88 STUDY OF BACTERIA 



Many bacteria stain in this way, and many do not. Important 

 bacteria often may be differentiated in this manner. 



Examples of Gram's stain are as follows: 



Gram positive Bact. aerogenus capsulatus^ Bvct. anthracis, Bad. 

 diphtheria, B. tetani, Bact. tuberculosis, Streptococcus pneumonia, 

 Staph. pyogenes, Strep, pyogenes. Gram negative B. coli, B. 

 dysenteria, Bact. influenza, Bact. mallei, Bact. pestis, B. pyocyaneus, 

 B. typhosus, Diplococcus intracellularis meningitidis, Micr. catarrh- 

 alis, Micr. gonorrhoea, Spirillum cholera. 



Thionin Blue, or Carbol Thionin. 



This is a useful stain, prepared thus: 



Thionin blue i gram. 



Carbolic acid 2.5 gram. 



Water 100 c.c. 



Filter. Good for staining bacteria in tissues. 



Special Stains. 



Wright's Stain. This not only stains, but fixes. It has a wide 

 range of usefulness in a bacteriological laboratory for the staining 

 of blood, pus, malarial parasites, trypanosomes, as well as many 

 bacteria, and is prepared as follows: 



5% solution of sodium bicarbonate 100 c.c. 



Methylene blue i gram. 



Mix and heat in sterilizer one hour at 100 C. Cool, filter, then mix ^ per- 

 cent yellowish eosin in water until the mixture loses its blue color and becomes 

 purplish. Of the eosin solution add 500 c.c. to each 100 c.c. of themethylene 

 blue mixture. Mix and collect the abundant precipitate which immediately 

 forms on a filter. Dry this and dissolve in methyl alcohol in the proportion of 

 i gram of powder to 600 c.c. of the alcohol. This is the staining fluid. Keep 

 well stoppered. Fresh alcohol may be added for that which evaporates. 



This complex stain represents a type of which Jenner's, Leish- 



