A FEW PHENOMENA CHARACTERISTIC OF FEAR

I

The edifice of the human body may be compared by those studying its chemical processes to a vast manufactory of which every corner and every door bears the inscription, 'No Admittance.’ The curiosity of the public could not be greater; fain would they force an entrance, for all know that the most marvellous things are fabricated therein—wonders which no human hand, no industry, can produce.

The workmen in this factory are very small—marvellously small—invisible to the naked eye, and so tightly pressed together that they sometimes resemble the cells of a beehive, and have, on this account, received the name of cells. Life proceeds entirely from these workmen, whose confederation is so perfect that not one can be touched without the others at once becoming aware of it.

The edifice is somewhat weak in parts, and here one might easily force an entrance and make a wide breach; but this violence would avail us little, for when we break into the building the machines stop, causing such disorder and confusion that we are quite bewildered. We hear a whirring and throbbing, the pipes burst, the fluids are spilt, the pumps stop, the valves open—then all grows cold and still; and this is the strike which we call death.

The history of the attempts made to discover the actual nature of the activity of these workmen who keep the secret of life is one of the most beautiful studies in science; in reading it, there comes over us a feeling of admiration and gratitude towards those men who, in all ages, have spent their whole life in investigations, accumulating experience, sacrificing worldly goods and honours for one little gleam of light, defying poverty and toil, making the hardest and most cruel sacrifices for the sake of one forward step, of lifting but a little the mysterious veil, sometimes only to stretch out a hand to help others to walk over their body.

Thousands of volumes have been written about this struggle, and those who only read an epitome of it in the treatises of physiological chemistry are yet astonished at the power of the human mind, and at the incredible, almost superhuman, difficulties with which it has to cope.

Never was there, nor will there be, any war even faintly resembling in ardour, perseverance, and power of intellectual means, this siege of centuries, which seeks to close every issue to Nature and force her to reveal the secret of her chemical operations.

It is wonderful to see how attacks are prepared in advance, what cunning traps are laid, and by what subtile signs the road of ingress is divined. Who can describe the joy of all besiegers when one step forward has been made, or a glimmer of light is detected in the darkness? The exultation and applause which welcome every invention which resolves, or analyses, or recomposes a molecule, every instrument which enables us to break one crumb off the immense rock of the Unknown? And who shall tell the tale of pain, of disappointment, bitterness, and error; of the forgotten or unknown deeds of heroism, of existences lost in the obscurity of the schools, of the laboratories, of the hospitals; of those who die unnoticed in these last trenches where spectators and witnesses to shout applause are lacking?

And yet this deters no one; all press onward. The soldiers of science renew their vigilance and redouble their caution, the phalanx of the living draws closer together, returning with fresh courage to the assault.

Nothing can resist this unremitting war, this wonderful harmony of aim, this iron will of man; we will die on the battle-field with the certainty that others will take up our weapons and that the victory will be ours.

II

The prohibition to enter the manufactory of the human body is not so strict but that we may advance a little. We can see everything which goes in, that is, certain substances called food, which we all know, because they are publicly offered for sale; nor is it difficult to obtain permission to follow them through the mouth which forms the entry, and a long corridor, called the oesophagus, into a large, damp, warm cavity called the stomach, in which all substances are reduced to a very fine pulp; the whitish juice runs into certain little canals which flow into the circulating stream called blood, of which we have already spoken, and out of which every workman, every cell, draws what is necessary for its work. But no one has ever really discovered what is done with this appropriated material—the manner of its digestion and elaboration.

We know that the motor force of the manufactory is due to a change—a chemical operation, by which the energy of the substances introduced is transformed and appropriated by the cells that manifest it externally in that force which we call muscular contraction cerebral activity, &c.

The most important chemical operations performed in the manufactory are three in number. The first consists in the transformation of food into protoplasm, or cell-substance; the second, in the discharge of the energy accumulated in these cells; the third, in the elimination of those substances which the cells have exhausted and rendered useless.

If we make a careful comparison, by means of chemical analysis, between the composition of the substances introduced and those eliminated, we always find that the chemical energy of the latter is much reduced, from which we may know that it is food which puts everything in movement, for with nothing, nothing is made.

The walls of the building are often moistened by a fluid which trickles through in drops, and is called perspiration. Physiologists have constructed most costly apparatus in order to collect the smoke of the chimney and the air which escapes from the mouths of the innumerable ventilators called pores. Every little thing was studied and conscientiously analysed, and all were surprised that these elaborate and most intricate operations of life should result finally in products so simple. We may say that our body only produces carbonic acid, urea, and a few salts.

III

Let us enter more fully into this subject, so that we may understand the meaning of certain phenomena accompanying fear.

The materials rendered useless in the operations of our factory are easily eliminated through the skin, which thus co-operates in one of the most important functions, that of internal cleansing, which is more particularly the office of the kidneys.

We have all observed that we usually perspire when the skin is red; but there are exceptional cases, as in fear, when we perspire, although we are pale and trembling. How does it happen that we have a cold perspiration, and a perspiration with a sensation of warmth in the skin? I shall here mention an experiment of Claude Bernard. Having severed a filament of the sympathetic nerves on the neck of a horse, he saw immediately afterwards, although the animal had not moved, an abundant secretion on that half of its head where the cut had been made. The mechanism producing this phenomenon is easily understood: as soon as the nerve is severed which held the blood-vessels in check, the latter dilate, blood flows more copiously to the sudoriparous glands, increasing their activity and causing an elimination of the secreted liquid.

When it is warm, or when we are feverish, and the blood tends to flow more abundantly to the surface of the body to cool itself, the secretion of perspiration is increased in a similar way. But we see anÆmic persons perspire—the consumptive, for instance, and the dying, in whom this more copious supply of blood is wanting. In this case the cause of abundant secretion is different; here it is the nerves. One of the finest discoveries which have been made of late years in physiology, is that of the nerve-filaments which connect the cerebro-spinal system with the glands of the body. Whereas formerly everything was attributed to the more or less copious flow of blood to the glands, the secretions of which were considered as a process of filtration, we now know that the matter is much more complicated, and that there are nerves which augment and diminish the activity of the cells charged with the secretion. It is nervous activity which produces the perspiration characteristic of attention, pain, epilepsy, tetanus.

In order to prove that the secretion of perspiration may be accomplished independently of the circulation of the blood, we make an incision in the leg of a cat immediately after death and irritate the sciatic nerve; we then see that a secretion of perspiration still appears on the sole of the foot. From this we can understand how in the death-agony and the extreme pallor of fright, when all the vessels of the skin are contracted, there yet may appear a peculiar secretion of perspiration which we call cold perspiration.

IV

There is another part of the body which opens periodically to allow of the ejection of the refuse of the factory; it consists in a cloaca and a cistern which contains a yellow liquid. It is a less beautiful part of the organism, but during violent emotions involuntary movements are produced in it so characteristic of fear that we must turn our attention to it. Physicians thought that these irregularities were caused by a paralysis of the sphincter muscle, but this is not the case. The researches which I made with Prof. Pellicani[26] showed that, in man as well as in animals, there are strong contractions of the bladder which correspond to psychic facts. Scarcely have we experienced some slight emotion or been excited by some thought but there is an immediate change in the state of the muscles of this organ. I regret that the nature of this book does not permit of the reproduction of the curves traced by the plethysmograph, which show that psychic phenomena and any irritation of the sensory nerves produce a contraction of the bladder.

This is the reason why, during emotion, we feel the urgent and repeated need to expel the urine, without the amount of accumulated liquid being such as to explain the necessity. We can no doubt all remember the annoyance which the contraction of this organ caused us on certain solemn occasions; for instance, when we had to make a speech, or present ourselves for an examination, or were anxiously expecting something.

The feeling of contraction and pressure in the abdomen when we approach a precipice, or when we are in great apprehension, is solely due to the involuntary contraction of the bladder. We have shown that all causes producing a contraction of the blood-vessels have the same effect on the muscles of the bladder. I have often seen excitable, good-tempered dogs, in whom caresses and the sight of food were sufficient to produce such a contraction of the bladder, that the urine was expelled; and this suffices to confirm the fact that in our organism the same phenomena may be produced by opposite causes.

In emotions violently agitating the nervous system, and especially in fear, the contraction of the bladder is so forcible that the will can no longer hinder the expulsion of the accumulated liquid; it is therefore not a paralysis, but too forcible a contraction of the walls of the bladder which causes the involuntary expulsion.

Let us throw a passing glance at what takes place in the cloaca maxima. The intestinal walls are as contractile as those of the bladder; nor need this surprise us, as they are furnished with smooth muscles, and receive nerves and blood-vessels from the same source. We know, indeed, that this canal is subject to rapid movements, for we have all frequently heard that rumbling noise of the intestines which we cannot suppress. If the abdominal walls were transparent, we should see, when this occurs, that there is a limited contraction of the intestinal walls which propagates itself slowly in the direction of the egress. These movements, called peristaltic, are present even when we hear no noise; they serve to mix the food in the stomach, promote digestion, and convey the useless residuum to the rectum.

In paroxysms of fear the rapidity of these movements is so greatly increased that, in a very short time, they convey substances introduced into the stomach to the terminal portion of the intestines before there has been time to elaborate, digest, and condense them. It is therefore no paralysis which may, in certain circumstances, make the most courageous men appear ridiculous, it is a stream overflowing its banks—the intestines contracting so violently as to eject their contents rapidly from the organism.

One of my friends, who served as a volunteer in 1866, described to me the physical disturbances which he suffered the first time he was under fire. 'Believe me,’ he said, 'nothing can give you an idea of the furious shower of bullets which whizzed about our ears. We were near a cemetery; perhaps it was the sight of the crosses and of some corpses lying by the road-side which increased my terror, but the bullets burying themselves in the walls and trees, the cries of wounded comrades, the grim rattle of musketry, the roar of the cannon, seemed to tear me inwardly. The dysentery was so terrible that my body seemed to fall to pieces. I was always cowering in the ditches, could only stumble forwards, scarcely even rise from the ground. I was ashamed; I could have killed myself only to be able to look death bravely in the face, but, indeed, my organism could not bear that terrible sight!'

V

A still more characteristic phenomenon in the picture of fear is goose-skin. Let us see how and why the skin corrugates in this way. We know that besides the sudoriparous glands there are other glands at the surface of the body which secrete a peculiar fat called sebum, which oils the surface of the skin and gives it that gloss which we notice on the face of some people.

If we take a vertical section of the skin, we can see with the microscope a close network of muscular fibres which traverse the skin in an oblique direction, and surround every hair in the manner of the ribs of an umbrella. It is wonderful to see this mechanism under the microscope, how every hair has its own gland, its own muscle and its own nerve, its own arteries and veins. When these muscles contract, the meshes of the skin contract likewise and express the contents of the glands. We do not notice these movements of the skin, because the muscles contract very slowly.

Sometimes special muscles appear in the skin called cutaneous muscles, which play an important part in the life of animals.

We all know how the hedgehog rolls himself into a ball on the approach of danger. This movement, as we have already stated, is executed by means of a muscle covering the whole of the body, like a hood or purse which may be drawn together on one side. In the mole, too, these muscles are very strong, and we have already mentioned that dogs and horses twitch the skin to rid themselves of flies, and that this movement is due to a rapid contraction of one of these muscles. When animals curl themselves up, with the muzzle close to the tail, as the sleeping dog does, head and limbs are more easily held in this position by means of these muscles. I have found them more or less in all superior animals, and shall now consider the possible uses of these muscles which exist also in man.

It does not seem to me correct to say that they serve to drive the flies away, because they are well developed in reptiles and fish, and in many animals of which the skin is insensible to the stings of insects; also, if the fly-hypothesis were the correct one, the cutaneous muscles should be best developed on those parts of the animal which cannot easily be reached with the head, the leg, or the tail, but the contrary is the case.

Certainly the muscles are made use of for this purpose, but this is an accidental fact, as is also, I believe, the circumstance that these muscles serve to erect the hair when the animal is excited or afraid. When one dog approaches another in a hostile mood, there is such an agitation of his nervous system that he begins to tremble, not through fear, but excessive excitement. All the muscles contract, those of the blood-vessels, of the bladder, of the intestines, therefore it is comprehensible that the cutaneous muscles should also contract, raising the hair on the dog’s back.

If we look at the skin of the arms or legs when we step into a cold bath, or when we uncover ourselves on rising in the morning while the temperature of the room is low, we notice the appearance of goose-skin.

Whenever there is, for some reason, a contraction of the blood-vessels, these muscles contract also and the hair rises. The simultaneous appearance of these two phenomena is, I believe, useful to the animal, because, in raising the hair or feathers, the stratum of air enclosed by these appendages is increased, the loss of heat in this way diminished, and the cooling of the skin prevented. It is, perhaps, for this reason that horses, dogs, cats, and birds ruffle their hair or feathers when cold.[27]