The stomach consists functionally of two parts namely, the fundus 

 and the pyloric end. In the fundus of the stomach are found the glands 

 which secrete an acid juice. In the pyloric end the glands are devoid of 

 oxyntic cells and the mucous membrane is much more closely adherent 

 to the subjacent muscular coats. After a full meal the food forms a mass 

 lying in the fundus of the stomach, the pyloric portion being at first quite 

 empty. The movements, which occur from 20 to 30 minutes after the taking 

 of food, involve only the pyloric half of the stomach, the fundus gradually 

 contracting on its mass of food, so that the portions which are already 

 partially digested are squeezed into the pyloric mill, where thorough 

 admixture of the food with the juices takes place. It seems that such 

 absorption as occurs in the stomach takes place solely at its pyloric 

 end. If, then, there be a gastric secretin, we should expect it to be formed 

 in the cells of the pyloric mucous membrane under the influence of 

 the acid or food passing to this end of the stomach from the fundus. 

 Injection of an extract made by treating pyloric mucous membrane 

 with the products of gastric digestion should provoke a secretion of gastric 

 juice. On such lines Edkins made his observations. Extracts of the 

 pyloric mucous membrane were made by rubbing this up with 5 per cent, 

 dextrin, with dextrose or maltose, or with peptone. A dog's stomach, 

 which had been previously washed out, was filled up with normal salt 

 solution under slight pressure. No absorption of salt solution takes place 

 through the stomach, so that at the end of an hour the salt solution could 

 be recovered unchanged. If, however, the extracts made, as just de- 

 scribed, were injected in repeated small doses into the veins of the animal 

 under observation, the salt solution removed from the stomach at the end 

 of an hour was found to contain hydrochloric acid as well as pepsine, 

 showing that secretion had been excited in the stomach. Injections of 

 dextrin, maltose, etc., by themselves were without effect, so that the 

 secretory results must be due to the injection of some substance produced 

 in the pyloric cells under the influence of these digestive products. 

 This substance, which Edkins calls gastrin, but which would be better 

 named gastric secretin, is produced only from the pyloric mucous mem- 

 brane, extracts made by rubbing up digestive products with fundus 

 mucous membrane being without influence on the gastric secretion. 

 Edkins has shown that the substance is not destroyed by boiling, so that 

 it evidently belongs to the same class of bodies as the pancreatic secretin 

 described in my last lecture. 



It is an old theory, as propounded by Schiff, that certain constituents 

 of the food have a special influence in promoting the secretion of 

 gastric juice. These substances, among which Schiff placed dextrin, were 

 called by him peptogenous, and it seems from Edkins's researches that 

 this term is justified and that our future definition of peptogenous sub- 

 stances will be such bodies as can by their action on the pyloric mucous 

 membrane give rise to the production of gastric secretin. 



. The movements of the pyloric mill have the effect of squirting into 

 the first part of the duodenum, at intervals of a few minutes, a small 



