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IC-NRLF




ORY



HERING



UNIVERSITY OF CALIFORNIA

MEDICAL CENTER LIBRARY

SAN FRANCISCO





Ex Libris
C. K. OGDEN



MEMORY

LECTURES ON THE SPECIFIC ENERGIES
OF THE NERVOUS SYSTEM



BY

PROF. EWALD.HERING
I . -'

UNIVERSITY OF LEIPZIG






FOURTH EDITION, ENLARGED



1913

THE OPEN COURT PUBLISHING COMPANY
CHICAGO LONDON



COPYRIGHT BY

THE OPEN COURT PUBLISHING COMPANY
1913









PUBLISHERS' PREFACE



DR. EWALD HERING, professor of psychology at the Uni-
versity of Leipsic, is not a voluminous writer, but he has done
considerable work in investigating the nature of specific color-
sensations and the processes of life. The results of his
studies have largely been accepted by his colleagues and his
little essay "On Memory" which contains a popular exposi-
tion of this fundamental problem has become classical. Con-
cerning its significance for physiology, Prof Michael Foster
of the University of Cambridge says in the Encyclopedia
Britannica, Vol. XIX, page 22:

"If the ingenious speculations of Hering, that specific color-
sensations are due to the relation of assimilation (anabolism)
to dissimilation (katabolism) of protoplasmic visual sub-
stances in the retina or in the brain, should finally pass from
the condition of speculation to that of demonstrated truth,
we should be brought face to face with the fact that the mere
act of building up or the mere act of breaking down affects
the condition of protoplasm in other ways than the one which
we have hitherto considered, viz., that the building up pro-
vides energy to be set free and the breaking down lets the
energy forth. In Hering's conception the mere condition of
the protoplasm, whether it is largely built up or largely broken
down, produces effects which result in a particular state of
consciousness. Now, whatever views we may take of con-
sciousness, we must suppose that an affection of consciousness
is dependent on a change in some material. But in the case
of color-sensations that material cannot be the visual sub-
stance itself, but some other substance. That is to say, accord-
ing to Hering's views, the mere condition of the visual sub-
stance as distinct from a change in that condition determines
the changes in the other substance which is the basis of con-
sciousness. So that, if Hering's conception be a true one



(and the arguments in favor of it, if not wholly conclusive are
at least serious), we are led to entertain the idea that, in
addition to the rough propagation of explosive decompositions,
there are continually passing from protoplasm to protoplasm
delicate touches compared with which the nervous impulses
which with such difficulty the galvanometer makes known to
us are gross and coarse shocks. And it is at least possible,
if not probable (indeed present investigations seem rapidly
tending in this direction) that an extension of Hering's view,
with such modifications as future inquiry may render neces-
sary, to other processes than visual sensations, more especially
to the inner working of the central nervous system, may not
only carry us a long way on towards understanding inhibition
and spontaneous activity but may lay the foundation of a
new molecular physiology. This however is speculative and
dangerous ground, but it seemed desirable to touch upon
it since it illustrates a possible or probable new departure.
What we have said of it and of the more manageable mole-
cular problems of physiology will perhaps show that, vast and
intricate as is the maze before the physiologist of to-day, he
has in his hand a clue which promises, at least, to lead him
far on through it."

Two other popular expositions of highly important problems
in physiology have been translated for the Open Court Pub-
lishing Company and are included in this edition, since
their extraordinary significance renders it desirable that
they be made accessible to the English reading public.

PAUL CARUS.
Chicago, September, 1913.



CONTENTS

LECTURE I Page

MEMORY AS A GENERAL FUNCTION - 1

LECTURE II

THE SPECIFIC ENERGIES OF THE
NERVOUS SYSTEM 25

LECTURE III

THE THEORY OF NERVE-ACTIVITY - 43

INDEX 71



MEMORY AS A GENERAL FUNCTION OF
ORGANIZED MATTER 1



WHEN a scientist leaves behind him his own spe-
cial province of inquiry to make an excursion
into the realm of philosophy, he may cherish the hope
of solving the great problem which underlies the minor
questions to which he has devoted his life, but he
must be prepared for being secretly discredited with
those of his colleagues who still remain quietly at work
with the subjects of their specialty, and at the same
time must expect the mistrust of the rightful represen-
tatives of the empire of speculation. He runs the risk
of losing his reputation with the former and of gaining
nothing with the latter.

The subject for which I ask your attention on this
occasion is a most alluring one; but in accordance
with what I have just said, it is not my intention to
abandon the domain of natural science to which my
studies have been devoted, but only to attempt to reach
a higher ground from which we may enjoy a freer and
more general survey.

It will seem in the course of this paper as though

'An address delivered before the Imperial Academy of Sciences, at
Vienna, May 30, 1870.



2 MEMORY.

I am not always faithful to this purpose; for I shall
often have occasion to tarry in the province of psy-
chology. Consequently, for my own justification, al-
low me to point out the extent to which psychological
inquiries form, not only an allowable, but also an in-
dispensable accompaniment of physiological research.

The animal human organism with its material
mechanism is the subject of physiology. But con-
sciousness is a simultaneous datum. Besides the mov-
ing of the atoms of the brain according to certain laws,
the inner life of our soul is woven of sensations and
conceptions, of feeling and will.

Everyone experiences this in himself ; and it is a fact
also which beams forth from the faces of his fellow-
beings. It breathes in the life of all higher organized
animals, and even the simplest creatures bear some
vestiges of it. Who can fix the limit of empsychosis
in the empire of organic nature?

In the face of such a dual aspect of organic life
jvhat can physiology best do? Shall science be blind-
folded on the one side, in order the better to compre-
hend the other?

As long as a physiologist is a mere physicist and
I use the word physicist now in its most comprehensive
sense his method of inquiring into organic nature is
altogether one-sided. But it is justly so. As a crystal
is to the mineralogist, so to the physiologist of this
class is a man or an animal a mere lump of matter.
An animal feels, of course, pleasure and pain, and with
the material phenomena of the human body mental
emotions are connected; but that is no reason why a
physicist should take a different view of the corporeal
existence of man, who to him remains a compound of



MEMORY. 3

matter subject to the same irrefragable laws as stones
and plants; like a machine, his motions are casually
connected with each other and dependent upon their
surroundings.

Neither sensation nor conception nor conscious will
can form a link in the chain of the material processes
of which the physical life of organisms consists. When
I answer a question, the initial material process is con-
ducted from the organ of hearing by sensory nerve-
fibers to the brain, and must pass through it as a ma-
terial process in order to reach the motor nerves of the
organ of speech. It cannot, after having arrived at a
certain spot in the brain, enter into something imma-
terial, in order to be re-transformed, in some other
place of the brain, into another material process. A
caravan in the desert might just as well enter the oasis
of a mirage, to return thence after a refreshing rest
into the actual desert.

Such is the physiologist, so far as he is a physicist.
He stands behind the stage and carefully observes the
working of the machinery and the movements of the
actors, but he misses the meaning of the action which
a spectator readily understands. Now, should a phys-
iologist never be allowed to change his point of view?

True, his object is not to understand a world of
concepts, but a world of realities. Nevertheless, if
now and then he changes his point of observation and
looks at things from the other side, or at least accepts
from trustworthy observers the results of their expe-
rience, he will derive much benefit from such an at-
titude and will better comprehend both the apparatus
he is studying and its methods of working.

For this very reason psychology is an indispen-



4 MEMORY.

sable auxiliary of physiology. If the latter science has
hitherto not made much use of the former, it has not
been wholly the fault of physiology. Psychology has
only lately worked her fields with the plough of induc-
tion, and it is only in such a soil that the fruits can be
raised for which the physiologist has most need.

The neurologist is thus placed between the phys-
icist and the psychologist. The physicist regards the
causal continuity of material processes as the basis of
his inquiry; the thoughtful psychologist seeks for the
laws of conscious life, and in so doing works accord-
ing to the rules of inductive methods, assuming the va-
lidity of an inalterable order. Now, if the physiologist
learns from simple self-observation that conscious life
is dependent upon his bodily functions, and vice versa
that his body to some extent is subject to his will, he
has only to assume that this interdependence of mind
and body is arranged according to certain laws, and the
link is found which connects the science of matter with
the science of consciousness.

Thus considered, phenomena of consciousness ap-
pear to be functions of material changes of organized
substance, and vice versa. As I wish to avoid all mis-
conceptions, let me mention (although it is included
in the term function) that the converse of this asser-
tion means that material processes of the cerebral sub-
stance also appear to be functions of the phenomena
of consciousness. For if two variables are dependent
upon each other according to certain laws, a change
of the one demanding a change of the other and vice
versa, the one is called a function of the other.

This does not mean that the two variables, matter
and consciousness, are connected with each other as



MEMORY. 5

cause and effect; for we do not know anything about
that. Materialism explains consciousness as the out-
come of matter, idealism takes the opposite view, and
a third position might postulate the identity of spirit
and matter. The physiologist, as such, should not
meddle with such questions.

Aided by this hypothesis of a functional connec-
tion between spiritual and material facts, modern phys-
iology is enabled to bring the phenomena of conscious-
ness within the domain of its inquiry, without leaving
the terra firnia of scientific method. The physiolo-
gist, as a physicist, observes how a beam of light, a
wave of sound, or a vibration of heat affects the organs
of sensation; how they enter the nerves, are trans-
formed into an irritation of the nerve-fibers and con-
ducted to the brain-cells. Here he loses all trace of
them. On the other hand, he observes a spoken word
coming from the mouth of a speaking person ; he sees
the person move his limbs, and finds these movements
are caused by muscular contractions produced through
motor nerves irritated by the nerve-cells of the central
organs. Here again he is at his wit's end. The bridge
which should lead him from the irritated sensory nerve
to the irritated motor nerve, is indicated in the laby-
rinthian connections of the nerve-cells, but he lacks a
clue to the infinitely involved processes which are in-
terposed in this place.

It is here the physiologist successfully changes his
point of view. Here matter no longer reveals the
secret to his inquiring glance; but he finds it in the
mirror of consciousness, not directly, but indirectly and
figuratively yet in lawful connection with what he
inquires into. Here, in observing how one idea re-



6 MEMORY.

places another, how conception rises from sensations,
how Will starts from conceptions and how emotions
and thoughts interweave, he will suppose that there is
a corresponding series of interconnected material proc-
esses accompanying the whole action of conscious life
according to the law of the functional interdependence
of matter and consciousness.

After this introduction I may venture to combine
under one point of view a long series of phenomena
which are apparently widely separated and belong
partly to the conscious, partly to the unconscious life,
of organic nature. These we shall consider, compre-
hensively, as the results (Aeusserungen) of one and
the same faculty of organized matter, viz., memory, or
the faculty of reproduction.

Memory, as generally understood, is merely the
faculty of voluntarily reproducing ideas or a series of
ideas. But if faces and events of past days appear,
uncalled for, and take possession of our consciousness,
should we not also call this with the same right, re-
membering? We are justly entitled to include in the
concept of memory all involuntary reproductions of
sensations, conceptions, emotions, and aspirations. In
doing so, memory becomes. an original faculty, being
at once the source and unification of all conscious life.

It is well known that sensuous perceptions, if con-
stantly repeated for a time, are impressed into what we
call the memory of the senses in such a way that often
after hours, and even after we have been busy with a
hundred other things, they suddenly return into con-
sciousness in the full sensuous vivacity of their original
perception. We thus experience how whole groups
of sensations, properly regulated in their spatial



MEMORY. 7

and temporal connections, are so vividly reproduced as
to be like reality itself. This clearly shows that after
the extinction of conscious sensations, some material
vestiges still remain in our nervous system, implying
a change of its molecular and atomic structure, by
which the nervous substance is enabled to reproduce
such physical processes as are connected with the corre-
sponding physical processes of sensations and percep-
tions.

Every one can observe in his daily and hourly ex-
perience such phenomena of sense-memory, although
in fainter forms. Consciousness produces legends of
more or less faded memory-pictures of former sensu-
ous perceptions. They partly are called in voluntarily,
and partly crowd in spontaneously. Faces of absent
persons come and go as pale and volatile shadows, and
sounds of melodies which have long died away haunt
us, if not audibly, yet perceptibly.

Of many things and events, especially if they have
been perceived only once or very superficially, merely
single, unusually striking qualities are reproducible ; of
other things only those qualities are reproducible which
have been remarked on former occasions, our brain
being in this way prepared for their reception. Such
are responded to more strongly and enter consciousness
more easily and energetically. Thus their ability of
being reproduced increases. In this way, what is com-
mon to many things and hence has been most fre-
quently perceived, will by and by be so reproducible
as to be easily called forth by a slight internal impulse,
without any exterior and real stimulus. Such a sen-
sation, which is, as it were, produced internally for
instance, the idea of white is not of the same vivacity



8 MEMORY.

as the sensation of white color externally produced by
white light. But it is, after all, essentially the same,
being a weak repetition of the same material brain-
process and of the same conscious sensation. Thus
the idea of white is an almost imperceptibly weak per-
ception.

In this way the qualities which are common to
many things are, as it were, separated from them in
entering our memory. They attain an independent ex-
istence in consciousness as concepts or ideas, and the
whole rich world of our concepts and ideals is con-
structed of these materials of memory.

It is easily seen that memory is not so much a fac-
ulty of conscious as of unconscious life. What was
conscious to me yesterday and again becomes con-
scious to me to-day, where has it been in the interim?
It did not exist as a fact of consciousness, and yet it
returned. Our concepts appear on the stage of con-
sciousness only transiently ; they quickly disappear be-
hind the scenes, ,to make room for others. Only on
the stage are they conceptions, as an actor is king only
on the stage. As what do they remain behind the
scenes ? For we know that they exist somehow ; a cue
only is needed to make them reappear. They do not
continue as conceptions, but as certain dispositions of
the nervous substance (Stiinmung der Nervcnsub-
stanz) by virtue of which the same sound that was
produced yesterday can again be evoked to-day.

Innumerable reproductions of organic processes in
our cerebral substance constantly combine with each
other, according to certain laws, each in its turn stimu-
lating another; but the phenomenon of consciousness
is not necessarily joined with each link of such a series



MEMORY. 9

of processes. Accordingly, chains of conceptions some-
times seem to lack proper connections when conveyed
to the cerebral substance through processes unaccom-
pained by consciousness. Therefore, also, a long se-
ries of ideas may follow the correct logical order and
have a proper organic structure, although the differ-
ent premises that are indispensable to such combina-
tion do not become conscious at all. Some ideas
emerge from unconscious life into consciousness, with-
out being connected with any conscious conception
whatever; others sink into unconsciousness without
ever having been connected with conscious ideas.

Between what I am to-day and what I was yester-
day, a gap of unconsciousness lies, the nocturnal
sleep ; and it is only memory which spans a bridge be-
tween my to-day and my yesterday. Who can hope to
unravel the manifold and intricately infertwined tis-
sues of the inner life by simply following the threads
of consciousness ? You may as well gather your infor-
mation about the rich organic life of the oceanic world
from those few forms which now and then emerge
from the surface of the sea merely to disappear again
into the depths of the ocean.

Thus the cause which produces the unity of all
single phenomena of consciousness must be looked for
in unconscious life. As we know nothing of this ex-
cept w r hat we learn from our investigations of matter,
and since in a purely empirical consideration, matter
and the unconscious must be regarded as identical, the
physiologist may justly define memory in a wider
sense to be a faculty of the brain, the results of which
to a great extent belong to both consciousness and un-
consciousness.



10 MEMORY.

Every perception of an object in space is a highl
complicated process. For instance, a white ball sue
denly looms up before my eyes. It is necessary, IK
only to convey to consciousness the perception of whil
but the circular periphery of the visible ball as wel
also its globular form, as it is recognized from the di:
tributions of light and shade; then the exact distanc
from my eyes must be considered, and from this \\
form an estimate concerning its size. What an aj
paratus of sensations, perceptions, and conclusions
apparently necessary for accomplishing all this! An
yet the actual perception of the sphere is performe
in a few seconds, without my becoming conscious c
the single processes which construct the whole; tt
result enters my consciousness complete.

The nervous substance faithfully preserves tt
records of processes often performed. All functior
necessary for correct perception, which at first operate
slowly and with difficulty with the constant help of coi
sciousness, are afterwards reproduced summarily an
without an intensity sufficient to push each single lin
of the chain beyond the threshold of consciousnes
Such chains of unconscious nerve processes, which ;
last end in a link accompanied with consciousnes
have been called unconscious chains of perceptions, c
unconscious conclusions; a name which is justifiafr
from the standpoint of psychology. For psycholog
might frequently lose sight of the soul, if unconsciot
states were not taken into consideration. To a phy:
ical consideration, however, unconscious and materi;
mean the same, and a physiology of the unconscious
no philosophy of the unconscious. 2

2 Refers to Von Hartmann's "Philosophy of the Unconscious." 7



MEMORY. 11

Almost all movements which man performs are the
result of long and difficult practice. The harmonious
co-operation of the different muscles, the exactly
gauged amount of work which each one must contrib-
ute to the common labor, must be learned for most
movements with great trouble. How slowly a begin-
ner at the piano finds the single notes, the eye direct-
ing his fingers to the different keys, and then how
marvellous is the play of the virtuoso ! With the swift-
ness of thought each note finds an easy passage through
the eye to the finger, to be performed correspondingly.
One quick glance at the music suffices to transform
into sound a whole series of chords; and a melody
which has been sufficiently practised may be played
while the player's attention is directed to other sub-
jects.

In such a case the will no longer directs each sin-
gle finger to produce the desired movements, and so
close attention is not needed to watch the whole execu-
tion carefully. The will is only commander-in-chief.
The will issues an order, and all the muscles act ac-
cordingly. They continue to work as long as they move
in their customary tracks, till a slight hint of the will
prescribes some other direction.

This would be impossible, if those parts of the cen-
tral nervous system which bring about the movement
were not capable of reproducing entire series of states
of irritation. When they have been previously prac-
tised under a constant accompaniment of conscious
ness, they can be called forth, as it were, independ-
ently on the slightest impulse of consciousness, being
executed more quickly and more perfectly, the oftener
the reproductions have been repeated. All this is pos-



12 MEMORY.

sible only if they remember what they did before. Our
perceptive faculty would forever remain in its lowest
stage if we should consciously construct every single
perception from the given single materials of sensa-
tion. Our voluntary motions would never surpass the
awkwardness of a child, if in every case we should re-
incite with conscious will the different single impulses
and reproduce over again all our single conceptions;
or, to state it briefly, if the nervous motor system
were not endowed with memory, i. e., an unconscious
memory. What is called "force of habit," is the
strength of this memory.

It is to memory that we owe all we are and have.
Ideas and concepts are products of it; each percep-
tion, each thought, each motion is carried by it.
Memory unites all the innumerable single phenomena
of consciousness into one entirety; and as our body
would be dispersed into myriads of atoms if it were
not held together by the attraction of matter, so, but
for the binding power of memory, consciousness
would be dissolved into as many fragments as there
are moments.

We have seen that only a part of the reproductions
of organic processes, as effected by the memory of
nervous substance, enters our consciousness; no less
important parts remain unconscious. And the same
may be proved by numerous facts relating to parts of
the nervous system which are exclusively subservient
to the unconscious processes of life. For the memory
or reproductive faculty of the so-called sympathetic
nervous system is by no means weaker than that
of the brain and the spinal cord. Medical art, to a
great extent, makes good use of this.



MEMORY. 13

In concluding this part of my investigation, let me
leave the subject of nervous substance for a moment
in order to take a cursory view of other organic mat-
ter, where we meet with the same reproductive fac-
ulty, but in a simpler form.

Daily experience teaches us that muscles grow
stronger the oftener they are used. Muscle-fiber, which
in the beginning but feebly responded to the irritation
of a motor nerve, works with more energy the oftener


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