5S2 COLLECTED STUDIES IN IMMUNITY. 



which, as a result of biological experiences, I had always looked 

 forward to. 



The correctness of the amboceptor theory formulated by Morgen- 

 roth and myself is confirmed by another important link in the chain 

 > of evidence. As far back as 1900, in the Croonian lecture, I stated 

 that, according to the amboceptor theory, three antilytic antibodies 

 *J were possible. In addition to the substances which act as anticom- 

 plements, we could conceive of antiamboceptors of two different 

 kinds. One of these inhibits the action of the amboceptor by pre- 

 venting the union of amboceptor and cell, the other by occupying the 

 complementophile groups. So far as the confirmation of the ambo- 

 ceptor theory is concerned, it is evident that the demonstration of 

 antiamboceptors directed against the complementophile group is by 

 far the most important; for, owing to the mode of origin, the devel- 

 opment of cytophile groups of the amboceptor as reaction products 

 of the specific counter-group (the cell-receptor) is self-evident. It 

 was therefore particularly gratifying when I found that Bordet 

 had recently furnished the demonstration that the antiamboceptor 

 developed with an immune, or with a normal serum, is usually directed 

 against the complementophile group. This discovery very prettily 

 demonstrates that the mechanism of hsemolysin action proceeds 

 according to the amboceptor theory. The error contained in our 

 earlier conception, that anti-immune bodies were usually antibodies 

 directed against the cytophile group, is practically only an error in 

 the localization of the point of attack. This must now be corrected 

 by regarding the complementophile group as the point attacked by 

 the antiamboceptor. 



We know that it is possible to produce antiamboceptors by im- 

 munizing with normal serum, and Pfeiffer and Friedberger have 

 shown that the action of the antiamboceptor serum extends to all 

 the amboceptors of the animal species whose serum was used for 

 immunization. These facts are only apparently a contradiction of 

 the specificity of amboceptors, for the specificity of the amboceptors 

 applies only to the cytophile group. On the other hand, we must 

 assume that all the amboceptors of the same animal species are at 

 least partly similar in structure so far as the complementophile 



ceptor. This of course destroys the foundations of Noguchi's calculations, which 

 are based on the assumption that the reaction is reversible; it also disposes of 

 certain statements made by Bredig. 



