HEART PERICARDIUM. 57 



7. Examine the windpipe ; insert a finger, and stretch it , 

 note its C-shaped cartilages. Its lining is a Mucous Membrane. 



8. Lay the heart and lungs on their ventral surface, with 

 the posterior end nearer you. Using the handle of the scal- 

 pel as a chisel, clear away any tissue covering the windpipe, 

 and trace it to the lungs ; its branches are the Bronchi. How 

 many bronchi are there ? Here are often found small, oval, 

 brownish masses, the Lymphatic Glands, imbedded in connective 

 tissues. Scrape these loose with the scalpel handle. 



9. Lay the lungs on their dorsal surface, with the anterior 

 ends toward you. Note how easily the heart may be moved 

 about in its case, the Pericardium. Slit the pericardium along 

 its ventral side, and note the smoothness of its lining and of 

 the surface of the heart. Observe the Pericardial Fluid. 



10. Carefully compare the right and left sides of the 

 heart. Running obliquely across the surface of the heart is 

 a groove in which are blood tubes, often covered with fat. 

 The part at the right of the groove is the Right Ventricle ; at 

 the left is the Left Ventricle. 



11. At the base (anterior end) of the heart on each side 

 are the right and left Auricles. 



12. Tip up and toward you the apex of the heart. Com- 

 pare its width and thickness ; compare the ventral and dorsal 

 surfaces as to length, convexity, etc. Compare its width and 

 thickness ; press the two ventricles, and compare them in 

 firmness. 



13. Turn the heart to the left, and examine the right auri- 

 cle; find a large, flabby, red-lined tube entering its anterior 

 surface, the Precaval Vein. Prick a small hole in it near the 

 pericardium and insert the blowpipe ; hold firmly around the 

 opening and inflate the right auricle ; the Postcaval Vein should 

 now be discovered entering the auricle from the posterioi 



