_THE BEATING OF THE HEART_
I
In all ages and by all peoples the heart has been looked upon as the
centre of the passions, of feeling and of strength. Our word courage
comes from 'cœur’--heart. Nearly two thousand years ago it was proved
by physiologists that the heart was not the centre of sensibility, and
yet poets and common opinion continue to say that the heart is the most
sensitive part of the body.
In August 1879 Biffi showed in the Instituto Lombardo the heart of a
youth, in the left wall of which, in the autopsy, he had found a needle
sticking. The youth, who was of good family, was a poor unfortunate who
had killed his father in a fit of insanity, had then tried repeatedly
to commit suicide, and at length died mad in the hospital. While he
was still living with his family, about two years before his death, he
had said that he had stuck a needle into his heart, in order to put an
end to his life, but no one believed him. During the whole time which
he spent in the hospital the movements of the heart were regular and
quiet, the pulse normal, respiration easy, sleep good; he could lie in
all positions, and he never complained of any oppression in the region
of the heart. When he was dead a needle with a rusted eye was found
buried in the flesh and covered with a sheath which had grown around
it; the sharp, polished point had penetrated into the cavity of the
heart. The irritation caused by the perpetual pricking had produced
fleshy excrescences at that point where the heart was continually
grazed.
This instance shows how insensible the heart is, and yet, in the
language of the poets and in the imagination of the people, it will
always remain the centre of the passions and of feeling, because during
fear, and in the decisive moments of life, we feel it hammering against
the walls of the chest like a machine hidden within, the force of its
contractions booming and echoing in our ears and head, exciting that
strange feeling of oppression which we imagine that this rebellious
organ, unchained by a storm of passion, alone produces.
The heart is nothing but a force-pump situated in the centre of the
blood-vessels, which, by the play of its valves and the contractions of
its muscles, keeps up the circulation in arteries and veins, driving
the blood into all parts of the body, an arrangement without which life
would be impossible.
II
In studying a machine one first seeks the most important part, without
which it could not move nor work. In the mechanism of our body, the
first part to develop and move is the heart, and it likewise is the
last to stand still. The development of this organ may be better
studied in the hen’s egg than in any other animal, as it can be seen on
the second day of incubation. At its first appearance it is in man, as
in animals, a fine, curved tube in the shape of an =S=. If we break an
egg taken from under a brood-hen towards the end of the second or the
beginning of the third day, the first rudiment of the heart may already
be seen pulsating. Towards the end of the fourth week after conception,
the human heart has already nearly the form which it preserves during
the whole of life. It is wonderful with what resistance the heart
struggles on its first appearance against every cause which threatens
its life. Professor Pflüger relates that a human embryo of about three
weeks’ gestation was left a whole night between two watch-glasses
in a cold room. In the morning it was found that the little heart
still contracted at intervals of twenty to thirty seconds, and these
movements were noticeable for almost another hour, becoming gradually
slower and weaker until the complete death of the embryo.
In animals incompletely developed there is no emotion capable of
modifying the rhythm of the heart. In a series of experiments which
I made on the heart in a hen’s egg during the first days of its
development, I found that the application of the strongest inductive
currents, such as were unbearable on the hands, produced not the least
effect. It was a strange sight, this surprising tenacity and unexpected
resistance in a little heart which was scarcely visible, and which
pulsated tranquilly under electrical discharges which would have killed
instantaneously the heart of a horse or an ox.
This shows us how well the organs are adapted to their functions. It is
the task of the heart in the chicken to work blindly and incessantly in
order to bring into circulation the little particles which gradually
build up the body of the animal, using for this purpose the materials
accumulated in the egg after it has received the spark of life through
fecundation. In the embryo there is no need to receive the impressions
of the outside world, and the organs for this purpose are still
lacking, the nerves have not yet appeared, the heart is free in the
midst of the chaos of matter in the course of organisation.
III
The fully-developed heart has a much more complicated innervation than
the other muscles. The arm or leg cut off from the body ceases at once
to move, but the heart removed from an animal continues to beat for
a long time. Those who frequent the anatomical lecture-rooms notice
sometimes with surprise slight movements at the base of the heart,
although the rest of the corpse has been cold and motionless for a
whole day. The heart owes this tenacity of life to the structure of
its thin walls, to its being immersed in blood, and, more than all,
to there being in its flesh little nerve-centres called ganglia. It
is on this account, however, by no means independent of the brain and
spinal cord, which can modify the rhythm and force of its pulsations
according to the needs of the internal economy. Our organism is one of
the most wonderful examples of that happy autonomy where liberty and
the functions of each organ are always subordinated to the interest
and advantage of all others, while the joint administration has as its
object the maintenance of life and the welfare of all.
The centre of the cardiac nerves is in the medulla oblongata, in the
most important part of the nervous system, near that point the wounding
of which even with a pin-point causes instant death, because there all
the paths of the nervous system converge.
Of the two nerves which carry commands to the heart, one serves
principally to slacken the pulsations, and has, since it acts as a
brake, received the name of inhibitory nerve; while the other, serving
to increase the frequency of the beats, to spur them on, so to speak,
is called the accelerator nerve.
The functions of the cardiac nerves, which may seem in this way to be
extremely simple, are in reality very complicated. Galvani was the
first who showed that an irritation of the spinal cord brought about an
arrest, or, as he called it, an _enchantment_ (_incantesimo_) of the
heart.
IV
Boccaccio describes in a masterly manner the effects and changes which
love produces on the pulse:
'Thus it happened that he sickened most seriously through excess of
passion. Then were several physicians called to restore him, but,
despite their careful watching, they could not guess his disease, and
despaired of his recovery. And so it came to pass that one day, while
a physician, still young indeed, but of profound science, sat near
the patient, holding his arm there where the pulse beats, Giannetta
came for some reason into the room where the youth was lying, who,
when he saw the maiden, did not indeed betray his emotion either by
word or gesture, but felt the ardour of passion increase in his heart,
wherefore his pulse began to beat more violently than before. This the
physician incontinently noticed and wondered, but remained still to see
how long these pulsations would continue. When Giannetta left the room,
the pulse became calmer. The physician, now deeming he had discovered
the reason of the malady, caused the maiden to be called on the pretext
of having a question to put to her, he still holding the patient by
the wrist. Scarcely had she come into the room than the youth’s pulse
beat more rapidly, slackening once more at her departure. Whereupon the
physician, believing himself in possession of the truth, arose, and
taking the parents of the young man aside, said to them: “The health of
your son needs not the physician’s art; it lies in Giannetta’s hands.”’
So Boccaccio describes the diagnosis of the illness of the Count
of Antwerp; and long before Boccaccio, Plutarch had already stated
that the physician Erasistratus discovered the love of Antiochus to
Stratonice from the tumultuous irregularity of his pulse.
We here touch upon one of the greatest problems which criminal science
will propound in the future, when it asks the physiologist: 'Tell us of
what does this man think, who remains impassive before the traces of
his crime? Tell us if within him there is nothing pulsating--nothing,
either human or animal?’
[Illustration: FIG. 3.--CURVE SHOWING CARDIAC PULSATIONS OF A QUIET DOG]
I have in my laboratory a dog which was of service to me in a few
studies on fatigue. He is such a good animal that for two years I have
kept him, together with two other dogs of which I have grown fond,
and which, like old friends, shall always stay with me, unless some
dog-lover comes to beg them from me, as so often happens with good,
faithful dogs, that only in the physiological laboratories can escape
from the certain and cruel death to which the Corporation condemns
them. As he is a quiet dog, it occurred to me one day to try the
effect of a violent noise upon him. I made use of a little instrument
called a _cardiograph_, because it transmits the heart-beats to a
lever which traces them on a cylinder covered with smoked paper. I
applied this instrument, which is about the size of a half-crown, on
the place where the heart beats between the ribs, fixing it by means of
an elastic band fastened round the thorax. At first it wrote the curve
of the cardiac pulsations represented in fig. 3, which is reproduced
by means of photozincography. I regret having to present the reader
with more curves, but when one is able to see what the heart itself
writes, it would be unpardonable to try to translate its characteristic
language into words. Besides, it is not difficult to understand these
curves. The line _T_ signifies the time; it is written by an electric
clock which raises a pen every second and marks a tooth. It is, so to
speak, a controlling line, indispensable in graphic studies by which
one wishes to learn with the greatest exactness the changes which the
frequency of the pulse undergoes. In the line _T_ eighteen seconds are
marked, and the heart-beats registered in the same time in line _A_
amount to twenty-nine. If I had applied the cardiograph to the thorax
of a man I should have obtained a similar curve with fewer pulsations.
At each beat of the heart the pen rises and falls rapidly, and then
writes below a trembling line during which the heart does not beat. As
the thorax rises and expands during inspiration, the pen resting on
the ribs must likewise rise, therefore the three or four pulsations
taking place during the expansion of the thorax are marked successively
higher, sinking again with the commencement of expiration, thus forming
waves, as it were. From this curve, traced while the animal was
tranquil, we see that its heart, as indeed is also the case in man,
beats more frequently during inspiration than during expiration, the
heart-beats being nearer to each other in the ascending portion of the
curve, and further apart in the lower portion which corresponds to the
end of each expiration.
While the animal was perfectly quiet I motioned to my servant to fire
a gun, but he failed. It was an old hunting-gun, badly loaded perhaps,
and only the cartridge had caught fire. The dog, however, at once tried
to rise, and became strangely excited, much to our surprise. I had my
hands on the instrument which lay on the ribs where the heart beats,
and felt that its palpitations had become stronger and more rapid.
About a minute later we succeeded in taking the curve _B_ in fig. 4,
from which may be seen how much more frequent the pulsations were. The
animal had become so restless that we had to give up the experiment
and set him at liberty. When he was on the ground he went round the
laboratory sniffing everywhere. Presently we took the curve _C_, fig.
4, from which we can see that the emotion was not yet over, since the
beating of the heart is still quicker than in the normal curve marked
in fig. 3.
[Illustration: _T_
_C_
_B_
FIG. 4.--CARDIAC PULSATION DURING EMOTION]
There were several of us together when this experiment was made--the
students of the laboratory, my assistants, and Professor Corona, and we
were all astonished at what took place. Some of the bystanders said at
once that it must be a hound. We had always taken him for a watch-dog,
as he was very big, and did not look in the least like a hound. We
determined to try a decisive experiment the next day.
We waited till the animal was perfectly quiet, and then held a gun so
that he could see it at a distance of a few steps from him, without
threatening him in any way. The dog at once recognised the weapon, and
again grew excited, showing a considerable change in the cardiac curve.
[Illustration: _D_
_T_
FIG. 5.--NORMAL CARDIAC PULSATION]
But the most evident proof that it was a hound was given by the very
violent emotion and the unexpected excitement which took possession
of him as soon as he heard the noise caused by the loading of the gun
and the click of the trigger. Even when he saw nothing, and this noise
was made at some distance from him, the beating of the heart changed
instantly (as may be seen in the following curve), and the animal
tried to rise and sniffed the air.
The curve _D_, fig. 5, shows the pulsations written with the
cardiograph applied to the thorax of the animal when quiet.
At a given time I signed to a person, whom the dog could not see,
to load the gun. Scarcely had the animal heard the clicking than he
moved; a few seconds passed, during which it was impossible to take
the curve, the dog being so restless. About a minute later I succeeded
in obtaining the curve _E_, fig. 6, in which one can see that the form
of respiration, as well as the frequency and force of the cardiac
pulsations, is altered.
[Illustration: _E_
_T_
FIG. 6.--ALTERATION OF THE CARDIAC PULSATION THROUGH EMOTION]
After we had assured ourselves that these alterations of the pulse were
much less marked after other noises which did not resemble the loading
of a gun, we wished to convince ourselves whether the agitation was
caused by a fear of weapons. The next day the dog was again brought
into the laboratory, and while he lay on the table, and the action of
the heart was being marked, someone walked past him with a gun on his
shoulder. The dog recognised it again, became restless, tried to rise,
his heart beat violently, he began to wag his tail, and followed the
hunter with satisfied glances.
V
When strong emotions such as fear are concerned, one must have recourse
to other methods of writing the pulse, as the animal is very uneasy
and tries to escape. As this is a question as yet little considered in
physiology, I shall communicate a few experiments which I made bearing
upon it. Fig. 7 represents the pulse of the carotid artery of a dog.
During line _F_ the animal was quiet; the pulse is somewhat irregular,
which, in the dog, is a physiological fact. In line _G_ five normal
pulsations may be seen, while at _A_ a shot was fired two steps from
the dog. The report caused such a vibration of the air that the pen
trembled, as may be seen from the irregular outline of the first two
pulsations. The effect of fear on the heart is immediate. The frequency
of the beats becomes at once three times greater than before.
We waited till the dog was quiet again. Fifteen minutes afterwards the
curve _H_, which represents the normal pulse-line, was written, then
came six pulsations of the line _I_, while at _B_ a second shot was
fired, and immediately the pulse was accelerated.
[Illustration: _F_
_G_
_H_
_I_
FIG. 7.--ACCELERATION OF THE CARDIAC PULSATIONS THROUGH FEAR (IN A AND
B)]
But why does the heart beat more rapidly and frequently in fear? In
order to explain the cause of this phenomenon I must remind the reader
of the observations which I made during my studies of the pulse, and
of the circulation of the blood in the human brain during sleep. In a
sleeping person, at the slightest noise or touch, the pulse becomes
more frequent without the sleep being interrupted. This change is
indispensable in order to accelerate the circulation and to utilise to
the utmost the strength of the organism in preparing it for defence.
Our machine is so made that it changes automatically as required,
without the interference of the will being necessary. The palpitation
of the heart from fear is the exaggeration of a fact which we always
notice, whenever the organism must develop its maximum of energy and
increase the circulation in the nerve-centres; the heart does not work
for itself, but for the brain and muscles, which are the instruments of
combat, attack, defence, and flight.
The greater or lesser frequency and force of the pulse in emotion
depends upon the greater or lesser excitability of the nerve-centres.
Women and children, who are more sensitive, experience this palpitation
in greater intensity. When we say that women have more tender hearts,
we refer to the fact that their hearts respond to stimuli to which the
hearts of men remain impassive. We say of anyone who blushes and grows
pale easily, and is soon moved to tears or laughter, that he has a good
heart and a sincere character. But even cold, sceptical, egotistic,
impassive men, when they are suffering from some illness, or when the
excitability of their nervous system is intensified by some cause or
other, may be deeply moved, and betray their feelings like children.
One must be a physician in order to see how the most courageous men
become faint-hearted at a trifling loss of blood, and timid people,
in consequence of a more abundant flow of blood to the brain, perform
miracles of bravery. Weakness quickens the heart-beat even when we are
not moved by anything. We all know that we avoid giving certain news to
the convalescent which at other times would have produced little effect
upon them.
One of my colleagues had been ill eight days from a quinsy. When he
recovered and came to the laboratory, I hastened to visit him, and
found him sitting in an arm-chair, pale and exhausted. I asked him
how he was, to which he answered 'Very well,’ but that while scolding
his servant on account of some trifling matter, such a feeling of
oppression had seized him that he had to desist, as he was scarcely
able to draw breath. I felt his pulse, and found that it was above a
hundred. He laughed, and said, 'I never dreamt that my strong body was
such a paltry piece of machinery as to run down during the few days I
have not eaten as usual.’
VI
It is necessary for the heart, as for all muscles, to be fed. For it,
indeed, this need is more imperative, as it may not stand still in
order to rest when it is tired. The continuous work to which it is
condemned explains to us how every alteration in the composition and
amount of blood is immediately manifested by changing its nutrition
and consequently its strength. Knowing that the heart is in constant
contact with the blood, that is, with the nutriment distributed by it
to all parts of the body, one might think that it could in this way
take the best part for itself, as it helps itself at first hand; at
the least, that it would take a more abundant portion than the other
organs, or that nature allowed it to satisfy its appetite unreservedly.
But this is not the case. In our body the rations of all organs are
calculated and distributed according to the need of each. There is also
a very strict economy of nutrition observed, because when any part of
the body works more than usual, its increased needs are supplied by
diminishing the rations of the other organs. The vaso-motor nerves are
charged with this distribution of victuals, if I may so express myself.
The heart, like all other muscles, takes as much blood as it needs for
its maintenance out of its cavity by means of the coronary arteries
branching off from the aorta. There is a control exercised over the
heart also, and the vaso-motor nerves could, if it were absolutely
necessary, diminish its rations and leave it barely sufficient strength
to distribute the food to all the other parts of the body.
Physiologists have endeavoured in vain during the last centuries to
find in the greater or lesser nutrition of the cardiac muscle the cause
of its more or less accelerated movements. One of the most daring
theories was propounded by Giovanni Lancisi, the celebrated Roman
court-physician, one of the most illustrious physiologists Italy has
ever possessed.
In his book 'De motu cordis,’ printed in the year 1728 by the Roman
University Press, he develops a theory so manifestly materialistic of
the origin of the pulsation of the heart during emotion and mental
suffering, that it seems almost impossible the book should have been
dedicated to the memory of Clement XI. and printed with the pontifical
types, by permission of the Sacred College. The Roman curia did not
foresee that those first steps would lead physiology so far away from
their dogmas, and did not suspect that such simple notions about the
functions of the human machine were pregnant with the innovative germs
of modern philosophy, since it allowed its great physician to speak
freely, and since it furnished him with the means for his physiological
investigations, heaped honours upon him, and handed down splendid
editions of his immortal books to posterity.
Mental functions are placed by Lancisi in close dependence on the
nerves, the ganglia, and the coronary vessels of the heart. The
material organs it is which influence mental movements. The heat of
passion, the storm of emotions, have in the heart mechanisms by which
they may be moderated and regulated. It is as though the nerves and
ganglia of the heart, by driving the blood with more or less violence
into the brain, could excite the instincts; as though the character
and disposition of the mind depended on the material structure and the
physical modifications of the body.