208 MAMMALIA (tHE RABBIT) 



B. Internal Morphology 



In your dissections, be careful not to injure the sternum, ribs, 

 or any other bones, as you will need them in your study of the 

 skeleton. 



Cut through the abdominal muscles along the median line 

 from the pelvis to the sternum. From the middle of this slit, 

 make a short one on each side at right angles to it, and turn 

 back the muscular flaps, exposing the internal organs. 



How do the abdominal muscles compare in thickness with 

 those on other parts of the body? Why? 



Before proceding with the dissection, or putting the specimen 

 into formaldehyd, insert the blowpipe in the trachea, inflate the 

 lungs, and tie a string tightly about the trachea below the blow- 

 pipe. 



1. Peritoneum, or lining of the body cavity. Its surface and 

 appearance? 



2. The Diaphragm. A muscular partition divides the body 

 into two portions, the anterior, containing the heart and lungs, 

 and the posterior, containing the abdominal viscera. 



3. Note the position of the organs in the body cavity? 



4. The Circulatory System. 



(1) The Pericardium. 



(a) Identify and describe it. 



(b) Use? 



(c) Contents? 



(2) The Heart. 



(a) Shape? 



(b) Size? 



(c) Use? 



(d) Number of auricles? 



(1) Position? 



(2) Use? 



(e) Ventricles. 



(1) Number? 



(2) Use? 



(3) The Arteries. (See Physiology.) Identify the firm, 



elastic aorta and its branches, and trace them to the 

 organs which they supply. 



