100 BACTERIAL POISONS OF INFECTIOVS DISEASES. 



reactions. Injections of the soluble ferments conferred immunity. 

 In 1892 Novy obtained immunity in rabbits by injection of blood 

 serum of immunized animals, and similar results were obtained 

 by De Schweinitz. In the same year Metschnikoff published 

 his studies on immunization with blood serum of rabbits im- 

 mime to hog cholera, but according to Smith and Moore, he did 

 not work with the hog cholera germ, but with that of swine 

 plague. The last-mentioned individual obtained only partial im- 

 munity with blood serum of immune guinea-pigs, and none with 

 that of rabbits. 



Rabbit Septicemia. — Hoffa has killed rabbits by inoculation with 

 pure cultures of the bacillus of this disease, and has isolated from 

 the bodies of these animals methylguanidin, while in the bodies of 

 healthy rabbits this poison could not be found. He ascertained that 

 the average fatal dose of methylguanidin for rabbits is 0.2 gm. 

 when given subcutaneously. Hueppe thinks that the bacterium of 

 chicken cholera is identical with that of rabbit septicsemia, and it 

 has been ascertained that chickens also may be poisoned with 

 methylguanidin and that the symptoms induced by this substance 

 resemble those of the disease. 



Pneumonia. — Bonardi reported the presence of certain poisonous 

 basic substances in cultures of the diplococcus of Frankel, but he 

 was unable to obtain these in quantity sufficient for ultimate analysis. 

 He also stated that he secured immunity against the germ by treat- 

 ing rabbits with a small quantity of the chemical poisons. How- 

 ever, temporary immunity to the diplococcus may be induced by 

 non-specific agents, and Vaughan ' concluded a research upon this 

 subject as follows : 



1. Rabbits and guinea-pigs may be protected against virulent cul- 

 tures of the diplococcus of pneumonia by previous treatment with 

 hypodermatic injections of a solution of yeast nuclein. 



2. The immunity thus secured is not due to the action of the 

 nuclein, as a germicide, directly on the germ. 



3. The process of securing this immunity is an educational one, 

 and, most probably, depends upon the stimulant effects of the nuclein 

 upon some organ whose Unction it is to protect the body against 

 bacterial invasion. 



4. The longer the nuclein injections are continued and the more 

 frequently they are administered, the more complete is the immunity 

 which is secured. 



5. In order to obtain this immunity the inoculation with the germ 

 must follow soon after the last treatment with the nuclein. 



^HuitiUme Omgrii International ^Hygient, 2, 44 



