SALIC YLATE OF SODA SILVER NITRATE 327 



to which strong alcohol is then added, drop by drop. The color 

 will begin to be extracted in the alcohol, and when the right inten- 

 sity has been reached, the material should be transferred to dilute 

 glycerine, where it is to remain while the glycerine slowly concen- 

 trates in a place protected against dust. Then permanent mounts 

 may be made in glycerine or glycerine-jelly. The stain given by 

 safranin is quite permanent. See also page 264 and the direc- 

 tions there given for the three-color method. 



Salicylate of Soda. A clearing reagent which for small 

 objects is not inferior to chloral hydrate is furnished by dis- 

 solving crystals of salicylate of soda in an equal weight of dis- 

 tilled water. With tincture of iodine added this reagent will 

 cause starch to swell, at the same time imparting a blue color to it. 



Salt. A 4 per cent, or stronger solution of common salt, 

 or of potassium nitrate, may be used to cause plasmolysis in living 

 cells. This process may be all the more clearly seen by adding 

 eosin to the salt solution. ji| jj* 



Shellac. A thick solution of shellac in alcohol, to each ounce 

 of which are added 20 drops of castor oil, makes an excellent 

 sealing medium for preparations mounted in glycerine or glycerine- 

 jelly, or in an aqueous medium. 



Silver Nitrate. A solution of silver nitrate is used to bring 

 out more clearly the striations in bast fibers and starch grains. 

 Sections containing striated bast fibers are allowed to dry and 

 are then impregnated with the silver salt. Without previous 

 washing the sections are transferred to a 0.75 per cent, solu- 

 tion of common salt. They are then placed in distilled water 

 and exposed to the light for a considerable time; thereafter they 

 are allowed to dry and may be examined to good advantage in 

 anise oil. 



Dry starch grains are put to soak in a 5 per cent, solution 

 of silver nitrate. After a time they are allowed to dry super- 

 ficially and are then treated with a 0.75 per cent, solution of 

 common salt, in which they are finally exposed to the direct 

 light of the sun to reduce the chloride of silver which has been 

 formed within the grains. The less dense laminae of the starch 



