28 LABORATORY METHODS OF UNITED STATES ARMY 



CARBOL-GENTIAN VIOLET. 



Saturated alcoholic solution of gentian 



violet 90.0 c.c. 



Five per cent, phenol in water . . 1000 . o c.c. 



This solution retains its staining powers for the Gram 

 method of staining for a longer period than does the ordinary 

 Gram solution, but is not as permanent as the Sterling 

 modification. 



POLYCHROME STAINS. The Romanowsky stain depends 

 on the formation of methylene azure and methylene violet 

 in alkaline solution of methylene blue. When this solution 

 is mixed with a solution of water-soluble yellowish eosin, 

 the eosinates of methylene azure, methylene violet, and 

 methylene blue are thrown down, as these eosinates are 

 insoluble in water. 



Wright's stain consists of a solution of these eosinates in 

 methyl alcohol. 



Any methylene blue and any yellowish water-soluble eosin 

 issued by the Medical Department can be used in preparing 

 the stain. 



WRIGHT'S STAIN. Add i gram of methylene blue to 100 

 c.c. of a 0.5 per cent, solution of sodium bicarbonate in water 

 and heat for one hour, after steam is up, in an Arnold sterilizer. 

 The flask containing the alkaline methylene blue solution 

 should be of such size that the depth of the fluid does not 

 exceed two and a half inches. When cool add to the methyl- 

 ene blue solution 500 c.c. of a i to 1000 eosin solution (yel- 

 lowish eosin, water soluble). Add the eosin solution slowly, 

 stirring constantly, until the blue color is lost and the mixture 

 becomes purple, with a yellow metallic luster on the surface 

 and there is formed a finely granular black precipitate. 

 The precipitate is the water insoluble eosinates of methylene 

 blue and of methylene azure and other oxidation products 



