806 W. H. GILBERT OX THE STAINING OF VEGETABLE TI88UKS. 



If the stem is at all brown, a solution (recommended by Mr. 

 Stiles, and whieli I have proved), of chloride ol lime, may be used. 

 A quarter oi an ounce of chloride is put into a pint of water and 

 well shaken, this is to stand till quite bright, pour off the fluid, 

 which is then ready for use. For stems this solution generally 

 answers, but it is not near strong enough for leaves : as not only do 

 they require bleaching, but all the cell-contents dissolved and re- 

 moved, in order to render them transparent : and as the solution 

 about to be described answers equally well for stems as leaves, and 

 acts more rapidly, it will perhaps be convenient to use only the 

 following solution of chlorinated soda, directions for the preparation 

 of which were given by Dr. A. Milne Edwards, in the " American 

 Naturalist," for May. 1869.* I have prepared it as follows : — 



T j one pint of water add two ounces of fresh chloride of lime, shake 

 or stir it well two or three times, then allow it to stand till the lime 

 has settled. Prepare meanwhile, a saturated solution of carbonate 

 of soda — common washing soda. Now pour off the clear super- 

 natant fluid from the chloride of lime, and add to it. by degrees, the 

 soda solution, when a precipitate of carbonate of lime will be thrown 

 down ; continue to add the soda solution till no further precipitate is 

 formed. Decant and filter the clear solution, which must be kept in 

 a well-stoppered bottle, and in the dark, otherwise it speedily becomes 

 useless. 



Those who do not care to take the small amount of trouble re- 

 quired to prepare their own bleaching fluid, can purchase it at most 

 manufacturing chemists, but it will not be so strong, and it will be 

 at twelve times the cost. 



In the staining of sections of stems, petioles. £c, let me again 

 recommend in all possible cases, the use of alcohol for bleaching, for 

 the reasons already given. 



B etions bleached in the chlorinated soda, must, when white, be 

 washed in clean water for twenty -four hours, changing the water four 

 or five times, and adding to the last but one a few drops of nitric 

 acid, at the rate of eight or ten drops to the half-pint, the last wash- 

 ing being in clean water. 



From water transfer them to alcohol, in which they must remain 

 for an hour or more. 



B .-etions may be stained in two colours with advantage. This 

 may be done in two ways — either by alternate or single immersion. 

 * See also Monthly Microscopical Journal, Vol. I (1S69), p. 361. 



