AGGLUTINATION OF RED BLOOD CELLS. 315 



they may, therefore, be easily flocculated by the electrolytes diffused 

 from the corpuscles, but it does not follow that this explanation 

 serves to explain their agglutinating power over corpuscles. 



It is not essential for a substance to be precipitated by salts 

 coming from corpuscles in order that the agglutination by this 

 substance be possible. We have already noted that barium sul- 

 phate agglutinates corpuscles readily and barium sulphate, as we 

 know, is much more susceptible to gravity than it is to electro- 

 lytes. It is no more flocculated by a strong concentration of salt 

 solution than it is by distilled water, in which latter solution it 

 sediments rather rapidly. 



We have undertaken to determine whether a fine suspension 

 that is flocculable by electrolytes can subsequently agglutinate 

 corpuscles after having been flocculated. 



For this purpose we have used calcium fluoride, which is a pre- 

 cipitate of rather colloidal appearance flocculable by 0.8 per cent 

 NaCl. We find that calcium fluoride that has been previously 

 flocculated by 0.8 per cent or by 2 per cent sodium chloride will 

 still agglutinate corpuscles in 0.6 per cent salt solution quite as well 

 as if it were in suspension in distilled water. If the saline con- 

 centration is increased to 3 per cent the calcium fluoride so treated 

 no longer agglutinates as well. This would prove simply, accord- 

 ing to our opinion, that the very dense accumulated masses of 

 colloidal precipitates are less effective on corpuscles, owing to the 

 fact that with such masses an intimate mixture of the corpuscles 

 and the calcium fluoride is no longer possible. When the masses, 

 on the contrary, are not so dense (for example, CaFl 2 in sodium 

 chloride, 0.8 per cent or 2 per cent) and consequently more easily 

 broken up, the effect of the suspension on the corpuscles is only 

 slightly attenuated. We should not conclude from these facts, 

 however, that the agglutination of corpuscles by calcium fluoride 

 is possible only when the state of dissociation of this substance is 

 such that it may be flocculated by the salts about corpuscles as they 

 pass out, but simply that the greater the intimacy of mixture 

 between the corpuscles and the calcium fluoride, the more intense 

 the agglutination.* 



* It is probable that the same holds true for the colloidal substances, which 

 become distinctly less active, as they are less easily flocculated by electrolytes. Mme. 

 Girard-Mangin and V. Henri asserted that flocculated colloids no longer aggluti- 



