98 DIGESTION. 



already referred to, it has been ascertained that, at the end 

 of two hours after a meal, the stomach is ordinarily empty. 

 How much time is needed to complete the digestion of 

 food, within the small intestines, is not certain ; but, from 

 what we have learned respecting their functions, it must 

 be evident that it largely depends upon the amount of 

 starch and fat which the food contains. 



41. In addition to the preparations which the food 

 undergoes in cooking, which we have already considered, 

 many circumstances affect the duration of digestion ; such 

 as the quality, quantity, and temperature of the food ; the 

 condition of the mind and body ; sleep, exercise, and habit. 

 Fresh food, except new bread and the flesh of animals 

 recently slain, is more rapidly digested than that which is 

 stale ; and animal food more rapidly than that from the 

 vegetable kingdom. 



42. Food should not be taken in too concentrated a form, 

 the action of the stomach being favored when it is some- 

 what bulky ; but a large quantity in the stomach often re- 

 tards digestion. If the white of one egg be given to a dog, 

 it will be digested in an hour, but if the white of eight 

 eggs be given it will not disappear in four hours. A wine- 

 glassful of ice-water causes the temperature of the stomach 

 to fall thirty degrees ; and it requires a half-hour before it 

 will recover its natural warmth about a hundred degrees 

 at which the operations of digestion are best conducted. 

 A variety of articles, if not too large in amount, is more 

 easily disposed of than a meal made of a single article; 

 although a single indigestible article may interfere with 

 the reduction of articles that are easily digested. 



43. Strong emotion, whether of excitement or depression, 

 checks digestion, as do also a bad temper, anxiety, long 

 fasting, and bodily fatigue. The majority of these condi- 



41. Circumstances affecting duration of digestion ? Fresh food ? 



42. Food in concentrated form ? A large quantity of food? Experiment on 

 the dog ? Ice-water ? Variety of articles ? 



43. Strong emotion ? The tongue of the patient ? 



