1010 



DIGESTION 



not only upon the force and frequency of the peristalsis, but also upon 

 the character of the food ingested. Thus, Cannon 1 has shown that the 

 carbohydrates begin to leave the stomach soon after their ingestion 

 and require only about one-half the time necessary for the complete 

 digestion of the proteins. Fats, when ingested alone, remain in the 

 stomach for a long time. Quite similarly, the simultaneous intake of 

 different foodstuffs markedly interferes with the evacuation of those 

 which otherwise escape very rapidly. Accordingly, if protein is fed 

 before the carbohydrates, the latter are retarded, whereas fat tends to 

 hinder the progress of both. In general, however, it may be said that 

 a moderate meal, consisting of all foodstuffs, should be out of the 

 stomach after four hours, and its ejection should begin within an hour 

 after its ingestion. The first portion of this chyme, therefore, may 

 have arrived at the iliocecal valve before its last portion has trav- 



FIQ. 514. SHADOWS OF THE HUMAN STOMACH OBTAINED WITH THE AID OF THE 



RAYS 15 MINUTES, 1 HOUB, and 4 HOURS AFTEH INGESTION OF THE BISMUTH MEAL. 



ersed the pyloric orifice. These facts imply that a stomach which 

 still contains material at the end of five hours, either lacks tonicity or 

 is unable to discharge on account of some obstruction, possibly a 

 pyloric stricture. Water and isotonic salt solutions are passed into the 

 duodenum very rapidly. Hypertonic solutions and other drinks, 

 such as coffee and tea, require a somewhat longer time. 2 As far as 

 the intake of moderately large quantities of water during meals is 

 concerned it may be stated in general that it serves the purpose of 

 hastening the formation of chyme, although it may also tend to dilute 

 the gastric juice to such an extent that its digestive power is unduly 

 diminished. In view of the results of Carlson, however, showing that 

 very abundant amounts of hydrochloric acid and pepsin are held in 

 reserve, the latter possibility is rather remote, and should be taken 

 into consideration only when a hypochlorhydria is present. 



Gastro-enterostomy. The operation of gastro-enterostomy con- 

 sists in uniting the lower duodenum directly with the stomach distally 

 to its sphincter antri pylori. Physiologically, it is of importance to 



1 Am. Jour, of Physiol., xii, 1904, 387. 



2 Arch, fur Exp. Path, und Pharm., lii, 1905, 370, and Muller, Zeitschr. fur 

 diat. und phys. Ther., viii, 1905. 



