208 ANTI-BACTERIAL PROPERTIES OF SERUM 



former case it is due to a few very active complement mole- 

 cules being brought into combination ; in the latter, to the 

 action of a larger number of weakly acting molecules, which 

 combine through the medium of the artificial immune-body. 

 In this hypothesis it is immaterial whether the normal 

 bactericidal action takes place by the direct union of 

 complement or by union through natural immune-bodies. 

 The existence of complement molecules of different degrees 

 of activity is the essential point in the explanation. 



Although the subject of anti-bacterial sera produced by 

 active immunization does not fall within the scope of the 

 present communication, some points of interest may be 

 referred to. In our work we have used three anti-sera, 

 namely, anti-F. Metchnikovi, anti-typhoid, and anti-staphy- 

 lococcus. In the first place, all these sera contain a con- 

 siderable quantity of specific immune-body, as shown by 

 the deviation or increased absorption of haemolytic com- 

 plement. The following table shows this in the case of 

 anti-staphylococcus serum. In each tube the guinea-pig's 

 complement is exposed to the absorbing action of a bouillon 

 culture of Staphylococcus aureus ; in one series alone, in the 

 other along with the homologous immune-body. The table 

 shows the amount of lysis which occurs in the test amount 

 (1 c.c. of a 5per cent, suspension) of sensitized ox's corpuscles, 

 added after two hours at 37 C. ; the amount of complement 

 taken up thus becomes manifest. 



Note. In a control tube containing 0-01 c.c. guinea-pig's serum + 



