The Self‐regulation of the Acidity of the Gastric Contents and the Real Acidity of the Gastric Juice

The acidity of the freshly secreted gastric juice is constant (0·5 per cent. HCL). 2. This acidity is rapidly lowered to a level which oscillates between 0·15 to 0·2 per cent. HCL. 3. The same thing happens when any acids foreign to the stomach are introduced into it. 4. This partial neutralisation is due to the reflux into the stomach of alkaline juices from the duodenum, the pancreatic juice being here the most important factor. 5. Neutral, alkaline, or feebly acid fluids introduced into the stomach provoke a secretion of the acid juice with the object of bringing up the acidity to the normal level. 6. The mechanism described for maintaining the optimum level of acidity ( 0·15 to 0·2 per cent. HCl) I propose to designate the self‐regulation of the acidity of the contents of the stomach.