Changes in the wall of the stomach sometimes reduce the total amount of hydrochloric acid in the gastric juice. Complete absence is exceedingly rare, occurring in about to per cent of people with disturbances of the stomach. Cases of decreased acid are, however, fairly frequent.

In most cases the digestion carried on in the intestines takes care of the absence of digestion in the stomach. With insufficient acid the stomach empties more rapidly than when acid is present. The treatment is to give small doses of dilute hydrochloric acid in a whole glass of water before each meal, as prescribed by the doctor.

However, the giving of plain water or any inert substance called a "placebo" of ten has the same effect, so that the result is probably more psychologic than actual. The functions of the stomach, including its secretions, aregreatly susceptible to influences from the nervous system.