90 MICROSCOPIC EXAMINATION OF BACTERIA. 



alcohol until the glass is clean. Dry and stain with anilin- 

 water fuchsin having a neutral reaction. Wash in water, 

 dry, and mount in Canada balsam. The stain is neutralized 

 with solution No. 2. If the organism produces alkalies, 

 solution No. 3 is added in the proportion of 1 drop to 1 c.c. 

 in 16 c.c. of the mordant. If the organism, on the other 

 hand, produces acids, solution No. 2 is added in the same 

 way. 



Loeffler has determined the exact quantity to be added to 

 each 16 c.c. of mordant solution for staining the flagella of 

 the following : 



Cholera spirillum, J-l drop of solution No. 3. 



Bacillus typhosus, 1 c.c. of solution No. 2. 



Bacillus subtilis, 2030 drops of solution No. 2. 



Bacillus of malignant oedema, 3637 drops of solution 



No. 2. 



Van Ermengen's method, though complicated, yields very 

 satisfactory results. The film is placed in a fixing solution 

 consisting of 1 part of a 2 per cent, solution of osmic acid 

 and 2 parts of a 10 to 25 per cent, solution of tannin, for one 

 hour at the room temperature. It is then thoroughly washed 

 in distilled water, and the film transferred for a few seconds 

 to a 5 per cent, solution of nitrate of silver ; then into the 

 following for a few seconds : 



Gallic acid, 5 grams ; 



Tannin, 3 " 



Fused potassium acetate, 10 " 



Distilled water, 350 c.c. 



Return the film to the silver solution, allowing it to remain 

 there until it has turned black ; wash well in water, dry, and 

 mount. 



Pittfield uses a method which is both a mordant and a stain. 

 The solution is prepared as follows : 



Saturated aqueous solution of alum, 10 c.c. ; 

 Saturated alcoholic solution of gen- 

 tian-violet, 1 " 

 Mix well and filter. Add : 



