166 ANTI-BACTERIAL PROPERTIES OF SERUM 



1. Hcemolytic action. 



The treated serum, like the heated serum, has practically 

 no haemolytic action. 



The normal serum produces lysis of the test corpuscles 

 in a dose of 0-015 c.c. 



2. Bactericidal action, tested on 

 culture of B. dysenterice (Kruse). 



c.c. of a bouillon 



The treated serum has thus lost its bactericidal action. 

 3. Opsonic action, tested on an emulsion of Staphylococcus 



aureus. 



Average number of cocci ingested per leucocyte 



The opsonic action of the treated serum is therefore as 

 low as that of the heated serum ; that is, the normal labile 

 opsonin has been absorbed by the serum precipitate. 



III. ABSORPTION BY BACTERIA TREATED WITH IMMUNE- 

 BODY ( ' SENSITIZED BACTERIA ') 



The method is the same as in the previous cases. The 

 bacteria, combined with immune-body, are washed in salt 

 solution and, after the salt solution is pipetted off as com- 

 pletely as possible, are added to fresh guinea-pig's serum. 

 The mixture is placed in the incubator for one and a half 

 hours, and then the bacteria are deposited by centrif ugaliza- 

 tion and the serum is pipetted off. 



