SECTION FIVE 



Technique: 



Place sandalwood oil or fluoroil between the slide and condenser. 

 Three sides of the microscope should be enclosed with a shield to 

 exclude extraneous light. 



Sections: 



1. Fix tissues in 5 to 10% formalin for twelve to twenty-four 

 hours; embed in paraffin wax and cut sections 5 to lo// in thick- 

 ness. 



2. De-wax as usual, taking care that all traces of wax are com- 

 pletely and finally removed from sections. 



3. Bring sections down to distilled water as usual; then flood 

 with the auramine solution and warm (not over 40° C.) for five to 

 ten minutes, afterwards washing with distilled water. 



4. Counterstain in methylene blue solution for thirty seconds; 

 then rinse in distilled water, dehydrate as usual ; clear in xylol and 

 mount in Fluormount. 



Smears: 



1. Stain for five minutes in the auramine solution, afterwards 

 washing with tap water and decolorizing in 25% sulphuric acid. 



2. Immerse in the potassium permanganate solution for about 

 thirty seconds to overcome any interfering fluorescence. 



Results: 



Tubercle bacilli appear as thin shining, slightly curved rods 

 against a dark background. 



An Improved Method of Staining Tubercle Bacilli 



(H. Lempert's Method) 



Solutions required: 



A. Phenol 3% in distilled water . . 100 ml. 

 Auramine O . . . . . . 0-3 gm. 



Dissolve by shaking. Do not apply heat, as aura- 

 mine decomposes when heated above 40° C. 



325 



