Streptococcus Pyogenes 261 



(chains of from four to ten), have been described by v. 

 Lingelsheim.* 



It is not motile and does not form endospores, though 

 sometimes large individuals much larger than the others in 

 the chain may be observed. Some believe these -to be 

 arthrospores. 



Staining. The organisms stain well with ordinary 

 aqueous solutions of anilin dyes, and by Gram's method. 



Isolation. The streptococcus can be isolated from pus 

 containing it, either by the usual method of "plating" or 

 by the inoculation of a mouse or rabbit, from whose blood 

 it may easily be secured after death. 



Fig. 76. Streptococcus pyogenes, from the pus taken from an ab- 

 scess. X 1000 (Frankel and Pfeiffer). 



Cultivation. The organism grows at both the room tem- 

 perature and that of incubation, its best and most rapid 

 development being at about 37 C. 



Colonies. Upon gelatin plates very small, colorless, trans- 

 lucent colonies appear in from twenty-four to forty-eight 

 hours. When superficial, they spread out to form flat disks 

 about 0.5 mm. in diameter. The microscope shows them to 

 be irregular and granular, to have a slightly yellowish color 

 by transmitted light, and to have numerous irregularities 



* " Zeitschrift fur Hygiene," Bd. x, 1891, p. 331; xn, 1892, p. 308. 



