386 BIOLOGY OF PNEUMOCOCCUS 



ceived both antibacterial and antitoxic serums. The results showed 

 that the antitoxin was without effect in staying the infection. 

 Sabin then tested the action of antipneumotoxin in rabbits in- 

 fected intradermally by the method of Goodner. Rabbits were 

 given an intradermal injection of 0.1 cubic centimeter of a 1 to 

 100 dilution of an eighteen-hour broth culture of virulent Type I 

 Pneumococcus. Three groups of rabbits so injected were treated 

 with the same serums as in the mouse experiments, some animals 

 receiving the serum injection six or seven hours after inoculation 

 and some twenty-four hours after inoculation. Of the untreated 

 controls and those animals receiving antitoxin only, all died within 

 the same time, and no beneficial effect was observed in the rabbits 

 treated with antitoxic serum added to antibacterial serum. 



The preliminary statement of Coca (1932) 245 regarding the 

 antigenic action of a pyrogenic and skin-reacting substance in 

 culture filtrates of Pneumococcus in raising the resistance of chil- 

 dren to the action of the antigen has already been mentioned. Not 

 only did the young subjects become immune to the pyrogenic sub- 

 stance and fail to react when the filtrate was injected into the 

 skin, but the serum of the children so treated neutralized the ac- 

 tion of the filtrate. Convalescent serum from patients recovering 

 from infection with Type I and II Pneumococcus also inhibited 

 the effect of the poisonous substance derived from pneumococci. 

 Therapeutic antipneumococcic serum, on the contrary, in the 

 amounts used, failed to neutralize minute amounts of the filtrate. 



In a more recent report (1936), Coca 246 described further ex- 

 periments with filtrates of pneumococcal cultures. The toxic prin- 

 ciple was neutralized by the serum of young human subjects pre- 

 viously injected with the filtrates and by the serum of patients 

 convalescing from lobar pneumonia. According to Coca, the neu- 

 tralizing action of the human immune serum was type-specific and 

 antitoxic in nature and not related to the type-specific polysac- 

 charide antibody. 



