H&MOLYSINS. 49 



In order that a normal serum of species A, in- 

 jected into species B, produce anti-complements 

 there, the side-chain theory demands that the com- 

 plements of A find fitting receptors in species B. 

 According to Ehrlich, however, normal serum con- 

 tains many different complements and not merely a 

 single one. Under the circumstances it is easily 

 possible that only a few of the complements in the 

 serum of A find fitting receptors in species B. We 

 shall then obtain an anti-complement serum which 

 inhibits the action of some but not of all the comple- 

 ments of species A. Thus it might inhibit the 

 action of a complement fitting to a certain bacteri- 

 cidal immune body, and not of one contained in the 

 same serum which fitted a certain haemolytic im- 

 mune body, etc. 



Auto-anticomplements. -- A question of great 

 practical importance now arises. Is it possible 

 under certain conditions for an organism to manu- 

 facture within itself anti-complements against its 

 own complements, i.e., auto-anticomplements? The 

 complements, owing to their ferment-like digestive 

 power, must play an important role in the living 

 organism ; for this concerns itself not only with the 

 destruction of bacteria, etc., an important factor in 

 the natural immunity against diseases, but also, 

 according to Ehrlich, Buchner, and the author, with 

 the solution and digestion of all kinds of foreign 

 albuminous bodies which enter the organism. Any 

 inhibition of this important function would there- 



