PATHOGENIC BACTERIA. 295 



diameters of the cocci vary from 0.4 to i /*. Attempts have 

 been made to create varieties of streptococci according to the 

 length of the chains. On that basis a Streptococcus brevis and 

 a Streptococcus longus have been described. 



Buerger* makes a tentative division of. streptococci into those 

 which (i) ferment dextorse, levulose, galactose, maltose, 

 saccharose, lactose, inulin, dextrin and mannite; (2) those which 

 ferment all but mannite; (3) those which ferment all but 

 inulin (4) all but inulin and mannite; (5) all but inulin and 

 lactose; (6) all but inulin, mannite, and saccharose. 



The Streptococcus pyogenes is not motile. It stains by 

 Gram's method. Escherichf recommended for the staining 

 of the streptococci found in the intestinal canal the following 

 modification of the Gram-Weigert procedure. It is probably 

 available for streptococci in general. 



THE STAIN. 



A. Gentian violet, 5 gms. 

 Water, 200 c.c. 

 Boil a half hour and filter. 



B. Absolute alcohol, n c.c. 

 Anilin oil, 3 c.c. 



Add 3 parts of A to i part of B. This stain keeps for about 2 or 3 weeks. 



THE DISCHARGING FLUID. 



Iodine-iodide of potassium solution (i part iodine, 2 parts iodide of potas- 

 sium, 60 parts water), and analine xylol mixed in equal parts. Moreover, 

 pure xylol. For contrast stain saturated alcoholic solution of fuchsin diluted 

 with equal parts of absolute alcohol. 



By the method of Hiss (page 49) capsules may sometimes be 

 demonstrated. It is facultatively anaerobic; grows best in the 

 incubator; more slowly at room temperature, and does not 

 liquefy gelatin. In gelatin plates it produces small, round, 

 white, punctiform colonies which are slow of development, and 



* Journal. Exper. Med. Vol. IX., 1907. pp. 428-435. 



t V. Lingelsheim in Kolle and Wassermann. Vol. III., 1903. p. 337. 



