THE CONSTRUCTION OF THE HORSE 143 



The Digestive System 



The digestive system, plus the accessory organs, 

 comprises the tongue, the teeth, the sahvary glands, the 

 pharynx, the oesophagus, or gullet, the stomach, the 

 small and the large intestines, the liver, and the pancreas. 

 For a description of the teeth the reader is referred to 

 the chapter dealing with these structures, namely, " The 

 Age of the Horse." 



The tongue is a muscular structure covered by mucous 

 membrane and numerous papillae. Its functions are to 

 assist in maintaining food in' the mouth, to ensure its 

 thorough ensalivation, and to hand it to the back part 

 of the mouth, that is into the pharynx, from which it 

 subsequently passes along the oesophagus directly into 

 the stomach. The tongue of the horse is relatively large, 

 and is maintained in its position on the floor of the mouth 

 through the medium of the hyoid bone and connective 

 tissue. 



The salivary glands are placed beneath the tongue, and 

 also immediately behind the jaw. Their function is to 

 secrete a fluid — the saliva — which, as it intermingles with 

 the food, converts, through the medium of a ferment, 

 the insoluble starch into sugar. Digestion really begins 

 in the mouth. 



The oesophagus, or gullet, passes down the neck 

 immediately behind or at the side of the trachea, and after 

 entering in the diaphragm is continued into the stomach 

 to form the cardiac end of the latter. Only one half of 

 the stomach of the horse is functional as far as digestion 

 is concerned, owing to the fact that the lining of the gullet 

 is continued as part of the lining of the stomach, forming 

 the cuticular portion of the last named. 



The stomach of the horse is comparatively small, only 

 having a capacity of three or four gallons. It possesses 

 many features of anatomical interest to which it is not 

 necessary to allude. Its position in the abdominal cavity 



