VI.. KOCH-BHRLICH METHOD OP STAINING TU- 

 BERCLE BACILLI IN COVER-GLASS PREPARA- 

 . TIONS. 



1 and 2 same as V (a). 



3. Float the cover-glass ("butter" side down) upon 

 Koch-Ehrlicli's aniline-water-gentian-violet (methylene- 

 blue or fuchsin) solution,^ for from twelve to twenty-four 

 hours at room-temperature, or one hour if heated, until a 

 vapor arises. 



4. Decolorize in 25 per cent, nitric acid, from ten to 

 thirty seconds. 



5. Wash in alcohol until no more color comes away. 



6. Contrast stain with a watery solution Bismarck- 

 brown (if fuchsin has been previously used with methy- 

 lene-blue) one or two minutes. 



7. Wash in water and place upon slide, or 



8. Dry and mount in balsam. 



iFor preparation of aniline-water-gentian-TioIet-fuchsin, or methy- 

 lene blue solutions (See lU, foot-note 2, a and b). 



25 



