TOXINS OF BACT. DYSENTERIAE 



507 



each before the serum was drawn. An endotoxin animal also 

 received 10 injections of 1 cc. each before the serum was used: 

 and after these injections both these animals were apparently 

 immune against the corresponding toxin. 



Owing to a shortage of animals we have made only one experi- 

 ment with rabbits. We chose to try endotoxin as this toxin 

 showed more distinct symptoms of poisoning than the exotoxin. 



In this experiment the sick animals and the one death occurred 

 in the tests made with heterologous toxin and antitoxin, while 

 the animals that were injected with the mixture of homologous 

 toxin and antitoxin were fairly well. 



We are quite aware that our doses were large and our animals 

 few. But we cannot free ourselves of the opinion that there 

 was a distinct antitoxic action exercised by the sera from the 

 animals immunized against the homologous toxins. The titra- 

 tion of this action in exact doses was hardly possible because 

 of the mild action. 



We now turned our attention to the effect of neutralizing 

 sera on mice, which, as noted previously, acted in a non-specific 

 manner to the action of exotoxin, and possibly in a specific manner 

 to that of the endotoxin. 



