A History of Science — Volume 4Williams, Henry Smith
History
A History of Science — Volume 4
Williams, Henry Smith
Science -- History
Hall gave an admirably clear and interesting account of his experiments
and conclusions in a paper before the Royal Society, "On the Reflex
Functions of the Medulla Oblongata and the Medulla Spinalis," from
which, as published in the Transactions of the society for 1833, we may
quote at some length:
"In the entire animal, sensation and voluntary motion, functions of
the cerebrum, combine with the functions of the medulla oblongata and
medulla spinalis, and may therefore render it difficult or impossible to
determine those which are peculiar to each; if, in an animal deprived
of the brain, the spinal marrow or the nerves supplying the muscles be
stimulated, those muscles, whether voluntary or respiratory, are equally
thrown into contraction, and, it may be added, equally in the complete
and in the mutilated animal; and, in the case of the nerves, equally in
limbs connected with and detached from the spinal marrow.
"The operation of all these various causes may be designated centric, as
taking place AT, or at least in a direction FROM, central parts of the
nervous system. But there is another function the phenomena of which
are of a totally different order and obey totally different laws, being
excited by causes in a situation which is EXCENTRIC in the nervous
system--that is, distant from the nervous centres. This mode of action
has not, I think, been hitherto distinctly understood by physiologists.
"Many of the phenomena of this principle of action, as they occur in
the limbs, have certainly been observed. But, in the first place, this
function is by no means confined to the limbs; for, while it imparts
to each muscle its appropriate tone, and to each system of muscles its
appropriate equilibrium or balance, it performs the still more important
office of presiding over the orifices and terminations of each of the
internal canals in the animal economy, giving them their due form
and action; and, in the second place, in the instances in which the
phenomena of this function have been noticed, they have been confounded,
as I have stated, with those of sensation and volition; or, if they
have been distinguished from these, they have been too indefinitely
denominated instinctive, or automatic. I have been compelled, therefore,
to adopt some new designation for them, and I shall now give the reasons
for my choice of that which is given in the title of this paper--'Reflex
Functions.'
"This property is characterized by being EXCITED in its action and
REFLEX in its course: in every instance in which it is exerted an
impression made upon the extremities of certain nerves is conveyed to
the medulla oblongata or the medulla spinalis, and is reflected along
the nerves to parts adjacent to, or remote from, that which has received
the impression.
Public-domain text, read in full here on John Shaqi.
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