THE RABBIT. 293 



156. In the female the uteri (§ 288) and ovaries (§ 251) 

 are seen when the intestines are turned aside : they are in- 

 conspicuous structures in young individuals, but very obvious 

 in adults. 



XIV. Make a small aperture in one side of the 

 diaphragm — say the left- — and note the immediate 

 collapse of the left lung. Dissect away the 

 pectoral muscles, cut through all the vertebral 

 ribs of the left side, except the last five, at about 

 a quarter of an inch from their junction with 

 the sternal ribs : from the posterior end of 

 the incision thus made, cut downwards {i.e. to- 

 wards the sternum) for about an inch, and 

 then forwards, cutting through the sternal ribs ; 

 turn forwards the flap thus separated, and carefully 

 dissect it away from the underlying tissues at its 

 anterior end, so as to detach it altogether without 

 injuring the jugular and brachial veins : proceed 

 in the same way on the right side, noting that the 

 right lung, like the left, does not collapse as long 

 as the thoracic walls of its own side are intact. 

 Note in the thoracic cavity thus laid open : 



157. The small size of the thoracic as compared with 

 the abdominal cavity : this is usually the case in herbivorous 

 animals. 



158. The heart, a dark-red, conical body in the centre of 

 the thoracic cavity, and enclosed in a thin membrane, the 

 pericardium : its broad base is turned forwards, its 

 blunt apex points backwards and somewhat to the left 

 side. 



159. The thymus gland, a soft, fat-like body, anterior 

 to, and partly hiding the base of, the heart. It is especially 

 large in young animals. 



