THE GLANDS OF THE STOMACH 



265 



From these observations we can form provisionally the following concep- 

 tion of the conditions for secretion in the stomach. Secretion of gastric juice 

 is started by a complicated reflex process, which is set in operation by the 

 sight of food as well as by its passage through the mouth and oesophagus, and 



Hours 12345678 123456789 10 12345 



Meat. Bread. Milk. 



FIG. 103. Hourly course of secretion of gastric juice in the dog's stomach, after Pawlow. Ex- 

 clusive diets of meat, bread, and milk were given. 



is mediated by the vagus. This secretion itself lasts for a fairly long time; 

 but it is augmented by the stimulating influence on the mucous membrane of 

 ingested water and, above all, of certain extractives, etc., contained in the food. 



Chigin's experiments on the course of the secretion in the blind sac with 

 the vagi preserved show very instructively how the activity of the mucous mem- 

 brane under the influence of the vagus reflexes and the excitation of the food, 

 is adapted to the momentary requirements upon it. With all the articles of 

 food thus far tested the secretion began at about the same time. It reached its 

 maximum during the first or the second hour (with milk during the third hour). 

 After the maximum was reached the secretion fell immediately and became 

 gradually less and less until it finally ceased. The absolute quantity of gastric 

 juice with the same article of food was greater, the greater the mass of food 



Hours 12345 

 10 



4 5 



Meat. 



Bread. 



Milk. 



FIG. 104. Hourly course of the digestive action of gastric juice on proteid, after feeding exclu- 

 sively meat, bread, and milk (Pawlow). 



introduced. The quantity secreted, for example, was greater with 200 g. of 

 meat than with 200 g. of bread or 600 g. of milk (Fig. 103). The digestive 

 power of the fluid secreted with the articles of food just mentioned, when tested 

 from hour to hour, shows characteristic variations (Fig. 104). Feeding meat, 



