HISTORIC DEVELOPMENT OF IMMUNOLOGY 49 



the infection. In other words, with each infec- 

 tion the patient endeavors to protect itself by 

 producing antibodies. When the protection is 

 insufficient, infection will spread ; when the anti- 

 bodies are in excess the infection is overcome; 

 when the forces are about equal, a stage of 

 chronicity may result in which the patient be- 

 comes accustomed to the invaders, and while the 

 infection does not spread rapidly it does not on 

 the other hand recede. In chronic conditions, 

 therefore, a dose of bacterial vaccine may excite 

 dormant or inactive cells to furnish an extra 

 quantity of antibodies and thus turn the tide. 

 In therapeutic inoculation, therefore, the funda- 

 mental principle is to stimulate in the interest 

 of the infected tissues the immunizing capacities 

 of the uninfected tissues. 



In this connection it should be remembered 

 that the usual forms of treatment should be 

 given while vaccine therapy is being instituted. 

 For instance, it is useless to employ a vaccine as 

 the sole means of treating a patient with a sup- 

 purative sinus. If an infected suture is directly 

 responsible for the suppuration, the suture 

 should be removed, if possible ; and after this is 

 done, a vaccine may be of considerable aid in 



