60 DISSECTION OF Til K II KM IT. 



notch between the auricle and ventricle. At the extreme left 

 of the right auricle is the mouth of the Cardiac (coronary) 

 Vein, which, running around between the left auricle and left 

 ventricle, brings blood from the ventral wall of the heart. 

 Near the mouth of this vein also empty the veins seen in 

 the dorsal wall of the heart. Pick out any clots that may 

 be found. Slit the anterior wall of the auricle, being careful 

 not to cross the groove between the auricle and ventricle, 

 and note the muscular columns within the appendage of the 

 auricle. 



3. Cut away the whole of the appendage of the right 

 auricle. Remember that the pulmonary veins from the right 

 lung run very close to the right auricle, and be careful not to 

 cut into them. Pin down the flap of the left auricle, so that 

 water may not enter the left half of the heart in the next 

 experiment. Hold the heart in the left hand, with the ven- 

 tral surface in the palm, and the tips of the fingers against 

 the right ventricle. Hold the heart under a faucet, or pour 

 from a pitcher, and let the water run first gently, then strongly, 

 through the right auricle into the right ventricle. Watch the 

 Tricuspid Valves as they float up and separate the auricle from 

 the ventricle. Empty the heart and fill it again, and as soon 

 as the valves rise, press with the fingers on the outside of the 

 ventricle. What effect has this pressure ? Let the nozzle of 

 the faucet project down between the valves, and again turn 

 on the water. Where does the water escape ? 



4. Empty the heart and examine the valves. They will 

 be found lying close against the walls of the ventricle. Note 

 the white cords, Chordae Tendineae. attached to the valves. 



5. Push the finger past these valves to the very bottom of 

 the ventricle ; from the outside cut through the wall of the 

 ventricle at this point, and cautiously cut upwards in both 

 directions along the border of the ventricle. Raise the outer 



