STAINING 189 



known, are of nearly every conceivable color and shade but 

 relatively A-ery few are used in bacteriological work. The 

 elementary student will rarely use solutions of other than 

 the three dyes fuchsin (red), methylene bhie and gentian 

 violet for staining bacteria, with occasionally Bismarck 

 brown, or eosin, or safranin as tissue contrast stains. 



The bacteriological dyes are kept "in stock" as saturated 

 solutions in 95 per cent, alcohol which are never used as 

 stains, but merely for convenience in making the various 

 staining solutions of which the following are the most 

 common : 



1. Aqueous (watery) gentian violet solution. 



Saturated alcoholic solution of gentian violet ... 1 part 

 Distilled water . 20 parts 



Mix well and filter. 



2. Anilin gentian violet. 



Saturated alcoholic solution of gentian violet . 1 part 



Anilin water (see below) . .10 parts 



Mix well and filter. 



3. Anilin Fuchsin. 



Saturated alcoholic solution of fuchsin . . 1 part 



Anilin water (see below) . . 10 parts 



Mix and filter. 



These stains rarely keep longer than ten days in the 

 laboratory (unless kept in the ice-box) and must be made 

 fresh on the first sign of a deposit on the glass of the container. 



Anilin Water. — Anilin water is made by putting 3 or 4 c.c. 

 of anilin "oil" in a 120 c.c. flask, adding 100 c.c. of distilled 

 water, shaking vigorously for a minute or so and filtering 

 through a wet filter, in other words, a saturated solution 

 of anilin in water. 



4. Loffler's (methylene) blue. 



Saturated alcoholic solution of methylene blue . 3 parts 



Aqueous solution of NaOH (or KOH), 1 to 10,000 . . 10 parts 

 Mix and filter. 



5. Carbol-fuchsin (Ziehl's solution). 



Saturated alcoholic solution of fuchsin . 1 part 



5 per cent, aqueous solution of carbolic acid . . 10 parts 



Mix and filter. 



