The normal stomach, empty of food, always contains some fluid and mucus. The stomach is therefore, strictly speaking, never empty. This fluid in the empty stomach is made up of (i) gastric juice and mucus, (2) saliva, (3) duodenal contents (pancreatic juice and bile). Pancreatic juice and bile are frequently absent, however. The total fluid content of the empty stomach as well as the chemistry of this fluid depend on several factors, such as the relative rate of gastric and salivary secretion, the tonus and contractions of the stomach, the rate of absorption in the stomach, and the rate of emptying of the stomach contents into the duodenum.
According to the more recent literature the fluid content of the empty stomach of normal persons varies within wide limits. Verhagen found the average to be 10 to 25 c.c., but occasionally as much as 50 c.c. were obtained. Moritz gives higher figures, or 24 to 64 c.c. Working on himself, Moritz obtained an average of 43 c.c. of fluid in the stomach in the morning, with an acidity of 0.11 per cent. Rehfus, Bergheim, and Hawk state that in normal persons the fluid in the empty stomach in the morning varies from 30 c.c. to 180 c.c. The average of more than two hundred observations on our gastric-fistula case, Mr. V., is 20 to 25 c.c. In Mr. V. the salivary factor is excluded as the esophagus is completely closed. The fluid content in the stomach in the morning before breakfast is greater than at noon before lunch. This is probably due to a lower tonus of the stomach in the morning. Sixty tests on eight normal medical students in the author's laboratory showed a variation from 10 to 120 c.c., with an average of 40 c.c. Some individuals tend to rim high; others are consistently low.