230 EXPERIMENTAL PHYSIOLOGY. 



with water; it distends the right auricle, passes into the right 

 ventricle, and rises to the same height in the P. A. tube as 

 the level of the fluid in the funnel. Compress the right 

 ventricle with the hand, the fluid rises in the P. A. tube; 

 and observe on relaxing the pressure that the fluid remains 

 stationary in the P.A. tube, as it is supported by the closed 

 semilunar valves. If the right ventricle be compressed 

 rhythmically, the fluid will rise higher and higher until it is 

 forced out at the top of the P.A. tube, and a vessel must be 

 held to catch it. Observe that the column of fluid is sup- 

 ported by the semilunar valves, and above the position of the 

 latter observe the three bulgings corresponding to the posi- 

 tion of the sinuses of Valsalva. 



(c.) Repeat (6.), if desired, on the left side, tying the long 

 tube into the aorta, and the short tube into a pulmonary 

 vein, ligaturing the others. 



(d.) Cut away all the right auricle, hold the heart in the 

 left hand, and pour in water from a jug into the tricuspid 

 orifice. The water runs into the right ventricle, and floats 

 up the tricuspid valves ; notice how the three segments 

 come into opposition, while the upper surfaces of the valves 

 themselves are nearly horizontal. 



(e.) With a pair of forceps tear out one of the segments of 

 the semilunar valves of the pulmonary artery. Tie a short 

 tube into the P. A., and to it attach an india-rubber tube 

 communicating with a funnel supported on a retort stand. 

 Pour water into the funnel, and observe that it flows into 

 the right ventricle, floats up and securely closes the 

 tricuspid valve. The semilunar valves have been rendered 

 incompetent through the injury. Turn the heart any way 

 you please, there is no escape of fluid through the tricuspid 

 valve. 



(/) Take a funnel devoid of its stem, and with its lower 

 orifice surrounded by a flange, and tie it into the aorta. 

 Cut out the aorta and its semilunar valves, leaving a con- 

 siderable amount of tissue round about it. Place the funnel 

 with the excised aorta in a filter stand, and pour water into the 

 funnel much of it will escape through the coronary arteries, 

 ligature these. The semilunar valves are quite competent 

 i.e., they allow no fluid to escape between their segments. 



