316 Microorganisms (chap. 20) 



celloidin protective coat. They also emphasize the need for good for- 

 malin; if the sections fail to turn blue, try a different batch. 



Tubercle Bacilli Staining 



Fluorescent Method (richards, et al., 1941; Richards, 1941; 

 BOGEN, 1941) 



fixation: 10% formalin for sections; smears by heat. 



solutions: 



Auramin stain: 



auramin O C.I. 41000 0.3 gm. 



distilled water 97.0 ml. 



melted phenol (carbolic acid) 3.0 ml. 



Shake to dissolve dye or use gentle heat. Solution becomes cloudy on 

 cooling, but is satisfactory. Shake before using. 



Decolorizing solution: 



hydrochloric acid, concentrated 0.5 ml. 



70% ethyl alcohol 100.0 ml. 



sodium chloride 0.5 gm. 



procedure: 



1. Deparaffinize and hydrate sections to water. 



2. Stain in auramin, room temperature: 2-3 minutes. 



3. Wash in running water: 2-3 minutes. 



4. Decolorize: 1 minute. 



5. Transfer to fresh decolorizer: 2-5 miniues. 



6. Wash in running water: 2-3 minutes. 



7. Dry smear and examine. Mount sections in fluorescent motmtant 

 (page 122) or Harleco fluorescent moimtant for examining. 



results: 



bacilli — golden yellow 



comments: 



Bogen counterstains with Loeffler's alkaline methylene blue sohuion 

 before mounting: 



methylene blue C.I. 52105 3.0 gm. 



absolute ethyl alcohol 30.0 ml. 



potassium hydroxide, 0.01% aqueous ...,,..,, 100.0 ml. 



