XV. RESEARCHES ON THE AGGLUTINATION OF RED 

 BLOOD CELLS BY CHEMICAL PRECIPITATES AND 

 ON THE SUSPENSION OF SUCH PRECIPI- 

 TATES IN COLLOIDAL MEDIA.* 



By Dr. OCTAVE GENGOU. 



Colloidal substances play so important a role in vital phenomena 

 that biologists have been following with great interest the advances 

 made by chemistry and physics in our knowledge of these substances. 

 Any analysis of the properties of organic colloids has been extremely 

 complicated by our ignorance of their composition; for this reason 

 we have resorted to such information as may be gained from a 

 study of simpler colloids. We have, in general, drawn our con- 

 clusions as regards organic colloids from the rules that have been 

 drawn from the better-known reactions with inorganic colloids. 

 One of the best-known phenomena afforded by these two groups 

 of substances is agglutination. Works dealing with this phe- 

 nomenon are numerous, and the recent publications of Perrin on 

 colloidal substances have stimulated biologists to a most active 

 study of it. 



Although the agglutination of bacteria and of red blood cells by 

 sera has been investigated with much diligence, the essential prin- 

 ciples of the reaction are still a mystery. The apparent analogy 

 between agglutination and the precipitation of colloids has given 

 rise to the hope that a careful analysis of this latter phenomenon 

 may lead to an explanation of agglutination. The works dealing 

 either with the precipitation of colloids or the agglutination of red 

 blood cells by suspensions (that is, by colloids or chemical precipi- 

 tates) have been very numerous since the publications of Perrin. 



Landsteiner and Jagic f were, we believe, the first to draw atten- 



* Recherches sur l'agglutination des globules rouges par les precipites chimiques 

 et sur la suspension de ces precipites dans les milieux colloidaux. Annales de 

 l'Institut Pasteur, XVIII, 1904, 678. 



f Landsteiner and Jagic, Wien. klin. Wochenschr., 1904, No. 3. 



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