250 Descriptive Zoology. 



joint is not a regular hinge joint, such as we find in a cat, 

 which allows of little more motion than a door hinge. 

 The rounded knob at the upper end of each jawbone fits 

 into a groove which runs front-and-back, thus allowing the 

 jaw to be moved forward and back. If one watches a 

 rabbit chewing, he will see that this motion is character- 

 istic in place of the more decidedly lateral movement seen 

 when a cow is ruminating. The ridges of the upper and 

 lower molars, therefore, are drawn back and forth over 

 each other, thus effectively grinding the food. 



The Process of Digestion. There are four pairs of 

 salivary glands on each side of the head, which pour their 

 secretions into the mouth to aid in digestion. At the base 

 of the tongue is the epiglottis, a cartilaginous cover which 

 turns down over the opening into the windpipe when the 

 food passes over it on the way to the stomach. The gullet 

 extends through the thorax, piercing the diaphragm, and 

 enters the large stomach, which lies back of the diaphragm, 

 partly separated from it by the liver. On the liver is the 

 bile sac, from which the bile is poured into the first part 

 of the intestine, called the duodenum. The long, coiled 

 small intestine finally joins the large intestine, and at their 

 junction is a long, blind tube, or sac, the cecum. Near the 

 stomach is the pale pancreas, which empties its secretion 

 by a duct into the duodenum. 



Since the rabbit eats food that is relatively poor in nour- 

 ishing material, it is obliged to eat a large amount ; and as 

 vegetable food, especially with a good deal of cellulose, is 

 difficult of digestion, we should expect to find the digestive 

 tube both long and capacious, and this is the case. The 

 intestine is about ten times the length of the rabbit's body. 

 While the rabbit sits in concealment during the day, the 

 slow process of digestion is going on. 



