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is the case, anti-amboceptors should be non-specific ; they are 

 directed against the complementophile groups, which are the same 

 in all amboceptors from the same species. This subject has not 

 yet been fully investigated, but Pfeiffer and Friedberger have 

 shown that the antibody to the immune body against the cholera 

 vibrio also acts against the antityphoid serum. Ehrlich also 

 showed that if anti-amboceptor be added to sensitized cells, these 

 are protected against the subsequent addition of complement. 

 This, of course, is attributable to the fact that the anti-amboceptor 

 unites with the free complementophile groups, and " blocks " them 

 against the subsequent access of the complement molecule. 



Ehrlich leaves undecided the question as to whether an anti- 

 cytophilic anti-amboceptor is ever produced, but holds that it 

 might be formed if by any process we could destroy the cytophile 

 haptophore of the amboceptor molecule. Under ordinary circum- 

 stances the complementophile group has a greater affinity for its 

 cell receptor than has the cytophile for the receptors with which 

 it could combine ; union takes place between the former, and the 

 latter is, so to speak, pulled out of the way of its affinity. 



It is now advisable to recapitulate briefly some of the main 

 points in Ehrlich's theory of the structure of the bacteriolytic and 

 haemolytic sera. Firstly, as regards complements : Of these there is 

 very great number, and each is especially adapted for the solution of 

 one or more varieties of cells, which it can dissolve in the presence 

 of a suitable amboceptor ; it is known as the dominant comple- 

 ment. Other complements, however, may help in the process, 

 and these are termed non-dominant. In general terms the comple- 

 ments, which are especially active in haemolysis, have but little 

 action on bacteria, and vice versa. Secondly, as regards the ambo- 

 ceptor : This is really a polyceptor, and is so constituted that it 

 can combine with the cell to be dissolved, on the one hand, and 

 with a large number of molecules of complement, on the other. 



Of the further complications of the theory which Ehrlich has 

 introduced to explain new phenomena as they arise, of the 

 amboceptoids, of loose and firm union, etc., we do not propose 

 to speak. That the theory needs these complications in order to 

 account for the phenomena is not necessarily in its disfavour, for 

 the phenomena themselves are complex in the extreme. And it 

 must be regarded as a strong argument in its favour that Ehrlich 

 has again and again deduced results from this theory which sub- 

 sequent research has shown to be correct ; and very few hypo- 



