The History of a Mouthful of Bread
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Jean Mace >> The History of a Mouthful of Bread
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Our history requires us to follow the fate of that golden aliment the
_chyle,_ which is now in a condition to support the life of the body,
and every drop of which will turn into blood--the blood which beats at
our hearts, nourishes our limbs, and sets at work the fibres of our
brain.
I ought to tell you first that the _chyle,_ when it leaves the
intestine, is very like milk. It is a white, rather fatty juice, having
the appearance, when you look closely at it, of a kind of _whey,_
in which a crowd of globules, or little balls if you prefer it,
infinitesimally small, are swimming about. Some people, whose curiosity
nothing can check, have put the tips of their tongue to it; so I am
able to tell you, if you care for the information, that it has rather
a saltish taste.
At this point it is what may be called new-born blood, and to carry
on the metaphor, blood whose education has yet to be completed. All
the elements of blood are there already, but in confusion and
intermingled, so that they cannot yet be recognised. A wonderful fact,
and one of which I have no explanation to offer you, because among the
many mysteries which are silently going on within us is this, that the
education of the new-born blood begins entirely of itself in the vessels
which are carrying it along. During their very journey, the confused
elements are setting themselves in order and forming into groups. In
short the _chyle,_ when it comes out of the chyliferous vessels,
is already much more like blood than when it entered them, and yet one
cannot account for the change. It is changed, however; its whiteness
has already assumed a rosy tinge, and if it is exposed to the air it
may be seen turning slightly red, as if to give notice to the observer
of what it is about to become.
You know that all our scavengers uniting together deposit their
sweepings in one large canal, which is called the _thoracic duct._
The _chyle_ scavengers arrive there just like the rest, and there
our poor friend finds himself confounded for a moment with all the
dross of the body, as sometimes happens to men who devote themselves
to the public good. But the crisis passes in an instant. A little
further off, the _thoracic duct_ pours its whole contents together
into a large vein situated close to the heart, and the blood has no
difficulty in recognising and appropriating what belongs to him.
Here, my dear little scholar, we conclude the first part of our story.
To eat is to nourish oneself; that is, to furnish all parts of the
body with the substances necessary to them for the proper performance
of their functions. The mouth receives these substances in their crude
condition, the intestinal canal prepares them for use, and the blood
distributes them.
After the history of the _preparation,_ comes naturally that of the
_distribution._
The first is called the DIGESTION. It is the history of the _chyle,_
which begins between the thumb and forefinger while as yet invisible,
hid in the thousand prisons of our different sorts of food, and ends in
the _thoracic duct, when, disengaged from all previous bonds, purified
and refined by the ordeals of its intestinal life, it leaps into the
blood, carrying with it a renewal of life and power.
The second history is that of the CIRCULATION. It is the history of
the _Blood,_ that indefatigable traveler, who is constantly
_circulating_ or describing a circle (the Latins called it _circulus_)
through the body; by which I mean that it is continually retracing its
steps, coming out of the heart to return to it, re-entering it only to
leave it again, and so on without intermission, until the hour of death.
The history of the _Digestion_, which we have just gone through,
goes on quietly from one end to the other without any complication.
That of the _Circulation_, which we are about to begin, is mixed
up with another history, from which it cannot be kept separate while
the description is going on, although the two histories are in reality
quite distinct from each other. The blood describes two circles, to
speak correctly: 1st. A wide one, which extends from the extremities
of the body to the heart, and back again from the heart to the
extremities. 2d. A more contracted one, which goes from the heart to
the lungs, and back from the lungs to the heart. Whilst circulating
in the lungs, it encounters the air we breathe; and here takes place,
between it and the air, one of the most curious transactions imaginable,
without which the blood would not be able to nourish the body even for
five minutes. This is called RESPIRATION, or the act of breathing.
Digestion, circulation, respiration, the three histories together form
but one--that of NUTRITION, or the act of nourishing; in other words,
of supporting life. This is what I called _eating_ at first, that
I might not mystify you at the beginning with hard words. But now that
we are growing learned ourselves, we must accustom ourselves to the
terms in use among learned people, especially when they are not more
formidable than those I have just taught you.
Our next subject for consideration, then, Will be the circulation; and
we will begin with the heart, since that is to the circulation what
the stomach is to the digestion--viz., master of the establishment.
He is a very important person, this heart, as I hardly need tell you.
Even ignorant people speak respectfully of him, and I am sure beforehand
that his history will interest you very much.
Do you feel as I do, my dear child? I am quite happy at having brought
you thus far on our journey, and at being able to take a rest with you
at the gateway of the new country into which we are about to enter,
like travelers sitting down upon a boundary frontier. What a distance
we have come, since the day when I took you by the hand to conduct you
inside this little body, of which you were making use without knowing
anything about it! How many things we have learned already, and how
many more remain to be learned, of which you have at present no idea!
I assure you I should be almost afraid myself of what is before us
yet, if I did not rely upon my own strong desire to instruct you, and
the tender affection I bear to you. Believe me, the greatest of
constraining powers is love; and when I get bewildered in the midst
of some difficult explanation which will not come out clearly, I have
only to place before me those laughing eyes of yours, where sleeps a
soul that must soon awaken to consciousness, in order to make the
daylight come into my own!
Must I add, too, that I am not working for you only? We are all placed
in this world to help each other, and in striving to bring down light
into your intellect, and good sentiments into your heart, I am thinking
also of those to whom you, in your turn, may render the same good
service hereafter, provided I have the happiness of succeeding now
with you. This ought to be so, ought it not? You should resolve to be
numbered one day among those who have not lived altogether for
themselves, but who have given the world something worth having as
they passed through it. To-day's labor will have been well employed
if, later on, it turns out that this history of the _chyle_ has
not been told you in vain!
LETTER XIII.
THE HEART.
There was once upon a time a banker, a millionaire, who could reckon
his wealth not by millions only, but by hundreds of millions and more;
who was, in fact, so tremendously rich that he did not know what to
do with his money--a difficulty in which nobody had ever been before.
This man took it into his head to build a palace infinitely superior
to anything that had hitherto been seen. Marbles, carpets, gildings,
silk hangings, pictures, and statues--in fact, the whole mass of
common-place luxuries as one sees them even in the grandest royal
abodes, fell short of his magnificent pretensions. He was an intelligent
man, and thoroughly understood the respect due to his riches; and the
common fate of kings seemed to him far too shabby for the entertainment
of his dynasty, which he looked upon as very superior to all the
families of crowned heads in the world. In consequence he sent to the
four quarters of the globe for the most illustrious professors, the
most skilful engineers, the cleverest and most ingenious workmen in
every department; and giving them unlimited permission as to
expenditure? ordered them to adorn his palace with all the wonders of
science and human industry.
Science, and human industry, and unlimited means--what will they not
accomplish? No wonder that nothing was talked of for a hundred miles
around but the magic building--of which, by the way, I do not venture
to give you a description, because it would carry me too far away. Let
it suffice to say, that never Emperor of China, Caliph of Bagdad, or
Great Mogul had such a habitation as our banker, and for a very good
reason--he was twenty times as rich as any such gentry as I have named
ever were in their lives.
When all was finished one trifling flaw was discovered: the place was
not supplied with water. A spring-seeker, who was summoned to the
premises, could only discover a small subterranean watercourse, a sort
of zigzag pipe, formed by nature, between two beds of clay, in which
the rain of the neighborhood collected as in a sort of reservoir. The
water was neither very clear nor very plentiful, as you may imagine;
and the professor appointed to examine it, having begun by tasting it,
made a horrible face, and declared there was no use in proceeding any
further; for it had a stagnant flavor which would not be agreeable to
my lord.
To the amazement of every body, my lord jumped for joy when he heard
this unpleasant news. It was proposed to him to fetch water from a
river which flowed a few miles' distance off; but he would hear of
nothing of the sort. What he wanted was something new, unexpected,
impossible--that was his object throughout. He took a pen and drew up
at a sitting the following programme, which caused our poor professors
to open their eyes in dismay:--
1st. We will use the water on the premises.
2ndly. It shall flow night day and in all parts of the palace at once.
3rdly. There shall be plenty of it, and it shall be good.
The professors looked at each other for some time without speaking,
and the gravest of them, whose fortunes and characters had been long
ago established, suggested that they should simply give my lord and
his money the slip, and so teach him to make fools of people another
time!
But the youngsters, less easily discouraged, cried out against this
with one accord. They declared that the honor of science was at stake,
and that they ought to return impudence for impudence, by executing
to the letter the impertinent programme! At length, after much
discussion and many propositions made against all hope, and thrown
aside one after the other as impracticable, a sudden inspiration crossed
the brain of an engineer who had not yet spoken; and the following is
what he proposed:--
What prevented the water from being sweet and fit to drink, was the
want of movement and air. What had to be done, therefore, was to erect
a pump, but a pump provided with numberless small pipes, extending to
the watercourse in all directions, and so arranged that by means of
them it should be able to draw up the water from all the corners and
windings where it lay stagnating, and then forcing it forward into a
pipe terminating in a rose, like that of a watering-pot, whence it
should gush out to fall down in fine rain, into a reservoir in the
open air. From thence another action of the pump was to bring it back
well aerated, to send it once more into a large pipe with numerous
lesser ramifications, which should convey it into every corner of the
palace.
Up to this point all seemed practicable, but the hardest part had not
yet come. The great difficulty was how to supply this enormous
consumption with so slender a runnel of water as the one at their
disposal. But our engineer had provided for this by a stroke of genius.
Under each of the taps (always kept open), which were dispersed all
over the palace, he would place a small cistern, from the bottom of
which should go a pipe communicating with the body of the force-pump
which drew up the water from the original watercourse. By which means
the water which ran from the taps would be taken up again and go back
to feed the reservoir in the open air; whence it would again return
to supply the taps; and so on and on, the same water continually keeping
the game alive, as people call it. Have you not sometimes seen at a
circus or theatre a large army represented by a hundred supernumeraries,
who file in close columns before the audience, going out at one side
of the stage and coming in at the other, following close at each other's
heels indefinitely? By a similar artifice the engineer would change
his meagre little runnel into an inexhaustible fountain. The water
drawn up from the watercourse by each stroke of the pump would fully
compensate for what was used in its passage through the palace by the
inhabitants. Lastly, as it might sometimes happen that the said
inhabitants washed their hands under the taps, the water on its return
to the cisterns, was to pass through a series of small filters, in
order to cleanse it from any impurity it might have contracted by the
way. Always flowing, always limpid, it would soon lose every trace of
its original source, and might defy comparison with the water of any
river in the world!
A unanimous buzz of congratulations welcomed this plan, at once so
simple and so bold, and our professors thought their troubles were
over, but they were not at the end of their difficulties yet. When it
came to the actual erection of the machine, (naturally a most
complicated one, as it had to set a-going a quintuple system of
pipes--pipes from the water-course to the pump, pipes from the pump
to the reservoir, pipes from the reservoir to the pump, from the pump
to the taps, and from the taps to the pump again,)--our banker, who
had got amused and excited as they went on, conducted them to a small
dark closet, only a few square feet in size, concealed in a corner of
the large apartments, and informed them with a laugh that he had no
other place to offer them. Besides which, he made them understand that
on account of its situation, there could be no question of furnaces
or boilers being set up there (he detested equally coal-smoke, fires,
and explosions)--nor of workmen employed about the machine (it would
not be decent to have them going up and down the front staircase)--
nor above all, of the frightful brake-wheels always screeching and
grinding, the unwieldy pistons rising and falling with a noise
sufficient to give one the headache. He himself slept near the little
dark closet, and the slightest noise was fatal to his repose. Having
explained all this, the rich man curtly made his bow and retired.
For once our professors owned themselves beaten. They had come forward
quite proud of their invention, and now they were received, not with
ecstasies of delight, but with fresh demands, more ridiculous even
than the first. They were decidedly being mystified, and were preparing
in consequence to pack up and begone, furious, and swearing by all
their gods that they would never again expose science to see itself
disgraced by a purse-proud vulgarian's scorn; when, lo! happily, a
good fairy, the special friend of learned men, came passing by that
way. She raised her enchanted wand with the tip of her finger, and all
at once a little girl dressed in rags appeared in the midst of our
astonished professors. Without giving them time to recover themselves,
the child put her hand into the little patched waist of her dress, and
drew forth a rounded object, about the size of her closed fist from
which hung a quantity of tubes spreading in all directions.
"See!" cried she; "here is the machine your banker demands of you."
Picture to yourself a small closed bag, narrowing to a point at the
end, and separated within into two very distinct compartments by a
fleshy partition which went across the inside from the top to the
bottom. Such was the object held up by the little girl. Prom each of
these compartments issued a thick tube, ramifying into endless smaller
ones; and they were moreover each surmounted by a sort of pouch, into
which ran another tube, of the same description as the first. Each of
these four portions (the two compartments and their pouches) was in
constant but independent motion, distending and contracting alternately;
and by carefully examining the noiseless play of this singular machine,
(the walls of which were, by the magic power of the fairy, rendered
transparent to the bystanders,) the learned assembly were very soon
enabled to convince themselves, that it fulfilled all the
monstrousconditions exacted of them by the fantastic millionaire.
All was in movement together, I told you; but let us begin at one end.
The right-hand compartment and its pouch represented the first pump;
the pump employed to draw, by the same stroke, the water from the
stagnant channel, and that from the taps. It was perfectly easy to
distinguish the two systems of pipes, and how they united together at
the small pouch on their arrival. When this was distended, a vacuum
was created inside, which was instantly filled by the liquid from the
tube which ran into it, (do not ask me why or how; I will explain that
presently). When it contracted again, the liquid which had just entered
was not able to get back, being prevented from so doing by a very
ingenious and simple contrivance, which requires a brief explanation.
Take off the lock from your chamber-door, which opens inside; then,
standing outside, push against it with your shoulder, and you will get
in without any difficulty. But when you are in, try to push the door
open again with your shoulder in order to get outside into the passage,
and you will find that you will not be able to pass through, and this
simply because it does not open on that side.
Which was exactly what happened to the liquid in the pouch!
The door between the tube and the pouch only opened inwardly, and the
liquid finding itself pressed on all sides in proportion as the pouch
contracted more and more, and unable to return, was obliged at last
to make its way through another similar door which led to the large
compartment below. Here the same game recommenced. The compartment
which had distended itself to receive it, contracted in its turn, and
the liquid finding the road again barred behind it, had no choice but
to force its way through the tube which led to the air-reservoir.
Here commenced the work of the second pump,--the pump of the left
compartment. The little pouch, when distended, was filled by the liquid
from the reservoir, and then forced it forward into the large
compartment below, always by means of the same process. This compartment
again drove it, by a powerful contraction, into the large conducting
tube charged with the office of its general distribution throughout
the body. At the end of all which, it returned once more into the
right-hand pump as before, to pursue the same course again, &c., &c.
Thus, as you see, the whole mechanism turned upon two little points
of detail, of the simplest description possible; namely, first, on the
entrance-doors only opening on one side; and secondly, on the elastic
covers of the pouches and compartments distending and contracting
spontaneously. It was the prettiest thing in the world to see this
unpretending-looking little bag working thus, quite naturally, without
a suspicion that it was solving a problem which so many men, proud of
their science, had given up as hopeless. Certainly here was a machine
which made no noise! Once installed in its dark closet, it would have
been necessary to place your hand upon it to find out that it moved
at all. My lord could certainly sleep beside it without disturbance.
"How much do you want for it?" said they to the poor little beggar
girl. "Name your price; have no fear; we will pay you anything you
wish."
"I cannot give it to you," replied the child; "I need it too much
myself: IT IS MY HEART. Now that you have seen it, make another like
it, if you can." And she disappeared.
It is said that the engineer, who longed to see his idea carried out,
tried hard to construct a similar machine with gutta-percha and iron
wires, and to set it in motion by electricity. But history does not
tell us that he succeeded, and we have yet to ask ourselves whether
the richest man in the world, aided by the wisest men in the world,
could ever provide himself with a miracle of wonder, such as the,
ragged child had received as a free gift from the hands of a gracious
Creator.
LETTER XIV.
THE ARTERIES.
If you have thoroughly understood the story I last told you, my child,
it will have revealed to you the whole mystery of the _circulation
of the blood,_ and you are at the present moment wiser than all the
learned men of antiquity and the middle ages, for they had none of
them the faintest surmise of the truth.
It may, perhaps, seem odd to you that men should have existed for
upwards of five thousand years without making inquiry into a matter
which so closely concerned them, and which was so easy to find out.
Is it not almost incredible that so many hearts should have beaten for
so long a period without any of their owners having felt a wish to
know exactly _why?_ Yet so it is. The action of the heart and the
flow of the blood have not been understood for much more than two
hundred years, and the man whose name is attached to this great
discovery richly deserves that we should say a few words about him.
He was called Harvey. He was an Englishman; physician to King Charles
I., who was beheaded in 1648; and when he first ventured publicly to
teach that the blood was constantly circulating from one end of the
human body to the other, perpetually returning and retracing its steps,
a great scandal was created in the world. He was called a fool,--an
impertinent innovator,--a madman. His words shattered old doctrines,
and he only received for his reward all the petty annoyances which men
are apt to lavish so freely upon any one who tells them something new;
because--do you see?--it is so disagreeable to be disturbed in one's
habits and preconceived ideas.
Harvey is not the only one in the history of mankind who has committed
the sin of being right in defiance of the opinions of his age. It is
true posterity takes account afterwards of the labors of genius, and
inscribes a fresh name upon her list. But one must pay for this glory
in one's lifetime. One cannot have everything at once.
This is an old story, my child, but always new nevertheless; and for
my own part it is, I own, one of my pleasures to amuse myself by
reflecting how much cause for laughter three-fourths of the great men
of the present day are providing for the little girls who shall be
alive two centuries hence. Time is a great avenger, and puts many
things and men in their proper places.
Let us pause here a moment while we are speaking of Harvey. I should
be curious to know what any one of the courtiers of Charles I., bedecked
in feathers, ribbons and laces, would have said to the valet who would
have placed the excellent Harvey, with his insane invention, above his
most gracious majesty, the lord and king of all Great Britain! And yet
what is his most gracious majesty to you to-day? What do you owe to
him? in what does he interest you? While you can never hear the name
of Harvey pronounced without remembering that you are under many
obligations to him! A thousand years hence, when society shall have
made the great progress which may reasonably be expected, the name of
Harvey will be familiar to every one who owns a heart, while that of
Charles I. will be only a vanished shadow; a souvenir lost in the maze
of history.
Our debt of remembrance paid, let us return to the heart--the little
closed bag which labors so prettily. We must now inquire the real names
of whatever has figured in our story.
The two great compartments are called _ventricles,_ the two small
pouches _auricles,_ and they are also distinguished as being on the
right or left side;--_right ventricle, left ventricle, right auricle,
left auricle._
The inner doors on which depends all the action of the machine, are
called _valvelets._ By-and-bye, when the pump and the steam-engine
are explained to you, you will meet again with these treacherous doors,
which never allow what has once entered to go back again; but then we
shall call them _valves._
The air-reservoir, I need scarcely tell you, is the _lung,_ to
which the blood goes to put itself in contact with the air.
The subterranean watercourse, of which I hope we have talked long
enough, is _the small intestine,_ in which the _chyle_ collects; and
the tubes which run into it are, of course, the _chyliferous vessels,_
the only channels by which anything reaches the heart which has not
previously gone out from it.
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