THEORIES OF IMMUNITY. 



as that in pnenmo-enteritis, however — of the 

 anti-infectious nature, and that the serum of the 

 immune animals did not contain an antitoxine. 

 As just stated and referred to by Metchnikoff, 

 the same thing was shown to occur in the arti- 

 ficial disease produced by the injection of the 

 cholera spirilla; in Pfeiffer's results (Zeit. f. 

 Hyg., 1894, T. XVI., p. 268) in cholera he ob- 

 tained a serum from highly immunized animals 

 with no antitoxic power, but with very active 

 anti-infectious properties. 



Such instances as these, together with many 

 others that may be found admirably summarized 

 in Metchnikoff 's book upon Immunity (chapter 

 VI.), together with the demonstration of a 

 marked excitation of the phagocytic reaction, 

 served at that time to turn the scale of judg- 

 ment in favor of the cellular theory of immunity, 

 but the discovery of " Pfeiifer's phenomenon " 

 seemed at the time to upset it entirely just as it 

 was about to be " at least admitted into court." 

 Buchner in the meantime had attempted to 

 reconcile the two theories by supposing that his 

 w alexines " originated in the phagocytes, but 

 that they were present in the body fluids and 



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