I7 8 TEXT-BOOK OF PHYSIOLOGY 



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. 



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 3 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 



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 pota- 

 toes 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 carbohydrates excite the secretion of 

 gastric juice they do not absorb the hydrochloric acid to any appreciable 

 extent. A combination of equal quantities of protein and carbohydrate 

 varies the rate of discharge of each separately. Thus under these circum- 

 stances the carbohydrates are not discharged so rapidly nor are the proteins 

 detained so long as usual; a combination of fat with either protein or carbo- 

 hydrate delays the time of discharge of both. From these facts it may be 

 inferred that the time any given food remains in the stomach will depend on its 

 chemic composition or the relative amounts of its contained protein, fat, 

 and carbohydrate principles. 



