280 INFECTION AND IMMUNITY 



have found support in the experiments of Levaditi/ who was able to 

 demonstrate the absence of complement in blood plasma, — i.e., where no 

 destruction of leucocytes had taken place — and in those of Cantacuz^ne,^ 

 who showed that cholera-immune guinea-pigs would succumb to intra- 

 peritoneal injection of these bacteria when the diapedesis of leucocytes 

 had been prevented by the administration of opium. 



The chapter of phagocytosis in its relation to bacterial immunity is 

 by no means closed. The problems involved in it are intricate and will 

 require much further study. The subsequent sections upon opsonins, 

 aggressins, and upon leucocyte extract, incorporate the more recent 

 studies which may be said to have followed logically in the footsteps 

 of Metchnikoff's work. 



1 Levaditi, Presse m^d., 1900. 



« Cavtacuzine, Ann. de I'inst. Pasteur, 1897 



