DIGESTIVE SYSTEM, 435 



1. The (esophagus commences at the hinder part of the 



buccal cavity, and runs back through the neck and 

 thorax to the stomach. In the neck it is thin-walled, 

 and dilates behind to form a large bilobed sac, the 

 crop. In the thorax the oesophagus lies between the 

 lungs and dorsal to the heart, and it is here much 

 narrower, and has thick muscular walls. 



2. The stomach, or proventriculus, lies dorsal to the left 



lobe of the liver : it is rather wider than the 

 oesophagus, and has thick glandular walls, in which 

 the gastric juice is secreted. Attached to the right 

 side of the proventriculus is a small red body, the 

 spleen. 



3. The gizzard is a large hard body, somewhat flattened 



laterally, and with very thick muscular walls, the 

 muscular fibres radiating outwards from a bluish 

 tendon in the centre of each lateral surface. It 

 forms a powerful mill for grinding the food. 



The proventriculus opens into the gizzard at its 

 dorsal border, and rather to the left side ; while the 

 duodenum leaves it a little to the right side of the 

 same spot. 



Split open the gizzard along its ventral edge, and loash 

 out the contents. Note the following points : — 



a. The great thickness of the muscular walls. 



b. The thick cuticular lining to the cavity of the 



gizzard, in which small stones are usually found 

 imbedded. 

 C. The openings of the proventriculus and duodenum, 

 placed side by side at the dorsal edge. 



4. The duodenum is a U-shaped loop, formed by the first 



part of the intestine. The pancreas lies between the 

 two limbs of the loop, the further dissection of which 

 will be postponed until the liver and parncreas are 

 examined. 



5. The small intestine is a much-convoluted tube, of nearly 



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