ON THE MOTIONS AND SOUNDS OF THE HEART. 207 
dered sonorous by the interposition of any rough substance 
between the rubbing surfaces, (as lymph, for example,) and 
supposing the heart's actions sufficiently vigorous, under ordi- 
nary circumstances, we might anticipate with confidence a 
duplication of murmurs at least—one systolic and one dia- 
stolic ; and this must be the principal element in the acoustic 
diagnosis of pericarditis, since effused lymph may be of any 
thickness, consistence, extent, &c., and be situate on any por- 
tion of the heart’s surface between its nearest part and its 
furthest; and may therefore cause friction-sounds of the most 
variable seat, depth, and character. But, of course, another 
physical means of distinction of great importance remains, 
viz. the comparatively equable diffusion of the sounds of peri- 
cardial friction all around the place of attrition, rather than 
in any one exclusive direction. 
12th. The sounds of the structurally-healthy heart are much 
liable to modification, by deviations from the normal standard 
in the state of the fluids and in the order and force and equa- 
bility of action of the carnez columne, and other contractile 
parts governing or influencing the action of the valves, and the 
closure and opening again of the orifices of the ventricles; 
and this dependence of the heart’s sounds on conditions dy- 
namic or material, wholly excluding structural defect, is so 
considerable, that the second sound may for a time be very 
variously modified or masked by strange murmurs, or even 
apparently suppressed in consequence of changes in the solids, 
of a purely dynamic character, and caused by humoral defect, 
in consequence of hemorrhage or from the introduction of 
poison into the veins. And the first cardiac sound, though 
never wholly wanting during the active existence of the heart, 
may still, under similar circumstances to those referred to, 
present various abnormal features; may, ea. gr., be as short as 
the second sound, or be attended or followed by anomalous 
murmurs, or be otherwise strikingly modified. 
15th. Other conclusions, more or less satisfactorily de- 
ducible, as the Reporter conceives, from the facts stated, are,— 
That the peculiar sounds occurring in pericarditis, and attri- 
buted to pericardial frictions, are not referable only to vas- 
cular turgescence or dryness, &c. of the pericardium, but to 
lymph effused by, and adhering to, that membrane, or other 
equivalent obstacle to the easy and noiseless gliding over each 
other of the adjacent parts of the pericardium. 
14th. That the ventricles are of equal capacity during life, 
and that the inequality usually met with after death is an illu- 
sion, as explained long since by Hervey. 
