5U STUDIES IX IMMUNITY. 



causes the complex to lose its affinity for alexin. Adsorption phe- 

 nomena frequently show similar precipitations of various substances 

 on one another; for example, if we wash a rather thick suspension of 

 barium sulphate over a firm paraffin surface, we find that the 

 paraffin becomes covered with a delicate white layer of sulphate 

 which adheres and resists washing. Let us now place a suspension 

 of red blood cells on such a paraffin surface that has been covered 

 with barium sulphate, and then wash with salt solution: we find the 

 corpuscles adhere to the sulphate with which the paraffin is covered; 

 the surface gradually takes a reddish color which resists washing in 

 salt solution. The paraffin adsorbs the sulphate which in its turn 

 adsorbs the corpuscles.* It is evident that in such an instance the 

 phenomenon may be expressed by saying that the sulphate func- 

 tions as amboceptor between the paraffin and the corpuscle. 



But are we always obliged to conclude that when a property 

 becomes manifest or disappears it is owing to the integrity of or 

 an alteration in a definite atom group? When a sensitized cor- 

 puscle that has been disintoxicatecl by antisensitizer fails to fix 

 alexin, must we suppose that the complementophilic group of the 

 sensitizer is thenceforth saturated? Such an interpretation, in 

 truth, cannot be reconciled with fact; experiment shows us that a 

 given antisensitizer, for example the one furnished by guinea-pigs 

 immunized against rabbit serum, neutralizes all the sensitizers from 

 the same animal species (in this case the rabbit), but has no effect 

 on sensitizers from other animal species. Studies on the fixation of 

 alexin show that the sensitizers of different animals make use of the 

 same alexin in bringing about either hemolysis or bacteriolysis; if 

 we were to use Ehrlich's terminology we should be forced conse- 

 quently to conclude that they have identical complementophilic 

 groups. According to Ehrlich's interpretation they should all be 

 neutralized by the same antisensitizer, and such is not the case. 

 We find, moreover, that sensitized corpuscles treated by a suitable 

 antiserum subsequently resist, whatever alexin be employed. And 

 what is more, the phenomenon of alexin fixation appears more and 

 more, as has been evidenced in the preceding pages, to be an adsorp- 



* Gengou's experiments, as is well known, have shown that barium sulphate 

 possesses the property of precipitating itself on red blood cells and forming clumps 

 with them. 



