Streptococcus Pyogenes 297 



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

 Lingelsheim,* but do not hold as separate species. 



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 by direct inoculation of a mouse or rabbit, 

 from whose blood it may easily be secured after death, or 

 by "plating." 



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 

 around the edges, due to projecting chains of the cocci. No 

 liquefaction of the gelatin occurs. 



Gelatin Punctures. In gelatin puncture cultures no 

 liquefaction is observed. The minute spheric colonies grow 

 along the whole length of the puncture and form a slightly 

 opaque granular line. 



Agar-agar. Upon agar-agar an exceedingly delicate 

 transparent growth develops slowly along the line of inocu- 

 lation. It consists of small, colorless, or slightly grayish 

 transparent colonies which do not readily coalesce. 



Blood-serum. The growth upon blood-serum resembles 

 that upon agar-agar. The colonies are small, white, dis- 

 crete, and do not affect the medium. 



Potato. The streptococcus does not seem to grow well 

 upon potato, the colonies being invisible. 



Bouillon. In bouillon the cocci develop slowly, seeming 

 to prefer a neutral or feebly acid reaction. The medium 

 remains clear, while numerous small flocculi are suspended 

 in it, sometimes adhering to the sides of the tube, sometimes 

 forming a sediment. When the flocculi-formation is distinct, 

 the name Streptococcus conglomerate (Kurth) is sometimes 



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



