8o IMMUNE SERA 



as before. The sedimented blood cells mixed with 

 normal salt solution showed haemolysis of a moder- 

 ate degree. The solution became complete when 

 a little normal serum was added. The supernatant 

 clear fluid separated by the centrifuge did not dis- 

 solve sheep red cells. On the addition, however, 

 of substance sensibilatrice it dissolved them com- 

 pletely. 



From this experiment Ehrlich concluded that the 

 substance sensibilatrice possesses one combining 

 group with an intense affinity (active even at o C.) , 

 for the red cell, and a second group possessing a 

 weaker affinity (one requiring a higher temperature) 

 for the alexin. 



Nomenclature. In place of the name substance 

 sensibilatrice Ehrlich first introduced the term 

 immune body; later on he called it the amboceptor, 

 to express the idea that it served as a link between 

 alexin and cell. Instead of the name alexin, Ehrlich 

 used the term complement in order to express the 

 idea that this body completes the action of the im- 

 mune body. 



The nomenclature introduced by Ehrlich is fol- 

 lowed to-day in practically all the literature dealing 

 with immunity. The term immune body is used 

 as a general name for all substances specifically 

 combining with antigens. The term amboceptor 

 is limited generally to those immune bodies which 

 combine with red blood corpuscles, and the term 



