204 ANTI-BACTERIAL PROPERTIES OP SERUM 



REACTIVATION OF PARTIALLY EXHAUSTED SERUM 

 The above results clearly show that a small quantity of 

 emulsion of a certain bacterium will reduce greatly the 

 bactericidal action of the serum for another organism 

 without producing a similar diminution in the hsemolytic 

 value. A serum treated in this way may be spoken of as a 

 partially exhausted serum. It is of course to be noted that 

 the fall in the bactericidal action in such a serum must 

 essentially be due to the abstraction of complement, as 

 already explained. A serum treated witn B. typhosus will 

 thus still contain any natural immune-bodies it possessed 

 for V. Metchnikovi, and it also contains complement (as 

 shown by haemolysis), yet its bactericidal action for V. 

 Metchnikovi is greatly reduced. The question is Can the 

 complement molecules in the partially exhausted serum be 

 rendered effective as regards bactericidal action by the 

 addition of an artificial immune-body ? In carrying out 

 experiments on this point we have used an anti- V. Metchni- 

 kovi serum obtained from the rabbit, which has been inacti- 

 vated at 55 C. The presence of an immune-body in this 

 serum is shown by its greatly increasing the bactericidal 

 action of normal serum, as well as by the greatly increased 

 amount of haemolytic complement taken up through its 

 medium by a given amount of emulsion of V. Metchnikovi 

 as compared with untreated emulsion. In carrying out 

 such experiments we have used three organisms, V. Metch- 

 nikovi, B. typhosus, and Staphylococcus aureus, as absorbing 

 agents, all of these being previously killed by heat. In 

 every case reactivation occurs by the addition of the 

 immune-body for V. Metchnikovi. The experiments are 

 carried out in three series as follows : 



In series (a) we use the normal serum in varying amounts. 

 In series (b) we use the serum in the same amounts along 

 with a certain amount of a dead emulsion of the organism 

 whose absorptive power is to be tested. 



