A TURTLE 155 



forward close to the spleen and the right lung, and enters the right 

 lobe of the liver. Trace its course. 



Joining the portal vein also are the abdominal veins, which have 

 already been studied. 



Exercise 31, Draw a diagram of the hepatic portal system so far as 

 observed. 



The Caval Veins. Cut the intestine back of the bile duct and 

 also at the end of the rectum, and remove it from the body. Bend 

 the heart forward and pin it there, exposing its dorsal surface and 

 the base of the large caval veins. 



Identify the ventricle, the two auricles, and the sinus venosus. 

 Four large veins enter the sinus : the right and left precaval veins, 

 bringing blood from the forward part of the body ; the left hepatic 

 vein, from the left lobe of the liver ; and the postcaval vein, which 

 brings blood from the hinder part of the body and from the right 

 lobe of the liver. 



Trace the left precaval vein ; it will be seen to be formed by the 

 union of two veins,— the subclavian coming from the foreleg and 

 the internal jugular from the side of the neck. Cut the skin be- 

 tween the forward border of the shell and the shoulder, find these 

 veins, and follow them as far as possible. 



Trace the postcaval vein. We have already seen that it passes 

 through the right lobe of the liver, and receives the right hepatic 

 vein not far from the heart. It may now be followed from the 

 hinder border of this right lobe to a mid-dorsal position in the ab- 

 dominal cavity, where it lies between the kidneys. Here it is 

 formed by the union of a number of renal veins from the kidneys 

 and genital veins from the genital glands. 



Exercise 32. Draw a diagram representing the caval veins and their 

 branches so far as observed. 



The Arteries. Make a midventral incision in the skin and ex- 

 pose the organs of the neck. Study the blood vessels which spring 

 from the anterior side of the ventricle, carefully dissecting them 

 free from the tissues surrounding them. Three large arteries will 

 be seen, side by side. The one on the animal's right is the innomi- 

 nate artery ; it divides at once into the right and left subclavian 



