The mechanisms concerned in the lowering of gastric acidity following digestion have been the subject of considerable research since Pavlov1 first noticed the apparent diminution of further secretion of hydrochloric acid when there was an accumulation of that substance within the gastric cavity. Although he did no further work on the subject, he originated the idea of intrinsic control of gastric acidity.
Rosemann2 noted that although the concentration of total chloride remained constant, or relatively so, in specimens of gastric content, the acid chloride measured as hydrochloric acid and the neutral chloride measured as sodium chloride varied in inverse proportion. He advanced the hypothesis that as the stimulus to gastric secretion became stronger, the amount of chloride ion secreted as hydrochloric acid became greater, and the amount secreted as neutral chloride became correspondingly less. When the stimulus was absent or less marked, the reverse occurred. Earlier investigators, notably