186 AVES (the bird) 



B. Internal Morphology 



1. Carefully lift the abdominal wall, and, with the scissors, 

 slit it from the posterior edge of the sternum to the anus. 

 Now, make a transverse slit on each side along the posterior 

 edge of the sternum and cut away the flaps of the abdominal 

 wall. 



2. Now make a tiny opening in the trachea below the string 

 you tied about it, insert the blowpipe, and inflate the lungs and 

 air sacs. 



Note (1) the paired abdominal sacs near the dorsal wall 

 anteriorly, but the ventral wall posteriorly, (2) the axillary sacs 

 under the wings, and (3) the branched interclavicular sac be- 

 neath the anterior end of the sternum and the wish-bone, or 

 clavicles. 



(4) Do you find other air sacs? 



(5) What part of the lung expands first in inflating? 



(6) Do you notice any movement of the appendages when 



you inflate the pigeon's lungs? 



(7) Explain how air blown into the lungs affects the bones. 



(8) Tie the trachea below the entrance of the blowpipe and 



keep the lungs inflated if you can. 



3. Next, disjoint the coracoid bones from the scapulae, or 

 shoulder-blades, and cut the ribs loose from the sternum. 

 Remove the coracoids, clavicles, and the sternum, thus exposing 

 the internal organs. Note the compactness with which the 

 internal organs are placed. Why? 



4. The Liver. 



(1) Color? 



(2) Location? 



(3) Number of lobes? 



(4) Use? 



(5) Identify and locate the gall-bladder. Use? 



(6) Trace the bile-ducts to the duodenum, or anterior 



loop of the intestine. 



5. The Circulatory System. 



(1) The Heart. Locate and identify the heart with its 

 pericardium, 

 (a) Carefully remove the pericardium. 



