3 ELEMENTARY BIOLOGY. [CHAP. 



between the skin and the subjacent muscular wall of 

 the abdomen ; also a vein which occupies the middle 

 line of the inner face of this wall and is usually 

 visible through it. 



4. Raise the muscular wall of the abdomen and cut it 

 in the same way, a little on one side of the middle 

 line, sufficiently to lay open the abdominal cavity, 

 taking great care to avoid the bladder which lies at 

 the posterior end of the cavity. Note the con- 

 spicuous vein (anterior abdominal) which lies beneath 

 the muscles in the middle line of the belly. The 

 liver, stomach and intestines will be seen; at the 

 sides, in the female, the ovaries and oviducts will be 

 very conspicuous in the breeding season. Insert a 

 small blow-pipe into the cloacal opening : air blown 

 in will distend the large bilobed urinary bladder. If 

 the lungs are distended with air, one will be visible 

 on each side of the anterior end of the abdominal 

 cavity, and the extremity of the bristle passed into 

 one of them, through the glottis, will be seen. Lay 

 open the stomach to see the end of the probe passed 

 into the oesophagus. 



By turning the intestines on one side, the kidney, the 

 corpus adiposum and the testis (in the male) will be 

 exposed. Notice a number of small white patches 

 on each side of the vertebral column. They are 

 accumulations of calcareous crystals. 



5. In front of the liver, the apex of the heart will be 

 seen through the pericardium. Lay the latter open 

 and observe the position of the heart. 



6. Cut away the left fore-limb and the left hind-limb, 

 with so much of the left half of the vertebral column 



