268 SIXTH REPORT — 1836. 



The heart was then grasped titroiigly under blood, and it con- 

 tinued to contract vigorously, and the first sound was heard (but 

 not loud) with the flexible tube as well as the common stethe- 

 scope. The heart was then taken out and held in the hand of 

 one of the Committee, when the first sound was distinct, but 

 feeble. 



On opening the right ventricle the columneee carnese were 

 distinctly seen contracting simultaneously with the ventricle. 



Such are the particulars of all the more successful experi- 

 ments of the Committee, with regard to those possible causes of 

 the normal sounds of the heart which have been investigated by 

 the Committee ; the principal of them are as follows. The first 

 sound has been attributed to 



1 . Impulse, or the beating of the heart against the parietes of 

 the chest. 



2. Muscular sound, or the resonance attending sudden mus- 

 cular contraction. 



3. Collisions of the particles of the blood amongst each other, 

 or against the parietes, valves, &c. of the heart's cavities. 



4. The action of the auricula-ventricular valves during sy- 

 stole. 



5. And the collisiofi of the opposite interior surfaces of the 

 ventricles in the same state. 



The normal or second sound has been attributed to 



1. Impulse of the heart against the thoracic jiarietes, owing 

 to its rapid expansion during diastole. 



2. ^n intrinsic sound attending the diastole, analogous to that 

 which the observations of the Committee prove to attend the 

 systolic action of the ventricles. 



3. Flapping of the atiriculo-ventricular valves during dia- 

 stole against the sides of the ventricles. 



4. The rushing of fluids into the great arteries after the sy- 

 stole. 



5. The rushing of the fluids from the auricles into the ven- 

 tricles during diastole. 



6. Sudden tension and flapping of the sigmoid valves after 

 the systole. 



Of the causes to which the first sound has been attributed, the 

 Committee feel it necessary to notice each separately, except the 

 last. With regard to the alleged causes, however, of the second 

 sound, they will feel themselves justified in being less minute, 

 partly to avoid tiresome repetitions, but principally on account 

 of the obvious preponderance of evidence, us the Committee con- 

 ceive, in favour of the theory last mentioned. 



First Sound — Valvular Tensioji. — To bctcin with the first 



