FOOD AND DIGESTION 



357 



then, by X-rays, getting the outline of the contents of the small 

 intestine at different periods. Carbohydrates were found to 

 pass on most rapidly and fats most slowly (fig. 156). Unless the 

 contents of the stomach are very fluid these movements do not 

 produce a very great mixing of the food taken (fig. 158). 



Nervous Mechanism of Gastric Movements. Even after the 

 section of all the gastric nerves, movements of the stomach may 

 be observed, but the mechanism of these movements has not 

 been fully studied. The action of the vagus and sympathetic 

 fibres is complicated, and their influence on the wall of the 



FIG. 158. Stomach of a Dog fed successively with three different foods 

 to show the absence of mixing. (ScHEUNKET.) 



stomach and the sphincters requires . further investigation. 

 Speaking generally, the vagus seems to increase the move- 

 ments, while the sympathetic fibres check them. The vagus 

 when stimulated generally causes inhibition of the cardiac 

 sphincter and contraction of the pylorus, but the result is not 

 constant. 



Absorption from the Stomach 



By ligation of the pyloric end, it has been found that the 

 stomach plays a very small part in the absorption of food. 

 Its chief function is to act as a reservoir. 



Probably the antiseptic action of its secretion is of considerable 



