STUDIES ON THE PNEUMONIC EXUDATE : IV. THE PRESENCE IN THE PNEUMONIC LUNG OF A SOLUBLE SUBSTANCE INHIBITING AGGLUTINATION BY THE HOMOLOGOUS SERUM.

Specific agglutinins for the homologous pneumococcus are lacking or present only in small amount in the pneumonic exudates due to the fixed types of pneumococci. Suspensions of fixed types of pneumococci in the supernatant fluid obtained after centrifuging the mash of the pneumonic lung give positive agglutination tests in dilutions not higher than equal parts of suspension and supernatant fluid (1:2). The pneumonic lung contains a soluble substance inhibiting agglutination of the fixed types of pneumococci by the homologous antipneumococcus serum.