386 BACTERIOLOGY. 



cholera serum is moderately effective against 

 snake venom, but without effect against the 

 others ; diphtheria antitoxin is powerless 

 against snake venom, tetanus toxin, ricin and 

 abrin ; the antitoxin sera of swine-erysipelas 

 and typhoid are powerless against all these 

 poisons. 



3. Within the animal body, also, specific 

 serum anti-toxin may exert an effect upon 

 specifically different poisons. The serum of 

 animals immunized against the venom of any 

 one species of snake protects animals against 

 snake venom of any other species and against 

 scorpion venom. The serum of animals im- 

 munized against cobra poison renders rabbits 

 immune to abrin. When Marmorek wished 

 to endow animals simultaneously with the 

 antitoxin protecting against diphtheria and 

 with that protecting against streptococci, and 

 for this purpose injected streptococci into horses 

 which Roux had previously immunized against 

 -diphtheria, the animals endured the treatment 



almost without reaction while animals not pre- 

 viously treated for diphtheria reacted very vig- 

 orously ; the diphtheria antitoxin, therefore, in 

 the body of the animal exerts a protective ac- 

 tion against the streptococci and their toxin. 



4. Antitoxins which in vitro neutralize 

 specifically similar or dissimilar toxins may 



