THE INTESTINES 



249 



soup and to which the name chyme is given forms between 

 this mass of food and the stomach wall. The object of 

 the movements of the stomach is in part to work this 

 fluid towards the pylorus. Constrictions form round the 

 stomach and each constriction moves towards the pylorus, 

 and ultimately reaches it. After a time the pylorus, which 

 has hitherto been closed, opens on the arrival of one of 

 these waves and some chyme is passed into the intestine. 



Fig. 78. 



a, the stomach, emptj' ; b, shortly after a meal, showing peristaltic 

 constrictions ; c, full. 



The pylorus then closes and remains closed till the chyme 

 in the intestine loses its acid reaction and becomes 

 alkaline as we shall see later is the case (p. 263). In 

 this way the larger part of the chyme is allowed to 

 enter the duodenum ; but a portion of the fluid (con- 

 sisting of a little fat together with some sugar may 

 be at once absorbed, making its way, by imbibi- 

 tion, through the walls of the delicate and numerous 

 vessels of the stomach into the current of the blood, 

 which is rushing through the gastric veins to the portal 

 vein. 

 11. The General Arrangemeiit and Stmcture of the 



