40 IMMUNE SERA. 



0.05 c.c. of the guinea-pig serum suffice to dissolve 

 the same, amount of rabbit blood, we conclude 

 that through this process the inter-body, i.e. the 

 immune body, has been increased forty times. We 

 know that the complement has not been increased, 

 but this is now able to act by means of forty times 

 increased combining facilities. This increase, how- 

 ever, is exclusively for rabbit blood-cells. In a 

 bactericidal immune serum this specific increase is 

 sometimes as much as 100,000 times that of normal 

 serum. The practical idea to be gained from this 

 for the therapy of infectious diseases is this: that 

 with the injection of an immune serum we supply 

 only one of the necessary constituents to kill and 

 dissolve the bacteria, and that is the immune body. 

 We do not, however, supply the second, i.e. the 

 complement, for this we have seen is not increased 

 by the immunizing process. As matters stand, 

 then, the use of a specified immune serum for thera- 

 peutic purposes assumes that the complement 

 which fits exactly to the immune body and which is 

 essential for the latter's action will be found in the 

 organism to be treated. Because in certain infec- 

 tious diseases the required complement is present 

 in too small amounts in the organism, I have sug- 

 gested that the curative power of many bacteri- 

 cidal sera might be increased by the simultaneous 

 injection of the sera of certain normal animals in 

 order to gain in this way an increased amount of 

 complement ; but we shall soon see that this pro- 



