ACCEPTED PHYSIOLOGY OF THE HEART. 187 
What, then, is the use of the auriculo-ventricular valves ? It 
is evident they cannot perform the service generally attributed 
to them. Let us, however, inspect them. The edges of the 
valves are peculiar for having numerous tendinous cords 
hanging from them : these cords are attached to fleshy 
projections, which constitute part of the contractile substance 
of the walls of the ventricles. When the walls become less, 
the fleshy pillars must diminish with them, and thus pull 
down the valves. The pulmonary artery, or the aorta, 
originate from the top of the ventricle. To send fluid into 
either of the vessels just named, one sudden push from behind 
were worth all the force laterally expended. With the con- 
traction of the ventricles the fleshy pillars also lessen, pull 
down the valves, give the desired impetus from behind, and 
thus immediately aid in sending the blood into the arteries. 
Mr. T. W. King, contributor of a paper to c Guy^s Hospital 
Reports,’ No. 4, April, 1837, has, in the * Encyclopaedia of 
Anatomy and Physiology/ a note awarded to his discovery of 
a safety valve to prevent the heart bursting during its con- 
tractions. Wonders wdll never cease. Did it never strike 
the learned editors of the above book that the semilunar 
valves, when there was fluid on both sides of them, become 
merely floating membranes ? They were then in a condition 
not like to a lock, with w T ater highest on one side, w hich is 
immoveable ; but resembling the aquatic key, wdien the water 
is on a level upon both sides ; the lock then loses all its firm- 
ness, and becomes simply a floating piece of wood, to which 
a child may give an impetus in any direction. The use of 
the semi-lunar valves, therefore, is to keep the blood left 
within the aorta, or pulmonary artery, from mingling with 
the fluid poured into the ventricles ; and thus to increase the 
quantity propelled into the vessels by the contraction of the 
heart. The w ay in wffiich I, according to my present con- 
viction, account for the supply of blood being continuous 
throughout the body, w hen either cavity is ossified, is this : — 
Say the auricles are thus affected ; of course these cavities 
are found changed to bone in a dilated state. With the 
alteration in the condition of the auricles or ventricles, the 
muscular coating of the veins becomes materially thickened. 
The veins, therefore, are made more energetic in their action. 
This circumstance I have repeatedly verified, as will no 
doubt be done in future by subsequent observers. 
W ell, the veins are rendered more impulsive ; the ventricle 
dilates ; the veins send into the heart an amount of blood 
sufficient to fill the dilated auricle and the venticle also. It 
does not matter essentially whether the top of a cavity be 
