132 



BIOLOGY AND HUMAN LIFE 



passes directly into the 

 gullet, or esophagus. In 

 the wall of the gullet is a 

 series of muscular rings 

 which contract one after 

 another, carrying the food 

 toward the stomach. If 

 you watch a horse drink- 

 ing water from a pond or 

 from a pail on the ground, 

 you can see him swallow 

 up ; and you can see one 

 wave of contraction after 

 another pass along the 

 gullet, from the head to 

 the trunk.- 



110. The stomach. The 

 fermentation started in 

 the mouth continues in 

 the mass of food until it 

 gets into the stomach. 

 Here it is stopped when 

 the acid, or sour, stomach 

 juice comes in contact 

 with the saliva. The swal- 

 lowed food is thoroughly 

 mixed with the gastric, or 

 stomach, juice by the ac- 

 tion of the muscles in 

 the stomach wall. These 

 muscles run in different 

 directions ; by their con- 

 tractions the contents be- 

 come thoroughly churned. 



The wall of the stomach also contains the glands in which the 



digestive fluids are produced (see Fig. 76). 



Fig. 74. The digestive organs in man 



a, entrance to mouth; b, the pharynx — a sort 

 of vestibule with seven passages leading out of 

 it, two to the nostrils, one to the mouth, one to 

 the gullet, one to the windpipe, and one to each 

 ear (the Eustachian tubes, see Fig. 115); c, 

 the gullet, or esophagus; d, the stomach; e, the 

 pylorus, opening from the stomach to the small 

 intestine; /, the liver; g, the gall bladder; //, 

 duct from the gall bladder and the liver to the 

 small intestine; i, duct from the pancreas to the 

 small intestine; ;', small intestine; k, large in- 

 testine; I, vermiform appendix; m, rectum; n, 

 the diaphragm, separating the chest cavity from 

 the abdominal cavity; 0, the pancreas. The ar- 

 rows indicate the course taken by food 



