AGGLUTININS 



57 



opposite effect, namely, disseminates the particles 

 of barium and gives a milky appearance to the 

 fluid. Can we, says Bordet, claim that by heating 

 this solution we have caused it to lose its agglu- 

 tinating group? Bordet agrees with Forges, who 

 believes that the hypothesis of such a group in the 

 antibody molecule has no foundation. Forges 

 found, on studying the effect of heat on the agglu- 

 tinating power of the albuminous substances of 

 serum for mastic emulsions, that he could obtain 

 results entirely similar to those that have been 

 noted for agglutinins. Bordet insists that we have 

 no right to localize the cause of agglutination in a 

 molecule of the antibody rather than in one of the 

 antigen. The hypothesis of a functional group in 

 the molecule of the agglutinin, he says, is all the 

 more doubtful, inasmuch as it is not the only sub- 

 stance which can render bacteria sensitive to the 

 flocculating action of salts. Bacteria that have 

 adsorbed iron, uranium, or aluminium compounds 

 are subsequently flocculable by salts, and silicic 

 acid is similar in its action. According to Bordet, 

 the essential phenomenon with agglutination, as 

 with other active substances in sera, is its union 

 with the antigen; as far as the agglutination itself, 

 which follows this union, is concerned, it is only a 

 secondary phenomenon on which we cannot depend 

 in considering agglutinins as functionally different 

 in molecular structure from the other antibodies. 



