1 68 VERTEBRATE ZOOLOGY 



Observe the organs in the body cavity, but without disturbing 

 them; note the compactness with which they are placed. The 

 body cavity may be subdivided into two spaces, — the large ab- 

 dominal cavity, which is lined with the glistening peritoneum and 

 contains most of the viscera, and the pericardial chamber, which 

 is formed by the pericardium and contains only the heart. 



Observe the pericardium surrounding the heart. Back of it is 

 the large two-lobed liver. Beneath and back of the left lobe is 

 the gizzard. Covering the organs back of the liver is a membrane 

 filled with fat. This is the great omentum,— the mesentery of 

 the stomach, of which the falciform ligament is the anterior 

 portion. Cut around the border of the great omentum and remove 

 it; observe the coils of the small intestine, which fill the hinder 

 part of the cavity, and the narrow pancreas which lies between 

 two of its folds. 



Exercise 5. Draw a semidiagrammatic sketch of the opened body 

 cavity within an outline of the bird, and of the organs as they lie 

 in it ; carefully label all. 



The Digestive System. This consists of the mouth, pharynx, 

 oesophagus, glandular stomach, gizzard, small intestine, large 

 intestine, cloaca, salivary glands, liver, and pancreas. 



Lift up the liver and find where the small intestine leaves the 

 gizzard, in the middle of its medial surface. The anterior portion 

 of the small intestine forms a great loop, called the duodenum, 

 within the bend of which lies the pancreas. Lift up this loop and 

 note its extent. Follow the intestine to its hinder end, so far as 

 this is possible without cutting any of the organs except the walls 

 of the air sacs. Note the mesentery of the intestine which joins 

 its coils with the dorsal body wall ; note also the large veins and 

 arteries which lie in it. 



Turn the liver forward and, without cutting anything, study its 

 dorsal surface. The large portal vein will be seen, which enters 

 the liver near the median plane and at once gives off branches 

 to its lobes. Near this point are the two bile ducts, which carry 

 bile from the liver to the intestine. Find them. The longer 

 duct is a large tube, about an inch in length, which runs from 



