oward the left of the
animal's body and is called the _left_ side of the heart; the other is the
_right_ side. Locate the right auricle and the right ventricle; the left
auricle and the left ventricle.

5. Lay the heart on the table with the front side up and the apex pointing
from the operator. This places the left side of the heart to his left and
the right side to his right. Notice the groove between the ventricles,
called the inter-ventricular groove. Make an incision half an inch to the
right of this groove and cut toward the base of the heart until the
pulmonary artery is laid open. Then, following within half an inch of the
groove, cut down and around the right side of the heart. The wall of the
right ventricle may now be raised and the cavity exposed. Observe the
extent of the cavity, its shape, its lining, its columns of muscles, its
half columns of muscles, its tendons (chordae tendineae), the tricuspid
valve from the under side, etc. Also notice the valve at the beginning of
the pulmonary artery (the right semilunar) and the sinuses, or
depressions, in the artery immediately behind its divisions.

6. Now cut through the middle of the loosened ventricular wall from the
apex to the middle of the right auricle, laying it open for observation.
Observe the openings into the auricle, there being one each for the vena
cava superior, the vena cava inferior, and the coronary vein. Compare the
walls, lining, shape, size, etc., with the ventricle below.

7. Cut off the end of the left ventricle about an inch above the apex.
This will show the extension of the cavity to the apex; it will also show
the thickness of the walls and the shape of the cavity. Split up the
ventricular wall far enough to examine the mitral valve and the chordae
tendineae from the lower side.

8. Make an incision in the left auricle. Examine its inner surface and
find the places of entrance of the pulmonary veins. Examine the mitral
valve from above. Compare the two sides of the heart, part for part.

9. Separate the aorta from the other blood vessels and cut it entirely
free from the heart, care being taken to leave enough of the heart
attached to the artery to insure the semilunar valve's being left in good
condition. After tying or plugging up the holes in the sides of the
artery, pour water into the small end and observe the closing of the
semilunar valve. Repeat the experiment until the action of the valve is
understood. Sketch the artery