84 NUTRITIONAL PHYSIOLOGY 



attention is decidedly less than when it is eaten in the 

 natural way, and when the psychic and chemical agencies 

 are combined. 



It is"unfortunate that our knowledge of this matter has 

 been drawn so largely from a carnivorous animal. Meat 

 might be expected to stimulate the stomach of the dog 

 more surely than other foods. How far the secretion may 

 be elicited by placing other compounds in the stomach is 

 imperfectly known. Milk is credited with some power to 

 call it forth, but its superiority to water seems doubtful. 

 Alcohol is said to have a positive action of the same kind. 



It is claimed that the dextrins, the intermediate bodies 

 produced in salivary digestion of starch, have the property 

 of starting the gastric flow. If this is true it is interesting 

 as establishing a connecting link between the two successive 

 processes, and making it apparent how one may tend to 

 insure the setting in of the other in due time. A link of 

 this sort exists between gastric digestion and pancreatic 

 secretion, as we shall have occasion to point out. The 

 condiments, such as pepper and spices, have a reputation 

 for stimulating the discharge of gastric juice, and un- 

 doubtedly do so when they favorably affect the flavor of 

 the food. They are known to increase the blood flow in the 

 lining of the stomach, which would perhaps help to con- 

 tinue the secretion process when once under way, but 

 whether they can actually initiate it apart from their 

 psychic effect remains uncertain. 



When gastric secretion is well started there is provision 

 for its maintenance as long as the stomach contains food. 

 It appears that some of the early products of digestion 

 act after the manner of the extractive substances of meat 

 and excite the glands to continued activity. The acid 

 itself has been found to be absorbed by the cells lining the 

 antrum and to set in motion a train of events leading to 

 the same result. This form of stimulation will evidently 

 cease only with the departure of the last portions of the 

 acid chyme. The flow of gastric juice is retarded by fats 

 and by alkaline mixtures. 



