ACTION OF THE GASTRIC JUICE. 229 



average time that food remains in the stomach after an ordinary meal may 

 be stated to be between two and four hours. 



Milk is one of the articles digested in the stomach with greatest ease. 

 Its highly nutritive properties and the variety of its nutritious constituents 

 render it very valuable as an article of diet, particularly when the digest- 

 ive powers are impaired and when it is important to supply the system 

 with considerable nutriment. Eggs are likewise highly nutritious and are 

 easily digested. Raw and soft-boiled eggs are more easily digested than 

 hard-boiled eggs. " Whipped " eggs are apparently disposed of with great 

 facility. As a rule the flesh of fish is more easily digested than that of the 

 warm-blooded animals. Oysters, especially when raw, are quite easy of 

 digestion. The flesh of mammals seems to be more easily digested than the 

 flesh of birds. Of the different kinds of meat, venison, lamb, beef and mut- 

 ton are easily digested, while veal and fat roast-pork are digested with diffi- 

 culty. Soups are generally very easily digested. The animal substances 

 which are digested most rapidly, however, are tripe, pigs' feet and brains. 

 Vegetable articles are digested in about the same time as ordinary animal 

 food ; but a great part of the digestion of these substances takes place in the 

 small intestine. Bread is digested in about the time required for the diges- 

 tion of the ordinary meats (Beaumont). 



Conditions which influence Gastric Digestion. The various conditions 

 which influence gastric digestion, except those which relate exclusively to 

 the character or the quantity of food, operate mainly by influencing the 

 quantity and quality of the gastric juice. It is seldom that temperature has 

 any influence, for the temperature of the stomach in health does not present 

 variations sufficient to have any marked effect upon digestion. 



As a rule, gentle exercise, with repose or agreeable and tranquil occupa- 

 tion of the mind, is more favorable to digestion than absolute rest. Violent 

 exercise or severe mental or physical exertion is always undesirable immedi- 

 ately after the ingestion of a large quantity of food, and as a matter of com- 

 mon experience, has been found to retard digestion. 



The effects of sudden and considerable loss of blood upon gastric di- 

 gestion are very marked. After a full meal, the whole alimentary tract 

 is deeply congested, and this condition is undoubtedly necessary to the 

 secretion, in proper quantity, of the various digestive fluids. When the 

 entire quantity of blood in the economy is greatly diminished from any 

 cause, there is difficulty in supplying the amount of gastric juice neces- 

 sary for a full meal, and disorders of digestion are likely to occur, es- 

 pecially if a large quantity of food have been taken. This is also true in 

 inanition, when the quantity of blood is greatly diminished. In this con- 

 dition, although the system constantly craves nourishment and the ap- 

 petite frequently is enormous, food should be taken in small quantities at a 

 time. 



As a rule children and young persons digest food which is adapted to 

 them more easily and in larger relative quantity than those in adult life or in 

 old age ; but ordinarily in old age digestion is carried on with more vigor 



