PIGEON. 117 - 



3. The blood-vessels (be careful not to injure 



them). 



Slit the trachea transversely in the middle neck- 

 region and ligature the neck through the slit 

 and under (i.e., not including) the skin. Cut 

 .off the head above the ligature. Open the 

 brain-cavity by shaving off the bone, exposing 

 cerebrum and cerebellum, and put the head at 

 once into formic aldehyde solution (as for 

 frog's brain). 



JtfaJce a transverse cut through the body-wall 

 of the abdomen posterior to the pectoral 

 muscles. 



4. Note the air-sacs. How many are visible ? 



5. Observe the intestine and the fat in the mes- 



entery. 



6. Find the falciform ligament, a thin membrane 



with a large vein, in the median vertical 



plane and attached to the middle line of 



the sternum beneath the keel. 

 7. Insert a tube into the trachea and bloiv up the 



structures connected with it. (Compare II. 



4., above.) 



Holding the sternum with the right hand press 

 gently with the left thumb upon the part of 

 the crop that lies against the pectoral muscles 

 and thus separate the crop from the anterior 

 border of the sternum. 

 Note beneath the crop : 



