OTHER COMMON PYOGENIC ORGANISMS. 281 



staphylococcus epidermidis albus (Welch), an organism 

 that may readily be confused with micrococcus pyogenes. 

 It is distinguished from the latter by the slowness with 

 which it liquefies gelatin and by the comparative absence 

 of pathogenic properties when injected into the circula- 

 tion of rabbits. Welch regards this organism as a 

 variety of micrococcus pyogenes. 



FIG. 55. 



Streptococcus pyogenes in pus. 



STREPTOCOCCUS PYOGENES (ROSENBACH), MIGTJLA, 

 1900. 



Synonyms: Streptococcus, Billroth, 1874; Streptococcus pyogenes, 

 Rosenbach, 1884. 



From a spreading phlegmonous inflammation prepare 

 cover-slips and cultures. What is the predominating 

 organism ? Does it appear in the form of irregular clus- 

 ters like those of grapes, or have its individuals a definite, 

 regular arrangement ? (See Fig. 55.) Are its colonies 

 like those of micrococcus aureus? 



Isolate this organism in pure cultures. In these cul- 



