PYOGENIC ORGANISMS 183 



'pyogenes alhus, the Streptococcus pyogenes, the gonococcus, 

 the pneumococci, the Bacillus tuberculosis, the bacillus of 

 typhoid, the Bacillus coli communis, etc. 



Pus may also be formed by the actinomyces (ray-fungus) 

 and by certain aspergilli ; all these may give rise to pus- 

 formation either alone or associated with other organisms. 

 The organisms most frequently found in pus are the 

 Staphylococcus pyogenes aureus and the Staphylococcus 

 pyogenes albus and the Streptococcus pyogenes; besides 

 these, there are others of the same group closely allied 

 to the foregoing, but they are of somewhat less frequent 

 occurrence. 



Staphylococcus Pyogenes Aureus. — This organism was 

 isolated and described by Eosenbach in the year 1884. 

 It is a spherical coccus, about 1 /n in diameter, which 

 sometimes occurs as a diplococcus, but more commonly 

 in grape-like masses, from which it derives its name. 



Method of Staining. — The organism stains with all the 

 usual aniline stains ; it can also be stained by Gram's 

 method. 



Growth on Media. — The coccus grows well on all the 

 ordinary media, both at room-temperature and at blood- 

 heat, and the cultures so made retain their vitality for 

 many months. 



Inoculated into broth, the organism produces a per- 

 ceptible turbidity in about eighteen hours, while the 

 gelatine begins to liquefy as soon as there is any visible 

 growth, the liquefaction occurring in stab culture all along 

 the stab. On agar and blood serum a thick streak 

 develops, which is at first pale in colour, but later on 

 develops the golden - yellow colour ; exposure to diffused 

 daylight is essential to the formation of the colour. The 

 organism is found chiefly on the surface of the body, 

 which appears to be its normal habitat ; it has been found 



