6 IMMUNE SERA. 



dissolve on the addition of the alexin of their own 

 serum. 



The Exciting Agent.' If we now seek to discover 

 the constituent part of the red cell which in the 

 treatment excites in the animal body the production 

 of the specific haemolysin, we find this to be, accord- 

 ing to Bordet and v. Dungern, the stroma of the red 

 cells. This separated from the cell contents and in- 

 jected into animals will likewise excite the produc- 

 tion of specific haemolytic serum. In opposition to 

 this, Nolf assumes that the stroma excites the 

 production of the above-mentioned agglutinins, 

 and that the production of the substance sensi- 

 bilatrice is called forth by the contents of the red 

 cells. 



Re*sume*. Reviewing the important facts we have 

 learned, we find them to be as follows: By means 

 of the treatment of one species of animal with the 

 red cells of a different one, the serum of the first 

 species acquires an uncommonly increased power 

 to dissolve and to agglutinate the red cells of the 

 second species. This increased haemolytic power 

 shows itself not only in vivo, so that an animal 

 so treated is able to cause red cells injected 

 into it rapidly to dissolve and disappear, but it 

 shows itself also in vitro when the serum of this 

 animal is used. The process consists in the com- 

 bined action of two substances, that which is ex- 

 cited in response to the injection, the substance 

 sensibila trice, and the alexin of normal serum. 



