ABDOMINAL VISCERA 305 



the thorax. To see it the liver should be pressed 

 back. 



12. The peritoneum is a glistening membrane which lines 



the abdominal cavity. The mesentery is a double 

 layer of peritoneum, reflected from the dorsal wall 

 of the abdomen, which supports and encloses at its 

 margin the alimentary canal : between its two layers 

 the vessels and nerves pass to and from the various 

 organs. The omentum is a special fold of perito- 

 neum, extending backwards from the stomach and 

 loaded with fat. 



13. The cceliac ganglia are a pair of closely apposed 



pinkish bodies situated in the mesentery, near its 

 dorsal margin and opposite the right adrenal body. 

 They receive right and left splanchnic nerves from 

 the main sympathetic trunks of the thorax, and 

 send numerous branches to the alimentary canal. 



IV. DISSECTION OF THE DIGESTIVE SYSTEM. 



In this section the abdominal portion of the digestive 

 system will alone be considered : the buccal cavity and 

 pharynx have already been dissected ; and the oasophagus will 

 be described with the neck and thorax. 



A. External Characters of the Digestive System. 



1. The stomach. 



Expose the stomach fully, by turning the liver forwards, 

 and the intestine over to the animal's left. 



The stomach is much dilated at its left or cardiac 

 end ; narrower towards the right or pyloric end ; 

 and markedly curved, the concavity being directed 

 forwards. Near the left end of its anterior border is 

 the cardia, or opening of the oesophagus ; and from 

 the thick-walled pyloric end a small aperture, the 

 pylorus, leads to the duodenum. 



2. The duodenum, or first portion of the intestine, runs 



from the pylorus along the right side of the ab- 



x 



