58 PULMONARY BLOOD-TUBES. 



region. Look for it outside, and on the dorsal side of the 

 pericardium, where it runs anteriorly from the diaphragm. 



14. Turn the heart to the right, and observe a large, light- 

 colored tube arising from the base of the right ventricle be- 

 tween the two auricles ; this is the Pulmonary Artery. Again 

 turn the heart to the left, and raise the right auricle ; find the 

 Aorta arising from the center of the base of the heart. Care- 

 fully separate the aorta from the pulmonary artery, and trace 

 the aorta as it arches over the left bronchus, and runs down 

 between the two lungs by the side of the gullet. Clear away 

 any fat or other tissue adhering to it. 



15. From the arch of the aorta arise the branches running 

 to the head and forelimbs. 



16. In the same way trace and clear the pulmonary artery. 



17. When the fork of the pulmonary artery has been 

 reached, lay the heart and lungs on their ventral surfaces, 

 with the posterior end toward you ; turn the windpipe back 

 toward you, and with the scalpel handle trace the branches of 

 the pulmonary artery into the lungs. Cut them off close to 

 the lungs. 



18. Keeping the parts in the same position, trace the Pul- 

 monary Veins. These are to be found on the ventral side of 

 the bronchi ; their general outlines may be shown by inflating 

 as follows : Cut off the first branch of the aorta as close as 

 possible to the arch. Insert one blade of the scissors in this 

 opening, pointing away from the heart, and make a slit two 

 inches long. Insert a cork toward the heart. It should fit 

 snugly, so that air may not escape. For a pig's heart a cork 

 about three-fourths of an inch in diameter at its larger end is 

 about right. Make a very small hole in the tip of the left 

 auricle, insert the blowpipe, holding firmly around it, and 

 inflate. This should distend the left auricle and the pul- 

 monary veins. With the handle of the scalpel scrape away 



