154 BOTANICAL MICROTECHNIQUE. 



a little eosin, which dissolves readily in it. The eosin at 

 once stains the cellulose walls a beautiful red, while not 

 changing the staining of the other walls. 



c. Ammonia-fuchsin. 



271. As was first recognized by Van Tieghem, ammonia- 

 fuchsin is well adapted to staining suberized and lignified 

 membranes. It is prepared by adding ammonia to a not 

 too concentrated alcoholic solution of fuchsin, until the solu- 

 tion becomes straw-yellow after a little shaking. The solu- 

 tion should be filtered after a few days, but can be kept only 

 a few weeks, even in well closed bottles. 



A double staining may be had by placing the sections 

 first in the above described ammonia-fuchsin solution for a 

 few minutes, and then passing them directly to an aqueous 

 solution of methyl blue, in which they are left a quarter of 

 an hour or longer, then washing with alcohol and mounting 

 in Canada balsam. 



d. Cyanin and Eosin. 



272. If sections are placed for several hours in a freshly 

 prepared, very dilute aqueous solution of cyanin, which may 

 be prepared by adding 20 drops of a concentrated alcoholic 

 solution to 100 ccm. of water, the lignified and suberized 

 membranes appear beautifully blue after washing in alcohol. 

 If clove-oil containing eosin be used in transferring to Can- 

 ada balsam, a fine double staining is obtained. The modified 

 walls are blue, the cellulose walls red. 



I obtained also a deep staining of the cuticle by leaving 

 sections for a considerable time in a solution of cyanin in 

 50$ alcohol and then washing out the stain with glycerine. 

 4. Gelatinized Cell-walls, Plant-mucilages, and Gums. 



273. The so-called gelatinized membranes are distin- 

 guished from cellulose walls chiefly by their different physi- 

 cal character, their strong power of swelling; and indeed 

 there occur all stages between pure cellulose, which takes up 

 little water, and the gums which are wholly soluble in water. 



