AGGLUTINATION OF RED BLOOD CELLS. 323 



sions of albuminous substances, but in the case of the corpuscles 

 the particles are larger than in the case of serum. Both serum and 

 corpuscles have the same negative electric charge.* 



How is it, then, that the addition of a given substance barium 

 sulphate produces such divergent effects in these two similar 

 emulsions? Agglutination and dissociation would indeed seem 

 to be the direct opposites of one another, but are they indeed as 

 different as at first seems? Are they not rather two different results 

 of a single fundamental phenomenon appearing either in the form 

 of an agglutination or of a dissociation, as the case may be? 



The agglutination of corpuscles with barium sulphate leads us 

 to think of some adhesion between the suspension and the cor- 

 puscles. In the dissociation of barium sulphate by serum, is there 

 not also an adhesion between the suspension and the albuminous 

 particles of the serum? According to this explanation the funda- 

 mental phenomenon would be adhesion between the suspension and 

 the corpuscles or the albuminous substances of serum; this adhe- 

 sion, however, would be followed in the one case by agglutination 

 and in the other by dissociation. 



The following experiments seem to prove the accuracy of this 

 hypothesis : 



EXPERIMENT 1. If there is some adhesion between the albuminous particles of 

 serum and barium sulphate, the dissociating property of the serum for the powder 

 should have a definite limit. In order to demonstrate this we add a large amount 

 of barium sulphate to a small amount of serum. We begin by centrifugalizing five 

 tubes, each of which contains 2 c.c. of our emulsion of sulphate, and then throw off the 

 supernatant fluids. One of these sediments is then suspended in the serum employed, 

 namely 0.5 of a cubic centimeter of fresh horse serum diluted with 1.5 c.c. of salt 

 solution. After allowing short contact the tube is then centrifugalized and the second 

 original sediment of sulphate is suspended in the supernatant fluid of the first tube; 

 this procedure is repeated with the third and fourth sediment and so on. We then 

 add to the serum that has been treated in this manner a small amount of barium sul- 

 phate and find that this serum has little or no dissociating property for the suspension. 

 Nor does it agglutinate CaFl 2 or inhibit the agglutination of corpuscles by either 

 CaFl 2 or by barium sulphate. The colloidal solution, which constitutes the serum, 

 loses its albuminous substance, then, as a result of contact with larger amounts of 

 barium sulphate, just as an emulsion of red blood cells in agglutinating the sulphate 

 solution loses its corpuscles. 



* It is to be noted that although Mangin and Henri consider serum as a nega- 

 tive colloid, other writers, notably Neisser and Friedemann, are doubtful of this 

 fact on account of Hardy's work. 



Mme. Girard-Mangin et V. Henri., Soc. de Biol., 1904, No. 24. 



Neisser et Friedemann, 1. c. 



