AGGLUTINATION OF RED BLOOD CELLS. 325 



to which they were fixed, we should be able to demonstrate it by a dissociation of barium 

 sulphate added to this fluid. This indeed proves to be true: barium sulphate added 

 to these two fluids and also to tube 3 is found to sediment rapidly in lube 2 and to 

 remain dissociated in tube 1 and in tube 3. Control tubes show that neither the wash 

 water nor the acetic acid have the slightest dissociating effect on barium sulphate. On 

 choosing, therefore, a suspension that is dissociated by serum and easy to dissolve, the 

 combination between the suspension and the colloidal substances that dissociated it 

 may be broken up* 



These experiments show, it seems, to us, that the phenomena of 

 agglutination and dissociation, at least in the instances we have 

 studied, although of different appearance, are nevertheless due to 

 the same fundamental fact, namely, the affinity of the suspension 

 for the corpuscles or the colloids of serum. Why are so widely 

 different phenomena produced under such apparently closely 

 related conditions? We cannot attempt to give the ultimate reason 

 for this difference, but will simply offer an hypothesis that we have 

 supported by a few facts. Since we know that an adhesion occurs 

 in both instances between a suspension and the particles either 

 of the corpuscle suspension or of the serum, the question arises if, 

 when these adhesions are produced, the respective properties of 

 the substances employed do not have some effect on the result of 

 the reaction? As we know, barium sulphate will sediment by its 

 own weight. If we add corpuscles which are particles that also 

 tend to sediment, to barium sulphate, may we not consider the 

 fact that the combination falls to the bottom of the tube as due to 

 the tendency of barium sulphate to sediment, which tendency is 

 only slightly modified by a contrary tendency on the part of the 

 corpuscles? In a mixture of barium sulphate and serum, however, 

 the sulphate meets with colloids which are very difficult to pre- 

 cipitate and the tendency of barium sulphate to sediment would 

 be counterbalanced by a marked opposing tendency. If this 

 opposing tendency prevails, a combination with barium sulphate 

 would not sediment at all, but remain dissociated in the fluid, as 

 indeed happens. According to this hypothesis the dissociation of 

 barium sulphate by serum would be due to the result of a struggle 



* It is to be noted that if hydrochloric acid is used in place of acetic acid and 

 the phosphates thus totally dissolved, barium sulphate is not dissociated by the 

 resultant fluid; it is also to be noted that barium sulphate sediments in serum to 

 which the same amount of hydrochloric acid has been added. In other words, 

 hydrochloric acid inhibits the dissociating effect of the serum. 



