4$ IMMUNE SERA. 



immunize against this just as well against a bac- 

 terial poison. For example, to keep to our illustra- 

 tion, rabbits are injected first with very small doses 

 of this specific haemolytic serum. The dose is 

 gradually increased until it is found that the animal 

 tolerates amounts that would be absolutely fatal to 

 animals not so treated. If some of the serum of 

 this animal is now abstracted and added to the 

 specific hsemolytic serum, it is found that the power 

 of the latter will be inhibited. This shows that an 

 anti-h&molysin has been formed. As we know that 

 the action of the haemolysin depends on the com- 

 bined action of two substances, the immune body 

 and the complement, the question arises to which 

 of these two the anti -haemolysin is related. Is it 

 an anti -immune body or an an ti -complement ? A 

 study of this question has shown that both these 

 substances are present. In the serum of the rabbit 

 treated with specific haemolysin, both an anti- 

 immune body and an anti-complement have been 

 found. For the details of the experiments of Ehr- 

 lich and Morgenroth and of Besredka, which dem- 

 onstrated this, I must refer to the original articles. 

 The first-named authors were further able to show 

 that the action of the anti -complement depended 

 on a haptophore group which it possessed, enabling 

 it to combine with the haptophore group of the 

 complement, thus satisfying this and hindering its 

 combination with the complementophile group of 

 the immune body (see figure). 



