82 MICROSCOPICAL EXAMINATION OF BACTERIA 



i. Absolute alcohol, for five to fifteen minutes. 



equal parts, for five to thirty 



2 . Absolute alcohol, , minutes (g fof bk)od 



Ether ' I milk). 



3. Osmic acid, i per cent, aqueous solution, for 

 thirty seconds. 



4. Corrosive sublimate, saturated aqueous solution, 

 for five minutes. 



5. Corrosive sublimate (Lang), for five minutes. 

 This solution is prepared by dissolving: 



Sodium chloride 0.7 5 gramme 



Hydrarg. perchloride 12.00 grammes 



Acetic acid 5 . oo grammes 



In distilled water loo.ooc.c. 



Filter. 



6. Gulland's solution, for five minutes. This solu- 

 tion is prepared by mixing : 



Absolute alcohol 25.00.0. 



Ether 25.00.0. 



Corrosive sublimate, 20 per cent, al- 

 coholic solution 0.4 c.c. 



7 . Formalin i o per cent . aqueous solution ( = 4 per cent . 

 aqueous solution of formaldehyde since formalin is a 40 

 per cent, solution of the gas in water). 



Either of these methods of fixation coagulates the 

 albuminous material and ensures perfect adhesion of 

 the film to the cover-slip. 



Clearing. Wash the cover-slip thoroughly in running 

 water and proceed with the staining. 



If the film has been prepared from broth, liquefied 

 gelatine, or pus or other morbid exudations, saturate 

 the film after fixation with acetic acid 2 per cent, and 

 allow it to act for two minutes. 



Wash with alcohol, then let the alcohol remain on 

 the cover-slip for two minutes. (This will " clear" the 

 groundwork and give a much sharper and cleaner film 

 than would otherwise be obtained.) 



