INDIVIDUAL FEATURES OF PYOGENIC BACTERIA. 101 



in pairs, as a diplococcus. Its appearance in pus as well as 

 in culture-media is the same in general as is seen in Fig. 47. 

 Principal Biologic Characters. The Staphylococcus pyogenes 

 aureus is a facultative anaerobic. It clouds bouillon in twenty- 

 four hours at 37 C., and shows from the second day a yel- 

 lowish precipitate, which gradually increases in color and at 

 the bottom of the tube appears of a golden yellow. It lique- 

 fies gelatin. Stab-cultures on this media at 20 C. on the 

 second or third day have the appearance of a funnel, at the 

 bottom of which is an orange-yellow deposit. At the end 

 of three days the gelatin in the tube is completely liquefied. 

 On gelatin plates colonies of a dark-yellowish color are 

 observed with a centre of more or less intense orange color. 



On agar-agar the colonies appear small, regularly spherical, 

 and of an orange-yellow. Plates made from this medium 

 have the same characteristics as on gelatin, being more or 

 less pigmented yellow. It does not liquefy agar. The cult- 

 ures on blood-serum have the same characteristics as on agar. 

 The Staphylococcus pyogenes aureus stains with all the anilin 

 dyes, and also by Gram's method. 



Pathogenesis. When inoculated into the blood of an animal, 

 the Staphylococcus aureus rapidly causes a fatal septicaemia. 

 Rabbits and guinea-pigs die, as a rule, in twenty-four to 

 forty-eight hours after inoculation, and the organisms may be 

 found generally disseminated in the blood-capillaries of the 

 organs, and are also found in the blood taken from the heart- 

 Inoculations into the peritoneal cavity cause a purulent 

 peritonitis of a virulent character, generally ending in death 

 of the animal. Injected under the skin, this organism pro- 

 duces localized abscesses. 



II. Staphylococcus Pyogenes Albus. 



The Staphylococcus pyogenes albus, like its companion the 

 aureus, exists as a saprophyte : a. on the surface of the skin 

 in man, and 6. in association with the aureus in abscesses 

 and superficial phlegmons. 



Although clinicians are in the habit of considering it as an 



