278 VERTEBRATE ZOOLOGY 



The small intestine, in turn, is divided into three parts: the 

 duodenum, the jejunum, and the ileum. The duodenum is that 

 portion immediately posterior to the stomach, which it joins at 

 the pylorus ; it forms a very long U-shaped loop. In the mesentery 

 joining the two limbs of this loop lies the diffuse pancreas, in the 

 form of more or less scattered pinkish, glandular bodies, many of 

 them following the courses of the blood vessels. The pancreatic 

 duct opens into the duodenum about an inch and a half beyond 

 the bend in the ascending limb. 



The two posterior divisions of the small intestine, the jejunum 

 and the ileum, are not separated from the duodenum or from each 

 other by definite boundaries ; at its posterior end, where it joins 

 the large intestine, the ileum is enlarged and forms a small globular 

 sac called the sacculus rotundus. 



The large intestine is made up of the caecum, the colon, and the 

 rectum. The caecum, or blind gut, is a very large, thick, thin- 

 walled sac, which extends in a spiral form from the sacculus 

 rotundus ; its surface is marked externally by a spiral constriction 

 which shows the line of attachment of a spiral fold within it. The 

 distal portion of the blind gut tapers off, and terminates in the 

 thick-walled appendix vermiformis. The large size of the caecum 

 is undoubtedly correlated with the herbivorous habits of rabbits ; 

 in carnivorous animals the caecum is very short, and no appendix 

 is present. The colon is a long tube, which takes its rise at the 

 proximal end of the caecum, very near the sacculus rotundus, 

 and in which an ascending, a short transverse, and a descending 

 limb can be distinguished ; the colon is characterized by three 

 longitudinal muscle bands, between which are rows of conspicuous 

 sacculations, which disappear toward its hinder end. The rectum 

 is a long, narrow tube which contains small, rounded masses of 

 fecal matter ; it passes through the pelvis to the anus. 



Study the form and position of the liver, but without cutting 

 any of its connections. It is composed of two main lobes, between 

 which the falciform ligament extends to the diaphragm and the 

 ventral abdominal wall ; each of the main lobes is subdivided into 

 two minor lobules. Turn the hinder portion of the liver forward 

 and pin it there. The gall bladder will be seen on the surface of 



