8o 



IMMUNE SERA 



of the blood cells. Of these a is present only in the 

 ox-blood cells, ^ only in the goat-blood cells, and ft 

 in both. If a rabbit is injected with ox blood, the 

 immune bodies corresponding to groups a and ft 

 will be formed. On subjecting such a serum to 

 absorption with ox-blood cells we shall find that 

 these, by means of their a and ft groups will be able to 

 absorb all the immune bodies, whereas goat-blood 

 cells will in a similar test absorb only the immune 



FIG. 7 



body of portion ft, leaving the immune body of 

 portion a in solution. 



According to Ehrlich's theory, then, the red cells 

 of the ox possess certain receptors which are identi- 

 cal with receptors possessed by the goat red cells. 

 From this it follows that in a single red cell there 

 are several or many groups each of which is able, 

 when it finds a fitting receptor, to take hold of a 



