STAINING BACTERIA. 193 



warmed ; as soon as steam arises, pour into a watch- 

 glass, and place the cover-glass on the stain. Allow it 

 to remain for four or five minutes, then wash in methy- 

 lated spirit until no more color comes away; drain thor- 

 oughly and dry, either in the air or over a spirit-lamp. 

 Mount in Canada balsam. The whole process, after the 

 sputum is dried, need not take more than six or seven 

 minutes. This process is also valuable for sections of 

 tissue containing bacilli, as they can be doubly stained 

 without the least trouble. I have not tried to do this 

 against time, but have merely placed the sections in the 

 stain and allowed them to remain for some hours, and 

 then transferred them to methylated spirit, where they 

 have been left as long as the color came out. In this 

 way beautiful specimens have been made, without the 

 shrinking which alwa} T s occurs in the nitric acid pro- 

 cess." Lancet, May 5, 1883. 



Cheyne recommends the Weigert-Ehrlich stain- 

 ing solution. The formula is : of a filtered watery 

 solution of aniline one hundred parts, of a satur- 

 ated alcoholic solution of the basic aniline dye 

 (methyl-violet, gentian-violet, fuchsin, etc.,) eleven 

 parts ; mix and filter. Rapid staining is obtained 

 by warming the solution. The specimens are then 

 decolorized by immersion in nitric acid (one part 

 in two of water), and stained in a suitable contrast 

 color. Very delicate sections are apt to be injured 

 by immersion in the nitric acid. In this case, after 

 staining them in the Weigert-Ehrlich fuchsin so- 

 lution, they may be washed in distilled water, im- 

 mersed in alcohol for a moment, and then placed 

 in the following contrast stain for one or two 



13 



