The Argentaffin Reaction 249 



(28%), drop by drop until the precipitate which forms is almost dis- 

 solved. Add 25 ml. distilled water. Store for 24 hours in brown bottle. 

 Filter before use. Good for 2 weeks. 



Methenamine silver solution B: (Gomori's Method) 



Solution I: 



methenamine, 3% (3 gin./ 100 ml. water) 100.0 ml. 



silver nitrate, 5% (5 gm./lOO ml. water) 5.0 ml. 



Shake until white precipitate disappears. Keeps for several months 

 if stored in a cool dark place. 



Solution II: 



M/5 boric acid (12.368 gm./lOOO ml. water) 80.0 ml. 



M/5 borax (19.071/1000 ml. water) 20.0 ml. 



pH should be 7.8 to 8.0 



Working solution: 



Stock solution I 30.0 ml. 



Stock solution II 8.0 ml. 



Gold chloride: 



gold chloride stock solution, 1% 10.0 ml. 



distilled water 100.0 ml. 



Safranin: 



safranin O, C.I. 50240 1.0 gm. 



distilled water 100.0 ml. 



Add a few drops of glacial acetic acid. 



procedure: 



1. Deparaffinize and hydrate slides to water. 



2. Treat ^vith Lugol's solution (page 410): 30 minutes to 1 hour. 



3. AVash in running water: 3 minutes. 



4. Bleach in sodium thiosulfate, 5% (5 gm./lOO inl. water): 3 min- 

 utes. 



5. Wash in running water: 5 minutes. The above treatment sup- 

 presses background staining. 



6. Treat with silver solution A in dark, room temperature: 18-48 

 hours. 



Alternate Method. Use Methenamine silver solution B, r)0°C: 3.5 

 hours; or at 37°C: 12-24 hours — until EC cells stand out black. 

 Then continue: 



