84 Dr. Philip’s experiments to ascertain the principle 
to pieces, or even by a hot wire, the heart after their destruction 
beats just as before it. But if either the brain or spinal marrow 
be instantly crushed, the heart immediately feels the shock. 
The thorax of a large frog was laid open, and the motion 
of the heart observed, which performed the circulation per- 
fectly, and with great farce. The brain was then crushed by 
the blow of a hammer. The heart immediately performed 
a few quick and weak contractions. It then lay quite still 
for about half a minute. After this, its beating returned, but 
it supported the circulation very imperfectly. In ten minutes 
its vigour was so far restored that it again performed the cir- 
culation with freedom, but with less force than before the 
destruction of the brain. An instrument was then introduced 
under the heart, and after ascertaining that this had produced 
no change on its action, the spinal marrow was crushed by 
one blow, as the brain had been. The heart again beat 
quickly and feebly for a few seconds, and then seemed wholly 
to have lost its power. In about half a minute it again began 
to beat, and in a few minutes acquired considerable power, 
and again supported the circulation. It beat more feebly, 
however, than before the spinal marrow was destroyed. It 
ceased to beat in about an hour and a half after the brain had 
been destroyed. In another frog, after the brain and spinal 
marrow had been wholly removed, the heart beat nine hours, 
gradually becoming more languid. 
In this experiment we see that the heart not only retains 
its power long after the brain and spinal marrow are removed, 
but that if they are destroyed in such a way as to impair and 
almost destroy the action of the heart, it can recover the power 
of performing its function, after they no longer exist; pre- 
