STAINING METHODS 



as for tubercle bacilli. Next wash the preparation with water and flood the cover- 

 glass with Gram's iodine solution. Some bacteriologists simply pour off excess of 

 aniline gentian violet and immediately drop on the iodine solution. It is well to 

 repeat the application of the iodine solution a second time.. The iodine solution is 

 left on one minute or until the preparation has a coffee-grounds color. 



GRAM'S IODINE SOLUTION 



Iodine i gram. 



Potassium iodide 2 grams. 



Distilled water 300 c.c. 



After washing off the excess of iodine solution at the tap, drop on 95% alcohol 

 and decolorize until no more violet color streams out. Now wash again and counter- 

 stain either with the dilute carbol fuchsin or with a saturated aqueous solution of 

 Bismark brown. 



The Gram-positive bacteria are stained a deep violet. 



In staining smears of pus for gonococci or other Gram-negative bacteria it is best 

 to first stain with the gentian-violet solution for two to five minutes. Then wash 

 and examine the preparation mounted in water. The organisms stand out promi- 

 nently. After noting the presence of the cocci treat the smear with the Gram 

 solution and proceed as in the usual Gram staining technic. 



STAINED BY GRAM'S METHOD 

 S. pyogenes aureus. 

 S. pyogenes albus. 

 S. pyogenes. 

 M. tetragenus. 

 Pneumococcus. 

 Anthrax bacillus. 

 Tubercle bacillus. 

 Lepra bacillus. 

 Tetanus bacillus. 

 Diphtheria bacillus. 

 B. aerogenes capsulatus. 

 Oidium albicans. 

 Mycelium of actinomyces. 

 Saccharomyces. 

 Hofmann's bacillus. 

 B. xerosis. 



NOT STAINED BY GRAM'S METHOD 

 Meningococcus. 

 M. catarrhalis. 

 M. melitensis. 

 B. typhosus. 

 B. coli communis. 

 B. dysenteriae (Shiga). 

 Sp. cholerae asiaticae. 

 B. pyocyaneus. 

 B. mallei. 



B. pneumonias (Friedlander). 

 B. proteus. 

 B. of influenza. 

 B. of bubonic plague. 

 B. of chancroid. 

 B. of Koch- Weeks. 

 Gonococcus. 



Practically all pathogenic cocci are Gram-positive, except the Gonococcus, the 

 Meningococcus ', the M . catarrhalis, and the M. melitensis. 



Practically all pathogenic bacilli are Gram-negative, except the spore-bearing 

 ones (exception B. malig. cedemat.}, the acid-fast ones, diphtheria and diphtheroid 

 organisms. 



The bacillus of glanders is Gram-negative. 



