tion of the spinal marrow, and for half an hour
after they are separated from their bodies, clearly
proves that an influx of a fluid from the nerves
into the muscles, is not necessary for their contraction
: ” &c. These experiments are so truly
interesting that I should think my account of this
subject incomplete without the following extract:
“ Immediately after decollating a frog, I destroyed
its spinal marrow, by pushing a small probe
down through its spine, which occasioned strong
convulsions of all the muscles, especially those of
the inferior extremities. Ten minutes after this, I
opened the thorax, and found the heart beating at
the rate of 45 times in a minute. Sixteen minutes
after decollation, it moved 40 times in a minute.
After half an hour it made 36, and after fifty minutes
only 30 pulsations in the minute, which were
now also become very small and feeble.
“ N. B. When I opened the thorax of another
frog immediately after decollation and destroying
its spinal marrow, I observed its heart beating at
the rate of sixty in a minute, which is four or five
pulsations less than J have generally seen the hearts
of frogs make in that time, when their thorax was
opened without decollation.
“ At nine minutes past eleven in the forenoon,
immediately after decollating another frog, I destroyed
its spinal marrow with a red hot wire, which
produced terrible convulsions in all the muscles, as
in the last experiment. I opened the thorax of this
frog thirty five minutes after decollation, and observed
its heart beating 30 times in a minute. The
contraction of the auricle regularly preceded that
of the heart: the auricle was not near so much
distended with blood, nor the heart so much swelled
as in those frogs which had a solution of opium
injected into their stomach and guts. At one
o’clock (viz. an hour and fifty-one minutes after
decollation) the heart of this frog made twenty pulsations
in a minute. At half an hour past two,
when the room was become warmer by the shining
of the sun, it beat 25 times in a minute ; and when
placed in the sun-beams, it performed 31 contractions
in that time. After this, I removed the frog
to an east window, where it was exposed to a cool
breeze ; upon which the motion of his heart became
slower, so that in a short time it only made 25
pulses in a minute. I then exposed it anew to the
sun-beams, by which its motion was soon quickened,
so that it beat 30 times in a minute.