214 PART II. — VEGETABLE HISTOLOGY. 



Corallin Solution. Weigh out three grains of sodium carbonate and ten 

 grains of corallin. Dissolve the former in two ounces of water, and in this 

 solution dissolve the corallin, and filter. Place in the bottle containing the 

 solution a few grains of camphor to prevent the solution from spoiling. It 

 stains cellulose and lignified tissues different shades of red, and stains sieve- 

 callus with special brilliancy. It also stains starch grains. The colors produced 

 by this stain are fugitive. 



Hanstein's Rosanilin Violet. This is an alcoholic solution of equal parts 

 of methyl-violet and fuchsin. It stains soft bast tissues scarcely at all, other 

 cellulose tissues a faint violet color, hard bast fibers a deep red, lignified tissues 

 a less brilliant red, cell-walls that have undergone the gummy degeneration a 

 different shade of red, resins are stained blue, tannin a peculiar foxy-red, proto- 

 plasm a bluish or violet color, and the nucleus and starch grains different shades 

 of red. It stains rapidly and is very useful in the study of vegetable sections. 



Picric Nigrosin. To a saturated solution of picric acid in water, enough 

 of a strong aqueous solution of nigrosin is added to give to the liquid a deep 

 olive-green color. It fixes and at the same time stains the nucleus, and is 

 especially useful in the study of filamentous algae. Specimens should be soaked 

 in it for from twelve to twenty- four hours. It is also serviceable as a double 

 stain for sections of stems, roots, etc., the nigrosin being taken up by the 

 cellulose and the picric acid by the lignified tissues. Preparations may be 

 anhydrated and mounted in balsam, or they may be mounted in glycerine jelly. 



Alkanet. An alcoholic tincture of the root is useful in detecting the 

 presence of resins and oils, these substances being stained a deeper red by it 

 than other cell-contents. 



MOUNTING OR ENCLOSING MEDIA. 



The most valuable are the following : 



Canada Balsam or Balsam of Fir. This should be nearly colorless and 

 entirely free from solid impurities. It is ordinarily best obtained in collapsible 

 tubes from the dealers in microscopical goods. The ordinary or natural bal- 

 sam, consisting of resin in solution in oil of turpentine, is preferable for most 

 purposes to the chloroform or benzol solutions. 



It must be remembered that before enclosing an object in any resinous or 

 oleo resinous medium, it must be thoroughly anhydrated. This is somewhat 

 troublesome, but barring the trouble, balsam mounts are among the best and 

 most durable. 



Shellac Solution. A solution of the best white shellac in absolute alcohol, 

 filtered and evaporated down to the consistency of rather thin syrup, may 

 also be used as an enclosing medium, but is more useful as a cement for fasten- 

 ing cover glasses, and for making shallow cells in which to mount certain 

 objects. 



Glycerin Jelly of good quality may be made as follows : Soak, for an hour 

 or more, one ounce of the best French gelatine in three ounces of distilled 

 water, then raise the temperature to nearly, but not quite, the .boiling point, 



