2H6 



COLLECTED STUDIES IN IMMUNITY. 



plement for goat blood disappeared after the injection while that 

 for the immune body sensitizing ox blood remained intact. The 

 following test may serve as an example: 



A rabbit of 1900 g. is injected intravenously with 22 cc. goat 

 blood. The change in the solvent power of the goat serum which 

 results from the injection may be seen from the following table: 



TABLE VII. 



Similar results are obtained in the absorption of rabbit serum 

 by means of goat blood in vitro, so that this experiment already justi- 

 fies us in assuming two different complements in rabbit serum. 



In one of these experiments with goat-blood injections the hae- 

 molysis of pig blood by means of rabbit serum was also tested, and 

 it was found that the complement of the normal hsemolysin for pig 

 blood, like that for sensitized ox blood, had remained unchanged. 

 Neither was it possible by means of intravenous injection of pig 

 blood to separate these two complements of rabbit serum, for in 

 this case, contrary to their previous behavior, both were absorbed, 

 while the complement for goat blood remained in the serum. For 

 the present we must therefore content ourselves with the knowledge 

 that we have brought forward positive proof of the existence of two- 

 different complements in rabbit serum; a proof which is strongly cor- 

 roborated by the divergent behavior of the two complements in the 

 absorption with goat blood and pig blood respectively. 



The difference between the two complements also manifests 

 itself in their different vulnerability to papain. While the com- 

 plementing power of rabbit serum toward the artificially produced 

 immune body for ox blood suffers considerable diminution under the 

 influence of papain digestion, the complement of normal hsemolysin 

 for goat blood is hardly affected, so that this experiment also sub- 

 stantiates our demonstration of at least two complements in rabbit 

 serum. 



Some rather cursory tests were finally made with dog and guinea- 



