12 



QUATERCENTENARY STUDIES IN PATHOLOGY 



Virulence of B, Pyocyaneus obtained direct from man. — Conservation 

 and Exaltation of Virulence. 



The virulence of the pyocyanic bacillus obtained from man varies. 

 In the case of the races obtained from the leg ulcer and from the intestine, 

 the virulence of the first subcultures were such that i loopful (2 mgr.) 

 injected intraperitoneal caused an acute lethal pyocyanic sepsis in the 

 guinea-pig within 12 hours. With cultures from the throat and from the 

 blood, the virulence was such that '25 loopful killed guinea-pigs acutely. 

 The virulence was well maintained, even for months, in cultures grown 

 on agar stabs at 37° C. for 24 hours, and subsequently at 20° C. 



From each of the four races used in the experiments, passages were 

 made through both rabbits and guinea-pigs to determine whether and to 

 what extent exaltation is possible. After the death of the animal the 

 bacillus was recovered from the heart blood, grown on agar for 24 hours, 

 and inoculated into the peritoneum of the next animal in series. 



(168) 



