Streptococcus Pyogenes 265 



in the heart's blood and in the organs. In less virulent cases 

 minute disseminated pyemic abscesses are sometimes found. 



According to Marmorek,* the virulence of the strepto- 

 coccus can be increased to a remarkable degree by rapid 

 passage through rabbits, and maintained by the use of a cul- 

 ture medium consisting of three parts of human blood-serum 

 and one of bouillon. The blood of the ass or ascitic or pleu- 

 ritic exudates may be used instead of the human blood-serum 

 if the latter be unobtainable. By these means Marmorek 

 succeeded in intensifying the virulence of a culture to such 

 a degree that one hundred-thousand-millionth (un cent mil- 

 liar di^me) of a cubic centimeter injected into the ear vein 

 was fatal to a rabbit. 



Petruschky f found the virulence of the culture to be well 

 retained when the organisms were planted in gelatin, trans- 

 planted every five days, and when grown, kept on ice. 



Hoist J observed a virulent Streptococcus brevis that re- 

 mained unchanged upon artificial culture media for eight 

 years without any particular precautions having been taken 

 to maintain the virulence. 



Dried streptococci are said by Frosch and Kolle to retain 

 their virulence longer than those growing on culture media. 



Lubenau || found that cultures of the streptococcus when 

 grown in glucose containing bouillon produced a hemolytic 

 substance streptokolysin not seemingly present in cul- 

 tures grown in ordinary bouillon. Besredka** found that 

 streptokolysin was produced only by highly virulent cultures 

 of the streptococcus and not by saprophytic organisms that 

 have been for some time under cultivation in the laboratory. 



Levinff investigated the subject thoroughly and found 

 that different strains of streptococci produced streptokolysin 

 in very varying quantities, that its production is entirely 

 independent of that virulence, that it is destroyed by heat 

 (37 C. in some days; 55 C. in one-half hour) ; that acidity 



*" Ann. de 1'Inst. Pasteur," t. ix, No. 7, July 25, 1895, p. 593. 

 f'Centralbl. f. Bakt. u. Parasitenk.," Bd. xvm, No. 16, May 4, 

 1895, p. 551. 



llbid., Bd. xix, No 11, March 21, 1896. 

 Fliigge's "Die Mikroorganismen." 



|| "Centralbl. f. Bakt.," etc., 1901, Bd. xxx, Nos. 9 and 10. 

 ** " Annales de 1'Inst. Pasteur," 1901, S. 880. 

 tf'Nord. Med. Ark.," 1903, n, No. 15, p. 20. 



