Mammalia. 141 



be seen, and finally the aorta divides into two large branches, 

 the common iliacs, supplying the two hind limbs. 



4. Turn the stomach and intestines to the left, and observe 

 the two veins running forward from the two hind limbs. These 

 are the two external iliac veins. By their union they form the 

 postcaval vein. 



5. Observe the veins from the kidneys, the renal veins. 



6. Trace the postcaval vein to the liver. Observe the vein 

 that gathers the blood from the intestine, the mesenteric vein. 

 This vein is joined by a vein from the stomach, the gastric 

 vein, one from the spleen, the splenic, and one from the pan- 

 creas, the pancreatic; together these form the portal vein, 

 which empties into the liver. Unlike other veins, the portal 

 vein subdivides, distributing the blood into the liver. The blood 

 thus distributed through the liver is re-collected, and by the 

 hepatic veins joins the postcaval vein, close to the diaphragm, 

 and almost wholly concealed by the liver. 



7. The postcaval vein passes by the liver, through the dia- 

 phragm, and on to the right auricle. 



8. On removing the skin of the neck, there should be found 

 on each side the large jugular vein. Each of these is formed 

 by the union of the internal and external jugular veins. 



9. Just before each jugular vein enters the chest cavity it 

 is joined -by a vein coming from the corresponding fore limb, 

 the right and left subclavian veins. The union on each side 

 forms the innominate vein. The two innominate veins, uniting, 

 make the precaval vein, which enters the right auricle. In the 

 rabbit there are two precaval veins. 



THE VALVES IN THE VEINS. 



Dissect back the skin from the throat of the rabbit, cat, or 

 dog, till the jugular veins are well exposed. Let the head of 

 the animal hang over the edge of the table ; note that as the 

 blood presses back toward the head it causes marked bulging 

 at certain points ; with the handle of the forceps slightly stroke 



