STAINING BACTERIA 99 



4. Bismarck brown solution. 



Water 100 c.c. 



Bismarck brown sufficient to saturate. 

 Filter and use a contrast stain. 



5. Weigert's aniline gentian violet stain. 



Gentian violet i gram. 



Dissolve in absolute alcohol 15 c.c. 



Distilled water 80 c.c. 



Then add to this 



Aniline oil 3 c.c. 



Mix, shake and filter. 



This stain can also be prepared by taking a 



Sat. watery solution of aniline oil 100 c.c. 



Filter, then add 



Sat. alcoholic solution gentian violet 10 c.c. 



Sterling's permanent solution is made by mixing 2 c.c. of aniline oil with 

 10 c.c. of 95 percent alcohol; the mixture is shaken and 88 c.c. of distilled 

 water added; 5 grams of gentian violet powdered in a mortar receives the 

 above fluid, added slowly while grinding; filter. This solution while expen- 

 sive to make, requires only a sm,all quantity, stains rapidly and keeps well. 



This is a very intense bacterial stain used for demonstrating 

 bacteria by the Gram method. 



Gram's method of staining. 



A cover-glass is spread with a smear of bacteria, or pus to be 

 examined. After air-drying it, and fixing it in the flame, the ani- 

 line gentian violet is poured on, allowed to stand for three minutes, 

 then poured off and the preparation treated with 



Iodine crystals i gram. 



Potassium iodide 2 grams. 



Water 100 c.c. 



for two minutes. This renders the purplish preparation grayish 

 in appearance. Alcohol is now poured upon the preparation re- 

 peatedly until the alcohol does not dissolve any more color. A 

 contrast stain of Bismarck brown or dilute fuchsin or safranin is 



