STUDY OF MOLECULAR ADHESION. 431 



III. 



The two preceding chapters have been given over to the consid- 

 eration of adsorption phenomena which occur between substances 

 neither of which is cellular, properly speaking. Certain of them, 

 such as barium sulphate, calcium fluoride and the like, are insoluble 

 inorganic substances; and others are stable colloids (gum and the 

 like) or electrolytes (sodium citrate). 



In the mutual adhesion between these substances which we have 

 considered, one of them, the colloid, may be replaced by a cellular 

 element. As we have previously shown,* barium sulphate, when 

 mixed with red blood cells that have been washed free of all serum 

 and suspended in salt solution, adheres to the corpuscles and pro- 

 duces agglutination in large clumps composed of suspension and 

 corpuscles. The agglutination is followed by dissolution of the 

 corpuscles when sufficiently large doses of barium sulphate are used. 



We have here an adhesion phenomenon between two suspended 

 substances which may be studied by subjecting it to the various 

 influences which we have employed in dealing with other adhesion 

 phenomena, as the one between barium sulphate and starch. 

 We find here, too, that the agglutination of barium sulphate with 

 corpuscles does not occur when a stable colloid like serum, or when 

 sodium citrate, is present, any more than it does in the adhesion 

 of barium sulphate with starch. We know from what we have seen 

 in the preceding chapters what takes place under these conditions ; 

 it may be that another complex, namely, barium sulphate plus 

 serum or barium sulphate plus citrate, takes the place of the com- 

 plex, barium sulphate plus corpuscles, which occurs under normal 

 conditions ; in other words, one phenomenon of adhesion takes the 

 part of another similar phenomenon. 



We have already demonstrated that the particles of the complex, 

 barium sulphate plus citrate, which remain separate in the solution 

 in which they have been formed, without any tendency toward 

 mutual adhesion, are agglutinated on the addition of a salt such as 



* Gengou, C. R. Acad. Sciences, Paris, 1904. Landsteiner and Jagic noted 

 the effect of colloidal silicic acid on corpuscles some time before (Wein. klin. 

 Wochenschr., 1904, No. 3). Shortly after our communication, Madam Girard- 

 Mangan and v. Henri (C. R. Soc. Biol., 1904) in turn studied this phenomenon 

 very extensively with various colloids. 



