was destroyed, the circulation in the tail ceased
altogether. The action of the heart continued
for an hour or* more.
An eel was placed so that the circulation in
the tail could be observed. It proceeded rapidly;
A fine wire was passed down the spinal canal.
From this moment the circulation, without being
at all immediately arrested, became gradually
slower,
A ligature was applied tightly an inch and a
half below the pectoral fin in a small eel; and
the lower part was removed. The circulation still
continued perfect in the pectoral fin. A stilet
was then passed up, so as slowly to destroy the
spinal marrow. The circulation in the fin became
slower, and gradually ceased altogether.
The circulation in the tail of an eel was observed
to be rapid and vigorous. A fine wire
was passed slowly down the spinal canal twice.
The circulation soon became enfeebled, arid at
length ceased in the tail, continuing vigorous in
the dorsal fin. It then gradually ceased along the
dorsal fin, remaining-vigorous in the pectoral fin.
A difference in the vigour of the circulation was
frequently quite obvious within the space of an
inch along the dorsal fin. The circulation at length
ceased in the pectoral fin. On exposing the heart,
it was still found beating regularly, though feebly.
All these experiments appear to prove that the
action of the heart is enfeebled from the moment it
is deprived, at once, of the influence of the brain and
spinal marrow. The connexion of this organ, with
the nervous system seems to be precisely of the same
nature as that of the voluntary muscles. Both
possess a degree of irritability independently of
the large masses of the nervous system ; both,
if separated from these masses, gradually lose this
irritability. The irritability is doubtless a faculty
or property of the muscular fibre; yet it may
become extinct without any obvious change in that
fibre. Its continuance or renewal depends ultimately
upon the masses of the nervous system.
The experiments which have been detailed, seem
to prove that, from the moment of the abstraction
of the brain and spinal marrow, the irritability
of the heart begins to fail. The circulation is
first enfeebled, then lost, in the most distant
parts of the system, then in parts less and less
remote. The distance to which it extends may
be aptly taken as expressive of the remaining