METHOD FOR STAINING CAPSULES 97 



GRAM-POSITIVE ORGANISMS. GRAM-NEGATIVE ORGANISMS. 



Staph. pyogenes aureus and albus Bact. mallei 



Strept. pyogenes Bact. aerogenes 



Bact. anthracis B. typhosus 



Bact. tuberculosis B. coli communis 



B. alvei B. cholera? suis 



B. tetani M. gonorrhea? 



Bact. acidi lactici Msp. deneke 



Bact. bulgaricum Msp. finkler-prior 



B. megaterium Spirocheta obermeieri 



B. subtilis Proteus tulgaris 



B. myeoides Ps. medicaginis 



B. mesentericus vulgatus B. amylovorus 



M. tetragenus Ps. campestris 



Streptothrix actinomyces B. phytophthorus 



Sacch. cerevisice and other yeasts B. caratovorus 



Molds 



REFERENCE 



BENIANS, T. H. C.: "Observations on the Gram-positive and Acid- 

 fast Properties of Bacteria." Jour, of Path, and Bact., Vol. 

 XVII, pp. 199-211 (1912). 



EXERCISE 33. METHOD FOR STAINING CAPSULES 



Some bacteria possess a gelatinous envelope or " cap- 

 sule " which in some species surrounds each individual 

 organism, and in others, groups of organisms. The pres- 

 ence of this capsule may be demonstrated by various 

 special staining methods. The capsule takes the stain 

 much less quickly than does the organism, leaving a light- 

 colored halo about it. The presence of a capsule does not 

 always indicate that the organism forming it is a slime- 

 forming organism, nor does the fact that an organism is a 

 slime-former preclude the possession of a capsule. 



Apparatus. Clean cover-glasses; clean slides; platinum 

 loop; cover-glass forceps; filter paper, pieces; glacial 

 acetic acid; gentian violet, aqueous-alcoholic. 



