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PUBLIC HEALTH BACTERIOLOGY 



(should dry at once). Fix by passing three times through 

 the flame. Stain for two or three minutes. Wash with 

 water and examine on clean slide in water-drop (using oil 

 immersion). In water-drop bacteria look larger, can be 

 restained, and can be kept longer than when mounted 

 direct in Canada balsam. To preserve : allow to dry, 

 remove from slide, roll up, and label. 



Counterstain with eosin or other stain in dilute solution 

 for i to 2 minutes. Eosin stains cell protoplasm red. 



Films are also made on slides, which are more easily 

 handled than coverslips. 



Gram's Method of Staining Depends on the fact 

 that some bacteria when well stained retain the stain after 

 treatment with a solution of iodine and subsequent washing 

 with alcohol (strong or absolute). This is believed to be 

 due to the stain and the iodine forming a combination 

 which resists decoloration. 



Table. 



Method. Stain for 5 minutes with aniline-oil-gentian- 

 violet, or carbol-gentian-violet. Pour off excess of stain 



