It has become increasingly evident that the acidity of gastric contents depends not entirely on variations in the secretory activity of the stomach, but also on the degree to which the secreted acid is neutralized. It has been demonstrated, for example, that pure gastric juice, actively secreted, reaches a constant acidity of about 0.5 per cent hydrochloric acid (about 140 degrees). As found in normal gastric contents after an adequate stimulus, the acidity is much lower, indicating that this value has been reduced until it is usually about from one third to one fourth of this level. Although it is generally agreed that neutralization brings about this reduction, there is still some dispute about its mechanism.
From a variety of evidence summarized in previous communications from this clinic,1 it appeared that this neutralizing action took place in the stomach largely by the action of regurgitated alkaline pancreatic juice, which