270 SIXTH REPORT — 1836. 



mittee in several experiments on animals, in which pressure of 

 the arteries, partial obstruction of the auriculo-ventricular ori- 

 fices, and suspension of the action of the sigmoid valves, were 

 repeatedly accompanied by this phaenomenon. The thrill ac- 

 companying this sonorous passage of liquid was in every case 

 sensible to the finger. 



6. To this we may add that the experiments of MM. Pigeaux 

 and Piorry have been repeated by the Reporter in the presence 

 and with the assistance of Dr. Edwin Harrison, and other gen- 

 tlemen not of the Committee ; but in no instance of several trials 

 was anything like the first sound produced. 



From the preceding facts the Committee conclude that the 

 normal first sound of the heart is in no degree referable to any 

 collisions of the particles of the fluids amongst themselves or 

 against the parietes, &c. of the ventricles. 



First Sound — Impulse. — The facts relating to the connexion 

 of impulse with the first sound that are contained in the pre- 

 ceding experiments, are the following : 



In a variety of circumstances in which it is difficult to see 

 how impulse could occur to cause sound, the systolic sound was 

 distinctly audible, viz. 



1. When the heart lay exposed, deprived of its pericardium, 

 and supported by the mediastinum alone, as in Experiment 1. 



2. When the heart was held between the fingers with some 

 force of pressure, the left side cavities being empty, or nearly 

 so, as in Experiment 5. 



3. When the heart was imbedded in tow. Experiment 14. 



4. When the heart hung out of the thorax by its vessels, re- 

 moved from all contact to which sound might be referred, as in 

 Experiment 9. 



Note. In the four experiments just referred to the instrument 

 was applied to the arteries near their roots. 



5. When the heart was severed from all its attachments, and 

 grasped strongly in the hand, as in Experiment 12. On the 

 other hand, several facts show that the impulse against the ribs 

 may produce sound. 



6. In Experiment 11, and in others in the memoranda of 

 which the fact has been omitted, the heart during systole was 

 felt, both outside and inside the chest, to press with force against 

 the sternum and cartilages. 



7. In our observations on the effects of posture we remarked 

 that leaning to the left or forwards gave additional force to the 

 impulse and loudness to the sound; while inclination of the body, 

 such as to cause the heart to gravitate away from the ribs, di- 

 minished at once the sound and impulse. 



