BIOCHEMICAL FEATURES 89 



greatly reduced in number, but the rate of destruction and regen- 

 eration was somewhat slower than that of the platelets, while leu- 

 cocytes were slightly, if at all, affected. Reimann and Julianelle 

 emphasized the differences between the hemolysin and the purpuri- 

 genic principle in pneumococcal extracts. Both the thrombolytic 

 and hemolytic properties were destroyed by heating in vitro, al- 

 though such heated extracts still were able to produce purpura but 

 not a severe anemia in mice. Extracts adsorbed with either blood 

 platelets or erythrocytes showed a marked diminution in throm- 

 bolytic and hemolytic activity in vitro. Adsorbed extracts, how- 

 ever, caused purpura as well as severe anemia and thrombopenia in 

 mice. 



In a further study, Julianelle and Reimann 690 offered the follow- 

 ing additional conclusions: 



The purpura-producing principle of Pneumococcus is non-antigenic 

 in the sense that it does not stimulate the formation of antibodies ; white 

 mice acquire an increased resistance to purpura as a result of repeated 

 injections of toxic doses of the purpura substance; the serum of rabbits 

 immunized with the purified purpura principle, with smooth and rough 

 strains of Pneumococcus or with cell extracts, autolysates or the nucleo- 

 protein fraction of the organism, does not confer upon white mice pro- 

 tection against purpura ; the purpura principle does not exist preformed 

 in the cell, but is rather an autolytic derivative, since it is formed only 

 when pneumococci undergo autolysis, and it is not found when the auto- 

 lytic ferments are inactivated ; the purpura substance is associated with 

 the proteose fraction of active pneumococcus extracts. 



Pittman and Falk, 1092 still more recently, substantiated the re- 

 sults of Julianelle and Reimann by causing purpura in white mice 

 with extracts of pneumococci made by alternate freezing and thaw- 

 ing. This extract also protected mice against an infection with 

 pneumococci of low virulence when the extract was injected twenty- 

 four hours prior to inoculation, but when both extract and culture 

 were given simultaneously death ensued. The effect has some resem- 

 blances to the action of Bails' aggressin. The strange selective af- 

 finity of bacterial proteins for blood cells reminds one of the he- 



