

MICROSCOPICAL TECHNIQUE 43 



cent alcohol. These stock solutions keep well, but cannot be 

 used for staining purposes. From them the solution used is 

 prepared by dilution with distilled water, and filtering the 

 mixture. 



1. Aqueous solution of fuchsin is made by adding to 95 cc. 

 of distilled water 5 cc. of the saturated alcoholic solution. 



2. Aqueous solution of methylene blue is similarly 

 prepared. 



3. Aqueous solution of gentian violet is similarly prepared. 



4. Loeffler's, or alkaline methylene blue, is made by mixing 

 30 cc. of saturated alcoholic solution, 1 cc. of a 1 per cent 

 potassium hydrate solution, and 100 cc. of distilled water. 



5. Carbol-fuchsin is made by adding to a 5 per cent solu- 

 tion of carbolic acid a saturated alcoholic solution of fuchsin 

 until a metallic luster is noted on the surface of the liquid. 



6. Aniline-water gentian violet is prepared as follows : To 

 98 cc. of distilled water are added 2 cc. of aniline oil. Shake 

 vigorously. Filter, and to 75 cc. add 25 cc. of saturated alco- 

 holic solution of gentian violet. The solution should be re- 

 filtered after standing twenty-four hours, to remove drops of 

 oil that may have settled out. 



7. Iodine solution (Lugol's or Gram's solution) is prepared 

 as follows : One gram of iodine is dissolved in a solution made 

 of 2 grams of potassium iodide in 300 cc. of distilled water. 



These staining solutions keep well with' the exception of 

 aniline-water gentian violet, which must be renewed at fre- 

 quent intervals. 



Exercise. From the saturated alcoholic solutions furnished, pre- 

 pare 50 cc. of an aqueous solution of methylene blue, gentian violet, 

 aniline-water gentian violet, carbol-f uchsin, and iodine solution. Place 

 them in dropping bottles, or in bottles provided with corks through 

 which a piece of small glass tubing is passed, by which small quan- 

 tities of the solution can be removed without spilling. 



