66 PHYSIOLOGY AND TEMPERANCE. 



pharynx. When it reaches a certain point the involuntary 

 muscles, first of the pharynx, then of the gullet, begin to act, 

 and by alternately relaxing and contracting, the food is 

 passed on into the stomach. This motion may be seen when 

 a horse is drinking. 



14. The CEsophagUS. The gullet is a tube about nine 

 inches in length, extending from the pharynx to the stomach. 

 This tube is made of three coats the lining or mucous mem- 

 brane, a middle coat of connective tissue, and the outer mus- 

 cular coat, consisting of two layers. The fibres of muscle lie 

 lengthwise in the outer layer, and in the inner layer they 

 circle around the tube. As the muscular rings .contract, one 

 after another, they force the food towards the stomach. 



15. The Stomach. The chief organ of digestion is situ- 

 ated within the abdominal cavity, immediately beneath the 

 diaphragm. It is conical in shape, something like a pear, 

 with the small end turned a good deal to one side. It has 

 also been compared to a bag-pipe. It is placed across the 

 body, the large end to the left. The gullet enters the stomach 

 near this end, on the upper surface. This is called the car- 

 diac opening, because it is near the heart. The small end to 

 the right is turned upward, narrowed for a little distance, 

 and is continuous with the intestine. The opening at this 

 end is called the pylorus, or gate guardian. The healthy 

 stomach of the adult will contain about three pints to two 

 quarts of liquid. 



The stomach has four coats ; three similar to those of the 

 gullet, and an outside coat of smooth serous membrane, which 

 prevents friction from the movements of the stomach. The 

 serous membrane, after covering the stomach, passes to the 

 inner wall of the body, and holds this organ in place. The 

 muscular coat has two layers, one with its fibres lengthwise, 

 the other running round the organ, and at the large end an 

 additional layer of oblique fibres. The united action of these 



