CHAPTER XIII. 



MAMMALIA (Continued}. 



DISSECTION OF THE HEART AND LUNGS. 



THE heart and lungs of a sheep, pig, or calf are better to 

 study on account of their greater size. 



1 . Hold up the mass by the windpipe, with the heart away 

 from you. The end now uppermost is the anterior end, that 

 below is the posterior end ; the lung to your right is the right 

 lung, the one to your left is the left lung ; the surface nearest 

 you is the dorsal surface, and that opposite is the ventral surface. 



2. Observe the windpipe, or trachea, with the stiff rings of 

 gristle, or cartilage. The thick part of the anterior end is the 

 larynx. 



3. Running along the dorsal surface of the windpipe is a soft 

 red tube, the gullet or esophagus. At about the middle of the 

 windpipe separate the gullet and windpipe for three or four 

 inches. Note that next to the gullet the windpipe is soft and 

 yielding, where the gaps of the C-shaped cartilages are filled 

 with muscular and elastic tissue. Make a slit two inches long 

 in this soft membrane. 



4. Inflate the lungs as follows : Take a wooden faucet, slip 

 the small end of the faucet into the slit just made in the wind- 

 pipe, and hold or tie firmly, but do not cut off either gullet 

 or- windpipe. Inflate through the spout, then shut off the air ; if 

 the lungs have not been punctured they should now remain 

 distended. In holding up the lungs, take hold of the windpipe 

 above where the faucet enters, and hold in such a way as to pull 

 the windpipe up and at the same time press the faucet down. 

 If this is done, it will not be necessary to tie the faucet in. Note 



