TOXINS AND ANTITOXINS. 31 



Experiments by Behring and Kitasato^ have 

 shown that the tumors of a vaccinated animal, 

 freed from all organized matter visible under the 

 microscope by filtration through porcelain, contains 

 principles capable of directly or indirectly protect- 

 ing other animals from the disease caused by the 

 corresponding virus. Meanwhile, experiments have 

 shown that the vaccinating matters are totally 

 eliminated; nevertheless, after their elimination, 

 the immunity acquired remains with the animal, 

 which then continues to be protected against the 

 corresponding virus. 



Interest in this subject has incited numerous 

 researches with a regard to bringing to light the 

 mechanism of this immunization; and this will 

 form the subject of another volume of this collec- 

 tion. We may state here, however, that there 

 have been recognized two concurrent causes of 

 this preservative action; the one, called phagocy- 

 tosis, results from the fact that the microbe intro- 

 duced into the vaccined organism becomes incapable 

 of producing its usual toxins, while on the other 

 hand the immunization renders the organism 

 capable of secreting substances possessing an 

 activity contrary to that of the virus, in fact true 

 counter-poisons, comprised under the general name 

 antitoxins. 



* Deutsche Med, Wochenschr., 1890, p. 1113. 



