On the Mechanism of Agglutination

Abstract

1. The hypotheses of Pfeiffer, Emmerich and Löw, attributing agglutination to a vital paralysis due to the action of a bacteriolytic enzyme, and those of Gruber, Dineur, and Nicolle, which ascribe the action to the glutinous nature of the membranes or cilia, are insufficient to account for the observed phenomena.2. The views of Paltauf and Duclaux that a specific precipitate is formed in the medium which mechanically carries the bacilli together are sufficient, but probably do not account fully for the agglutination of washed bacilli.3. Arrhenius's assumption that the gas laws are applicable to the partition of agglutinin between bacilli and medium is improbable since the conditions under which these laws can be applied are absent.4. The formula given by Arrhenius for the partition of agglutinin seems to be a special case of a general formula holding for the absorption of substances from solution by substances with highly developed surfaces,e.g., the adsorption of iodine from solution by charcoal. A superficial analogy between the gas partition law and the adsorption partition law for equilibria is to be expected, likewise an equally superficial analogy between reactions in true solutions and colloidal solutions,e.g., of agglutinin, for the velocity of reaction.5. The special formula given by Arrhenius does not apply to the entire range of agglutinin solutions and the change which must be made in the constants is incompatible with the application of the gas laws, but agrees with the view that the fixation of agglutinin is due to adsorption.6. The fixation of agglutinin from two different typhoid immune sera by living typhoid bacilli did not correspond to the partition law deduced by Arrhenius from the experiments of Eisenberg and Volk.7. The rate of addition of bacillary suspension to agglutinating serum is a factor determining the amount of agglutinin fixed by the bacilli. By adding the suspension in parts more agglutinin is removed than in the case where the whole amount of suspension is added at once. This points to the equilibria belonging to the class met with in absorption.8. Similar adsorption equilibria are obtained by experiments on staining.9. The cell contents probably play an important part in agglutination as the washed membranes are but slightly agglutinated.10. Motile cultures ofB. typhosusgrown at 37°C., and non-motile cultures grown at 42°C., agglutinated equally well, the agglutinable substance probably being unchanged.11. The law governing the fixation inB. typhosus, heated to 58°C. for 30 minutes, is probably different to that holding for living cultures owing to modification of the agglutinable substance.