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change taking place in the nerve fibre itself; and
it must be admitted that some of the most recent anatomi-
cal observations in Germany favour this view, inasmuch as
fine terminal filaments of nerve fibre destitute of germinal matter
said to ramify amongst the anatomical elements of certain are
tissues. And these fibres are- represented as terminating in
free ends, which may reach the surface of the cuticle for
example, and even come into actual contact with anything
which touches it. But those who describe and figure such
fibres amongst the epithelial cells of an epidermic tissue,
do not tell us how they were formed, and how they came
into the positions in which observers profess to demonstrate
them. Many of the appearances represented in recent
drawings of the supposed nerve terminations, have long
been familiar to me, but I cannot accept the interpretation
which has been given. It is curious that lines between
certain epithelial cells, which by some have been looked
upon as nerves, have been regarded by other observers as
lymphatics, the tubes of which it has been said have been
actually filled with colouring matter. Careful observation,



124 OF MIND.



under most favourable circumstances, has forced me to dis-
sent entirely from both views. In every case in which I
have been able to demonstrate the finest nerve fibres I have
succeeded in proving the existence of germinal matter in
connection with them.

There is, however, no doubt that nerve action is influ-
enced by pressure upon the fibre of a nerve without any
change in germinal matter. In many nerves of the higher
animals a considerable length of axis cylinder intervenes
between the nerve centre and the peripheral distribution of
the nerve fibres, which is destitute of germinal matter, but
which, nevertheless, receives and transmits nervous impres-
sions made upon it in this part of its course. So that, although
absence of germinal matter from a considerable extent of
peripheral nerve fibre does not justify the conclusion that
the nerve fibre in question is not an active fibre, the mere
statement that very fine fibres have been seen amongst
epithelial or other cells, and constitute the essential part of
the peripheral nerve apparatus, must be received with the
greatest caution. Until these supposed nerve fibres have
been actually followed into undoubted nerve trunks, and
the manner in which they were formed has been clearly
pointed out, we cannot be expected to assent to the conclu-
sion that the appearances described are really due to nerves
at all. In all tissues of vertebrata in which I have studied
the very fine peripheral nerve fibres, I have succeeded in
tracing them into undoubted nerve trunks, and I have
always detected numerous masses of germinal matter in
connection with these fibres, as will be found figured in my
drawings. Moreover, the germinal matter is more abun-



ON NER VE A CTION IN GENERAL. 1 2 5

dant in the terminal portions of the peripheral nerve organs
that I have studied than in any other situations. I should,
therefore, doubt if terminal fibres which were destitute of
germinal matter were nerve fibres at all.

From a consideration of the facts we are led to conclude
that the nerve fibre in all cases transmits the nerve current
as a conductor, and that pressure, &c., upon any part of its
course will affect the rate of transmission of the current and
the conducting property of the fibre, but that the current
originates in germinal matter.

That the masses of germinal matter, which I have
shown to be numerous in the fine nerve fibres of nerve
organs, besides taking part in the formation of the fibres,
are concerned in nervous action, appears therefore to me
probable from the following facts :

1. They are very numerous in the peripheral ramifica-
tions of all nerves.

2. All special peripheral nerve organs, as the retina, the
expansions of the olfactory and auditory nerves, the papillae
of touch and taste, as well as the peripheral nervous expan-
sions beneath sensitive mucous membranes, the skin, &c.,
are remarkable for the great number, as well as for the
large size, of the masses of germinal matter.

3. The proportion of germinal matter is always very
great in nerve centres, which there is abundant reason for
regarding as the principal seats of development of the
nerve force.

4. That where, as in the sensitive "papilla upon the toe
of the frog, the nerve organ is more acutely sensitive (or
more active in any other way) at one part of the year than



126 OF MIND.



at another, its increased activity is associated with a great
increase in the amount of the germinal matter.

5. The principal change which takes place in a texture
which in health appears to be but slightly sensitive, and
becomes eminently so when inflamed, as the peritoneum, is
a very great increase in the germinal matter which it contains
and this often proceeds to such an extent that the ramifica-
tions of the nerves appear as lines of oval masses of ger-
minal matter, so that when a tissue which in the healthy
state gives no evidence of sensation becomes acutely pain-
ful when inflamed, the feeling of pain must be due in some
way to an increase of the germinal matter of the nerves as
well as that of other tissues.

Of the Nerve Current. The nerve current itself probably
results in a great measure from changes occurring in the
germinal matter of the nerve centres, or more probably in
the chemical compounds immediately formed by it ; and the
masses of germinal matter in the peripheral nerve organs
most likely give origin to feeble currents in much the same
way. In disease the intensity of the currents formed at the
periphery of the nerves is probably increased.

With regard to the nature of the nerve current little
positive is known, the general opinion of physiologists being
that it is some mode of force correlated with heat, electricity,
&c., but not exactly identical with any form or mode of
energy known. The arguments upon which this opinion
is based appear to me very inconclusive. Is it reasonable
to assume new modes or forms of force ? Surely the
evidence is strongly in favour of the view that the nerve
current is electricity, and I think that most, if not all,



OF THE NERVE CURRENT. I2 y

the phenomena familiar to us may be explained upon this
view. Some physiologists have sought to account for the
wonderful phenomena of the nervous system by supposing
that some force or power of a peculiar and exceptional kind
is at work, and it seems scarcely to have occurred to them,
if ordinary force, as electricity, be made to travel in different
directions, and the currents combined in various ways and
made to traverse series of conducting cords very specially
arranged, according to design, the phenomena may be
accounted for without resorting to the hypothesis of the
existence of a peculiar mode or form of force not yet dis-
covered.* And it is more probable that the various effects
are determined by alterations in the intensity of the current,
and in the conducting properties of the fibres than by
different kinds of nerve force. It is surely more in accordance
with reason to endeavour to explain the phenomena by the
action of forces we know something about, than to attribute
them to the influence of other forms or modes of force
which are purely fanciful and fictitious. At any rate it
will be time to call in the aid of such airy nothings when
all attempts to explain the facts by known forces shall have
failed. No one has yet succeeded in rendering it probable
that the nerve current is not electricity while a great number

* Physicists and chemists see no difficulty whatever in assuming the
existence of many modes of force of which they can form no conception,
and think it very satisfactory to refer phenomena which they cannot
understand to some at present undiscovered form or mode of ordinary
motion but if any one attributes these same phenomena to the influence
of some equally undiscovered form of force having no connexion what-
ever with primary energy or motion, he is ridiculed, because, say the
physicists and chemists, " there is but one force in kosmos !"



128 OF MIND.



of well ascertained facts are strongly in favour of this
inference.*

But if conclusive proof had been afforded that the nerve
current was electricity, we should not even in that case have
ascertained the whole truth, and, indeed, should have
advanced but a little way towards a true explanation of nerve
phenomena. For action and work are due not to force
alone, but to the machinery by which the force is con-
ditioned, and this is determined in nerve organs by the
arrangement of the fibres and centres in short, by the
form or structure of the nerve apparatus. And this form
and structure are the result of a long series of changes of
the most complex character, which cannot be fully explained
in the present state of our knowledge, but can be proved
to be dependent upon the germinal matter ; and since it has
been shown that the nervous system at an early period con-
sists entirely of germinal matter, and that in the fully
developed state there is much germinal matter associated
with every part of it that is active, especially all nerve
centres and all peripheral organs, it is obvious that we can-
not advance one step towards the explanation until we have
determined the nature of the changes occurring in the
germinal matter.

But unfortunately we are not yet acquainted with the
exact structure even of the simplest nervous apparatus.

* It is a source of regret to me that my friend Dr. Child should
have so mistaken my views upon this matter, as to tell his readers
("Essays on Physiological Subjects." Second edition, p. 277) that I
look "upon nerve force as a form of vital force," which is a view
contrary to that which I have taught for the last twenty years.



STRUCTURE OF NERVE APPARATUS.



129



We do not know exactly what is essential for nervous action,
and the study of the constitution of the ultimate active
part of nerve tissues is a matter of the greatest difficulty.
But how can we hope, without an accurate knowledge
of the construction of the simplest type of nerve instrument,
to learn much about the working of the most complex
nervous apparatus ? Is not the kind of work performed by
an ordinary machine determined by its construction, and
has not every bit of the work done a particular form or
character stamped upon it which may be traced, as it were,
through the machine to its designer? To say that the work
done by any machine is the result of force, is, therefore, but
a half truth, nay, it is not truth at all, for force alone can-
not do the work or produce the machine which performs
the work. Both the work and the machine exhibit character
or form which was not derived from force, but from mind,
or whatever that may be called which governs, directs,
designs. There is no mechanism, animate or inanimate,
simple or complex, which has resulted only from the influence
of ordinary force ; and although it has been asserted over
and over again that force forms and builds tissues, not the
slightest evidence can be advanced in support of this
arbitrary dogma. It would not be more absurd to assert
that motion designs, originates, and creates, than it is to
maintain that force forms and builds. Nor will all the
energy, authority, and influence the physico-chemical school
can bring to bear, succeed in forcing thoughtful and in-
telligent people to accept such assertions. What strikes one
as most wonderful is that any one should try to make people
believe that ordinary force can form, or has ever formed, any

K



I 3 o OF MIND.



mechanism or other thing in this world capable of working
or acting.

OF MENTAL NERVOUS ACTION.*

After the admissions I have been obliged to make of the
failure of attempts to demonstrate the mere structure of
comparatively simple nerve organs, it may seem almost a
waste of time to venture upon the consideration of the action
of the highest and most complex of them all ; but, in fact,
opinions have been formed and conclusions have been
arrived at upon the subject. There can be little impro-
priety, therefore, in enquiring what is the general conception
of mental nerve action to be derived from contemplating
the structure and arrangement of the tissues concerned, as
far as these have yet been elucidated, in conjunction with
a careful consideration of important general facts and prin-
ciples discovered in studying other and less complex nerve
phenomena.

There can be no doubt that the most important part of
the mechanism engaged in mental action is situated in the
grey matter of the cerebral convolutions ; and the results of
observations upon the structure, as well as experiments
upon the action of other nerve organs, justify us in the con-
clusion that nerve-cells consisting of germinal matter and
formed material, and nerve fibres composed of formed
material only, are the active agents. These are so arranged

* It is hoped that the new facts and observations recorded in this
section will, in some slight degree, atone for the occasional introduction
of what will now be regarded by many modern authorities an obsolete
metaphysic.



OF ME NT A L NER VO US A CTION. 1 3 T

as to constitute a mechanism (if this term may be properly
applied to it) of marvellous perfection and complexity.
The fibres, many being of extreme tenuity, are seen to
interlace with one another, and run in every conceivable
direction, so that when the observer realizes the actual
arrangement as it exists in a very small portion of grey
matter, and this is the utmost he can hope to do, he marvels
how it has been brought about. Though he is convinced
that the whole has been, as it were, laid down according to
a definite plan and has been designed to fulfil a special
purpose, he is unable to picture to himself the gradual
changes by which the result has been attained, and he
cannot discover the laws which have governed them. There
can, however, be no question that our knowledge upon these
matters will increase as investigation advances, although it
is not likely we shall ever be able to explain with exactness
the nature of the power, force, or property which determines
at the first the ultimate structure and exact arrangement the
mechanism shall at length acquire. To state that this is due
to crystallisation, or formifaction, or differentiation, and to
offer any such vague assertion as an explanation of the facts
observed, is not adding to our knowledge.

After having shown (p. 87) in what particulars the for-
mation of the simplest structure differs from the process
of crystallisation, it is unnecessary to discuss the question
with reference to the highest and most complex tissue
known. But even if we could explain the formation of the
complex structure of the cerebral convolutions, we should
have advanced but a little way towards a knowledge of
mental action, for, as it were, behind all this structure,

K 2



132 OF MIND.



operating now on one part of the mechanism, now on
another, is the mind, the will, the thinking power itself.
What is the nature of this, and how does it act upon the
mechanism ? If the conclusions to which I have been led
with regard to the importance of germinal matter in all
ordinary nervous acts be correct, it is almost certain that
mental nervous action is very intimately associated with
changes occurring in a particular kind of living growing
matter. We find a large proportion of germinal matter
present in the grey matter of every kind of brain, and at
every period of life. Even in old age, when the proportion
of germinal matter in the various tissues and organs of the
body has become much reduced, a large amount is still
found in the grey matter of the brain. Moreover, the mental
excitement, wakefulness, and delirium, so remarkable in
many cases of fever and inflammation of the membranes
and superficial portion of the grey matter of the convo-
lutions, are invariably associated with changes in the
germinal matter. In such cases I find the masses of
germinal matter are much larger than in the healthy tissue,
and, in some instances they are twice as large. I have also
seen the enlarged mass in the centre of the caudate nerve-
cells dividing into several masses which resemble pus
corpuscles, and have the same appearance as the pus
corpuscles which are sometimes seen in epithelium
(PL VIIL, p. 34).

But if it be admitted that mental phenomena are entirely
due to changes in the germinal matter of the cerebral con-
volutions, there will be much difference of opinion con-
cerning j.th^. precise way in which this germinal matter

S A



ARE MENTAL ACTIONS REFLEX? 133

operates \ and, in connexion with this question, it must be
admitted there is much room for speculation. I shall
venture to bring under notice the view which, in my opinion,
appears, upon the whole, to be most in accordance with
facts of observation and experiment. But, in the first
place, I propose to refer very briefly to some of the opinions
which have been entertained upon this matter, and to the
general principles upon which these have been based.

Every one will admit that the nerve tissue of the brain
is the instrument through which alone thought works and
mind acts, and I think the facts I have advanced render it
impossible for any one to deny that this instrument is formed
by, or is the result of, changes taking place in germinal
matter; but we are not now inquiring how the material
channels which convey the mandates of the will are formed,
but rather how these mandates originate, from what they
emanate, and what is their nature.

Are Mental Nervous Actions of the Nature of Reflex
Actions ? In all animals which possess nerve organs we
find that an external impression is followed by a certain
internal change, and we explain this by saying that the
physical disturbance is conducted by the afferent nerves to
the nerve centre, whence it is reflected by motor nerves
distributed to the muscles, which are thus caused to contract,
and in many cases the intensity of the contraction varies
with the character of the external impression. Such are
the so-called physical or reflex nervous actions. In mental
nervous actions, however, the impression starts from within,
not from without, and although certain of the lower mental
operations may perhaps without impropriety be included



'34



OF MIND.



in the category of reflex actions, we are all conscious of
others, and these the highest of all nervous phenomena and
peculiar to man himself, which require no external stimulus
for their excitation. These, on the contrary, attain their
highest perfection when the mind is absorbed in contem-
plating its own peculiar states, and has succeeded, as it
were, in withdrawing itself to the utmost possible extent
from the influence of surrounding conditions which operate
physically upon the peripheral portion only of a mechanism,
the central portion of which is in some way under the im-
mediate control of mind. To say, then, in answer to the
question, "What happens in the brain when its possessor
thinks ?" that what he terms ideas and thoughts are excited
by, and are the consequence of, changes occurring outside
him, the result of an external impulse, and due to a sort
of reflex action, appears to me a very unsatisfactory reply,
not approaching an explanation. For, in the first place, if
we admit that mental action results from external impres-
sions, these must be stored up in some unknown manner,
and lie dormant for a long period of time, while actions
which are ordinarily termed reflex are characterized by
immediately following the external impressions. Secondly,
in mental nervous acts, no one has shown that the supposed
mental reflex action bears any relation whatever to the
external physical impulse supposed to excite it ; or how is
to be explained, upon the reflex hypothesis, the fact that
a very slight external impression may excite excessive
mental action, or vice versa ? Thirdly, when the mind is most
active, ordinary reflex phenomena are often in complete
abeyance. Fourthly, the organs concerned in ordinary



MIND AND THE ORGANS OF SENSATION.



135



reflex actions are in an active state long before mental
nervous organs are developed, and it is difficult to see why
the mental apparatus should be so much slower in develop-
ment than other reflex apparatus if it is of this nature.
The reflex mechanism soon attains its highest state of per-
fection. The mental apparatus advances slowly in develop-
ment, but continues to improve for years after it has been
formed, and we can form no conception of the state of per-
fection it may possibly attain. The mental apparatus
exhibits a capacity for altering its structure and of making
itself more perfect. Fifthly, in man, mental actions con-
tinue to improve long after the organs concerned in reflex
actions have begun to deteriorate. And, lastly, a capacity
for mental action of the highest kind is not unfrequently
associated with a nervous system below the average, as
regards the performance of ordinary reflex acts. It is,
therefore, doubtful if mental action is a kind of reflex
nervous action.

Nor can it be maintained that mind is but a consequence
of the action of the organs of the senses ; for, although we
are dependent upon these for obtaining the knowledge, with
which the mind works, the mind itself can have nothing
more to do with these or other organs, seeing that they may
be entirely removed or destroyed, and the mind work as
actively as ever. It cannot obtain new knowledge to
work with ; but the perfection of its working is one thing,
the amount of knowledge acquired is another, and we
know that these things are sometimes even in inverse ratio,
one individual being remarkable for the excellence of his
mental capacity, but having little knowledge, while another



136 OF MIND.



has vast information of which he can make but little use for
lack of intellect.

The Brain is not a Gland. Some have looked upon
brain as a sort of gland by which thoughts and ideas were
formed or secreted, as if thought, which can neither be
touched, weighed, measured, nor in any way physically
estimated, was a thing allied to the bile, the saliva, or the
gastric juice, which are material substances, and can be
analyzed and otherwise experimentally studied. It would
not be more unreasonable to maintain design or will to be
a part of the material framework of the organism, than to
assert that mind, like certain kinds of matter, is secreted.
Thought is no more material than that peculiar capacity
which makes living matter of a certain kind at length
become oak, cabbage, dog, man, &c. Nay, it is further
removed from the material, for while the property or power
referred to influences the very particles of matter, and
makes them take up certain fixed and definite positions,
thought only produces a sort of evanescent vibration, which
results in the expression of ideas which are themselves as
immaterial as the thought itself.

Of Mind as a Function of the Brain. Mental energy
has been regarded as the function of the brain, but if it be so
it is a function of a very different order from that discharged
by other organs. Function implies an act in which will,
purpose, design, are not concerned, and in which material
changes can be proved to take place. The function of a
gland is to produce a secretion. Certain conditions neces-
sitate the production of this or that particular secretion,
which may vary to some extent, according as the conditions



OF MIND AS A FUNCTION OF THE BRAIN. 137

are changed. The function of a muscle is to contract and
become relaxed, but the material change only occurs in
definite directions, necessitated by the structure of the
instrument and the force which acts upon it. The exercise
of choice is neither possible nor conceivable. So, too, with
reference to the function of nerves. These transmit cur-
rents. The paths which the currents are to traverse having
been determined and formed, the currents are developed
and transmitted along the nerves.

But the discharge of function on the part of the organ
of the mind is an operation very different from any of these.
The great characteristic in this case is choice selective
capacity. If the cells of the liver chose for themselves
whether they would secrete bile or not, or determined the
kind of bile to be secreted, or the bile chose for itself by
which ducts it should pass, whether it would flow quickly,


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Online LibraryLionel S. (Lionel Smith) BealeProtoplasm : or, Life, matter, and mind → online text (page 10 of 12)