STREPTOCOLYgni. 519 



pends on the use of different strains of the organ- 

 ism in experimental work. The amount of endo- 

 toxin which virulent strains contain is subject to 

 great variations. Aronson found practically none 

 in the killed cells of a very virulent strain. It 

 seems probable that the endotoxin is rather sus- 

 ceptible to heat, since cultures which are killed 

 by mild methods,, as by chloroform, are more toxic 

 than those which are killed by heat. The nitrates 

 of old bouillon cultures are more or less toxic. A 

 strong "toxin" was prepared by Marmorek by 

 growing a virulent strain in a mixture of serum 

 and bouillon for three months and filtering the 

 culture. More recently he uses a medium contain- 

 ing glycocol and leucin. Toxic precipitates from 

 fluid cultures have also been obtained. Bouillon 

 filtrates of virulent cultures after two to fourteen 

 days of growth have low toxicity (Aronson). 



Besredka, and later G. F. Ruediger, showed that streptoco- 



lysin and 



virulent streptococci produce a hemolytic toxin Leucoe 



. . , , -n 3- Toxin. 



when grown in various heated serums. Euediger 

 proved that this hemolysin ( strep tocoly sin) is a 

 true toxin, possessing a haptophorous and toxo- 

 phorous structure. This discovery has an im- 

 portant bearing on the fact that the blood in fatal 

 streptococcus infections, especially in rabbits, is 

 often more or less laked. Streptocolysin is de- 

 stroyed by a temperature of 70 C. in two hours, 

 by peptic digestion, deteriorates rapidly at ordi- 

 nary temperatures, and is non-dialysable. Certain 

 normal serums contain antistreptocolysin (Rue- 

 diger). Another significant fact is that virulent 

 strains, when grown in serum and ascitic fluid, 

 produce a substance which kills leucocytes and 

 inhibits phagocytosis. This may explain the fail- 



