158 HAEMOLYSIS ANTICOMPLEMENT AND COMPLEMENTOID 



occurred was that the haptophore radical of the complement had 

 been "blocked " by the anticomplement. 



In a few cases anticomplements which will act on some only 

 of the complements of a sera can be produced, and from the study 

 of these additional evidence in favour of the multiplicity of com- 

 plements has been adduced. 



As regards the nature of these anticomplements, this is readily 

 explicable on the side-chain theory. Ehrlich supposes that when 

 a foreign serum is injected into an animal it may find no receptors 

 for which it has an affinity ; in this case it forms no anticomple- 

 ment, and such cases are known to occur. Or it may find receptors 

 which it can activate completely, just as the normal complement 

 of the animal can do ; in this case also there will (under ordinary 

 circumstances) be no formation of anticomplement. Lastly, it 

 may find receptors with which it can combine, but the resulting 

 combination may be useless in the nutrition of the cell ; in this 



FIG. 39. SHOWING EFFECT OF ADDITION TO SENSITIZED CORPUSCLES OF A 

 MIXTURE OF COMPLEMENT AND COMPLEMENTOID. 



The former unite with the complementophile haptophore groups of the ambo- 

 ceptor ; the latter, which have decreased in combining affinity, do not. 



case the receptor will be cast off, and will constitute anti- 

 complement. 



Lastly, Ehrlich was able to show that in some cases an 

 aiito-anticomplement may be formed i.e., an antibody which can 

 neutralize the complement normally present. The proof for this 

 is elaborate, and will not be given here. 



The change of toxins into toxoids is paralleled by the change of 

 complements into complementoids. We have previously spoken of 

 the complements as being destroyed by heat, but this is not quite 

 correct ; they lose their zymophore groups, but retain their hapto- 

 phore portions, though these appear to lose some of their combining 

 affinity. The proof of the existence of complementoids is simple : 

 when injected into animals they call forth the production of 

 anticomplements, just as toxoids call forth the production of 

 antitoxin. 



For some time it was found impossible to demonstrate the 



