Laboratory Outline for General Bacteriology 



STAINS 



Their Composition and Methods of Use 



Standard Alcoholic Solutions. Standard alcoholic solutions of 

 anilin colors, especially fuchsin, gentian violet, and methylene blue, 

 are made by dissolving 10 grams of dry color in 100 cc of 95% 

 alcohol. These are used as stock solutions from which the various 

 stains are made. 



Watery Fuchsin. Made by diluting one part of standard alco- 

 holic solution of fuchsin with nine parts of distilled water. 

 Use. Leave on 1 minute, wash with water. 



Watery Gentian Violet. Made by diluting one part of standard 

 alcoholic solution of gentian violet with nine parts of distilled 

 water. 



Use. Leave on 1 minute, wash with water. 



Carbol Fuchsin. Made by diluting one part of standard alco- 

 holic solution of fuchsin with nine parts of a five per cent, solution 

 of carbolic acid. 



Use. Leave on 1/2 minute, wash with water. 



Methylene blue, Loeffler's. Made by adding thirty cc of stand- 

 ard alcoholic solution of methylene blue to seventy cc of potassium 

 hydroxide solution (1-10,000). 



Use. Leave on 10 minutes, wash with water. 



Gram's stain (Chester). Made by shaking 1 cc of aniline oil 

 with 10-15 cc of distilled water vigorously for several minutes and 

 filtering. To 10 cc of the filtrate add 1 cc of standard alcoholic 

 solution of gentian violet and filter again. This is the stain. The 

 Gram's solution has the following composition: 

 Metallic iodine 1 gram 



Potassium iodide 2 grams 



Water, distilled 300 cc 



Use. Anilin gentian violet Vr> minute, wash with water 



Gram's mixture (iodine) 

 Alcohol 95 ', about 1 



Flagella stain (Duckwall). Mordant is prepared as follows: 

 Desiccated tannic acid 2 grams 



Water, distilled 15 cc 



Saturated alcoholic solution 



of fuchsin 1 cc 



Normal NaOH solution 2-4 drops 



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