176 TEXT-BOOK OF PHYSIOLOGY. 



mode of preparation and the time required for the digestion of different 

 foods are exhibited : 



TABLE SHOWING THE DIGESTIBILITY OF VARIOUS ARTICLES OF FOOD. 



Hours. Minutes. Hours. Minutes. 



Eggs, whipped i 20 Soup, barley, boiled I 30 



Eggs, soft boiled 3 . . Soup, bean, boiled 3 



Eggs, hard boiled 3 30 Soup, chicken, boiled 3 



Oysters, raw 2 55 Soup, mutton, boiled 3 30 



Oysters, stewed 3 30 Sausage 3 20 



Lamb, broiled 2 30 Green corn, boiled 3 45 



Veal, broiled 4 . . Beans, boiled 2 30 



Pork, roasted 5 15 Potatoes, roasted 2 30 



Beefsteak, broiled 3 . . Potatoes, boiled 3 30 



Turkey, roasted 2 25 Cabbage, boiled 4 30 



Chicken, boiled 4 . . Turnips, boiled 3 30 



Chicken, fricasseed 2 45 Beets, boiled 3 45 



Duck, roasted 4 . . Parsnips, boiled 2 30 



The time required for the stomach to discharge any given article of 

 food has been shown by Cannon to depend partly on its chemic composition 

 and partly on its capacity for absorbing hydrochloric acid. From an 

 examination of the stomach and duodenum of the cat by means of Rontgen 

 rays and the fluoroscopic screen, after the administration of equal quantities, 

 25 c.c., of pure protein, fat, and carbohydrate, mixed with 5 grams of bismuth, 

 it became possible to determine the rate at which they left the stomach from 

 the length of the food masses in the duodenum and small intestine as indi- 

 cated by the shadows on the screen, at intervals of half an hour or longer. 

 The duration of the observations extended over a period of seven hours. 



When a pure protein, e.g., boiled beef free from fat, boiled haddock, or 

 the white meat of fowls is administered, foods which not only excite the 

 flow of gastric juice but readily absorb hydrochloric acid, the pylorus remains 

 closed for some time, scarcely any protein leaving the stomach during the first 

 half hour. Shortly after this when free hydrochloric acid makes its appear- 

 ance, the signal for the relaxation of the sphincter, the pylorus opens from 

 time to time and the passage of the protein into the duodenum begins and 

 gradually increases in rapidity until the maximum speed is attained, about 

 two hours after ingestion; from this time on, the speed of discharge gradually 

 diminishes until the end of the observation period. 



When fat, e.g., beef, mutton, or pork fat, is administered, they remain 

 in the stomach for some time and when they begin to leave, the rate of dis- 

 charge is so slow that they are digested and absorbed almost as fast as 

 discharged and hence seldom accumulate in the small intestine. These 

 compounds delay the secretion of gastric juice and therefore free hydrochloric 

 acid, the presence of which appears to be necessary for the relaxation of the 

 pyloric sphincter. When carbohydrates, e.g., starch paste, boiled rice, 

 boiled mashed potatoes, are administered their discharge begins shortly 

 after their entrance into the stomach ; they pass out rapidly, the velocity of 

 discharge reaching its maximum at the end of two hours, after which the 

 speed declines to the end of the observation period. The reason for the 

 early and rapid discharge is to be found in the fact that while the carbo- 

 hydrates excite the secretion of gastric juice they do not absorb the hydro- 

 chloric acid to any appreciable extent. A combination of equal quantities 



