324 DISSECTION OP THE RABBIT 



diaphragm and runs forwards, slightly to the 

 right of the median plane, to open into the 

 posterior end of the right auricle. 



b. Arising from the right ventricle. 



i. The pulmonary artery conveys the venous blood 

 from the heart to the lungs. It arises from 

 the anterior border of the right ventricle ia 

 the mid- ventral line, and arches over to the 

 dorsal surface of the left auricle, where it 

 divides into the right and left pulmonary 

 arteries, supplying the two lungs. 



c. Opening into the left auricle. 



i. The pulmonary veins return the blood from the 

 lungs to the heart. There are two main 

 veins on each side, which converge to open 

 into the dorsal surface of the left auricle. 



d. Arising from the left ventricle. 



i. The aorta conveys arterial blood from the heart 

 to all parts of the body. It arises from the 

 middle of the base of the heart, dorsal to 

 the root of the pulmonary artery, runs for- 

 wards about half an inch, and then arches 

 over to the left side, and runs back along the 

 left side of the vertebral column. Its thoracic 

 portion is readily seen on turning aside the 

 left lung. 



The ductus arteriosus is a ligamentous 

 band, connecting the aorta with the pulmonary 

 artery, just before the division of the latter 

 iato right and left branches. During em- 

 bryonic life it forms a tubular coimection 

 between the two vessels. 



B. The Veins. 



The veins form three distinct systems, communicating 

 with one another only through capillaries, and containing 

 different kinds of blood. 



