CIRCUMSTANCES WHICH INFLUENCE STOMACH-DIGESTION. 251 



Most of the facts recorded in the ahove table are in accordance with the popular ideas 

 regarding the digestibility of various articles, based upon general experience. With these 

 as a guide, the following may be taken as a summary of what is known regarding the 

 facility with which different articles are disposed of in the stomach : 



Milk is one of the articles digested in the stomach with greatest ease. Its highly-nu- 

 tritive properties and the variety of principles which it contains render it extremely valu- 

 able as an article of diet, particularly when the digestive 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. 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, veni- 

 son, lamb, beef, and mutton are easily digested, while veal and fat roast-pork are digested 

 with difficulty. Soups are generally very easily digested. The animal substances which 

 were found to be digested most rapidly, however, were tripe, pigs' feet, and brains. 

 Vegetable articles are represented in the table as being 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 digestion of 

 the ordinary meats. 



Circumstances which influence Stomach-Digestion. 



The various conditions which influence stomach-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, if ever, that temperature has any 

 influence ; for the temperature of the stomach in health does not present variations suffi- 

 cient to have any marked effect upon digestion. Experiments in artificial digestion have 

 shown that alimentary substances are most vigorously acted upon when maintained in 

 contact with gastric juice at or near 100 Fahr. 



As a rule, gentle exercise, conjoined with repose or agreeable and tranquil occupation 

 of the mind, is more favorable to digestion than absolute rest. Violent exercise or severe 

 mental or physical exertion is always undesirable immediately after the ingestion of a 

 large quantity of food, and, as a matter of common experience, has been found to retard 

 digestion. Sleep, if light and taken in the sitting posture, seems almost necessary to easy 

 digestion in many persons ; but it should be continued for only a few minutes. A pro- 

 longed and deep sleep immediately after a full meal is almost always injurious, and ex- 

 traordinary heaviness at that time is generally an indication that too much food has been 

 taken. 



The effects of sudden and considerable loss of blood upon stomach-digestion are very 

 marked. After a full meal, the whole alimentary tract is deeply congested, and this con- 

 dition is undoubtedly necessary to the secretion, in proper quantity, of the various diges- 

 tive fluids. When the entire quantity of blood in the economy is greatly diminished from 

 any cause, there is a difficulty in supplying the amount of gastric juice necessary for a 

 very full meal, and disorders of digestion are apt to occur, especially 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 condition, although the system constantly craves nourish- 

 ment and the appetite is frequently 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, ordina- 

 rily, in old age, the digestive processes are carried on with more vigor and regularity 

 than the other vegetative functions, such as general assimilation, circulation, or respiration. 



