ON THE MOTIONS AND SOUNDS OF THE riEAttT. 5^ 



sound. It is well known that several eminent writers have at- 

 tributed it to the sudden closure and tension of the auriculo- 

 ventricular valves during the systole. With reference to that 

 question, the Committee have made the following observations : 



1. Inverting the auricles, and passing the finger into the au- 

 riculo-ventricular orifices, does not prevent the first sound, though 

 it must prevent the action of the valves. Experiments 5, 8, &c. 



2. In the experiments just referred to, the action of the mi- 

 tral valve, as felt by the finger, was of too gradual and feeble a 

 kind to be capable of producing sound; while on the right side 

 the tightening of the tricuspid was not strong enough to be sen- 

 sible to the finger at all. 



3. Various instances where the ventricles were treated so as 

 to obliterate their cavities by pressure, and render valvular ac- 

 tion impossible, gave, nevertheless, the first sound. Experi- 

 ments 6, 7j &c. 



From these facts the Committee conclude that valvular action 

 is not a cause of the first sound. 



First Sound — Collision in the Fluids, Sfc. — The following are 

 the facts observed by the Committee with regard to the alleged 

 resonant collisions of the particles of blood amongst themselves, 

 or against the parietes, valves, &c. of the ventricles. 



1. The obstruction of the auriculo-ventricular orifices by the 

 fingers introduced by inverting the auricles does not materially 

 modify the first sound. Experiments 5, 8, &c. 



2. The heart being pressed between a finger introduced through 

 the auricle to the bottom of the left ventricle, and the other hand 

 placed outside the right ventricle, continued still to emit the first 

 sound. Experiments 5 and 12. 



3. The heart being grasped firmly in the hand, after separation 

 from its attachments, and while immersed in blood, gave the first 

 sound distinctly. The pressure in this case must, in the opinion 

 of the Committee, have prevented collision between the opposite 

 interior surfaces of the organ. 



4. The division of the aorta and pulmonary artery, and even 

 the extraction of the heart, does not prevent the first sound. 

 Elxperiment 12. 



5. The Committee made also various experiments in order to 

 ascertain the power of fluids to produce sound when in contact 

 with solids. 



On compressing by the stethescope the gum elastic bottle 

 filled with water, and under water, they could not succeed in 

 producing any other sound than a bellows sound. The power of 

 obstructed currents of liquid to produce the various modifica- 

 tions of the bellows sound was further illustrated to the Com- 



