32 PHYSIOLOGY AND HEALTH. 



53. This ever-watchful door-keeper has a special duty to 

 perform. Its business is to retain the food in the stomach 

 until it be digested, and then to let it pass onward. For this 

 purpose, it seems to be endowed with a kind of intelligence, 

 by which it discriminates between the crude and the dis- 

 solved matters that present themselves to it, and with a sort 

 of discretionary power, by which it opens and lets the finish- 

 ed chyme pass out, but closes and prevents the passage of 

 that which is not so reduced to a pulp. While the stomach 

 is empty, it may be relaxed, and the doorway left open ; but 

 as soon as any food is swallowed, it shuts the door, and holds 

 it tight until this food be digested. As fast as any portion 

 oi the food is turned into chyme, it is carried by the motions 

 of the stomach to the right end ; then the valve relaxes, the 

 door opens, and the digested food passes out. But, with a 

 quick perception of the differences of condition of the food, 

 it closes the moment the digested portion has gone out, and 

 the undigested portions offer themselves. 



54. We, sometimes eat food of a kind which the stomach 

 cannot digest. We sometimes eat more at a meal than the 

 gastric juice can dissolve. In these cases, the stomach di- 

 gests what it can, and makes great effort to digest the rest. 

 When it becomes wearied with its unsuccessful efforts, it en- 

 deavors to relieve itself of the indigestible portion by thrust- 

 ing it through the aperture at the right end into the intesti- 

 nal canal. But as this crude matter is neither digested nor 

 prepared for the action of the next organ, the valve refuses 

 to open and let it go through. Again this is sent back, and 

 again the stomach makes its fruitless attempts to digest it ; 

 and thus failing a third and a fourth time, presents it to this 

 doorway for passage. This is refused over and over ; the 

 valve closes with a greater and even more painful force ; 

 until, at last, fatigued with the resistance, it yields to the im- 

 portunity of the stomach, and permits the undigested and 

 indigestible matter to go through. While this struggle is 

 going on, we feel a distressing oppression about the ri^ht 

 side, just below the short ribs. This usually happens within 



