STUDY OF THE IMMUNITY AGAINST BACILLUS PYOCYANEUS 1 7 



3. Bouillon cultures killed by toluol are toxic to guinea-pigs and 

 rabbits. 



4. The toxicity of such cultures is largely referable to endotoxins 

 which have diffused out of the bodies of the bacilli. Some of the toxic 

 action may also be due to products developed from the medium in which 

 the bacillus is growing. 



5. The degree of immunity induced by living or dead cultures is not 

 high, the animals seldom being able to withstand more than a few lethal 

 doses of the living culture. 



6. The blood serum of animals immunised with living or dead 

 cultures possesses no bactericidal properties when tested in vitro upon 

 cultures of the bacillus. 



7. The serum of animals immunised with dead or living cultures 

 shows an increased opsonic effect in comparison with normal serum. 



8. The recovery from pyocyanic infection in rabbits is probably due 

 to phagocytosis, preceded by the opsonic action of the serum. 



(173) 



