The History of a Mouthful of Bread

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If your body were made of glass, so that you could look through it to
watch the intestine at work, it would appear to you like an enormous
worm coiled up into a bundle, heaving and moving with all its rings
at once. You never suspected there was such a movement within you; yet
it has been going on there continually ever since you were born, and
will not cease till you die. Your internal machinery never goes to
sleep, not even when you are sleeping yourself. It is a workshop in
constant operation, providing night and day for your necessities; and
in this respect the inner man sets a first-rate example to the outer
one! You will recollect what I said to you the other day about the
internal republic, and the provinces which are under your sole
government. It would be very disgraceful for the kingdom to be doing
nothing while the republic is working so hard; and a queen who
understands her office will make it a point of honor to banish idleness
from her household; in the houses of her neighbors this word is unknown.

The _chyme_ once launched into this moving tube, is in no danger
of remaining stationary there; the fear is, of its passing on too
quickly, as you will soon see. But this danger has been provided
against. Along the whole course of its journey, though chiefly at the
commencement, it encounters at intervals certain elastic fleshy valves
which interrupt its progress, and do not allow it to pass till it has
accumulated in sufficient force to push them before it, and so escape.
In consequence of which it is always being checked in its advance; and
during these stoppages a most important work goes on upon it at leisure.

You must understand first, that the substances of which our food is
composed, and which are afterwards decomposed in the stomach, are not
all invited to enter the blood. Our aliments are something like the
stones which the gold-seekers of California reduce to powder in order
to extract therefrom the hidden particles of gold they contain. The
gold of our food is that portion of it which the blood is able to
appropriate to his own advantage; the rest he rejects as refuse. And
this explains why a small slice of meat nourishes you more than a whole
plateful of salad. Meat is a stone absolutely full of gold, while the
salad has only a few veins of it here and there, and by far the greater
part of the material it sends to the intestines, has, in consequence,
to be thrown away.

Now it is in the first portion of the small intestine, the part known
by the Latin name _duodenum,_ which signifies twelve (because it
is about the length of twelve finger-breadths), that the division takes
place between the parts which go to nourish the blood, and those which
are useless refuse. It is an important operation as you may suppose,
and were the _chyme_ to pass rapidly through the small intestine
the gold would run the risk of being carried off with the refuse.

After the delay in the stomach, the food-substances make another halt
in the _duodenum,_ which, being very thin and slender, would have
great difficulty in containing them at the time of their grand entry,
an hour or two after a meal, were it not that it possesses the property
of expanding itself to such an extent, that it swells out on grand
occasions to the usual size of the stomach itself, so that it has
sometimes been considered as a second stomach. And no doubt the
operation which takes place in it gives it a claim to the appellation,
for thereby the finishing stroke is put to the work previously begun
in the stomach, and one may fairly say that, but for this last touch,
very little would be accomplished at all.

Above the _duodenum_, and hid behind the stomach, is a kind of sponge,
similar in nature to those we have already observed in the mouth. To
this has been given the somewhat ridiculous name of _pancreas_; I call
it ridiculous because it is derived from two Greek words which signify
_all flesh_; whereas the _pancreas_, which is a sponge of the same
description as the salivary glands, presents the appearance of a grayish
granulous mass which is not fleshy at all. Whatever be its name,
however, our sponge communicates with the _duodenum_ through a small
tube, by means of which it pours into the _chyme_, as it accumulates, a
copious supply of a fluid exactly like the _saliva_ of the mouth.

Just by the place where the tube from the _pancreas_ empties itself into
the _duodenum_, another tube arrives bringing also a fluid, but of a
different sort. This last comes from the liver, where there is a
manufactory of _bile_--an unpleasant yellowish-green liquid, the name of
which you have no doubt heard before, and which plays a very important
part in the transformation of the aliments.

These new agents, the bile and the liver, are far too important to be
passed over in a few words; I reserve them, therefore, for my next
letter. Meantime, not to leave you longer in suspense, I may say that
the separation between the gold and the refuse in the _chyme_ takes
place as soon as the latter has received the two liquids furnished
by the liver and the _pancreas_. If you ask in what manner the
division is accomplished, I confess, to my shame, that I am not able
to explain it! What takes place there is a chemical process, and
hereafter I shall have occasion to explain the meaning of that phrase.
But the Great Chemist has not in this instance seen fit to divulge to
man the secret of the work.

Indeed, you must prepare yourself beforehand, my dear child, to meet
with many other mysteries besides this, if we pursue to the end our
study of this flesh and bone which constitute the body of man. And
here I recall what Camille Desmoulins is reported to have said about
St. Just, viz., that he carried his head as high as if it were a
consecrated Host.

[Footnote: The young Protestant reader who has never lived
in a Catholic country, will perhaps need to be told, that what
is here called Consecrated Host, is the sacramental wafer, or communion
bread of the church. In French called _hostie_, in Italian, _ostia_.

In all their religious processions, which are very frequent, the host
is carried by the priest highest in authority, in a glass box placed
on a staff about four feet long, which he holds before him and so far
elevated that he has to look up to it. Over his head a richly
embroidered canopy of satin is always carried by several men; and while
these are passing, all good Catholics uncover the head and bend the
knee, wherever they may be.

It is the custom also for the priest to be called to administer the
sacrament to any one about to die, on which occasion he always walks
under this canopy, dressed in his priestly robes, carrying the host
and preceded by some boys, ringing a bell, when the same ceremony is
observed. In passing a regiment or company of soldiers, the column is
halted, wheeled into line, and with arms presented, the whole line,
officers and men, kneel before it, and the priest usually turns and
offers a benediction. When he goes in the evening to the house of the
dying, it is customary for the people to go out upon the balconies
with lighted lamps and kneel while the host is being carried by.]

You will read about these two men by-and-by in history. Meantime I
will not bid you do exactly the same as St. Just, because you would be
laughed at; but in one point of view he was not altogether wrong. The
human body is, in very truth, a temple in which the Deity maybe said
to reside, not inactively, not veiling his presence, but living and
moving unceasingly, watching on our behalf over the mysterious
accomplishment of the everlasting laws which equally guide the
_chyme_ in its workings through our frames, and direct the sun
in its course through the heavens. We mortals eat, but it is God who
brings nourishment out of our food.

LETTER XI.

THE LIVER.

I fear you will be getting a little weary, my dear, of dwelling so long
on this intestinal tube, where things which looked so well on one's
plate become so transformed that they cannot be recognized, and where
there is nothing to talk about but _chyme_, and _bile_, and the
_pancreas,_ and all sorts of things neither pleasant to the eye nor
agreeable to the ear.

But what is to be done? It is always the same story with useful things.
The people by whose labor you live in this world, are by no means the
handsomest to look at, and so it is in the little world we carry about
in our bodies.

Never mind! Keep up your heart. We are getting to the end. We shall
very soon be following the nourishing portion of our food, on its
journey to the blood, and you will find yourself in new scenes.

First, though, let us say a few words about the liver--the
bile-manufacturer; and to begin with, I will describe the place he
occupies in our interior.

The interior of the human body is divided into two large compartments,
placed one above the other; the _chest_ and the _abdomen_. These are two
distinct apartments, each containing its own particular class of
tenants: the upper one being occupied by the heart and the lungs (the
respective offices of which I will presently explain to you); while in
the lower are the stomach, the intestines, and all the other machinery
which assists in the process of digestion. These two stories of
apartments are separated as those of our houses are, by a floor placed
just above the pit of the stomach. This floor is a large thin, flat
muscle, stretched like canvas, right across the body; and it is called
the _diaphragm_--another hard word! Never mind; but do your best to
recollect it, for we shall have great need of it when we come to the
lungs. If you had been born in Greece, you would have no difficulty with
the word, for it is Greek for _separation_. It means, in fact, a
_separating partition_, or, as I called it just now, _a floor._ All this
is preparatory to telling you that the liver is hooked to the diaphragm
in the abdomen. It is a very large mass and fills up, by itself alone,
all the right side of the lower compartment, from the top downwards, to
where the bones end which protect the abdomen on each side, and which
are called _the short ribs._ Place your hand there, and you will find
them without difficulty.

Large as the liver is, it hangs suspended to a mere point of the
diaphragm, and shakes about with even the slightest movement of the
body. It is partly on this account that many people do not like to
sleep lying on the left side, especially after a good dinner, because
in this position the liver weighs upon and oppresses the stomach, like
a stout gentleman asleep in a coach who falls upon and crushes his
companion at every jolt of the vehicle. The liver within you produces,
then, the same effect that a cat, lying on the pit of your stomach
would do, and the result is that you have the nightmare.

The liver is of a deep-red color. It is an accumulation of excessively
minute atoms, which, when united, form a somewhat compact mass, and
within each of which there is a little cell, invisible to the naked
eye, where an operation of the highest importance to our existence is
mysteriously carried on. It appears a very simple one, it is true, yet
hitherto it has baffled all attempts at explanation. Listen, however;
the subject is well worthy your careful attention, whether it can be
explained or not, and we must look back to take it up from thebeginning.

I told you about the thousand workmen constantly busied in every part
of our bodies, who call on the blood without ceasing for "more, more."
You will remember further that it is to enable the blood to supply
these constant demands, that we require food.

This being understood, it is not difficult to see why we grow; the
difficulty is, rather, to explain why we do not continue to grow.

Consider, for instance, the quantity of food you have eaten during the
last year. Picture to yourself all the bread, meat, vegetables, fruits,
cakes, &c., piled upon a table. Put a whole year's milk into a large
earthenware pan, all the sweetmeats into a large jar, all the soup
into a great tureen, and see what a huge heap you will have collected
together. Then try to recollect how much you have increased in size
with all this nourishment, which has entered your body. But reckoning
in this way--even supposing the little workmen had used only a half
or even a third of the materials in question, and rejected the rest
as refuse--you would have to stoop in order to get in at the door; and
as for your papa, whose heap must have been bigger than yours, his
case would be desperate indeed; and yet he has not grown at all!

This is very curious, and I dare say you have never thought about it
before.

Do you know the story of a certain lady called Penelope, who was the
wife of Ulysses, a very celebrated king of whom the world has talked
for the last 3000 years--thanks to a poet called Homer, who did him
the honor of making him his hero! The husband of Penelope had left her
for a long time to go to the wars, and as he did not return, people
tried to persuade her to marry again. For peace and quiet's sake, she
promised to do so when she should have finished a piece of cloth she
was weaving, at which she worked all day long. They thought to get
hold of her very soon, but her importunate lovers were disappointed;
for the faithful wife, determined to await the return of her husband,
unwove every night the portion she had woven during the day; and I
leave you to judge what progress the web made in the course of a year!

Now, every part of our bodies is a kind of Penelope's web, with this
difference--that here the web unravels at one end as fast as the work
progresses at the other. As the little masons put new bricks to the
house on one side, the old ones crumble away on another--in this manner
the work might go on forever without the house becoming bigger; while,
on the other hand, the house is always being rebuilt. People who are
fond of building, as some are, would quite enjoy having such a mansion
as this on hand!

At your early age, my love, fewer bricks drop out than are added, and
this is why you grow from year to year. At your papa's age, just the
same number perish and are replaced; and therefore he continues the
same size, although in the course of the year he swallows three times
his own weight of food. But when I say this, do not suppose it is an
offensive remark, or that I think him either too little a man, or too
great an eater; seeing that there are 365 days in the year, and that
a quart of water weighs two pounds: I need not say more!

But the next question is, what becomes of all the refuse which this
perpetual destruction produces?

What becomes of it? Have you forgotten our steward who looks after
everything? He is a more active fellow than I have represented him!
To the office of purveyor-general he adds that of universal scavenger.
But in the latter department he obtains help. Wherever he passes along,
troops of little scavengers press forward, like himself always busy;
and while he holds out a new brick to the mason as he hurries by, the
little scavenger slips out the old one and conveys it away. The history
of these scavengers is a very curious one, and we shall have to speak
about it a little further on. They are minute pipes, _i.e. ducts_,
spread all over the body, which they envelope as if with fine net work.
They all communicate together, and end by emptying the whole of their
contents into one large canal, which, in its turn, empties itself into
the great stream of the blood. Imagine all the drains of a great town
flowing into one large one, which should empty itself into the river
on which the town was built, and you will have a fair idea of the whole
transaction. What the river would in such a case be to the town, the
blood is to the body--the universal scavenger, as I said before. But
you will ask further, What does the blood do with all this?--a question
which brings us back once more to the liver.

You must have seen, just now, that the pockets of our dear steward
would be rapidly overloaded, were he to keep constantly filling them
with the old worn-out materials which the builders rejected, unless
he had some means of emptying them as he went along. Accordingly, a
wise Providence has furnished the body, on all sides, with clusters
of small chambers or cells, in which the blood deposits, as he goes
by, all the refuse he has picked up, and which makes its exit from the
body sometimes in one way, sometimes in another. Now, the cells of the
liver are among these refuse-chambers. One may even consider them as
some of the most important ones. When the blood has run its course
through the lower compartment, I mean the _abdomen_, it collects
from all directions and rushes into a large canal called the _portal
vein_, which conveys it to the liver. As soon as this canal has
entered the liver, it divides and subdivides itself in every direction,
like the limbs and branches of a tree diverging from the trunk; and
very soon the blood finds itself disseminating through an infinity of
small canals or pipes, whose ultimate extremities, a thousand times
finer than the finest hairs of your head, communicate with the tiny
cells of the liver. There, each of the imperceptible little drops,
thus carried into these imperceptibly minute cell-chambers, rids
itself--but no one knows how--of a part of the sweepings it has carried
along with it. Which done, the little drops thread their way back
through other canals as fine as the first, and which go on uniting
more and more to each other, like the branches of a tree on their way
to the trunk--forming at last one large canal, through which the blood
escapes from the liver, once more relieved from its weight of rubbish,
and ready to recommence its work.

You are going to ask me, "What is all this to me--this history of the
blood and its sweepings? It was the bile you undertook to tell me
about, that liquid you spoke of as so necessary for the transformation
of the food: we were to get out of the intestinal tubes by the help
of the bile, you promised me."

Well, my little impatient minx, it is the history of the bile that I
have been relating to you, and what is most remarkable about it is
this. You have perhaps heard of those wholesale ragpickers, who
makelarge fortunes by collecting out of the mud and dirt of the streets,
the many valuable things which have been dropped there? Well, the liver
is the master-ragpicker of the body. He fabricates, out of the refuse
of the blood, that bile which is so valuable in the economy of the
human frame. This bile is neither more nor less than the deposit left
by the little drops of blood in the innumerable minute liver-cells.
See what an ingenious arrangement, and in what a simple way two objects
are effected by one operation!

Now you have learnt the genealogy of the bile, and the double office
of the liver, which benefits the blood by what it takes from it,
benefits the _chyme_ by what it gives it, and is an economist at
the same time--since it only gives back what it has received. This was
what I particularly wished to explain to you: the rest you will easily
learn.

The bile does not make a long stay in the little cells, it also escapes,
by canals similar to those which carry off the blood, after
itspurification; and which in a similar way unite by degrees together,
until at length they terminate in a single canal, communicating with
a little bag placed close against the liver, where the bile accumulates
between the periods of digestion--so forming a stock on hand, ready
to pour at once into the _duodenum_ when the latter calls for its
assistance. The next time the cook cleans out a fowl, ask her to show
you the little greenish bladder which she calls the gall and which she
takes such care not to burst, because it contains a bitter liquid
which, if spilt upon it, would quite ruin the flavor of the fowl. Such,
precisely, is the bag which holds the bile. Moreover, it is close by
the liver of the fowl that you will find it placed: and you can convince
yourself in a moment by it, that the little provision I tell you of
is always stored away therein.

We have also within us a multitude of minute electric telegraphs, which
transmit intelligence of all that occurs from one part of the body to
another, in a more wonderful manner even than the telegraphs of man's
making; later we shall see how they work. By their means the little
bag by the liver is made aware in the twinkling of an eye of the
entrance of the _chyme_ into the _duodenum,_ and forthwith the bile
returns for some distance by the canal which brought it, and then
branches off into a larger one which opens into the _duodenum._

The liver, on getting this intelligence, sets to work more diligently
than ever, and the bile flows in streams into the _duodenum,_ where it
mixes as it arrives with the current which comes from the _pancreas._
Thus combined, the two liquids flow over the _chyme,_ which they
saturate on all sides; and here, as I have said, the work of the
intestinal canal ends. What is serviceable for the blood is separated
from the useless refuse, and nothing remains but to get it out of the
intestines. It is true that in their character of tubes these are closed
on all sides. But do not trouble yourself: a means of escape is
prepared.

Before we part, however, I must apologize for something. I have not
described to you what the bile consists of, or what kind of refuse the
blood leaves in the liver; nevertheless, as you take an interest in
this much-neglected book of nature, you ought to know these things.

It is, however, very difficult to lead you by the hand through so many
wonder*, where the secrets of nature are all in operation at once, and
to explain each as soon as we meet with it. They combine, and progress
together like the waves of the sea, where one breath suffices to agitate
the whole mass.

When we have talked about the lungs, we will have another word to say
about the liver.

LETTER XII. THE CHYLE.

To-day we have to begin by making acquaintance with a new term. I would
willingly have spared you this, if I could, for the word is neither
a pretty, nor a well-chosen one, but we cannot get on without it.

You are aware now that the learned, unknown sponsors, who gave names
to the different parts of the body, bestowed the odd-enough one of
_chyme_ on that pasty substance which passes out of the stomach when the
cooking is over. We have said quite enough about it, and you know enough
of it I am sure. Well! the people seem to have had quite a fancy for the
word _chyme_, for they adopted it again, with only a very slight
alteration, when they wanted to specify separately the quintessence of
the _chyme_ (the useful part that is), which has to unite with the
blood, and which we have been speaking of as the _gold_ of the aliments
--this then they called _chyle_. I give you the name as I received it,
but have no responsibility in the matter.

In concluding the last chapter I said we were sure to find there was
a plan for extracting the best part of the _chyme_, viz. the _chyle_,
from the intestinal canal; and a very simple one it is. A complete
regiment of those little scavengers lately described, are drawn up in
battle-array along the whole length of the small intestine, but
especially round about the _duodenum._ There, a thousand minute pipes
pierce in all directions through the coat of the intestine, and suck,
like so many constantly open mouths, the drops of _chyle_ as fast as
they are formed. They are called _chyliferous vessels_ or chyle-bearers,
just as we might call hot-air stoves _caloriferous_ or heat-bearers--
from the Latin word _fero,_ which means to carry or bear. I mentioned
before that there were, within the intestine, certain elastic valves
which obstruct the progress of the _chyme,_ and oblige it to be
constantly stopping. There are in fact so many of these, and the skin
which lines the intestinal canal is so folded and plaited, that if it
were stretched out at full length on a big table, it would cover at
least as large a surface as that other skin, with which you are so well
acquainted, which entirely clothes the body outside.

Now, the _chyliferous vessels_ we have been speaking of insinuate
themselves into all the plaits and folds alluded to, and thus they
reach at last the very centre of the _chymous_ paste, and not a single
drop of _chyle_ can escape them. They do their work so well, that the
separation is effected long before the paste reaches the large
intestine; and when that has forced its way through the door which
guards the entrance, and which prevents its ever returning again, the
_chyle_ is already far off on its mission. It has threaded its way along
the little pipes, and, always creeping nearer and nearer, is on the
high-road to the heart, where it is anxiously expected.

And what becomes of the rest? There is nothing further to be said about
it, but that it shares the fate of everything else which, having
answered its purpose in its place, is no longer wanted and must be got
rid of. Thus in works where iron-stone smelting is carried on, the
refuse that remains after the ore is extracted, though available for
road-making or other purposes, is thrown out of the manufactory as a
useless incumbrance there.

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