DIGESTION AND ABSORPTION IN THE STOMACH. 



777 



size the fact that in the normal secretion of gastric juice, that 

 is to say, in the secretion which takes place during an ordinary 

 meal, we must distinguish between a nervous secretion due to 

 the action of the secretory fibers in the vagus, and a chemical 

 secretion due to the chemical stimulation of the secretogogues 

 or of the hormones produced by them. 



The researches of Pawlow and his co-workers seem also to in- 

 dicate that the quantity and properties of the secretion vary with 



, Quantity of secretion. 



, Acidity. 



, Digestive power. 



Fig. 295. Diagram showing the variation in quantity of gastric secretion in the dog after a 

 mixed meal; also the variations in acidity and in digestive power. (After Khigine.) 



the character of the food. The quantity of the secretion varies, 

 also, other conditions being the same, with the amount of food to 

 be digested. The apparatus is adjusted in this respect to work 

 economically. Different kinds of food produce secretions varying 

 not only as regards quantity but also in their acidity and diges- 

 tive action. The secretion produced by bread, though less in 

 quantity than that caused by meat, possesses a greater digestive 

 action. On a given diet the secretion assumes certain characteris- 



