CHEMICAL EQUILIBRIA 129 



jected erythrocytes, is called the " immune body " or 

 "amboceptor" (Ehrlich). 



The amboceptor is absorbed very rapidly and in 

 great quantity by the red blood-corpuscles against 

 which it is specific (cf. p. 105). These are not 

 haemolyzed by it. If they are mixed (in physiological 

 salt solution) with fresh blood-corpuscles of the same 

 kind, these slowly take up a part of the amboceptor. 

 Blood-corpuscles which are loaded with a quantity 

 of amboceptor not too small become laked when 

 brought into contact with complement. 



Bordet, who was the first investigator of this 

 field, supposed that the amboceptor acts as a 

 " sensitiser " of the blood-corpuscles when they are 

 attacked by the complement. Ehrlich, on the other 

 hand, supposed that the amboceptor binds the 

 complement and that the addition product is a so- 

 called " compound haemolysin." This question 

 could evidently be decided by quantitative measure- 

 ments, and Ehrlich invited me to carry out the 

 necessary determinations in his laboratory. In the 

 following table I reproduce as example a series of 

 observations on the haemolysis of erythrocytes of an 

 ox. The emulsion contained 2 per cent of erythro- 

 cytes and had a total volume of 2-5 cc. In it were 

 dissolved a cubic millimetres of the inactivated goat 

 serum, which contained the amboceptor specific 

 against blood-corpuscles from oxen, and b cubic 

 millimetres of the complement, natural serum from 

 guinea-pigs. The quantity of haemolysin is called 



x and is taken to be proportional to the square root 



K 



