ABSORPTION FROM STOMACH. 215 



assisted by the churning motion of the stomach caused by 

 the action of the muscular coat. The food is thus gradually 

 reduced to a pulpy mass called Chyme. During the first part 

 of digestion in the stomach, the thick ring of circular fibers 

 called the Pylorus (gatekeeper) around the opening of the 

 stomach into the intestine, keeps the passage nearly closed, 

 leaving a small orifice for liquids only. 



Such rings of muscular fibers, guarding openings, are 

 called Sphincter Muscles. There is a similar one at the anal 

 opening. 



But as the food is reduced to the proper condition the 

 pyloric muscles relax, and allow the chyme to pass into the 

 intestine. And at last any indigestible substances are allowed 

 to pass (usually). 



The time required for the complete digestion of any ordi- 

 nary meal is from three to four hours ; though this may be 

 much longer if very indigestible substances have been eaten, 

 or if the condition of the body or mind is such as to retard 

 the process of digestion. 



Some parts of the food that are already digested, or such 

 matters as are soluble, e.g., water containing sugar, peptone, 

 salts, etc., may be absorbed immediately through the walls of 

 the mouth and stomach into the blood capillaries. 



Recent experiments show that the amount of absorption 

 from the stomach is much less than was formerly supposed ; 

 water, for instance, " when taken alone, is practically not ab- 

 sorbed at all in the stomach. As soon as water is introduced 

 into the stomach, it begins to pass out into the intestine, be* 

 ing forced out in a series of spurts by the contractions of the 

 stomach." 



The rest of the food, now called chyme, is passed on into 

 the small intestine. It is acid, and in a liquid or semiliquid 

 condition. Chyme, as it enters the intestine, is a mixture of 



