A GENERAL RESUME' OF IMMUNITY. 513 



substances with the theory of a complementophilic group? If 

 it had been found that the sensitizer could absorb complements 

 without the presence of antigen, the theory would have been forti- 

 fied, but no such thing happens. As with intact alexin, so alexin 

 that has been altered by a graduated temperature is absorbed, not 

 by the sensitizer alone, but only by the complex, corpuscle-sensi- 

 tizer; in other words, the general law holds. 



As regards the arguments furnished by a study of cobra venom 

 and lecithin, there is nothing to prove that they are applicable to 

 sensitizers and alexin. The researches of Kyes and of Neisser and 

 Friedemann have shown clearly that the venom, although in itself 

 unable to destroy certain corpuscles, does hemolyze them when 

 added to lecithin; in other words, the complex, venom-lecithin is 

 remarkably active. But what reason is there to suppose that sen- 

 sitizer and alexin necessarily act as do venom and lecithin? There 

 would seem, on the contrary, no parallel between them. The union 

 of venom and lecithin, which may perfectly well be a simple adsorp- 

 tion phenomenon, is easily demonstrable experimentally, whereas 

 no such union between sensitizer and alexin is evident. What is 

 more, corpuscles that resist the action of venom alone but are he- 

 molyzed by the complex of lecithin and venom, are unable to fix 

 venom when lecithin is not present, whereas we have seen that the 

 sensitizer in hemolytic serum can always be absorbed by the cor- 

 puscles in the absence of alexin. 



Experiments on antisensitizers, and particularly those which I 

 published in 1904, have been made use of by Ehrlich and Sachs as 

 favoring the existence of a complementophilic group. I found that 

 sensitized corpuscles, when mixed with a suitable antisensitizer, lose 

 their power of absorbing alexin; in other words, the antisensitizer 

 really cures the corpuscles since it annuls the effect that the sensi- 

 tizer has produced. From this observation Ehrlich and Sachs con- 

 cluded that the antisensitizer unites with a complementophilic 

 group of the amboceptor and consequently satisfies its affinities, 

 According to these authors this interpretation is the only one which 

 is compatible with the fact that the antisensitizer drives out the 

 sensitizer from the corpuscle. It is, indeed, true, as I noted in my 

 article, that the antisensitizer unites with the corpuscle-sensitizer 

 complex but does not eliminate the latter substance. It simply 



