DIGESTION AND ABSORPTION IN THE STOMACH. 781 



of the general fact that the secretion is due to the action of vagus 

 fibers is furnished by such experiments as these : Pawlow divided the 

 esophagus in the neck and brought the two ends to the skin so as to 

 make separate fistulous openings to the exterior. Under these con- 

 ditions, when the animal ate and swallowed food it was discharged 

 to the exterior instead of entering the stomach. The animal thus 

 had the enjoyment of eating without actually filling the stomach. 

 Eating in this style forms what the author called a fictitious 

 or sham meal (Scheinfutterung) . It was found that it causes 

 an abundant flow of gastric juice as long as the vagi are intact, 

 but has no effect on the secretion when these nerves are cut. 

 Evidently, therefore, the sensations of taste, odor, etc., developed 

 during the mastication and swallowing of food, set up reflexly 

 a stimulation of secretory fibers in the vagus. Pawlow desig- 

 nates a secretion produced in this way as a psychical secretion, 

 a term which implies that the reflex must be attended by 

 conscious sensations. In favorable cases the fictitious feeding has 

 been continued for five or six hours and a large amount of gastric 

 juice (700 c.c.) has been collected from a fistula, although no food 

 actually entered the stomach. It is important to note, also, that a 

 psychical secretion, once started, may continue for a long time after 

 the stimulus (the eating) has ceased. Experiments have been made 

 upon human beings under similar conditions. Thus, Hornborg* 

 reports the case of a boy with a stricture of the esophagus and a 

 fistula in the stomach. Food when chewed and swallowed did not 

 reach the stomach, but was regurgitated; it caused, nevertheless, 

 an active psychical secretion in the empty stomach. 



Normal Mechanism of the Secretion of the Gastric Juice. 

 It has usually been assumed that the gastric glands are quiescent 

 whenjthe stomach is empty and are stimulated to activity during the 

 eating and digestion of food. According to the results published 

 by Carlson f this view is not wholly correct Even in the period 

 of fasting there is a small continuous secretion varying from 2 to 

 50 c.c. per hour. But during the act of eating and throughout the 

 period of gastric digestion the rate of secretion is increased greatly, 

 reaching a flow of as much as 3.5 c.c. per minute. The modern ex- 

 planation of the origin, maintenance, and regulation of this flow of 

 secretion is due chiefly to Pawlow. Contrary to a former general be- 

 lief, he showed that mechanical stimulation of the gastric mucous > 

 membrane has no effect on the secretion of the tubules. This factor 

 may, therefore, be eliminated. In an ordinary meal the secretion 

 first started is due to the sensations of eating that is, it is a psych- 

 ical secretion. The afferent stimuli originate in the mouth and 



*Hornborg, " Skandinavisches Archiv f. Physiologic," 15, 209, 1904; see 

 also Bickel, "Verhandl. Kongr. f. innere Medizin," 23, 491, and Carlson, "The 

 Control of Hunger in Health and Disease," Chicago, 1916. 



f Carlson, loc. cit. 



