l economy is that termed involuntary: it depends upon the
principle of irritability and requires the IMMEDIATE application of
a stimulus to the nervo-muscular fibre itself. These three kinds of
muscular motion are well known to physiologists; and I believe they are
all which have been hitherto pointed out. There is, however, a FOURTH,
which subsists, in part, after the voluntary and respiratory motions
have ceased, by the removal of the cerebrum and medulla oblongata, and
which is attached to the medulla spinalis, ceasing itself when this
is removed, and leaving the irritability undiminished. In this kind of
muscular motion the motive influence does not originate in any central
part of the nervous system, but from a distance from that centre; it is
neither spontaneous in its action nor direct in its course; it is, on
the contrary, EXCITED by the application of appropriate stimuli, which
are not, however, applied immediately to the muscular or nervo-muscular
fibre, but to certain membraneous parts, whence the impression is
carried through the medulla, REFLECTED and reconducted to the part
impressed, or conducted to a part remote from it in which muscular
contraction is effected.

"The first three modes of muscular action are known only by actual
movements of muscular contractions. But the reflex function exists as
a continuous muscular action, as a power presiding over organs not
actually in a state of motion, preserving in some, as the glottis, an
open, in others, as the sphincters, a closed form, and in the limbs a
due degree of equilibrium or balanced muscular action--a function not, I
think, hitherto recognized by physiologists.

"The three kinds of muscular motion hitherto known may be distinguished
in another way. The muscles of voluntary motion and of respiration may
be excited by stimulating the nerves which supply them, in any part of
their course, whether at their source as a part of the medulla oblongata
or the medulla spinalis or exterior to the spinal canal: the muscles of
involuntary motion are chiefly excited by the actual contact of stimuli.
In the case of the reflex function alone the muscles are excited by a
stimulus acting mediately and indirectly in a curved and reflex course,
along superficial subcutaneous or submucous nerves proceeding from the
medulla. The first three of these causes of muscular motion may act on
detached limbs or muscles. The last requires the connection with the
medulla to be pr