The Mind and Its Education

G >> George Herbert Betts >> The Mind and Its Education

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THE CEREBELLUM.--Lying just back of the medulla and at the rear part of
the base of the cerebrum is the cerebellum, or "little brain,"
approximately as large as the fist, and composed of a complex
arrangement of white and gray matter. Fibers from the spinal cord enter
this mass, and others emerge and pass on into the cerebrum, while its
two halves also are connected with each other by means of cross fibers.

[Illustration: FIG. 8.--View of the under side of the brain. B, basis of
the crura; P, pons; Mo, medulla oblongata; Ce, cerebellum; Sc, spinal
cord.]

THE CEREBRUM.--The cerebrum occupies all the upper part of the skull
from the front to the rear. It is divided symmetrically into two
hemispheres, the right and the left. These hemispheres are connected
with each other by a small bridge of fibers called the _corpus
callosum_. Each hemisphere is furrowed and ridged with convolutions, an
arrangement which allows greater surface for the distribution of the
gray cellular matter over it. Besides these irregularities of surface,
each hemisphere is marked also by two deep clefts or _fissures_--the
fissure of Rolando, extending from the middle upper part of the
hemisphere downward and forward, passing a little in front of the ear
and stopping on a level with the upper part of it; and the fissure of
Sylvius, beginning at the base of the brain somewhat in front of the
ear and extending upward and backward at an acute angle with the base
of the hemisphere.

[Illustration: FIG. 9.--Diagrammatic side view of brain, showing
cerebellum (CB) and medulla oblongata (MO). F' F'' F''' are placed on
the first, second, and third frontal convolutions, respectively; AF, on
the ascending frontal; AP, on the ascending parietal; M, on the
marginal; A, on the angular. T' T'' T''' are placed on the first,
second, and third temporal convolutions. R-R marks the fissure of
Rolando; S-S, the fissure of Sylvius; PO, the parieto-occipital
fissure.]

The surface of each hemisphere may be thought of as mapped out into four
lobes: The frontal lobe, which includes the front part of the hemisphere
and extends back to the fissure of Rolando and down to the fissure of
Sylvius; the parietal lobe, which lies back of the fissure of Rolando
and above that of Sylvius and extends back to the occipital lobe; the
occipital lobe, which includes the extreme rear portion of the
hemisphere; and the temporal lobe, which lies below the fissure of
Sylvius and extends back to the occipital lobe.

THE CORTEX.--The gray matter of the hemispheres, unlike that of the
cord, lies on the surface. This gray exterior portion of the cerebrum is
called the _cortex_, and varies from one-twelfth to one-eighth of an
inch in thickness. The cortex is the seat of all consciousness and of
the control of voluntary movement.

[Illustration: FIG. 10.--Different aspects of sections of the spinal
cord and of the roots of the spinal nerves from the cervical region: 1,
different views of anterior median fissure; 2, posterior fissure; 3,
anterior lateral depression for anterior roots; 4, posterior lateral
depression for posterior roots; 5 and 6, anterior and posterior roots,
respectively; 7, complete spinal nerve, formed by the union of the
anterior and posterior roots.]

THE SPINAL CORD.--The spinal cord proceeds from the base of the brain
downward about eighteen inches through a canal provided for it in the
vertebrae of the spinal column. It is composed of white matter on the
outside, and gray matter within. A deep fissure on the anterior side and
another on the posterior cleave the cord nearly in twain, resembling the
brain in this particular. The gray matter on the interior is in the form
of two crescents connected by a narrow bar.

The _peripheral_ nervous system consists of thirty-one pairs of
_nerves_, with their end-organs, branching off from the cord, and twelve
pairs that have their roots in the brain. Branches of these forty-three
pairs of nerves reach to every part of the periphery of the body and to
all the internal organs.

[Illustration: FIG. 11.--The projection fibers of the brain. I-IX, the
first nine pairs of cranial nerves.]

It will help in understanding the peripheral system to remember that a
_nerve_ consists of a bundle of neurone fibers each wrapped in its
medullary sheath and sheath of Schwann. Around this bundle of neurones,
that is around the nerve, is still another wrapping, silvery-white,
called the neurilemma. The number of fibers going to make up a nerve
varies from about 5,000 to 100,000. Nerves can easily be identified in a
piece of lean beef, or even at the edge of a serious gash in one's own
flesh!

Bundles of sensory fibers constituting a sensory nerve root enter the
spinal cord on the posterior side through holes in the vertebrae. Similar
bundles of motor fibers in the form of a motor nerve root emerge from
the cord at the same level. Soon after their emergence from the cord,
these two nerves are wrapped together in the same sheath and proceed in
this way to the periphery of the body, where the sensory nerve usually
ends in a specialized _end-organ_ fitted to respond to some certain
stimulus from the outside world. The motor nerve ends in minute
filaments in the muscular organ which it governs. Both sensory and motor
nerves connect with fibers of like kind in the cord and these in turn
with the cortex, thus giving every part of the periphery direct
connection with the cortex.

[Illustration: FIG. 12.--Schematic diagram showing association fibers
connecting cortical centers with each other.--After JAMES and STARR.]

The _end-organs_ of the sensory nerves are nerve masses, some of them,
as the taste buds of the tongue, relatively simple; and others, as the
eye or ear, very complex. They are all alike in one particular; namely,
that each is fitted for its own particular work and can do no other.
Thus the eye is the end-organ of sight, and is a wonderfully complex
arrangement of nerve structure combined with refracting media, and
arranged to respond to the rapid ether waves of light. The ear has for
its essential part the specialized endings of the auditory nerve, and is
fitted to respond to the waves carried to it in the air, giving the
sensation of sound. The end-organs of touch, found in greatest
perfection in the finger tips, are of several kinds, all very
complicated in structure. And so on with each of the senses. Each
particular sense has some form of end-organ specially adapted to respond
to the kind of stimulus upon which its sensation depends, and each is
insensible to the stimuli of the others, much as the receiver of a
telephone will respond to the tones of our voice, but not to the touch
of our fingers as will the telegraph instrument, and _vice versa_. Thus
the eye is not affected by sounds, nor touch by light. Yet by means of
all the senses together we are able to come in contact with the material
world in a variety of ways.

5. LOCALIZATION OF FUNCTION IN THE NERVOUS SYSTEM

DIVISION OF LABOR.--Division of labor is the law in the organic world as
in the industrial. Animals of the lowest type, such as the amoeba, do
not have separate organs for respiration, digestion, assimilation,
elimination, etc., the one tissue performing all of these functions. But
in the higher forms each organ not only has its own specific work, but
even within the same organ each part has its own particular function
assigned. Thus we have seen that the two parts of the neurone probably
perform different functions, the cells generating energy and the fibers
transmitting it.

It will not seem strange, then, that there is also a division of labor
in the cellular matter itself in the nervous system. For example, the
little masses of ganglia which are distributed at intervals along the
nerves are probably for the purpose of reenforcing the nerve current,
much as the battery cells in the local telegraph office reenforce the
current from the central office. The cellular matter in the spinal cord
and lower parts of the brain has a very important work to perform in
receiving messages from the senses and responding to them in directing
the simpler reflex acts and movements which we learn to execute without
our consciousness being called upon, thus leaving the mind free from
these petty things to busy itself in higher ways. The cellular matter of
the cortex performs the highest functions of all, for through its
activity we have consciousness.

[Illustration: FIG. 13.--Side view of left hemisphere of human brain,
showing the principal localized areas.]

The gray matter of the cerebellum, the medulla, and the cord may receive
impressions from the senses and respond to them with movements, but
their response is in all cases wholly automatic and unconscious. A
person whose hemispheres had been injured in such a way as to interfere
with the activity of the cortex might still continue to perform most if
not all of the habitual movements of his life, but they would be
mechanical and not intelligent. He would lack all higher consciousness.
It is through the activity of this thin covering of cellular matter of
the cerebrum, the _cortex_, that our minds operate; here are received
stimuli from the different senses, and here sensations are experienced.
Here all our movements which are consciously directed have their origin.
And here all our thinking, feeling, and willing are done.

DIVISION OF LABOR IN THE CORTEX.--Nor does the division of labor in the
nervous system end with this assignment of work. The cortex itself
probably works essentially as a unit, yet it is through a shifting of
tensions from one area to another that it acts, now giving us a
sensation, now directing a movement, and now thinking a thought or
feeling an emotion. Localization of function is the rule here also.
Certain areas of the cortex are devoted chiefly to sensations, others to
motor impulses, and others to higher thought activities, yet in such a
way that all work together in perfect harmony, each reenforcing the
other and making its work significant. Thus the front portion of the
cortex seems to be devoted to the higher thought activities; the region
on both sides of the fissure of Rolando, to motor activities; and the
rear and lower parts to sensory activities; and all are bound together
and made to work together by the association fibers of the brain.

In the case of the higher thought activities, it is not probable that
one section of the frontal lobes of the cortex is set apart for
thinking, one for feeling, and one for willing, etc., but rather that
the whole frontal part of the cortex is concerned in each. In the motor
and sensory areas, however, the case is different; for here a still
further division of labor occurs. For example, in the motor region one
small area seems connected with movements of the head, one with the arm,
one with the leg, one with the face, and another with the organs of
speech; likewise in the sensory region, one area is devoted to vision,
one to hearing, one to taste and smell, and one to touch, etc. We must
bear in mind, however, that these regions are not mapped out as
accurately as are the boundaries of our states--that no part of the
brain is restricted wholly to either sensory or motor nerves, and that
no part works by itself independently of the rest of the brain. We name
a tract from the predominance of nerves which end there, or from the
chief functions which the area performs. The motor localization seems to
be the most perfect. Indeed, experimentation on the brains of monkeys
has been successful in mapping out motor areas so accurately that such
small centers as those connected with the bending of one particular leg
or the flexing of a thumb have been located. Yet each area of the cortex
is so connected with every other area by the millions of association
fibers that the whole brain is capable of working together as a unit,
thus unifying and harmonizing our thoughts, emotions, and acts.

6. FORMS OF SENSORY STIMULI

Let us next inquire how this mechanism of the nervous system is acted
upon in such a way as to give us sensations. In order to understand
this, we must first know that all forms of matter are composed of minute
atoms which are in constant motion, and by imparting this motion to the
air or the ether which surrounds them, are constantly radiating energy
in the form of minute waves throughout space. These waves, or
radiations, are incredibly rapid in some instances and rather slow in
others. In sending out its energy in the form of these waves, the
physical world is doing its part to permit us to form its acquaintance.
The end-organs of the sensory nerves must meet this advance half-way,
and be so constructed as to be affected by the different forms of energy
which are constantly beating upon them.

[Illustration: FIG. 14.--The prism's analysis of a bundle of light rays.
On the right are shown the relation of vibration rates to temperature
stimuli, to light and to chemical stimuli. The rates are given in
billions per second.--After WITMER.]

THE END-ORGANS AND THEIR RESPONSE TO STIMULI.--Thus the radiations of
ether from the sun, our chief source of light, are so rapid that
billions of them enter the eye in a second of time, and the retina is of
such a nature that its nerve cells are thrown into activity by these
waves; the impulse is carried over the optic nerve to the occipital lobe
of the cortex, and the sensation of sight is the result. The different
colors also, from the red of the spectrum to the violet, are the result
of different vibration rates in the waves of ether which strike the
retina; and in order to perceive color, the retina must be able to
respond to the particular vibration rate which represents each color.
Likewise in the sense of touch the end-organs are fitted to respond to
very rapid vibrations, and it is possible that the different qualities
of touch are produced by different vibration rates in the atoms of the
object we are touching. When we reach the ear, we have the organ which
responds to the lowest vibration rate of all, for we can detect a sound
made by an object which is vibrating from twenty to thirty times a
second. The highest vibration rate which will affect the ear is some
forty thousand per second.

Thus it is seen that there are great gaps in the different rates to
which our senses are fitted to respond--a sudden drop from billions in
the case of the eye to millions in touch, and to thousands or even tens
in hearing. This makes one wonder whether there are not many things in
nature which man has never discovered simply because he has not the
sense mechanism enabling him to become conscious of their existence.
There are undoubtedly "more things in heaven and earth than are dreamt
of in our philosophy."

DEPENDENCE OF THE MIND ON THE SENSES.--Only as the senses bring in the
material, has the mind anything with which to build. Thus have the
senses to act as messengers between the great outside world and the
brain; to be the servants who shall stand at the doorways of the
body--the eyes, the ears, the finger tips--each ready to receive its
particular kind of impulse from nature and send it along the right path
to the part of the cortex where it belongs, so that the mind can say, "A
sight," "A sound," or "A touch." Thus does the mind come to know the
universe of the senses. Thus does it get the material out of which
memory, imagination, and thought begin. Thus and only thus does the mind
secure the crude material from which the finished superstructure is
finally built.

CHAPTER IV

MENTAL DEVELOPMENT AND MOTOR TRAINING

Education was long looked upon as affecting the mind only; the body was
either left out of account or neglected. Later science has shown,
however, that the mind cannot be trained _except as the nervous system
is trained and developed_. For not sensation and the simpler mental
processes alone, but memory, imagination, judgment, reasoning and every
other act of the mind are dependent on the nervous system finally for
their efficiency. The little child gets its first mental experiences in
connection with certain movements or acts set up reflexly by the
pre-organized nervous system. From this time on movement and idea are so
inextricably bound together that they cannot be separated. The mind and
the brain are so vitally related that it is impossible to educate one
without performing a like office for the other; and it is likewise
impossible to neglect the one without causing the other to suffer in its
development.

1. FACTORS DETERMINING THE EFFICIENCY OF THE NERVOUS SYSTEM

DEVELOPMENT AND NUTRITION.--Ignoring the native differences in nervous
systems through the influence of heredity, the efficiency of a nervous
system is largely dependent on two factors: (1) The development of the
cells and fibers of which it is composed, and (2) its general tone of
health and vigor. The actual number of cells in the nervous system
increases but little if at all after birth. Indeed, it is doubtful
whether Edison's brain and nervous system has a greater number of cells
in it than yours or mine. The difference between the brain of a genius
and that of an ordinary man is not in the _number_ of cells which it
contains, but rather in the development of the cells and fibers which
are present, potentially, at least, in every nervous system. The
histologist tells us that in the nervous system of every child there are
tens of thousands of cells which are so immature and undeveloped that
they are useless; indeed, this is the case to some degree in every adult
person's nervous system as well. Thus each individual has inherent in
his nervous system potentialities of which he has never taken advantage,
the utilizing of which may make him a genius and the neglecting of which
will certainly leave him on the plane of mediocrity. The first problem
in education, then, is to take the unripe and inefficient nervous system
and so develop it in connection with the growing mind that the
possibilities which nature has stored in it shall become actualities.

UNDEVELOPED CELLS.--Professor Donaldson tells us on this point that: "At
birth, and for a long time after, many [nervous] systems contain cell
elements which are more or less immature, not forming a functional part
of the tissue, and yet under some conditions capable of further
development.... For the cells which are continually appearing in the
developing cortex no other source is known than the nuclei or granules
found there in its earliest stages. These elements are metamorphosed
neuroblasts--that is, elementary cells out of which the nervous matter
is developed--which have shrunken to a volume less than that which they
had at first, and which remain small until, in the subsequent process of
enlargement necessary for their full development, they expand into
well-marked cells. Elements intermediate between these granules and the
fully developed cells are always found, even in mature brains, and
therefore it is inferred that the latter are derived from the former.
The appearances there also lead to the conclusion that many elements
which might possibly develop in any given case are far beyond the number
that actually does so.... The possible number of cells latent and
functional in the central system is early fixed. At any age this number
is accordingly represented by the granules as well as by the cells which
have already undergone further development. During growth the proportion
of developed cells increases, and sometimes, owing to the failure to
recognize potential nerve cells in the granules, the impression is
carried away that this increase implies the formation of new elements.
As has been shown, such is not the case."[1]

DEVELOPMENT OF NERVE FIBERS.--The nerve _fibers_, no less than the
cells, must go through a process of development. It has already been
shown that the fibers are the result of a branching of cells. At birth
many of the cells have not yet thrown out branches, and hence the fibers
are lacking; while many of those which are already grown out are not
sufficiently developed to transmit impulses accurately. Thus it has been
found that most children at birth are able to support the weight of the
body for several seconds by clasping the fingers around a small rod, but
it takes about a year for the child to become able to stand. It is
evident that it requires more actual strength to cling to a rod than to
stand; hence the conclusion is that the difference is in the earlier
development of the nerve centers which have to do with clasping than of
those concerned in standing. Likewise the child's first attempts to feed
himself or do any one of the thousand little things about which he is so
awkward, are partial failures not so much because he has not had
practice as because his nervous machinery connected with those movements
is not yet developed sufficiently to enable him to be accurate. His
brain is in a condition which Flechsig calls "unripe." How, then, shall
the undeveloped cells and system ripen? How shall the undeveloped cells
and fibers grow to full maturity and efficiency?

2. DEVELOPMENT OF NERVOUS SYSTEM THROUGH USE

IMPORTANCE OF STIMULUS AND RESPONSE.--Like all other tissues of the
body, the nerve cells and fibers are developed by judicious use. The
sensory and association centers require the constant stimulus of nerve
currents running in from the various end-organs, and the motor centers
require the constant stimulus of currents running from them out to the
muscles. In other words, the conditions upon which both motor and
sensory development depend are: (1) A rich environment of sights and
sounds and tastes and smells, and everything else which serves as proper
stimulus to the sense organs, and to every form of intellectual and
social interest; and (2) no less important, an opportunity for the
freest and most complete forms of response and motor activity.

[Illustration: FIG. 15.--Schematic transverse section of the human brain
showing the projection of the motor fibers, their crossing in the
neighborhood of the medulla, and their termination in the different
areas of localized function in the cortex. S, fissure of Sylvius; M, the
medulla; VII, the roots of the facial nerves.]

An illustration of the effects of the lack of sensory stimuli on the
cortex is well shown in the case of Laura Bridgman, whose brain was
studied by Professor Donaldson after her death. Laura Bridgman was born
a normal child, and developed as other children do up to the age of
nearly three years. At this time, through an attack of scarlet fever,
she lost her hearing completely and also the sight of her left eye. Her
right eye was so badly affected that she could see but little; and it,
too, became entirely blind when she was eight. She lived in this
condition until she was sixty years old, when she died. Professor
Donaldson submitted the cortex of her brain to a most careful
examination, also comparing the corresponding areas on the two
hemispheres with each other. He found that as a whole the cortex was
thinner than in the case of normal individuals. He found also that the
cortical area connected with the left eye--namely, the right occipital
region--was much thinner than that for the right eye, which had retained
its sight longer than the other. He says: "It is interesting to notice
that those parts of the cortex which, according to the current view,
were associated with the defective sense organs were also particularly
thin. The cause of this thinness was found to be due, at least in part,
to the small size of the nerve cells there present. Not only were the
large and medium-sized cells smaller, but the impression made on the
observer was that they were also less numerous than in the normal
cortex."

EFFECT OF SENSORY STIMULI.--No doubt if we could examine the brain of a
person who has grown up in an environment rich in stimuli to the eye,
where nature, earth, and sky have presented a changing panorama of color
and form to attract the eye; where all the sounds of nature, from the
chirp of the insect to the roar of the waves and the murmur of the
breeze, and from the softest tones of the voice to the mightiest sweep
of the great orchestra, have challenged the ear; where many and varied
odors and perfumes have assailed the nostrils; where a great range of
tastes have tempted the palate; where many varieties of touch and
temperature sensations have been experienced--no doubt if we could
examine such a brain we should find the sensory areas of the cortex
excelling in thickness because its cells were well developed and full
sized from the currents which had been pouring into them from the
outside world. On the other hand, if we could examine a cortex which had
lacked any one of these stimuli, we should find some area in it
undeveloped because of this deficiency. Its owner therefore possesses
but the fraction of a brain, and would in a corresponding degree find
his mind incomplete.

NECESSITY FOR MOTOR ACTIVITY.--Likewise in the case of the motor areas.
Pity the boy or girl who has been deprived of the opportunity to use
every muscle to the fullest extent in the unrestricted plays and games
of childhood. For where such activities are not wide in their scope,
there some areas of the cortex will remain undeveloped, because unused,
and the person will be handicapped later in his life from lack of skill
in the activities depending on these centers. Halleck says in this
connection: "If we could examine the developing motor region with a
microscope of sufficient magnifying power, it is conceivable that we
might learn wherein the modification due to exercise consists. We might
also, under such conditions, be able to say, 'This is the motor region
of a piano player; the modifications here correspond precisely to those
necessary for controlling such movements of the hand.' Or, 'This is the
motor tract of a blacksmith; this, of an engraver; and these must be the
cells which govern the vocal organs of an orator.'" Whether or not the
microscope will ever reveal such things to us, there is no doubt that
the conditions suggested exist, and that back of every inefficient and
awkward attempt at physical control lies a motor area with its cells
undeveloped by use. No wonder that our processes of learning physical
adjustment and control are slow, for they are a growth in the brain
rather than a simple "learning how."

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