340 THE HUMAN BODY. 



in great part gradually dialyzed into the blood and lympha- 

 tic vessels of the gastric mncons membrane and carried off, 

 along with other dissolved dialyzable bodies, such as salts 

 and sugar. After the food has remained in the stomach 

 some time (one and a half to two hours) the chyme begins 

 to be passed on into the intestine in successive portions. 

 The pyloric sphincter relaxes at intervals, and the rest 

 of the stomach, contracting at the same moment, injects a 

 quantity of chyme into the duodenum ; this is repeated 

 frequently, the larger undigested fragments being at first 

 unable to pass the orifice. At the end of about three or 

 four hours after a meal the stomach is again quite emptied, 

 the pyloric sphincter finally relaxing to a greater extent 

 and allowing any larger indigestible masses, which the gas- 

 tric juice cannot break down, to be squeezed into the intes- 

 tine. 



The Chyle. When the chyme passes into the duodenum 

 it finds preparation made for it. The pancreas is in reflex 

 connection with the stomach, and its nerves cause it to 

 commence secreting as soon as food enters the latter; hence 

 a quantity of its secretion is already accumulated in the 

 intestine when food enters. The gall-bladder is distended 

 with bile, secreted since the last meal; this passing down 

 the hepatic duct has been turned buck up the cystic duct 

 (Dc, Fig. 100*) on account of the closure of the common 

 bile-duct. The acid chyme, stimulating nerve-endings in 

 the duodenal mucous membrane, causes reflex contrac- 

 tion of the muscular coat of the gall-bladder, and a relaxa- 

 tion of the orifice of the common bile-duct; and so a gush 

 of bile is poured out on the chyme. From this time on, 

 both liver and pancreas continue secreting actively for 

 some hours, and pour their products into the intestine. 

 The glands of Brunner and the crypts of Lieberkuhn are 

 also set at work, but concerning their physiology we know 

 yery little. All of these secretions are alkaline, and they 

 suffice very soon to more than neutralize the acidity of the 

 gastric juice, and to convert the acid chyme into alka- 

 line chyle, which, after an ordinary meal, will contain a 

 great variety of things: mucus derived from 1 the alimen- 



* P. 324. 



