THE CARDIOGRAPH. 231 



Hold a lighted candle under the valves, and observe through 

 the water in the funnel how they come together, and close 

 the orifice; observe also the triradiate lunules in apposition 

 projecting vertically. 



(g.) Slit open the pulmonary artery, and observe the 

 form and arrangement of the semilunar valves. 



(h.) Make a transverse section through both ventricles, 

 and compare the shape of the two cavities, and the relative 

 thickness of their respective walls. 



(i.) Study two casts of the heart (after Ludwig and 

 Hesse), (1) in diastole, and (2) in systole. 



(j.) Ligature any large vessel attached to the heart, one 

 feels the sensation of something giving way when the 

 ligature is tightened. Cut away the ligature, open the 

 blood-vessel, and observe the rupture of the coats produced 

 by the ligature. 



2. The Stethoscope Heart Sounds. 



Ji.) Place the patient or fellow-student in a quiet room, 

 let him stand erect and expose his chest. Feel for the 

 cardiac impulse, apply the small end of the stethoscope 

 over this spot, and listen with the ear applied to the opposite 

 end of the instrument. The left hand may be placed over the 

 carotid or radial artery to feel the pulse in either of those 

 arteries ; compare its time-relations with what is heard over 

 the cardiac impulse. 



(6.) Two sounds are heard the first or systolic coincides 

 with the impulse, and is followed by the second or diastolic. 

 After this there is a pause, and the cycle again repeats 

 itself. The first sound is longer and deeper than the 

 second, which is of shorter duration and sharper. 



(c.) Place the stethoscope over different parts of the 

 praecordia, noting that the first sound is heard loudest at 

 the apex beat, while the second is heard loudest at the 

 second right costal cartilage at its junction with the sternum. 



3. The Cardiograph. Several forms of this instrument are in 



