120 THE THEORY OF IONS 



constituent said by him to be present in the blood 

 serum, and called the complement. The complement 

 is also a normal constituent of the blood serum, but 

 has no direct relation to the cell. It is harmless by 

 itself, but, like toxin, has a toxophore and a hapto- 

 phore group. The amboceptor-laden cell is exposed 

 to the action of the complement of the serum, and 

 the latter acts upon the cell through the influence 

 of the amboceptor. Complement and amboceptor 

 stand in a direct relation to one another, and become 

 anchored together. This is not a relationship due 

 to a maximum chemical affinity ; but rather a loose 

 relationship with perhaps a reversible action. 



The amboceptor is able to combine with substances 

 of the most varied kind, providing they possess 

 fitting receptors. The peculiar power of the ambo- 

 ceptor to fix a large number of complements is, 

 therefore, not to be wondered at. But if the entire 

 mass of amboceptors reacted in an active manner 

 upon the entire mass of the complement, the latter 

 would all be anchored to the complementophile 

 group of the amboceptors, and there would be no 

 free complement in the living body. This would 

 produce a grave condition of affairs. For as soon 

 as there arose occasion for the action of comple- 

 ments with any special kind of amboceptor there 

 would be no complement available, all being used 

 up by the action of indifferent amboceptors. It is 

 owing to the fact that the complements are free or 

 only loosely joined to amboceptors that they are 

 ready for use at any given moment. The maximum 

 stimulus to action is made possible by anchoring 

 the amboceptor to the erythrocyte, the avidity of 



