86 BIOLOGY OF PNEUMOCOCCUS 



curves of hemolytic titer and growth seemed to Cowan to denote 

 that hemolysin production was not essentially the result of autoly- 

 sis. Hemolytic power diminished in old cultures, due to oxidation, 

 but could be restored by reducing agents. The hemolysin was not 

 type-specific nor was it related to virulence. It filtered readily, was 

 rapidly destroyed at 56°, was antigenic, and was produced by all 

 but two of twenty-eight strains. The observation that the sub- 

 stance appears in broth cultures agrees with that of Sickles and 

 Coffey, but it would seem that Cowan had not sufficiently ruled out 

 the factors of autolysis to justify the conclusion that the hemoly- 

 sin is extracellular in origin. 



While Neill 952 found that pneumo-antihemolysin was without 

 effect on the hemotoxins of tetanus and Welch bacilli, Todd 1412 

 reported that he was able, to a certain extent, to neutralize pneu- 

 mococcal hemolysin and tetanolysin with the serum of horses hy- 

 perimmunized against streptococci, the action being ascribable to 

 the content of highly active antistreptolysin in the immune se- 

 rum. Todd added that the degree of neutralization was not neces- 

 sarily correlated with the antistreptolytic titer and that the differ- 

 ent hemolysins were distinguishable by quantitative serological 

 methods. This partial antigenic overlapping of hemolysins could 

 only be demonstrated by the use of hyperimmune serum. 



Purpura Production 

 Somewhat analogous to the effects of the hemolysin and hemo- 

 toxin produced by Pneumococcus, but probably not a direct con- 

 sequence of their action, is the purpuric condition seen in both 

 natural and experimental pneumococcal infections. Claude 236 in 

 1896 was among the first to note the occurrence of purpura in an 

 infant dying of pneumonia. The lesions tended to have black cen- 

 tral nodes leading to ulcerative necrosis. But, more important still, 

 the causal relation between Pneumococcus and purpura was dem- 

 onstrated by the isolation by Claude of pneumococci both from the 

 blood and from the center of the purpuric lesions. A similar case 



