THE MECHANISM OF AGGLUTINATION. 147 



that agglutination proper is also due to the formation of a pre- 

 cipitate outside of the bacteria which retracts and becomes agglu- 

 tinated and thus presses together the bacteria and forces them to 

 unite and become adherent. As a matter of fact this idea was 

 already offered by Paltauf * before Nicolle's work. Dineur in a 

 recent article has discussed this theory and offered objections to 

 it. f We shall consider this hypothesis in its proper place. 



4. Paltauf 's hypothesis. According to this author the agglu- 

 tination of bacteria is due to their being mechanically drawn 

 together in the interstices of a coagulum formed outside of the bac- 

 teria in the surrounding fluid, as a result of the reaction between 

 the agglutinin and the agglutinable substances from the bacteria. 



5. Dineur' s hypothesis. According to Dineur the clumping is 

 due to the formation of an adhesive substance which keeps the 

 bacteria together. This adhesive substance is formed particularly 

 on the cilia. As may be seen, Dineur attributes essential import- 

 ance in agglutination to the presence of cilia. Agglutination would 

 be caused, then, by an adhesion and interlacing of these cilia. 



*** 



We have thus reviewed in the preceding pages the various in- 

 terpretations of agglutination that have been proposed, with em- 

 phasis on their exact significance. We have, however, only touched 

 on the experimental facts that corroborate or eliminate them. 

 There are already enough of these facts to allow of a discussion 

 founded on adequate data, and it is this consideration that we pro- 

 pose to take up. 



Among the interpretations that have been offered there are some 

 which evidently are so little in relation to fact that they may be 

 dismissed pree'mptorially. For example, Dineur's hypothesis which 

 attributes a maximum importance to the existence of cilia. Such 

 an opinion is evidently unsatisfactory, as agglutination may occur 

 with bacteria that have no cilia or even with such elements as red 

 blood ceils, or particles of casein which obviously do not possess 

 these appendages. Dineur, to be sure, also emphasizes the produc- 

 tion of an adhesive substance which collects the bacteria subjected 



* Wiener klinische Wochenschrift, 1897. 



t Dineur, Recherches sur le mecanismede 1'agglutination du bacille typhique. 

 Bulletin de 1'Academie de Medecine de Belgique, 1898, p. 652. 



