190 



PATHOGENIC BACTERIA. 



STREPTOCOCCUS PYOGENES. 



Another organism whose colonies are frequently ob- 

 tained from the pus containing the staphylococci is the 

 Streptococcus pyogenes of Rosenbach (Fig. 53). It was 

 found by him in 18 of 33 cases of 

 suppurative lesions studied, fifteen 

 times alone and five times with the 

 Staphylococcus aureus. It is a 

 spherical organism of variable size 

 (0.4-1 // in diameter), constantly 



FIG. 53. Streptococcus pyogenes, from the pus 

 taken .from an abscess; x 1000 (Frankel and 

 Pfeiffer). 



FIG. 54. Streptococ- 

 cus pyogenes : culture 

 upon agar-agar two days 

 old (Frankel and Pfeif- 

 fer). 



associated in pairs and chains of from four to twenty in- 

 dividuals. A special variety of it, known as Streptococ- 

 cus longus, sometimes forms chains of more than one 

 hundred members. 



The organism stains well with ordinary aqueous solu- 

 tions of the anilin dyes, and also by Gram's method. Like 

 the coccus already described, it is not motile and does not 

 seem to form spores, though sometimes a large individual 

 much larger than the others in its chain may be ob- 

 served, and may suggest the thought of arthro-sporulation. 



