314 VETERINARY PHYSIOLOGY 



kind of food and with the course of digestion. It is higher 

 and persists longer after a diet of bread, which is difficult to 

 digest, than after a diet of flesh, which is more easily 

 digested. (4) The percentage of acid does not vary 

 markedly. When more acid is required, more gastric juice 

 is secreted. (5) The work done by the gastric glands, as 

 measured by the amount of secretion multiplied by its 



EYE 



MOUTH 



STOMACH 



POUCH 



Fig. 151. — To show the Nervous Mechanism of Gastric Secretion and how it 

 is reflexly induced through various ingoing channels. 



activity, is greater in the digestion of bread than in the 

 disfestion of flesh. 



(7) Nervous Mechanism of Gastric Secretion. — 

 («,) Intrinsic. — It has been proved that in the dog the 

 secretion of gastric juice can go on after the nerves to the 

 stomach have been divided, and this has been ascribed to a 

 reflex stimulation of the nerve plexus in the submucosa. 



(b) Extrinsic. — Pavlov found that, when the vagus is cut 



