INFECTION AND IMMUNITY. 435 



human beings, indicates the moment at which the poison- 

 ous products, manufactured by the bacteria located in 

 the lungs, are present in the circulation in amounts 

 sufficient to call forth in the tissues the reactive change 

 that results in the production of the antidotal substance 

 that has the power of rendering the poisons inert. 



At the time of the crisis in pneumonia the bacteria 

 themselves are in no way affected. They remain in 

 the lungs, and can be detected, in full vigor and viru- 

 lence, in the sputum of patients a long time after the 

 disease is cured. They have lost none of their power 

 of producing poisonous products, and still possess their 

 original pathogenic relations toward susceptible animals. 

 It is only after the crisis that their poisons are neutral- 

 ized by this antidotal proteid that has been produced 

 by the cells of the tissues, and as this occurs the sys- 

 temic manifestations gradually disappear. The Klem- 

 perers claim to have isolated from cultures of the micro- 

 coccus lanceolatus a proteid body that is the agent 

 concerned in producing the tissue reaction which results 

 in the formation of the protecting substance. They like- 

 wise isolated from the serum of immunified animals a 

 proteid that possesses the same powers as the serum 

 itself, viz., of affording immunity and curing the dis- 

 ease. 



Here, again, it appears that the processes of infection 

 and immunity are chemical in their nature, the active 

 poisons of the invading organisms " the pneumo- 

 toxins " being instrumental in producing the dis- 

 eased condition, while the antidotal or resisting body of 

 the tissues " the anti-pneumotoxin " is the agent by 

 which the poison is neutralized. 



Results in general analogous to those of G. and F. 



