OPSONIC ACTION 



163 



off ; it has become slightly brownish in appearance. We 

 shall speak of such a serum as treated serum, and we may 

 compare it as regards hsemolytic, bactericidal and opsonic 

 qualities, with normal guinea-pig's serum, and with the 

 same serum heated at 55 C. for an hour. 



1. Hcemolytic Action of the Three Serums. 



This is tested on 1 c.c. suspension of ox's corpuscles 

 treated with immune-body. The results are : 



The treated serum is practically without effect, 0-2 c.c. 

 giving no lysis. 



The heated serum, of course, is likewise without effect. 



The normal serum produces complete lysis in a dose of 

 0-015 c.c. 



The treated serum has thus lost its haemolytic action, or, 

 in other words, the complement concerned in haemolysis 

 has been removed from it. 



2. Bactericidal Action 



This is tested by the method of Neisser and Wechsberg. 

 A small quantity, -g^oo c.c., of a one day's bouillon culture 

 of the bacterium is added to each of a series of tubes along 

 with different amounts of the serum (0-05, 0-1, 0-2 c.c.) 

 and a few drops of bouillon ; the mixtures are made up 

 to 1 c.c. with salt solution. The tubes are placed in the 

 incubator for three hours and at the end of that time 

 0-025 c.c. from each is added to a tube of melted agar and 

 the agar is then plated. The colonies are counted after 

 incubation at 37 C. 



(a) s-oVo- c.c. of a bouillon culture of B. typhosus. 



M 2 



