MICROSCOPIC STUDY AND STAINING 103 



Decolorize with ninety-seven per cent alcohol until no further 

 traces of the stain can be washed out of the preparation. This takes 

 usually thirty seconds to two minutes, according to thinness of prepara- 

 tion. 



Wash in water. 



Counterstain with an aqueous contrast stain, preferably Bismarck 

 brown. 1 



Paltauf's Modification of Geam's Stain.^— The staining fluid as 

 prepared by this modification possesses the advantage of retaining its 

 staining power for a longer period than does the anilin-water-gentian- 

 violet described in the original method. 



The staining fluid is prepared as follows.- 



3-5 c.c. anilin oil are added to 

 90 c.c. distilled water and 

 7 c.c. absolute alcohol. 



This mixture is thoroughly shaken and filtered through a moist 

 filter paper until clear. Then add: 



Gruebler's gentian- violet 2 gm. 



The fluid should stand twenty-four hours, during which a precipi- 

 tate forms. This is filtered before use. 



This gentian-violet solution retains its staining power for from four 

 to six weeks. It is good only when a metallic luster develops on the 

 surface. 



It is used in the foUowing way: Spreads on cover-slips or slides are 

 dried and fixed as usual. 



Then apply: — 



Anilin water gentian-violet (as above) , three minutes. 



Gram's iodin solution, two minutes. 



Absolute alcohol (with stirring), thirty seconds. 



Counterstain, without washing in water, in aqueous fuchsin or in 

 weak carbol-fuchsin. .,. 



' To make up Bismarck brown solution, prepare a saturated aqueous solution of 

 the powdered dye by heating. AUow it to cool, and filter. Dilute one to ten with 

 distilled water. 



'Sharnosky, Proc. N. Y. Pathol. Soc, Oct., 1909, n. s.,ix, 5. 



