CONTRIBUTIONS TO THE STUDY OF IMMUNITY. 41 



to which the immune body is attached, the immunity reaction 

 will be exactly the same whether the injected blood is loaded with 

 immune body or not. If, however, the production of the immune body 

 is dependent entirely on the molecular group for which the immune 

 body possesses a specific affinity, no immune body will be developed 

 when a sufficient amount of inactivated blood immune serum is 

 added to the injected blood, since the group is already occupied by 

 immune body and no longer offers the cells a point of attachment. 



The experiments completely confirm the latter assumption. 

 When the blood loaded with immune body was injected, no immune? 

 body whatever was developed in the injected animal; whereas in a con- 

 trol rabbit, injected with exactly the same amount of cattle blood 

 (30 cc.), but without immune body, so much was produced that 

 the serum eleven days after the injection was able to dissolve com- 

 pletely eight times its volume of full blood provided sufficient com- 

 plement was added. 



This fact, like many others, speaks against the idea that the 

 immune bodies or the analogous antitoxins are not reaction products 

 of the organism but are derived by modification from the substances 

 introduced, a view still maintained by certain high authorities. The 

 phenomenon, however, is readily explained on the basis of the side- 

 chain theory. Since the particular groups of the erythrocytes, 

 which otherwise give rise to the immunity reaction, are already 

 occupied by immune body, it is impossible for them to be bound 

 by the side-chains, which are absolutely similar to the immune body. 



3. According to the researches of Ehrlich and Morgenroth, the 

 erythrocytes of sheep possess no affinity whatever for the complement 

 of normal goat serum. If instead of sheep blood-cells, one employs 

 those of cattle and allows them to act on rabbit blood serum, exactly 

 the same thing will be observed; the rabbit blood serum, centrifuged 

 after prolonged contact with the blood-cells, shows no diminution 

 in the content of complement. //, however, other cells, e.g., ciliated 

 epithelium from the trachea of cattle, be mixed with rabbit serum, the 

 result is directly opposite, the complement decreasing, and even under 

 some circumstances disappearing entirely. In like manner the rabbit 

 serum may lose its complement through the action of other cells. 

 In the case of various mammals and birds, every one of the organs 

 tested liver, spleen, kidney, testis, lung, and brain was able to 

 abstract more or less complement from the rabbit serum. Yeast 

 cells and fission-fungi were also able to effect this. Especially remark- 



