a sufficient quantity 

 of acetic acid. The gum is dissolved in a few days, if the vessel is 

 often shaken, and forms a syrupy fluid, which is filtered through 

 thick swansdown a process taking about twenty-four hours. 

 Enclosing Jluid for Carmine and Hcematoxylin (Logwood) preparations. This 

 is prepared as above, excepting that, instead of acetate of potash or 

 of ammonia, a concentrated solution of chloral hydrate, to which is 

 added 5 to 10 per cent, glycerine, is used. After some time this 

 fluid may become turbid, and it is then necessary again to filter it. 

 Preparations mounted in either of these fluids require no further en- 

 closing. 



Eosin. Strong s&lution in alcohol. Stains protoplasm deeply. Especially 

 useful for sieve-tubes, aleuron-grains with crystalloids,, etc. 



31 



