CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION II. THE IDENTITY OF PRECIPITIN AND AGGLUTININ*

Although the unit&an theory of antibodies has gained general acceptance since its formulation by Zinsser and others (l), quantita-tive evidence for the identity of agglutinins and precipitins has been lacking. Zinsser (2) has attempted to reconcile mathematically the apparent discrepancy between the serum dilutions in which agglutina-tion and precipitation occur and Jones (3) has shown that collodion particles coated with egg albumin are agglutinated by small quantities of anti-egg albumin serum. Antibody concentrates, purified by Felton and Bailey (4), have been found to contain precipitins, agglu-tinins, opsonins, and protective antibody, but quantitative data were lacking until after the writers ’ preliminary report (5). The development of quantitative micro methods for the estimation of precipitins (6, 7) and agglutinins (8) has now made it possible to investigate the quantitative correspondence of precipitin and agglu-tinin. Pneumococcus Type I specific polysaccharide (acetyl form) (9): a Chamber-land filtrate of an autolyzed 8 day Type I Pneumococcus culture, Pneumococcus * The work reported in this communication was carried out under the Harkness Research Fund of the Presbyterian Hospital, New York. Submitted by Mr. El-vin A. Kabat in partial fulfilment of the requirements for the degree of Docto