IMMUNOLOGICAL BEHAVIOR 129 



and /// vilro of completely neutralized nieningococciis and B. cvli 

 reacting factors. The factors are non-specific, heat-labile and seem 

 to bear no relationship to the complement. Heating of immune 

 sera to a temperature destructive for the reactivating property 

 l)ut innocuous to the neutralizing antibodies raises considerably 

 tlieir neutralizing potency. 



