SECTION SEVEN 



Technique: 



1. Air-dried bacterial films are fixed by passing through the 

 bunsen flame in the usual manner. 



2. Stain with aniline gentian violet or carbol gentian violet for 

 two to three minutes. 



3. Pour off stain and flood the film with Gram's iodine for one 

 minute. 



4. Blot and dry in air. 



5. Decolorize with absolute alcohol (if aniline gentian violet 

 has been used) until no more colour comes out ; if carbol gentian 

 violet has been used, decolorize with aniline xylol instead of 

 alcohol. 



6. Wash with water; drain. 



7. Counterstain with a mixture consisting of i volume of Ziehl 

 Neelsen's carbol fuchsin and 9 volumes distilled water. 



8. Wash with distilled water; blot and dry in air. 



Results: 



Gram-positive organisms, violet. Gram-negative organisms, 

 red with pink nuclei. 



GRAM'S STAIN 

 Jensen's modification 



Solutions required: 



A. Methyl violet 6B (Jensen). 



B. Lugol's iodine. 



C. Neutral red (Jensen). 



Technique: 



1. Air-dried bacterial films are fixed as above. 



2. Stain for twenty to thirty seconds with 0*5% methyl violet 

 6B in distilled water. 



3. Pour off; wash film with Lugol's iodine; and allow the 

 iodine to act on the film for one half to one minute ; then pour off. 



369 



