444 



H^EMOLYSINS AND ALLIED BODIES 



is represented in (3) of Fig. 21. It is to the presence of these that 

 the blood serum of an animal comes to be able to hsemolyse 

 erythrocytes having receptors with the same mouldings as these 

 of the erythrocytes used for injection, that is, the erythrocytes of 

 the same animal or of one closely related to it. 



This double receptor (Aa) is called an amboceptor, because it 



Conv 



FIG. 22. Receptors of (Third Order (Ehrlich's theory); 

 Mechanism of Hasmolysin Formation. 



has two combining groups. The ferment-like body which becomes 

 attached to one end of it is, according to Ehrlich and Morgenroth, 

 nothing more or less than what Bordet called the alexin, which, it 

 will be remembered, is present in the tissue fluids as a physio- 

 logical constituent, and which is easily destroyed by heat or by 

 contact with the air. Since the amboceptors cannot act on the 

 cells (e.g. produce haemolysis) unless they be combined with 



