388 BACTERIOLOGY. 



immunize animals against rabies, but does 

 against snake venom. The serum of rabbits 

 which have been immunized against rabies 

 protects animals against cobra venom almost 

 as well as does the cobra anti-venin itself. 

 Dogs, however, which are immunized against 

 rabies, and possess a serum protecting other 

 animals against snake venom are themselves 

 susceptible to snake venom. On the other 

 hand rabbits immunized against snake venom 

 have become resistant towards the " street- 

 virus " ' of rabies, but still succumb to the 

 more virulent rabies of rabbits. 



6. A protective and curative effect may be 

 wrought without the specific antitoxin. Ani- 

 mals immunized for abrin are immune against 

 anthrax (Calmette). Rabbits immunized 

 against anthrax are relatively immune against 

 abrin, but their serum contains no anti-abrin. 

 The fact that fowls immunized against tetanus 

 possess no tetanus antitoxin has already been 

 mentioned. The antitoxin that is present in 

 the blood after immunization is therefore at 

 least superfluous for purposes of protection. 



The specificity of action of the anti-sub- 

 stances is obviously not essential to their anti- 

 dotal effect, and it is therefore not necessary 

 to assume it in a causal interpretation of im- 



1 Therabic virus procured from dogs which is of a constant intensity. 



