There is apparently a gastric element in appetite. The contractions of the stomach institute hunger. Its profuse and rich secretion causes an entirely different sensation—not painful, but pleasant. Carlson concludes that the appetite or psychic gastric juice described by Pawlow1 stimulates sensory nerve endings in the gastric mucosa. The resulting sensation resembles that which follows the first few mouthfuls of good food at a meal to which one has come hungry, and directs the flow of consciousness toward the matter of taking food.
Pediatric literature contains many references to this secretion. Bauer and Deutsch found no gastric juice in the baby's stomach after it had reached eagerly for its bottle. Pfaundler noted that in babes who nursed actively the stomach emptied sooner, and the degree of acidity attained was higher than in babes who were fed passively or through the tube. Cohnheim and Soetbeer, working with gastrotomized new-born
TAYLOR R. HUNGER AND APPETITE SECRETION OF GASTRIC JUICE IN INFANTS' STOMACHS. Am J Dis Child. 1917;14(4):258-266. doi:10.1001/archpedi.1917.01910100027002