SPECIAL METHODS OF STAINING AND MODIFICATIONS 41 



Gram's Method for Tissues (Modified byGunther}: 



I. Stain in anilin-water gentian- violet . . . i minute. 

 II. Dry between filter-paper. 



III. lodin potassium iodid solution 2 minutes. 



IV. Alcohol \ minute. 



V. 3 per cent, solution hydrochloric acid 



in alcohol 10 seconds. 



VI. Alcohol, oil of cloves, and Canada balsam. 



Behavior of the More Important Bacteria to Gram's Stain. 

 Positive means that the bacteria retain the primary color, or 

 gentian-violet, negative that they do not. 



Positive. Negative. 



Tubercle bacillus. Colon bacillus. 



Smegma bacillus. Typhoid bacillus. 



Lepra bacillus. Cholera bacillus. 



Anthrax bacillus. Influenza bacillus. 



Tetanus bacillus. Friedlander's bacillus. 



Diphtheria bacillus. Plague bacillus. 



Pneumococcus. Diplococcus intracellularis. 



Streptococcus. Gonococcus. 



Staphylococcus. Koch-Weeks' bacillus. 



Cocci of the urethra. Conjunctivitis bacillus of Morax. 



To Stain Spores. Since spores have a very firm capsule, 

 which tends to keep out all external agents, a very intensive 

 stain is required to penetrate them, but once this object is 

 attained, it is equally as difficult to decolorize them. 



A cover-glass prepared in the usual way, i. e., drying and 

 passing the specimen through the flame three times, is placed in 

 a watch-crystal containing ZiehPs carbol-fuchsin solution, and 

 the same placed upon a rack over a Bunsen burner, where it is 

 kept at boiling-point for one hour, careful to supply fresh solution 

 at short intervals lest it dry up. 



The bacilli are now decolorized in alcohol containing J per 

 cent, hydrochloric acid. A contrast color, preferably methyl- 

 ene-blue, is added for a few minutes. 



