32 



Scientific Proceedings (70). 



that produced in the hen that brings about in her the same result, 

 although there is no direct evidence to show that this is the real 

 explanation. 



20 (1084) 



Agglutination of bacteria in vivo ; its relation to the destruction of 

 bacteria within the infected host and to septicemia. 



By C. G. Bull. 



[From the Laboratories of the Rockefeller Institute for Medical 



Research.] 



An intravenous injection of immune serum causes an abrupt 

 disappearance of the bacteria from the circulating blood of animals 

 having a bacteremia or a septicemia. This is due to an immediate 

 agglutination of the bacteria and to an accumulation of the 

 bacterial clumps in the lungs, liver, spleen, etc. The clumps of 

 bacteria are phagocyted and destroyed mainly by the polymorpho- 

 nuclear leucocytes which accumulate in the internal organs 

 following an intravenous injection of foreign protein substances. 

 The septicemia or bacteremia does not recur as long as the immune 

 serum is kept in the blood in a sufficient concentration. 



These phenomena occur very typically following intravenous 

 administration of specific immune sera in rabbits infected with 

 pneumococci or Shiga dysentery bacilli. If the rabbits are actively 

 immune to these bacteria, the same phenomena follow an intra- 

 venous injection of the bacteria. If the immune animals are 

 given sufficient quantities of the bacte ia, death may be caused 

 by intoxication in the absence of a septicemia. 



In natural immunity the above described phenomena follow 

 immediately upon an intravenous injection of the bacteria. 

 Rabbits have a comparatively high natural immunity to many 

 bacteria, of which the following have been studied in this respect: 

 typhoid bacilli, colon bacilli, dysentery bacilli of the Flexner group, 

 Staphylococcus aureus and albus, non-virulent bacilli of the mu- 

 cosus capsulatus group, and non- virulent influenza bacilli. All of 

 these are agglutinated, phagocyted, and destroyed in normal 

 rabbits as pneumococci are in immune rabbits and none of them 

 causes a true septicemia in these animals. 



