OPSONIC ACTION 179 



a normal serum as tested by the Staphylococcus aureus. We 

 have accordingly tested the effect on the opsonin of our 

 immune serum. In the following tables the comparative 

 results are shown : 



Normal Serum 



Opsonic count 



Normal serum of rabbit (unheated) ... . . 38-0 



treated with Staphylococcus aureus 0-02 



Bacillus coli . . . 3-3 



V.Metchnikovi . . 4-11 



Bacillus tuberculosis . 2-6 



Bacillus pyocyaneus . 34 



Immune Serum 



Opsonic count 



Anti-staphylococcus serum (heated at 55 C.) . . .7-8 

 ,, treated with Staphylococcus aureus 0-36 



Bacillus coli . . 8-8 



V. Metchnikom . . 7-5 



Bacillus tuberculosis . 7-9 



Bacillus pyocyaneus . 6-7 



The tables show that emulsions of all the organisms tested 

 produce a marked diminution of the normal opsonin, whereas 

 none of them, with the exception of the Staphylococcus, 

 have any appreciable effect on the immune opsonin. 



In another experiment we treated the heated immune 

 serum twice with large quantities of B. coli, B. dysenterice, 

 Cholera spirillum, B. typhosus, Staphylococcus pyogenes albus. 

 In the case of the last mentioned there was apparently a 

 slight diminution of the opsonic power, viz. from 26-7 to 20-3 

 a comparatively trifling effect in view of the close relation- 

 ships of the two organisms ; the untreated serum was, how- 

 ever, practically without opsonic effect on the Staphylococcus 

 albus. In the case of the other bacteria mentioned, there 

 was no diminution whatever of the opsonin after treatment 

 with the organisms. 



These experiments, by the method of absorption, bring 



N2 



