«^-fJ INFECTION ANt) IMMUNITY 



more favorable 7iidus, and probably has to do with an evolution in the 

 bacterial resistance to the protective powers, rather than a decrease in 

 protective strength on the part of man. Indeed, both of these processes 

 may increase hand in hand, and we may have septicemias extending over 

 weeks, months, and even years. We may have, in fact, an "armed 

 peace" and the prepared bacterial army is not to be routed by the 

 application of means which under other circumstances might prove effi- 

 cacious, for we have seen how the bacteria may possibly become resist- 

 ant to the protective agents of the animal body, and may continue to 

 survive attacks which might well prove fatal to less well-adapted 

 members of their species. 



Theoretically, then, we are safe in assuming that the infections in 

 man which most closely simulate the usual artificial infection in animals 

 are fresh local infections, and infections of any character, in their earliest 

 stages, before the bacteria have been adapted to carry on their fight 

 with the powers of the infected body. 



The point which should be made clear is that the outcome of our 

 attempts to treat infectious diseases is, if we have the real means in our 

 hands, probably more dependent on the degree of adaptation of the 

 germs than the actual powers of resistance of the patient. These latter, 

 of course, determine largely the picture of the disease, but give little 

 information as to the power of the invader. This has been forced on us 

 by the fact that, although we are able to cure positively acute septice- 

 mias in animals, the more subacute septicemias of man do not yield 

 readily to our present modes of treatment, whereas even extremely 

 severe acute and chronic localized diseases, due to the same organisms, 

 respond to treatment. 



