B&MOLYSINS. 41 



cedure, while of great value in animal experiments, 

 presents certain difficulties. 



All that has here been said regarding the specific 

 increased haemolytic power of sera applies equally 

 to the specific increased agglutinating power follow- 

 ing the injection of animals with certain cells. As 

 a result of such injections, that agglutinin which 

 stands in specific relation to the blood-cell injected 

 is increased according to the laws of the side-chain 

 theory, and such a serum therefore possesses an 

 increased agglutinating power for these particular 

 cells. With the agglutinins this increase in power 

 is sometimes an enormous one. If, for example, a 

 normal serum is just able to agglutinate a certain 

 cell when diluted i to 10 with normal salt solution, 

 it is possible by means of the immunizing process to 

 obtain a serum which in dilutions of one to several 

 thousands will still completely agglutinate the cells. 



In such a sketch as this, I cannot dwell on 

 the practical importance that this specific increased 

 agglutinating power has in the serum diagnosis of 

 certain infectious diseases, such as typhoid, etc. 



Nature of the Immune Body Partial Immune Bodies 

 of Ehrlich. Turning now to a closer study of the 

 nature of the immune body, we again find a differ- 

 ence of opinion. Whereas Bordet, Metchnikoff, 

 and Besredka assume each immune body to be a 

 single definite substance, Ehrlich and Morgenroth 

 as a result of their experiments hold to a plurality 

 of bodies. These authors say that each immune 



