ALEXIN ABSORPTION. 403 



What ideas concerning the mode of union of the alexin with sen- 

 sitized corpuscles are suggested by these facts? One of us* has 

 already expressed the opinion that this fixation of alexin is not a 

 chemical combination, strictly speaking, between the alexin and a 

 particular group of the sensitizer (complementophilic group of the 

 amboceptor, according to Ehrlich), but represents simply a phenom- 

 enon of molecular adhesion (adsorption). This point of view was 

 still further elaborated in 1906 f by the authors of the present 

 article. We regard the union of the sensitizer and red blood cells as 

 constituting a complex with more adsorption avidity for the alexin 

 than the normal corpuscle : the alexin tends to precipitate on the 

 sensitized corpuscle, the alteration of which is the more marked 

 the greater the sensitization. How, from this standpoint, does 

 the inhibiting serum act? It would seem to us that it holds the 

 alexin in a state of more or less definite suspension in the medium, 

 and gives it a more stable equilibrium; with salt solution, on the 

 other hand, the equilibrium is more unstable, that is to say, the 

 alexin condenses or precipitates more readily on those cells that 

 attract it. 



This idea seems to us to be in harmony with the observations 

 of Gengou on colloids and suspensions of inorganic precipitates. 

 Gengou$ found that if washed red blood corpuscles are added to 

 salt solution containing such an inert inorganic precipitate as barium 

 sulphate in suspension, the cells and the precipitate clump and 

 hemolysis occurs. But if a trace of serum is previously added 

 to the precipitate, this phenomenon of agglutination and hemolysis 

 does not occur. It was found that serum causes a dissociation of 

 the particles of barium sulphate and gives it a milky appearance 

 which delays the clarification of the fluid by sedimentation. And 

 serum, then, inhibits the precipitation of alexin on the corpuscles 

 just as it prevents the sedimentation of barium sulphate. 



Citrate of sodium produces an effect on barium sulphate similar 

 to the one caused by serum, and also changes it into a milky fluid 

 and, as Gengou has found, deprives it of its property of agglutinat- 

 ing and hemolyzing red blood cells. And there is a still further 

 analogy, in respect to the citrate, between the precipitation of 



* Bordet, Hemolytic sera, p. 186, and Cytolytic sera, p. 228. 

 t Bordet and Gay, On the relation of sensitizers, etc., p. 363. 

 J Gengou, Researches on the agglutination of red blood cells, etc., p. 312. 



