gg IMMUNE SERA 



single immune body. Ehrlich and Morgenroth, 

 therefore, claim that the immune body of a haemo- 

 lytic serum is composed of the sum of the partial 

 immune bodies which correspond to the individual 

 receptors used to excite the immunity. It may be 

 assumed, then, that not all of the combining groups 

 of a cell, be this a blood cell or a bacterium, will 

 find fitting receptors in every animal organism, 

 and that therefore not all the possible partial im- 

 mune bodies will be equally developed. In one 

 animal there may be receptors which are not pres- 

 ent in another, and in this way there might be a dif- 

 ferent variety of partial immune bodies in the two 

 animals. This would lead to the possibility of the 

 occurrence of immune bodies, for the 'same species 

 of blood cell or bacterium, differing from each other 

 in the partial immune bodies composing them, 

 according to the variety of animals used in prepar- 

 ing the serum. 



Metchnikoff's Views. This view is directly op- 

 posed to that of Metchnikoff and Besredka, who 

 believe that a certain immune body, e.g., one spe- 

 cific for ox blood, is always the same no matter from 

 what animal it is derived. The point is not merely 

 theoretical, but under certain circumstances of 

 great practical importance. If we believe, with 

 Ehrlich, that the immune body differs according 

 to the species of animal from which it is derived, 

 i.e., that it is made up of different partial-immune 



