172 ELEMENTARY BIOLOGY. [XIII. 



c. The common iliac vein, -which passes to the outer 

 edge of the kidney and is distributed to that 

 organ, whence the blood is carried to the vena 

 cava inferior by the renal veins. 



d. The dorso-lumbar vein, which lies along the 

 transverse processes of the vertebrae and receives 

 blood from the walls of the abdomen and from 

 the interior of the spinal canal, opens iato the 

 common iliac. 



3. The system of the anterior abdominal vein, formed by 

 the union of the ventral ends of the pelvic veins (2. b). 

 It receives blood from the urinary bladder and the 

 walls of the abdominal cavity, and at its anterior 

 end divides into two branches — a right and a left. 

 These branches go to the corresponding lobes of the 

 liver, the left receiving a large communicating branch 

 from the gastric division of the vena portce. 



4. The system of the vena portce formed by the union of 

 two veins ; one, gastric, which brings back the blood 

 from the stomach, the other, lieno-intestinal, which 

 returns that from the spleen and intestines. 



[Hence the right lobe of the liver and part of the left 

 lobe are supplied with systemic venous blood, more or less 

 mixed with gastric venous blood, while only part of the 

 left lobe is supplied with intestiaal venous blood. Besides 

 this venous blood, it must be recollected that the liver 

 receiyes arterial blood by the hepatic artery.J 



5. The system of the pulmo'iiary vein, formed by the 

 union of the veins of the right and left lungs. 



In addition to the apparatus of the circulation of the 

 blood, the Frog possesses two pairs of lymph-hearts. These 



