58 THE VETERINARY SCIENCE 



and under the lower jaw and up into the cheek muscles, 

 entering the mouth opposite the fourth molar tooth. These 

 tubes, known as steno's ducts, are about as large as straws 

 and convey the saliva from the gland into the mouth. The 

 next pair are situated under the pair first mentioned. Their 

 tubes enter into the bottom part of the mouth. The third 

 pair are siuated under the tongue, one on each side. They 

 pour their secretion into the mouth by several small openings 

 near the front under the tongue. This can be seen by exam- 

 ining closely. This is a very important fluid in connection 

 with the digesting of the food. 



3. The Gullet is a cavity situated just behind the mouth. 

 It is chiefly made up of muscles which perform the act of 

 swallowing the food. It is lined with the continuation of the 

 mucous membrane of the mouth. 



4. The Oesophagus, or the continuation of the gullet, is 

 a tube extending from the gullet to the stomach, and is used 

 to carry the food to that organ. It is made up of two coats, 

 the muscular and the mucous. The former contains fibres 

 which, when once the food enters the tube, contract behind 

 it, forcing it along to the stomach. Its lining is a continu- 

 ation of the mucous membrane of the mouth and gullet. In 

 tracing the tube down the neck from the gullet, note that it 

 passes down the left side of the neck, entering the thoracic, 

 or chest cavity, between the lungs over the heart through 

 the large muscular curtain known as the diaphragm, then 

 enters the stomach an inch or two after passing the dia- 

 phragm. 



5. The Stomach. — This organ is very small in the horse 

 in comparison with that of the ox. It holds only about four 

 gallons, and is situated just behind the curtain which sep- 

 arates it from the lungs. It lies mostly to the left side. The 

 walls of the stomach are composed of three coats. That on 

 the outside is called the serous membrane, a name applied to 

 membranes which line closed cavities, such as the abdominal, 

 or belly cavity. The inside lining is a continuation of the 

 mucous membrane lining the organs before mentioned. The 

 lining in the left part of the stomach or the part where the 

 food is prepared for digestion is the same color as that of 

 the mouth. The lining of the right part of the stomach, 

 which is the true digestive part, is of a deep red color re- 

 sembling velvet, and when placed under a microscope has the 



