32 IMMUNE SERA. 



as that of the specific haemolytic sera, on the com- 

 bined action of two bodies: one, the inter-body, 

 which corresponds to the immune body of the spe- 

 cific sera, and a second or complement. In speaking 

 of the constituents of normal serum, Ehrlich and 

 Morgenroth prefer to ,use this term inter-body to 

 distinguish it from the immune bodies of specific 

 haemolytic sera. 



Action Not Entirely Specific. It has also been 

 found that there frequently exist normal sera which 

 are haemolytic not only for one species of red cell 

 but for several. We saw, for instance, that normal 

 goat serum dissolved the red cells of guinea-pigs 

 and rabbits. The question now arises, Is this prop- 

 erty of normal goat serum due to two inter- 

 bodies existing in the serum side by side, one fitting 

 the red cells of the guinea-pig, the other those of 

 the rabbit? Ehrlich and Morgenroth answered 

 this in the affirmative, for in the following experi- 

 ment they succeeded in having each of the two 

 inter-bodies combine with its respective cell. To 

 some inactive normal goat serum they added rab- 

 bit blood and centrifuged the mixture. To the 

 separated clear fluid they again added some rab- 

 bit red cells as well as normal horse serum to 

 reactivate the mixture. Horse serum is not hae- 

 molytic for rabbit red cells. The mixture re- 

 mained unchanged, no haemolysis taking place. 

 If, however, they added some of this normal horse 

 serum to the centrifuged red cells, the latter imme- 



