186 CHEMISTRY OF THE IMMUMTY REACTIOX^ 



portance, but it does not explain all the facts of agglutination, nor is 

 the relation between agglutinating and precipitating power of im- 

 mune serums a constant one. In support of this hypothesis is the 

 observation of Scheller ' ^ that mixtures of typhoid bacilli and agglu- 

 tinating serum lose their agglutinability by vigorous shaking, which 

 may be interpreted as the result of disintegration of the agglutinating 

 precipitate. Shaking of either 'bacteria or serum alone is without 

 effect. Neisser and Frieduiann '- found that if the bacterial cells were 

 saturated with lead acetate, washed in water until all soluble lead was 

 removed, and then treated with IToS, they were promptly agglutin- 

 ated and precipitated, supporting other observations that indicate 

 that precipitation within the bacterial cells can lead to agglutina- 

 tion. This sort of agglutination is related to the process of formation 

 of" coarse flocculi in solutions, and probably depends upon alterations 

 in surface tension. 



Bordet and Gay described, under the term conglutination, the 

 observation that in ox serum there is a substance which combines 

 with corpuscles (or bacteria) that have been acted upon by aggluti- 

 nating sera, and augments the agglutination.'^^ Dean finds that, in 

 general, agglutination requires two agents, one being the specific 

 antibody, and the other a precipitable substance, probably a globu- 

 lin. When cells have combined with the antibody the precipitable 

 substance is aggregated on their surfaces and, presumably, determines 

 the agglutination. Co-agglutination, described by Bordet and Gen- 

 gou as the agglutination by an antigen and the homologous antibody, 

 of the corpuscles of another animal, is probably closely related to these 

 phenomena (Dean). 



Bordet ^* made the important observation that agglutination would 

 not occur if both the bacterial suspension and the agglutinating 

 serum were dialyzed free from salts before mixing; but if, to such 

 mixtures, a small amount of NaCl was added, agglutination and pre- 

 cipitation of the bacteria occurred at once. This observation brought 

 the phenomenon of bacterial agglutination into close relation with the 

 precipitation of colloids by electrolytes, Bordet comparing it to the 

 precipitation of particles of inorganic matter suspended in the fresh 

 water of rivers that occurs when the fresh water meets the salt water 

 of the ocean. He found that the agglutinin combined with the bac- 

 teria in the absence of the salts, and the resulting compound was pre- 

 cii)itated by the addition of minute amounts of electrolytes,"''' which 

 alone did not ])recipitate or agglutinate the bacteria or the serum. 



71 Cent. f. Bakt., 1910 (.'54), l.'iO. 



"Miinch. med. Woeli., lOO-l (51), 4G5 and 827. 



T3 Litoraturo jrivon bv Dean, Proc. IJoval Soc. (V.) . 1011 (S4), 41(i: ITall. 

 Univ. Calif. Publ., Pathol., 1013 (2), 111." 



74 Ann. d. I'lnst. Pasteur. 1800 (1.3), 22.'). 



74a Corroborated for sensitized red corpuscles bv Eisner and Kriedeniann. Zcit. 

 Imniniiiiiit., 1014 (21), ,''>20. 



