34 IMMUNE SERA. 



views of these authorities. But the number of 

 active substances in normal serum is still greater, 

 for in the experiments of the last-named authors 

 it oftens happens that a specific inter-body shows 

 itself to be made up of several inter-bodies, all, to 

 be sure, fitting the same specific red cell, but dif- 

 fering from each other by their behavior toward 

 different complements. Ehrlich, therefore, re- 

 gards the substances concerned in haemolysis 

 which occur in normal serum to be of great 

 number and variety. Buchner and Bordet, on the 

 other hand, assume that only one substance is 

 concerned. 



The facts which we have thus far developed in 

 regard to the haemolysins of normal serum apply 

 equally well to its h&magglutinin$. As we men- 

 tioned in the beginning of this article, Bordet 

 showed that not only was the haemolytic action of 

 a specific serum increased for certain red cells, but 

 its agglutinating power was increased for the same 

 cell. According to this, then, as a result of the 

 immunizing process there are formed not only 

 haemolysins but also haemagglutinins. 



Haemagglutinins of Normal Serum. Analogous to 

 the haemolytic action of normal serum on the red 

 cells of certain other species, we find that nor- 

 mal serum is able to agglutinate the red cells of 

 many other species and bacteria. For example, 

 normal goat serum agglutinates the red cells of 

 man, pigeon, and rabbit; normal rabbit serum 



