87 



iodine which is insoluble in alcohol. Some bacteria are 

 stained by Gram's method and some are not. Those that are 

 not stained are sometimes said to be decolorized by the stain. 

 Those that stain have a purplish or blue-brown color. 



The following organisms do not stain by Gram's method : 



Micrococcus of gonorrhoea, or gonococcus. 



Bacillus of typhoid fever, or Bacillus typhosus. 



Bacillus coli communis. 



Spirillum of Asiatic cholera, or Comma bacillus. 



Bacillus of influenza. 



Bacillus of bubonic plague. 



Bacillus Mallei (glanders). 



Bacillus of malignant oedema. 



Bacillus of Friedlaender (pneumobacillus). 



Spirillum of relapsing fever. 



Diplococcus intracellularis meningitidis. 



Bacillus proteus vulgaris. 



Bacillus pyocyaneus. 

 Among the bacteria that are stained are the : 



Pneumococcus (Diplococcus pneumonias). 



Staphylococcus pyogenes. 



Streptococcus pyogenes. 



Bacillus of diphtheria. 



Bacillus tuberculosis. 



Bacillus of leprosy. 



Bacillus anthracis. 



Bacillus of tetanus. 



Bacillus aerogenes capsulatus. 



Streptothrix actinomyces. 



SPORES : Mention has been made of the peculiar resistance 

 exhibited by spores to extraneous influences. It is also very 

 difficult to stain them. The methods generally employed are 

 the same as those for staining the tubercle bacillus, but the 

 film must be exposed to the action of the stain for a longer 

 time. 



McFarland recommends the following method : Place the 

 preparation in a test-tube half filled with a carbol-fuchsin 

 solution and boil it for at least fifteen minutes. Decolorize 

 with 3 per cent, hydrochloric or a 2-5 per cent, acetic acid 



