THE PIGEON. 107 



12. Do you find a diaphragm? 



13. Find the gizzard. Describe it. 



14. The part of the intestine nearest the gizzard is 

 the duodenum. 



15. Iq a long loop formed by the duodenum, find 

 the pancreas. 



16. Trace the intestine, tearing it loose from a 

 thin, transparent membrane (mesentery) that holds it 

 in place. 



17. Find two very short side branches (caeca) near 

 the end. In some kinds of birds the caeca are very 

 long. 



18. Find the cloaca, which is the widened termi- 

 nation of the intestine. 



19. Find the glandular stomach, in front of the 

 gizzard. See the oesophagus leading into it. 



20. Remove the glandular stomach, gizzard, and 

 intestine. Examine the gizzard. Open it. Observe 

 its contents and its lining. Of what use is the giz- 

 zard? 



21. See the liver. How many lobes? Has it a 

 gall bladder? 



22. Can you find the spleen? This is a small red 

 body attached to the right side of the crop. 



The Circulation. 



1. Find the heart. Notice the thin sac (pericardi- 

 um) enclosing it. 



2. Find the large artery, the aorta, running for- 

 ward from the heart. What branches does the aorta 

 give off, and where does each go? Toward which 

 side of the pigeon does the aorta turn after leaving 

 the heart? 



3. The left subclavian is the name of the artery 

 which goes to the left wing. The left carotid is the 

 one which goes to the head. It branches off from the 



