122 BIOLOGY AND TECHNIQUE 



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 precipitate 

 forms. This is filtered before use. 



This gentian-violet solution retains its staining power for from 4 to 6 

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



It is used in the following 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. 



Jensen's Modification of the Gram Stain* 2 Jensen prepares his smears 

 in the ordinary way. He uses a 5 per cent solution of methyl violet, "6B." 

 This solution is stable. It is poured on the fixed smear for *4 to l /2 minute. 

 The methyl violet solution is poured off and, without washing, is covered 

 with LugoPs solution, and this is poured off and fresh Lugol added and left 

 on for 1/2 minute. 



The iodine solution is now poured off and the preparation washed with 

 98% alcohol. When decolorized, the 98% alcohol is washed off with a few 

 drops of absolute alcohol, and the preparation counterstained with a solution 

 of neutral red consisting of 1 gram of neutral red in a liter of water to 

 which 2 c.c. glacial acetic acid has been added. 



Apparently the important point in Jensen's stain is that the preparation 

 is never washed with water, and that the final washing off of the 98 alcohol 

 is done with a few drops of absolute. 



We have not used this stain as a routine and do not know how reliable 

 it is. 



STERLING'S MODIFICATION OF RAM'S METHOD. 2 c.c. anilin oil + 

 10 c.c. 95% alcohol. Shake ami add 88 c.c. distilled water. 5 grams 



23 Jensen, Berl. klin. Woch., 49, 1912, 1163. 



