The Relation of the Pneumococcus to Hydrogen Ion Concentration, Acid Death-point, and Dissolution of the Organism.* by Frederick

Lord 1 has called attention to the probable importance of an increase in the hydrogen ion concentration in the pneumonic lung in inhibiting the growth of the pneumococcus and favoring enzymatic action. In this article we wish to elaborate certain aspects of the relation of the pneumococcus to changes in acidity. The hydrogen ion concentrations were determined by the colorimetric method with standard solutions made according to Clark and Lubs' directions? As indicators, phenolsulfonephthalein was used on hydrogen ion concentrations ranging from 8.0 to 6.2, and sodium alizarin sulfonate from 6.0 to 4.0. Colored solutions were either dialyzed or the determinations made by the comparator rack method.