374 A MANUAL OF PHYSIOLOGY 



a gastric fistula, then a few days afterwards divided the 

 oesophagus through a wound in the neck, and stitched the two 

 cut ends to the edges of the wound. After the animals had 

 recovered, it was observed that when meat was given to them 

 by the mouth, a copious secretion of gastric juice followed in 

 five or six minutes, notwithstanding the fact that in this ' sham 

 feeding ' the food immediately escaped from the opening in the 

 upper portion of the divided oesophagus. Much the same 

 result was seen when the food was simply shown to the animal. 

 Indeed, when a hungry animal is tempted with the sight of 

 meat, the flow of gastric juice, always occurring after a latent 

 period of five or six minutes, may be even greater than with 

 sham feeding. Division of the splanchnic nerves had no effect 

 on this reflex secretion, while it could not be obtained after 

 division of both vagi below the origin of their cardiac and 

 pulmonary branches, by which disturbance of the heart and 

 respiration are avoided. Further, stimulation of the peripheral 

 end of the vagus in the neck* caused secretion. These experi- 

 ments show that secretory fibres for the gastric glands run in the 

 vagi. It is probable that the vagi also contain efferent fibres 

 which inhibit the gastric secretion. The excitation of the 

 secretory fibres is not produced reflexly by the processes of 

 mastication and deglutition as such. Dilute acid is the most 

 powerful chemical stimulus for the buccal mucous membrane, 

 and when it is introduced into the mouth of a dog with a double 

 cesophageal and gastric fistula, an abundant secretion of saliva at 

 once ensues. But no matter how long the animal continues to 

 swallow the mixture of saliva and acid, no gastric juice is formed. 

 The same is the case in sham feeding with salt, pepper, mustard, 

 smooth stones, and even extract of meat. It is the desire for 

 food the appetite, as we call it and the feeling of satisfaction 

 associated with eating food that the animal relishes, which is 

 the efficient cause of the gastric secretion in sham feeding. The 

 more eagerly the dog eats, the greater is the flow of gastric juice. 

 Pawlow also performed the converse experiment. In dogs 

 in which a pouch had been isolated from the stomach and 

 made to open to the exterior by the surgical procedure 

 illustrated in Figs. 144 and 145, he introduced into the large 

 stomach, without the animal's knowledge, food of various 

 kinds. This is best done in a sleeping dog. The secretion of 

 gastric juice, both in the main stomach and in the pouch or 

 miniature stomach, which is known in a great variety of condi- 

 tions to present an exact picture of the process of secretion in 



* The nerve was not stimulated till a few days after the section, so as to 

 allow the cardio-inhibitory fibres to degenerate. Otherwise the heart 

 would have been stopped by the stimulation. 



