THEORIES OF IMMUNITY. 



supporters of Ehrlich's explanation of the reac- 

 tions that occur, and this is especially emphasized 

 by the formulae presented in illustration. It is 

 to be supposed that these affinities are con- 

 cerned under normal circumstances in helping 

 on the normal food metabolism of the tissue 

 cells, and possibly other reactions. Ehrlich has 

 given the name of "haptine' : to the whole 

 group, and that the number is great may be 

 seen by those already known — lysins, aggluti- 

 nines, precipitines, complements, ferments, anti- 

 complements, ferments, etc. 



The production of an anti-complement, for ex- 

 ample, may be represented as follows : it may 

 be obtained by injecting serum containing com- 

 plement from one animal {e.g., a guinea-pig) 

 into another (e.g., rabbit) : 



The injected serum, molecule^H+L+X 

 The receiving blood cell, molecule=H+(H+H 



+H+H+H)+X+X 



The two are bound together, the special H 

 group is reproduced in excess, is thrown off, and 

 exists as H-fX=the anti-complement. 



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