64 GENERAL BACTERIOLOGY LESSON 



(d) Place it in Gram's iodine solution for one to two 

 minutes. 



(e) Wash it in absolute alcohol for half a minute and 

 then in acid alcohol (3 per cent hydrochloric acid) for not 

 longer than eight to ten seconds. 



(/) Again wash it in absolute alcohol till no more 

 stain comes off, and the specimen appears red. 



(g) Dehydrate it in absolute alcohol. 



(h) Clear it in xylol and mount it in xylol balsam. 



Examine it with a high power and -^ in. oil im- 

 mersion. The bacilli are stained blue on a red 

 ground. 



Staining of Paraffin Sections 



(1) Tubercle. 

 (i.) Slow Method. 



(a) Fix a section on a clean cover-glass (if possible with- 

 out egg albumen or any other fixing medium) and remove 

 the paraffin in the usual manner (heat, xylol, alcohol, and 

 water). 



(b) Float the cover-glass, specimen surface downwards, 

 on aniline fuchsine for twenty to twenty-four hours, or on 

 carbol fuchsine for two to three hours. 



(c) Now pass it through water, hydrochloric acid, spirit, 

 water, and methylene-blue in exactly the same manner as 

 was done in the case of sputum films. 



(d) Wash it in water, dehydrate in absolute alcohol, 

 clear in xylol, and mount. 



