The brain-machine, its power and weakness

Contents

PAGE

The Apology . . . vii

The Introduction . . .1

Introduction

Our lives are governed by two important factors :

Internal forces.

External resistance.

Or we may call it —

1. Our Mental Powers.

2. Our external surroundings, or Environ-

ment.

Thus to a large extent we are the Victims of Fate. We are but machines, yet so complex that there remains much at present unknown. By proper education, and by a knowledge of the machinery of the brain, we may not only improve our condition but may materially aid those who are in touch with us.

I first describe brief! y the structure and mechanism of the brain and nervous system, avoiding technicalities, and occasionally referring to collateral subjects.

I then pass to the mechanism of thought and mind entirely as a popular subject, so that one can erect sound principles which will guide us aright through debatable subjects, and through the many trying periods and conditions which so frequently confront us.

Chapter I. The Ascent Of Man

Though man stands at the top of the ladder in the animal kingdom, it must not be supposed that in construction he is absolutely different from the rest of the animal world.

There is a gradual ascent or development from the lowest to the highest. Each type is the same as the next lower type with something superadded ; while in the higher grades important structures are represented lower down by distinct animals.

Thus we may take the lowest form of life, such as is found in stagnant ponds, the “ Monera ” or “ Monads.” These consist of jelly-like material called Protoplasm without any definite organs, capable of altering its shape (Fig. 1). In this way it pushes out processes to enclose small particles of food, assimilating them.

Protoplasm is the basis of all animal tissues and textures.

Our blood contains two kinds of Corpuscles, red and white. The white are called Leucocytes, and are capable of wandering and changing their form, just like the Monads ; this is called Amoeboid Movement, after the Monad Amoeba (Figs. 2, 3, and 4).

We owe our daily protection to these small organisms. If one of us got a poisoned wound in the skin, it would rapidly swell up, due to the

THE ASCENT OP MAN.

transmigration of these corpuscles to destroy and shut off this poison from the rest of the body. Under the microscope we can see these corpuscles attacking bacilli and bacteria, surrounding them and digesting them. On their activity our recovery depends.

Cilia. — Hig her than the Amoebae are organisms with cilia or lashes, by which they propel themselves in water, or draw food into their rudimentary mouths. If we take a simple sponge we have in it a community like a walled-in city. Some apertures are small, some are large ; they are all connected by canals lined by inhabitants, like a huge Venice or Amsterdam.

The living material is jelly-like and lined with cilia, which waft continuous currents of water, in by the small pores and out by the large, absorbing nourishment from the water (see Figs. 5 and 6). We are dependent on the same kind of cilia to keep our breathing apparatus clean.

The nasal passages and bronchial tubes are lined with cilia, which continually bring up to the throat the dust which we constantly inhale. In asthmatics these cilia are destroyed, hence the violent spasms of coughing to remove irritating dust. The cilia are flat processes like hairs, ^nfo of an inch long. They appear structureless, but, as with Monads, their structure is too minute to unravel. They may be studied under the microscope by examining the gill (or beard) of an oyster (see diagram 7).

The Ear and Eye are with us most complex, but they are gradually evolved from the lower animals in successive stages.

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CHAPTER I.

Thus in the Nautilus family we have the most rudimentary eye. It is a simple fibrous sac, clear in front suggesting our cornea, and protected by cartilages. It contains a crystalline lens, and has a nerve passing backwards to a very rudimentary brain (Figs. 8 and 9).

The ear first of all appears in the Medusa, a bellshaped jelly-fish with tentacles which swims round our coasts ; the larger forms, armed with minute prongs like fish-hooks, may be unpleasant companions when swimming.

The Nautilus is not much more advanced in its order of hearing. Its ear consists of a small sac filled with fluid, containing two or three little chalkstones called Otoliths. The vibrations which these granules receive through the water are carried by delicate nerve th reads from the wall of the sac by a nerve to the rudimentary brain.

Fish have more developed ears, but as it is unpleasant to get water in the ears, Nature lias deprived tliem of the external ear, and ail is boxed in.

Nkrvous System.

This reaches the highest development in man. But we find nerves in the jelly-fish, Medusa, which is very low in the scale.

The Earthworm is low enough for illustration. It is marked by rings which divide the body into segments. Each segment contains a Ganglion or little mass of nerve-cells, from which spring fibres leading to the muscles which enable it to crawl. Thus a chain of nerve-ganglia runs the length of

THE ASCENT OF MAN.

the body. These nerves have no feeling, so that they suffer no pain when mutilated (see Fig. 10).

The same arrangement is carried ont in many of the lower animals. Thus the lobster has chains of ganglia, but of much higher development. In the cray-fish there are thirteen such ganglia. There is one large mass, a rudimentary brain, in front of the mouth ; it sends nerves to the eyes and eye muscles, to the ear sacs and antennae. There are six pairs in the thorax or chest, and six pairs in the abdomen. The ganglia are always connected with each other, forming a chain.

The cockroach is a very respectable individual, with a large rudimentary brain, which sends out nerves as in the cray-fisli.

There is another way in which nerve-ganglia are arranged, as seen in the Snail. There are three chief ganglia, — one in the head, one in the foot, and one in the stomach (see Fig. 11).

These various nerve-gauglia correspond to a distinct nervous system in the human body, called the Sympathetic Nervous System. It is a curious name, and undeserved, for they have no feeling, and might as well be called unsympathetic. They control in the lower animals the necessary functions of life. So in our case they control the heart and blood-vessels, the stomach and its digestive functions, the secretion of glands, saliva and perspiration, and other vital functions. We have a double chain of these ganglia in front of our spine or backbone, and like the snail a large mass at the pit of the stomach ; hence the danger of a blow there. And we also have important masses in the chest and neck.

CHAPTER I.

As soon as we rise to the Fish tribe, and later to the Frogs, Snakes, Birds, and Quadrupeds, we enter another kingdom or division, distinguished by the possession of a backbone or Spinal Column. In the lower types it is a rudimentary rod of cartilage, while in the higher forms it is composed of complex bones joined together to support the skull, ribs, and pelvis, while a bony canal or arch is formed behind to protect the spinal marrow or cord from injury. The spinal cord is a delicate and complicated nerve structure, the route of communication between the body and the brain. The number of vertebras or spinal segments varies in different animals. In man and other mammals there are seven in the neck, twelve in the back, and five in the lumbar region. It is curious to see that a giraffe has no more bones in its neck than we have.

Frogs have only ten vertebras, while some sharks have over 200, and some serpents over 300.

The following diagram (Figs. 12 and 13) shows very plainly the relationship of the nervous system in animals like ourselves, with a spinal cord, to the lower animals which have no spine. In a horizontal section of the latter (Fig. 12) we see a large circle with the digestive tube in the middle, and behind it the nerve-ganglia.

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A similar section of the Vertebrates (Fig. 13) shows the same circle with the sympathetic nerve-ganglia in the position of the ganglia of the Invertebrates ; but in addition there is a bony canal attached to the back of the circle containing the spinal cord. I will return to this subject in the chapter on Development.

Chapter II. The Brain : Its Coverings

The brain is the organ of the mind. It is a most complex machine, delicate in its structure and sensitive in its mechanism. Being of such great importance it requires most careful external protection.

It is made up of two elements, Nerve-cells and Nerve-fibres. These are embedded in a soft substance called Neuroglia, which acts as padding.

The whole brain is enclosed in a dense fibrous case filled up with fluid, so that in reality it floats ; this condition diminishes jar or shock during the movements of the body. Outside the membranous sheath is the skull, and externally the scalp.

The scalp is not ordinary skin, but a thick, tough, elastic hide, capable of resisting injury, and not sensitive to touch or temperature.

The Skull is a strong, thick, bony case, composed of eight bones, separate in infants, united in childflood, firmly welded together in the adult. The face is made up of fourteen bones. The skull varies in thickness in different parts, being as thin as a sixpence over the temple. In other parts it may vary from quarter to three quarters of an inch in different individuals.

CHAPTER II.

There are two layers or plates of bone in the skull. The outside casing is hard and dense, whilst the inner layer is softer and thinner. In children about the age of twelve the brows develop. Under that age the brow is not developed, for the two layers of bone are united.

But at the age of puberty the two layers of the skull separate in the region of the brow to form a cavity which communicates with the nose, and is lined with mucous membrane (Fig. 14, a).

This is evident in severe head colds, when the nasal catarrh spreads up to the brow cavities. As the raised brow represents a cavity filled with air, the phrenologist is wrong in attributing perceptive qualities to it. But the brow has a certain relation to the brain, in that if the brain be poorly developed or wasted the brow would be small, whereas if the brain developed more in the frontal region the brow would be more pushed forward.

The brows may be large on account of extra development of muscles attached to them. These muscles represent the thought and intelligence of the individual in the facial expression.

People of low mental power are usually expressionless.

In old people the skull gets thin by absorption, and the skull may be not thicker than a shilling.

At the back of the ear there is a large bony mass made up of air-cells in connection with the ear.

At the back of the head there is a round lump just above the neck. There is no brain here. It is a thick mass, and the ligament of the neck is attached to it (Fig. 14, b). In the cow and horse

THE BRAIN : ITS COVERINGS.

it is specially developed, oh account of their powerful necks.

In savage races and in criminals there are many irregular bony masses on the skull.

The skull is not symmetrical ; the left side is bigger than the right, and it varies in individuals.

The skull is joined on to the Spinal Column. The mechanism at the top of the spine is such that the head can move backwards and forwards and rotate. The whole spine has a fine S-shaped curvature.

In the lowest fish the spinal column is represented by a mere cartilaginous rod, which in the higher forms becomes segmented and slightly bony, the spinal cord or marrow resting on this backbone. As we ascend the scale two side arches form a protection to the marrow or cord. When we come to frogs, snakes, and birds, we find further developments and improvements, while in man they reach the highest perfection. In him the column is made up of segments or Vertebras. Bach vertebra consists of a body which is solid, and attached behind is welded on a bony round canal, to protect the spinal cord or marrow. There are apertures at the side for the nerves to pass through. (See Fig. 37.)

There are also series of processes and joints to give stability and movement.

The solid bodies of the spine and backbone are separated by buffers of dense fibrous material ; this is to break the jar or shock during active movements. In old people these cushions shrivel and waste more in the front part, so that the spine

CHAPTER II.

shortens and tilts forward. Thus in old age we get smaller and stoop, and incline to rest the chin on the neck.

The membranes of the brain are prolonged downwards, enveloping the spinal marrow, and finally forming sheaths to the nerves.

Chapter III. The Brain : Its Structure

When the tough membranes of the brain are cut through we find a soft pinky-brown, smooth, glistening mass, arranged in folds or convolutions. This is the Cortex, or outer layer of the brain. It is closely covered with a delicate membrane made up of small blood-vessels ; this is called Pia Mater. On section we find the cortex or bark is onty quarter to half an inch in thickness, and the interior of the brain is white and tougher (see Pig. 17). The cortical layer is made up of cells, the active thinking part of the mind, while the inner white substance is made up of fibres. The object of the folds or Convolutions is to obtain a larger superficial area for these active brain-cells ; so that the mental activity is in direct relationship to the development of the convolutions (see Fig. 17).

In the lower animals the Convolutions are very rudimentary, except in the apes. In the lower races of mankind they are also very poorly developed (see Figs. 34 and 35).

Intellectual activity does not depend on mass or weight, but on the quality of the brain — the development of these convolutions, although probably weight and mass represent force and power. Thus great intellects result usually from these two conditions.

CHAPTER III.

The brain is about one fortieth of the weight of the whole body, but receives one sixth of the whole blood-supply to nourish it. Man’s brain is relatively much heavier than that of any other animah It is for this reason that the lungs of other animals are sufficiently buoyant to support the head above water ; not so with man, who sinks by the weight of his head. The only animals with heavier brains than man are the elephant and finner whale ; the brain of the former is about 10 lbs., and of the latter about 6 lbs.

The human brain averages 3 lbs. in weight. A man’s brain is 48 to 50 oz., while a woman’s brain is from 44 to 45 oz. in weight. After sixty the brain diminishes in weight.

Among remarkable intellects —

Cuvier’s brain weighed 64-J oz. ; Abercrombie’s, 63 oz. ; Goodsir’s, 57^- oz. ; Sir J. Simpson’s, 54 oz. ; Dr. Chalmers’, 53 oz. The African brain weighs about 46 oz. in males, and 42 oz. in females. The Australian brain 42 oz. in males, and 39 oz. in females. The Oceanic races average in brain 46 oz. in males, and 43 oz. in females. The lowest brain weight compatible with intelligence is 30 oz.

But Dr. Peacock weighed four brains over 60 oz. where the intellect was poor, and Sir W. Turner had a brain 60 oz. weight from a boy fifteen years old. Idiots with very small heads have had brains weighing from 8 to 10 oz.

Lunatics, epileptics, and idiots frequently have large heavy brains over 60 oz. In them we have frequent nerve- storms and explosions in the shape of fits and mania — cases of misdirected energy.

THE BRAIN: ITS STRUCTURE.

Just as the blacksmith’s arm represents strength and force, so the delicate touch of the watchmaker’s hand is the outcome of fine development and skill. So with the brain : size may represent power, but intelligence depends on refined cell development. These convolutions have each a special function which cannot be performed by any other part of the brain.

The Sueface of the Brain

is therefore mapped out into Areas. This has been found out partly by observation in disease, and partly by experiments on animals. A certain portion of the brain may be diseased, causing paralysis of certain muscles ; conversely we know, when portions of the body are paralysed, that certain areas or convolutions of the brain are diseased ; while an experimenter applies electricit}^ to different convolutions, always with the same result. It may be a leg moves, or a toe or finger, perhaps an eyebrow, or a turning of the head in some definite direction.

If we remove the brain we see that there are two halves, right and left ; that it is large and massive, and ends below in a narrow cord about the thickness of a finger or thumb. This is the spinal cord, which represents the main telegraphic communication between the body and the brain.

The large mass of upper brain is called the Cerebrum. It occupies the bulk of the skull.

Below and behind is the little brain, or Cerebellum, also in two halves, and joined by a bridge called the Pons (see Figs. 15 and 16).

CHAPTER III.

A line drawn horizontally backwards from the ear-hole would separate the two brains.

The Medulla Oblongata

is the lowest part of the brain, and continuous with the spinal cord. It is the centre of all the vital processes of the body. The slaughterer penetrates it with a sharp axe in killing cattle, and any head injury which causes pressure on this part is rapidly fatal. It has to do with the heart, lungs, swallowing, vomiting, and other vital functions, therefore in future we will speak of it as the representative of the Commissariat department.

The Cerebellum

has chiefly to do with the balancing powers. It is specially developed in the shark and eagle, which excel in their rapidity of movement. It is well developed in birds which have to fly, and proportionately more rudimentary in slow-moving birds. When we come to the frog and the tortoise we find it almost absent. An acrobat is well favoured in this direction, but those of us who cannot claim special agility are still dependent on it for stability and steady gait. We see the opposite effects where alcohol, by paralysing the cerebellum, results in staggering and reeling. The same unsteady gait occurs in tumour or disease of the cerebellum, and an innocent person may be wrongly suspected of intoxication.

The Pons, or Bridge

is of importance as a connection between the larger brain above and the spinal nerves below,

THE BRAIN : ITS STRUCTURE.

and connects the two halves of the cerebellum. It also contains roots or cells from which important nerves originate. It resembles a central telephone office, used for connecting the different districts. Though so small, on account of its position, a tiny clot or patch of softening, as in old age, may cause serious paralysis.

It has already been stated that the brain floats in a dense fibrous capsule, while another delicate membrane full of blood-vessels lies on the grey matter nourishing the active brain-cells.

During sleep the blood leaves the skull for the abdomen, and so the brain becomes pale. During mental activity, and in delirium or mania, the brain surface becomes bright red. This is due to the injected blood-vessels of this membrane, the Pia Mater. The disease called Meningitis, or popularly “ brain fever,” is due to inflammation of this membrane. After such a disease the membrane is thickened and damaged, and as a result the brain is deprived of proper nourishment and degenerates, resulting in mental impairment. The same type of disease occurs from alcoholic intemperance, and in some forms of insanity.

This great activity of nerve structures and brain requires an extra supply of blood.

The veins of the nose are so intimately connected with the chief veins of the skull, that nose-bleeding is a safety-valve for congestive headaches (see Fig. 14). There is another venous outlet at the back of the ear, a convenient place for leeches.

If the blood leaves the skull its place is filled by the clear watery fluid in which the brain floats. So

CHAPTER III.

there is always a compensation of blood-pressure taking place inside the skull. The extra fluid goes in or out of the spinal canal. The brain contains cavities or Ventricles, which are filled with fluid (see Fig. 1 7, v).

In badly nourished children the brain suffers, and there is great excess of fluid formed, which dilates these cavities enormously, spreading out the brain and enlarging the skull. This is popularly known as “ water on the brain,” or Hydrocephalus. Many such are fatal in infancy, but some live. They grow up with large heads, flat on the top, and overhanging foreheads, the face looking small in proportion. Occasionally we find high intellectual development in such people, but more often fits in childhood, brain fag in youth, with much irritability and uncertainty of character, and great impulsiveness in manhood.

I once found 30 oz. of fluid in the brain of a youth aged eighteen, who was overworked in the City, got a heat-stroke, and died in three days. If his lot had been cast on a farm instead of in an office he might have lived many years in happiness, as the open-air life would have suited his slightly damaged brain.

Much may be done in childhood to correct this condition. Too frequently such delicate children are over-fed with meat and beef tea. All this is poison, as it keeps up the stimulation of a weak, exhausted brain, and the child ultimately deteriorates, especially when pressed at school. The great secret of such cases is to let the brain lie

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fallow and quiescent. Avoid all mental work, pro-

THE BRAIN : ITS STRUCTURE.

tect the child from all sources of irritation ; a quiet life, and plain farinaceous and vegetable diet. Porridge and milk in abundance. Thus the body develops more fully, and is able to nourish the brain better, and gives the brain a chance. Note the effect of porridge and milk in the Scotch character and intellect.

Having briefly outlined the general principle on which the brain acts, I will now go into detail of the general scheme, and the grouping of its areas of cells and their functions.

Chapter IV. The Anatomy Of The Brain

The brain is a duplicate organ, right and left connected by nerve bands.

The right half of the brain presides over the left half of the body, and vice vevscl. As we are mostly right-handed individuals, the left side of the brain is more educated and the more necessary in life (Fig. 15).

The nervous system is divided thus.

The Cerebrum, or large brain, which is the intellectual part.

The Cerebellum, or little brain, which directs complex movements.

The Medulla Oblongata, or vital centre.

The Pons, or bridge which connects these parts.

The Spinal Cord, which carries messages to and from the brain, sometimes acts on its own responsibility without the help of the brain.

The Nerves, which are like telegraph wires carrying messages to and from the brain and spinal cord.

Terminals, consisting in the terminations of all the nerves ;

In muscles, small plates on each fibre (see Eig.

In the skin as touch corpuscles, more numerous

THIS ANATOMY OF THE BRAIN.

in some parts like the fingers and face than on the back (Fig. 19). In special organs, as the eye (Fig. 20) and ear (Fig. 21), there are in each complex arrangements for the appreciation of the vibrations of light and sound.

From what has been said one gets the idea that the nervous system is like a huge telegraph system; in fact, it is made up of two elements — Cells and Fibres. The Cells occur chiefly in layers all over the outer surface of the brain, while other groups exist as ganglia or masses at the base of the brain, in the medulla and spinal cord.

The white substance of the brain and spinal cord is made up of fibres communicating between the cells. All cells and fibres are more or less embedded in soft material— Neuroglia. The object of this is to support and protect these delicate structures. The cells, in addition, are bathed or encased in fluid lymph, which fills the space between the neuroglia and the cell. There is a twofold purpose fulfilled. There is an extra protection against jar or concussion ; and second, the lymph is a nourishing fluid extracted from the blood ; carrying food and oxygen for the performance of the work of the cell, and removing the waste products which form as the result of nerve energy. The fresh lymph is clear, but after being used is turbid or milky. Therefore, when mental fatigue occurs, the exhaustion of the cell and the accumulation of waste material in the lymph cause a slight paralysis of the cell’s action, and the result is the temporary unconsciousness which we call Sleep. The same thing happens in the battery cell.

CHAPTER IV.

If we ring our bells too much, exhaustion follows, and the cell must rest before it can work aofain.

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So also brain workers, when fagged, should rest, and not drive their batteries too hard. Those who work continuously know too well the advantages of holida}^ in restoring their working powers.

The Nerve-cells

present special types according to the areas in which they exist, and the functions which they perform. But they all have the following common properties :

1st. A cell body containing a nucleus or vital spot.

2nd. An axon or fibre, which carries the impulse away from the cell.

3rd. Dendrons or branching processes, which bring nerve impulses to the cell. There are many of the latter, so that a cell can receive a variety of messages from many sources, invoking its action (see Fig. 22). But there is only one axon, as each cell is only capable of evolving one kind of energy. Take as example, a cell leading to a muscle in the arm may receive instructions from other cells ; some of them sight cells, some hearing, some smell, and others touch cells. To be accurate it would require a group of cells to control a group of muscles, but they all act on the same principle. The cells in the spinal cord exist in the grey matter ; most of them are very branched. Some are spindle-shaped and small. The motor cells are large and very branched (see Fig. 26). The soft bedding material in which all fibres and nerve-

THE ANATOMY OF THE BRAIN.

cells are placed contains a number ot‘ small round or branching cells (see Fig. 24). In certain diseases these cells multiply and form dense hard tissue, interrupting nerve-fibres and thus stopping communications. Such a disease is called sclerosis.

Different cells have different functions. In the spinal cord some are motor cells, some receive impressions of feeling, while others have to do with the functions of nutrition.

In the brain some cells are motor, some sensory ; others for sight, taste, smell, hearing, and so forth. No one cell can either translate or perform the duties of another.

The vibrations of light striking the delicate nerve rods of the retina (see Fig. 20) are carried to the roots of the optic nerves. Here the nerve-cells transmit them in some other form of energy to the sight cells in the back of the head. The former nerve centre transmits the pictures, like a railway office which receives goods, and passes them on, keeping none.

But the optic centre is like a museum or depository which receives all that it can, and keeps them permanently for reference. The same laws apply to the other organs and their brain centres.

The cerebellum contains most beautiful cells, with richly branching processes. There are two or three layers, each made up of different types of cells (see Fig. 23).

The Cerebrum, or larger brain, contains five or six layers of cells, all in regular order (see Fig. 24). The chief features are pyramidal cells — one layer small, another large ; other cells with processes

CHAPTER IV.

like spider’s legs. In the motor areas there are exceedingly large pyramidal cells. In the frontal and sight areas there are chiefly very small pyramidal cells.

Nerve-fibres are of two kinds :

Medullated, or insulated with a sheath :

Non-medullated, without a sheath. The non-medullated occur as the simple endings of a nerve, or as processes leaving a nerve-cell, and also in the sympathetic.

The medullated nerves are covered with a sheath of a true insulating material, just as ordinary telegraph cable wires. They make up the bulk of the fibres in the brain, cord, and nerves. It is obvious that, but for this insulation, there would be great confusion of nerve motion (see Fig. 25).

The nerve-fibres are continuous with the axons of the nerve-cells ; just as in electricity with copper, so with nerve-fibre, the current which runs so easily along the fibre or wire, meets with great resistance in trying to pass across them.