CIRCUMSTANCES WHICH INFLUENCE STOMACH-DIGESTION. 283 



sleep immediately after a full meal is almost always inju- 

 rious, and extraordinary 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, tho 

 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 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 has been 

 taken. This is also true in inanition, when the quantity of 

 blood is greatly diminished. In this condition, although the 

 system constantly craves nourishment and the appetite is 

 frequently enormous, food should be taken in small quanti- 

 ties 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, the digestive processes are carried on with more vigor 

 and regularity than the other vegetative functions, such as 

 general assimilation, circulation, or respiration. 



Influence of the Nervous System on the Stomach. It is 

 well known that mental emotions frequently have a marked 

 influence on digestion ; and this, of course, can take place 

 only through the nervous system. Of the two nerves which 

 are distributed to the stomach, the pneumogastric has been 

 the more carefully studied, experiments upon the sympathetic 

 being difficult and unsatisfactory. Though the complete 

 history of the influence of the pneumogastric nerves upon 

 digestion belongs to the section on the nervous system, it 

 will be interesting in this connection to consider briefly some 

 of the facts which have been ascertained with regard to the 

 influence which these nerves exert upon the stomach. 



