PATHOGENIC BACTERIA. 



291 



The term pyemia is used to describe the dissemination of 

 pyogenic bacteria in the circulating blood, with the formation 

 of metastatic abscesses. 



Staphylococcus Pyogenes Aureus.— A micrococcus of 

 variable size, arranged in irregular clumps, sometimes in pairs; 

 about 0.8 to 0.9 II in diameter; not motile (Fig. 65). It stains 

 by Gram's method; it is a facultative anaerobe; grows rapidly, 

 best at 30° to 37° C. It liquefies gelatin. Upon gelatin plates 



Fig. 65. — Staphylococcus pyogenes aureus, pure culture. (X 1000.) 



small colonies appear at the end of about two days. It grows 

 well upon all the culture-media. Milk is coagulated. It does 

 not lead to fermentation with the production of gas, but pro- 

 duces various acids. 



The growths in the first place are pale, subsequently be- 

 coming golden-yellow in color, but only in the presence of 

 oxygen. This color appears well on all media, and is especially 

 distinct on potato. Sometimes the color is slow in developing. 



The variability of resistance shown by the organism to higher 



