TUBERCULOSIS. 385 



The Ziehl-Neelsen method is preferred by the author both for 

 sections and cover-glass preparations. 



Koch's original method. — Cover-glass preparations or sections are laid 

 in Koch's solution (Xo. 23, c) for twenty-four hours, or for one hour if 

 the solution is warmed to 40° C. Rinse in water ; immerse in a watery 

 solution of vesuvin for two minutes ; rinse again in water, and examine ; 

 or, after rinsing in water, treat with alcohol, clove-oil, and Canada 

 balsam. 



EhrlicKs method. — Cover-glass preparations are allowed to float in a 

 watch-glass, containing a solution of gentian-violet or fuchsine, added to 

 aniline water. A saturated alcoholic solution of the dye is. added till 

 precipitation commences (10 ec. aniline water, and 10 to 20 drops of the 

 colour solution). The cover-glasses are left in the solution for about 

 half an hour ; then washed for a few seconds in strong nitric acid (one 

 part commercial nitric acid to two of distilled water), and rinsed in 

 distilled water. After-stain with vesuvin or methylene-blue, rinse in 

 water, dry and preserve in Canada balsam. 



Ehrlich-Koch method. 



Saturated alcoholic solution of methyl- violet or fuchsine 11 

 Aniline water . 100 



Absolute alcohol 10 



Preparations are left for twelve hours in this solution (colouring of 

 the cover-glass preparations can be expedited by warming the solution). 



Treat the preparations with (1 to 3) solution of nitric acid a few 

 seconds. 



Wash in alcohol (60 per cent.) for a few minutes (covec-glass prepara- 

 tions need only be rinsed a few times). After-stain with diluted solution 

 of vesuvin or methylene-blue for a few minutes. 



Wash again in 60 per cent, alcohol, dehydrate in absolute alcohol. 

 Clear with cedar-oil, mount in Canada balsam. 



Rindfldsch's method.— PTepa,ve a solution composed of 



Saturated alcoholic solution of fuchsine . . 10 drops 

 Aniline water . . -2 drams. 



Pour it into a watch-glass, and float the cover-glass ; warm the watch- 

 glass over a spirit-lamp until steam rises. Remove it from the flame, 

 and set it aside for five minutes. Take out the cover-glass, and transfer 

 it for a few seconds to acidulated alcohol (two drops of nitric acid in a 

 watch-glass fuU of alcohol). Wash in distilled water, dry, and preserve 

 in balsam. After-stain, if necessary, with Bismarck-brown, or methylene- 

 blue. 



Gibbeg' meiAod— Cover-glass preparations are placed in Gibbes' double- 

 staining solution which has been warmed in a test-tube, and, as soon as 

 steam rises, poured into a watch-glass. They are allowed to remain for 

 five minutes, and then are washed in methylated spirit till no more colour 

 comes away, dried in the air or over a spirit-lamp, and mounted in 

 Canada balsam. If the solution is used without warming, the cover-glasses 



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