Title: The History of a Mouthful of Bread - And its effect on the organization of men and animals
Author: Macé, Jean, 1815-1894
Language: English
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THE HISTORY OF A MOUTHFUL OF BREAD:
And Its Effect on the Organization of Men and Animals.

BY JEAN MACÉ.

Translated Prom the Eighth French Edition, By Mrs. Alfred Gatty.



EXTRACTS FROM THE PREFACE TO THE ENGLISH EDITION.

The volume of which the following pages are a translation, has been
adopted by the _University Commission at Paris_ among their prize
books, and has reached an eighth edition. Perhaps these facts speak
sufficiently in its favor; but as translator, and to some extent editor,
I wish to add my testimony to the great charm as well as merit of the
little work. I sat down to it, I must own, with no special predilection
in favor of the subject as a suitable one for young people; but in the
course of the labor have become a thorough convert to the author's
views that such a study--perhaps I ought to add, so pursued as he has
enabled it to be--is likely to prove a most useful and most desirable
one.

The precise age at which the interest of a young mind can be turned
towards this practical branch of natural history is an open question,
and not worth disputing about. It may vary even in different
individuals. The letters are addressed to a _child_--in the original
even to a _little girl_--and most undoubtedly, as the book stands, it is
fit for any child's perusal who can find amusement in its pages: while
to the rather older readers, of whom I trust there will be a great many,
I will venture to say that the advantage they will gain in the subject
having been so treated as to be brought within the comprehension and
adapted to the tastes of a child, is pretty nearly incalculable. The
quaintness and drollery of the illustrations with which difficult
scientific facts are set forth will provoke many a smile, no doubt, and
in some young people perhaps a tendency to feel themselves treated
_babyishly_; but if in the course of the babyish treatment they find
themselves almost unexpectedly becoming masters of an amount of valuable
information on very difficult subjects, they will have nothing to
complain of. Let such young readers refer to even a popular
Encyclopaedia for an insight into any of the subjects of the
twenty-eight chapters of this volume--"The Heart," "The Lungs," "The
Stomach," "Atmospheric Pressure,"--no matter which, and see how much
they can understand of it without an amount of preliminary instruction
which would require half-a-year's study, and they will then thoroughly
appreciate the quite marvellous ingenuity and beautiful skill with
which M. Macé has brought the great leading anatomical and physical
facts of life out of the depths of scientific learning, and made them
literally comprehensible by a child.

       *       *       *       *       *

There is one point (independent of the scientific teaching) and that,
happily, the only really important one, in which the English translator
has had no change to make or desire. The religious teaching of the
book is unexceptionable. There is no strained introduction of the
subject, but there is throughout the volume an acknowledgment of the
Great Creator of this marvellous work of the human frame, of the daily
and hourly gratitude we owe to Him, and of the utter impossibility of
our tracing out half his wonders, even in the things nearest to our
senses, and most constantly subject to observation. M. Macé will help,
and not hinder the humility with which the Christian naturalist lifts
one veil only to recognise another beyond.

It will be satisfactory to any one who may be inclined to wonder how
a lady can feel sure of having correctly translated the various
scientific and anatomical statements contained in the volume, to know
that the whole has been submitted to the careful revision of a medical
friend, to whom I have reason to be very grateful for valuable
explanations and corrections whenever they were necessary. In the same
way the chapter on "Atmospheric Pressure," where, owing to the
difference between French and English weights and measures, several
alterations of illustrations, etc., had to be made, has received similar
kind offices from the hands of a competent mathematician.

       *       *       *       *       *

MARGARET GATTY.

Ecclesfield, June, 1864.



NOTE TO THE AMERICAN EDITION.

In May '66, the seventeenth edition of this work was on sale in Paris.
The date of Mrs. Gatty's preface, it will be observed, is June '64,
and at that time, the eighth French edition only had been reached.
That it should be a popular book and command large sale wherever it
is known, will not surprise any one who reads it: the only remarkable
circumstance about it is, that it should not have been republished
here long ere this. Even this may probably be accounted for, on the
supposition that the title under which the translation was published
in England, was so unmeaning--conveying not the slightest idea of the
contents of the book--that none of our publishers even ventured to
hand it over to their "readers" to examine.

The author's title, _The History of a Mouthful of Bread_, while
falling far short of giving a clear notion of the entire scope of the
work, is shockingly diluted and meaningless, when translated _The
History of a Bit of Bread!_

To the translation of Mrs. Gatty, which is in the main an excellent
one, for she has generally seized upon the idea of the author and
rendered it with singular felicity, it may be very properly objected
that she has taken some liberties with the text when there was any
conflict of opinion between herself and her author, and has given her
own ideas instead of his, which is, probably, what she refers to when
she calls herself "to some extent editor."

The reader of this edition will, in all these cases, find the thought
of the author and not that of his translator; for the reason that a
careful examination of the original has convinced the publisher that
in every instance the author was to be preferred to the translator,
to say nothing of the right an author may have to be faithfully
translated.

Besides making these restorations, the copy from which this edition
was printed has been carefully compared with the last edition of the
author and a vast number of corrections made, and in its present shape
it is respectfully submitted and dedicated to every one (whose name
is legion, of course) who numbers among his young friends a "_my
dear child_" to present it to.



CONTENTS.

I.--INTRODUCTION

FIRST PART MAN.

II.--THE HAND
III.--THE TONGUE
IV.--THE TEETH
V.--THE TEETH (_continued_)
VI.--THE TEETH (_continued_)
VII.--THE THROAT
VIII.--THE STOMACH
IX.--THE STOMACH (_continued_)
X.--THE INTESTINAL CANAL
XI.--THE LIVER
XII.--THE CHYLE
XIII.--THE HEART
XIV.--THE ARTERIES
XV.--THE NOURISHMENT OF THE ORGANS
XVI.--THE ORGANS
XVII.--ARTERIAL AND VENOUS BLOOD
XVIII.--ATMOSPHERIC PRESSURE
XIX.--THE ACTION OF THE LUNGS
XX.--CARBON AND OXYGEN
XXI.--COMBUSTION
XXII.--ANIMAL HEAT
XXIII.--ACTION OF THE BLOOD UPON THE ORGANS
XXIV.--THE WORK OF THE ORGANS
XXV.--CARBONIC ACID
XXVI.--ALIMENTS OF COMBUSTION
XXVII.--ALIMENTS OF NUTRITION (_continued_)--NITROGEN OR AZOTE
XXVIII.--COMPOSITION OF THE BLOOD


SECOND PART.

ANIMALS.

XXIX.--CLASSIFICATION OF ANIMALS
XXX.--MAMMALIA (_Mammals_)
XXXI.--MAMMALIA. (_Mammals_)--_continued_
XXXII.--MAMMALIA--_continued_
XXXIII.--MAMMALIA--_continued_
XXXIV.--AVES. (_Birds_)
XXXV.--REPTILIA. (_Reptiles_)
XXXVI.--PISCES. (_Fishes_)
XXXVII.--INSECTA. (_Insects_)
XXXVIII.--CRUSTACEA--MOLLUSKA. (_Crustaceans and Mollusks_)
XXXIX.--VERMES--ZOOPHYTA. (_Worms and Zoophytes_)
XL.--THE NOURISHMENT OF PLANTS
CONCLUSION



I.

INTRODUCTION.

I am going to tell you, my dear child, something of the life and nature
of men and animals, believing the information may be of use to you in
after-life, besides being an amusement to you now.

Of course, I shall have to explain to you a great many particulars
which are generally considered very difficult to understand, and which
are not always taught even to grown-up people. But if we work together,
and between us succeed in getting them clearly into your head, it will
be a great triumph to me, and you will find out that the science of
learned men is more entertaining for little girls, as well as more
comprehensible, than it is sometimes supposed to be. Moreover, you
will be in advance of your years, as it were, and one day may be
astonished to find that you had mastered in childhood, almost as a
mere amusement, some of the first principles of anatomy, chemistry,
and several other of the physical sciences, as well as having attained
to some knowledge of natural history generally.

I begin at once, then, with the _History of a Mouthful of Bread_,
although I am aware you may be tempted to exclaim, that if I am going
to talk only about that, I may save myself the trouble. You know all
about it, you say, as well as I do, and need not surely be told how
to chew a bit of bread-and-butter! Well, but you must let me begin at
the very beginning with you, and you have no notion what an incredible
number of facts will be found to be connected with this chewing of a
piece of bread. A big book might be written about them, were all the
details to be entered into.

First and foremost--Have you ever asked yourself _why_ people eat?

You laugh at such a ridiculous question.

"Why do people eat? Why, because there are bonbons, and cakes, and
gingerbread, and sweetmeats, and fruit, and all manner of things good
to eat." Very well, that is a very good reason, no doubt, and you may
think that no other is wanted. If there were nothing but soup in the
world, indeed, the case would be different. There might be some excuse
then for making the inquiry.

Now, then, let us suppose for once that there _is_ nothing in the
world to eat but soup; and it is true that there are plenty of poor
little children for whom there is nothing else, but who go on eating
nevertheless, and with a very good appetite, too, I assure you, as
their parents know but too well very often. Why do people eat, then,
even when they have nothing to eat but soup? This is what I am going
to tell you, if you do not already know.

The other day, when your mamma said that your frock "had grown" too
short, and that you could not go out visiting till we had given you
another with longer sleeves and waist, what was the real cause of this
necessity?

What a droll question, you say, and you answer--"Because I had grown,
of course."

To which I say "of course," too; for undoubtedly it was you who had
outgrown your frock. But then I must push the question further, and
ask--How had you grown?

Now you are puzzled. Nobody had been to your bed and pulled out your
arms or your legs as you lay asleep. Nobody had pieced a bit on at the
elbow or the knee, as people slip in a new leaf to a table when there
is going to be a larger party than usual at dinner. How was it, then,
that the sleeves no longer came down to your wrists, or that the body
only reached your knees? Nothing grows larger without being added to,
any more than anything gets smaller without having lost something; you
may lay that down as a rule, once for all. If, therefore, nothing was
added to you from without, something must have been added to you from
within. Some sly goblin, as it were, must have been cramming into your
frame whatever increase it has made in arms, legs, or anything else.
And who, do you think, this sly goblin is?

Why, my dear, it is _yourself!_

Ay! Bethink you, now, of all the bread-and-butter, and bonbons, and
gingerbread, and cakes, and sweetmeats, and even soup and plain food
(the soup and plain food being the most useful of all) which you have
been sending, day by day, for some time past, down what we used to
call "the red lane," into the little gulf below. What do you think
became of them when they got there? Well, they set to work at once,
without asking your leave, to transform themselves into something else;
and gliding cunningly into all the holes and corners of your body,
became there, each as best he might, bones, flesh, blood, etc.,
etc. Touch yourself where you will, it is upon these things you lay
your hand, though, of course, without recognizing them, for the
transformation is perfect and complete. And it is the same with
everybody.

Look at your little pink nails, which push out further and further
every morning; examine the tips of your beautiful fair hair, which
gets longer and longer by degrees; coming out from your head as grass
springs up from the earth; feel the firm corners of your second teeth,
which are gradually succeeding those which came to you in infancy; you
have _eaten_ all these things, and that no long time ago.

Nor are you children the only creatures who are busy in this way. There
is your kitten, for instance, who a few months ago was only a tiny bit
of fur, but is now turning gradually into a grown-up cat. It is her
daily food which is daily becoming a cat inside her--her saucers of
milk now, and very soon her mice, all serve to the same end.

The large ox, too, of whom you are so much afraid, because you cannot
as yet be persuaded what a good-natured beast he really is, and how
unlikely to do any harm to children who do none to him--that large ox
began life as a small calf, and it is the grass which he has been
eating for some time past which has transformed him into the huge mass
of flesh you now see, and which by-and-by will be eaten by man, to
become man's flesh in the same manner.

But, further, still: Even the forest trees, which grow so high and
spread so wide, were at first no bigger than your little finger, and
all the grandeur and size you now look upon, they have taken in by the
process of eating. "What, _do trees eat?_" you ask.

Verily, do they; and they are, by no means, the least greedy of eaters,
for they eat day and night without ceasing. Not, as you may suppose,
that they crunch bonbons, or anything else as you do; nor is the process
with them precisely the same as with you. Yet you will be surprised
hereafter, I assure you, to find how many points of resemblance exist
between them and us in this matter. But we will speak further of this
presently.

Now, I think you must allow that there are few fairytales more
marvellous than this history of bread and meat turning into little
boys and girls, milk and mice turning into cats, and grass into oxen!
And I call it a _history_, observe, because it is a transformation
that never happens suddenly, but by degrees, as time goes on.

Now, then, for the explanation. You have heard, I dare say, of those
wonderful spinning-machines which take in at one end a mass of raw
cotton, very like what you see in wadding, and give out at the other
a roll of fine calico, all folded and packed up ready to be delivered
to the tradespeople. Well, you have within you, a machine even more
ingenious than that, which receives from you all the bread-and-butter
and other sorts of food you choose to put into it, and returns it to
you changed into the nails, hair, bones and flesh we have been talking
about, and many other things besides; for there are quantities of
things in your body, all different from each other, which you are
manufacturing in this manner all day long, without knowing anything
about it. And a very fortunate thing this is for you: for I do not
know what would become of you if you had to be thinking from morning
to night of all that requires to be done in your body, as your mother
has to look after and remember all that has to be done in the house.
Just think what a relief it would be to her to possess a machine which
should sweep the rooms, cook the dinners, wash the plates, mend torn
clothes, and keep watch over everything without giving her any trouble;
and, moreover, make no more noise or fuss than yours does, which has
been working away ever since you were born without your ever troubling
your head about it, or probably even knowing of its existence! Just
think of this and be thankful.

But do not fancy you are the only possessor of a magical machine of
this sort. Your kitten has one also, and the ox we were speaking of,
and all other living creatures. And theirs render the same service to
them that yours does to you, and much in the same way; for all these
machines are made after one model, though with certain variations
adapted to the differences in each animal. And, as you will see
by-and-by, these variations exactly correspond with the different sort
of work that has to be done in each particular case. For instance,
where the machine has grass to act upon, as in the ox, it is differently
constructed from that in the cat which has to deal with meat and mice.
In the same way in our manufactories, though all the spinning-machines
are made upon one model, there is one particular arrangement for those
which spin cotton, another for those which spin wool, another for flax,
and so on.

But, further:

You have possibly noticed already, without being told, that all animals
are not of equal value; or, at least, to use a better expression, they
have not all had the same advantages bestowed on them. The dog, for
instance, that loving and intelligent companion, who almost reads your
thoughts in your eyes, and is as affectionate and obedient to his master
as it were to be wished all children were to their parents--this dog
is, as you must own, very superior, in all ways, to the frog, with its
large goggle eyes and clammy body, hiding itself in the water as soon
as you come near it. But again, the frog, which can come and go as it
likes, is decidedly superior to the oyster, which has neither head nor
limbs, and lives all alone, glued into a shell, in a sort of perpetual
imprisonment.

Now the machine I have been telling you about is found in the oyster
and in the frog as well as in the dog, only it is less complicated,
and therefore less perfect in the oyster than in the frog; and less
perfect again in the frog than in the dog; for as we descend in the
scale of animals we find it becoming less and less elaborate--losing
here one of its parts, there another, but nevertheless remaining still
the same machine to all intents and purposes; though by the time it
has reached its lowest condition of structure we should hardly be able
to recognize it again, if we had not watched it through all its
gradations of form, and escorted it, as it were, from stage to stage.

Let me make this clear to you by a comparison.

You know the lamp which is lit every evening on the drawing-room table,
and around which you all assemble to work or read. Take off first the
shade, which throws the light on your book--then the glass which
prevents it smoking--then the little chimney which holds the wick and
drives the air into the flame to make it burn brightly. Then take away
the screw, which sends the wick up and down; undo the pieces one by
one, until none remain but those absolutely necessary to having a light
at all--namely, the receptacle for the oil and the floating wick which
consumes it.

Now if any one should come in and hear you say, "Look at my lamp,"
what would he reply? He would most likely ask at once, "What lamp?"--for
there would be very little resemblance to a lamp in that mere ghost
of one before him.

But to you, who have seen the different parts removed one after another,
that wick soaked in oil (let your friend shake his head about it as
he pleases) will still be the lamp to you, however divested of much
that made it once so perfect, and however dimly it may shine in
consequence.

And this is exactly what happens when the machine we are discussing
is examined in the different grades of animals. The ignoramus who has
not followed it through its changes and reductions cannot recognize
it when it is presented to him in its lowest condition; but any one
who has carefully observed it throughout, knows that it is, in point
of fact, the same machine still.

This, then, is what we are now going to look at together, my dear
little girl. We will study first, piece by piece, the exquisite machine
within ourselves, which is of such unceasing use to us as long as we
do not give it more than a proper share of work to perform. Do you
understand? We will see what becomes of the mouthful of bread which
you place so coolly between your teeth, as if when that was done nothing
further remained to be thought about. We will trace it in its passage
through every part of the machine, from beginning to end. It will
therefore be simply only the _History of a Mouthful of Bread_ I
am telling you, even while I seem to be talking of other matters; for
to make that comprehensible I shall have to enter into a good many
explanations.

And when you have thoroughly got to understand the history of what you
eat yourself, we will look a little into the history of what other
animals eat, beginning by those most like ourselves, and going on to
the rest in regular succession downwards. And while we are on the
subject, I will say a word or two on the way in which vegetables eat,
for, as you remember, I have stated that they do eat also.

Do you think this is likely to interest you, and be worth the trouble
of some thought and attention?

Perhaps you may tell me it sounds very tedious, and like making a great
fuss about a trifle; that you have all your life eaten mouthfuls of
bread without troubling yourself as to what became of them, and yet
have not been stopped growing by your ignorance, any more than the
little cat, who knows no more how it happens than you do.

True, my dear; but the cat is only a little cat, and you are a little
girl. Up to the present moment you and she have known, one as much as
the other on this subject, and on that point you have therefore had
no superiority over her. But she will never trouble herself about it,
and will always remain a little cat. You, on the contrary, are intended
by God to become something more in intelligence than you are now, and
it is by learning more than the cat that you will rise above her in
this respect. To learn, is the duty of all men, not only for the
pleasure of curiosity and the vanity of being called learned, but
because in proportion to what we learn we approach nearer to the destiny
which God has appointed to man, and when we walk obediently in the
path which God himself has marked out for us, we necessarily become
better.

It is sometimes said to grown-up people, that it is never too late to
learn. To children one may say that it is never too early to learn.
And among the things which they may learn, those which I want now to
teach you have the double merit of being, in the first place amusing,
and afterwards, and above all, calculated to accustom you to think of
God, by causing you to observe the wonders which He has done. Sure am
I that when you know them you will not fail to admire them; moreover
I promise your mother that you will be all the better, as well as
wiser, for the study.



FIRST PART.--MAN.

LETTER II.

THE HAND.

At the foot of the mountains, from whence I write to you, my dear
child, when we want to show the country to a stranger, we commence by
making him climb one of the heights, whence he may take in at a glance
the whole landscape below, all the woods and villages scattered over
the plain, even up to the blue line of the Rhine, which stretches out
to the distant horizon. After this he will easily find his way about.

It is to the top of a mountain equally useful that I have just led
you. It has cost you some trouble to climb with me. You have had to
keep your eyes very wide open that you might see to the end of the
road we had to go together. Now then, let us come down and view the
country in detail. Then we shall go as if we were on wheels.

And now let us begin at the beginning:

Well, doubtless, as the subject is eating, you will expect me to begin
with the mouth.

Wait a moment; there is something else first. But you are so accustomed
to make use of it, that you have never given it a thought, I dare say.

It is not enough merely that one should have a mouth; we must be able
to put what we want within it. What would you do at dinner, for
instance, if you had no hands?

The hand is then the first thing to be considered.

I shall not give you a description of it; you know what it is like.
But what, perhaps, you do not know, because you have never thought
about it, is, the reason why your hand is a more convenient, and
consequently more perfect, instrument than a cat's paw, for instance,
which yet answers a similar purpose, for it helps the cat to catch
mice.

Among your five fingers there is one which is called the thumb, which
stands out on one side quite apart from the others. Look at it with
respect; it is to these two little bones, covered over with a little
flesh, that man owes part of his physical superiority to other animals.
It is one of his best servants, one of the noblest of God's gifts to
him. Without the thumb three-fourths (at least) of human arts would
yet have to be invented; and to begin with, the art not only of carrying
the contents of one's plate to one's mouth, but of filling the plate
(a very important question in another way) would, but for the thumb,
have had difficulties to surmount of which you can form no idea.

Have you noticed that when you want to take hold of anything (a piece
of bread, we will say, as we are on the subject of eating), have you
noticed that it is always the thumb who puts himself forward, and that
he is always on one side by himself, whilst the rest of the fingers
are on the other? If the thumb is not helping, nothing remains in your
hand, and you don't know what to do with it. Try, by way of experiment,
to carry your spoon to your mouth without putting your thumb to it,
and you will see what a long time it will take you to get through a
poor little plateful of broth. The thumb is placed in such a manner
on your hand that it can face each of the other fingers one after
another, or all together, as you please; and by this we are enabled
to grasp, as if with a pair of pincers, whatever object, whether large
or small. Our hands owe their perfection of usefulness to this happy
arrangement, which has been bestowed on no other animal, except the
monkey, our nearest neighbor.

I may even add, while we are about it, that it is this which
distinguishes the hand from a paw or a foot. Our feet, which have other
things to do than to pick up apples or lay hold of a fork, our feet
have also each five fingers, but the largest cannot face the others;
it is not a thumb, therefore, and it is because of this that our feet
are not hands. Now the monkey has thumbs on the four members
corresponding to our arms and legs, and thus we may say that he has
hands at the end of his legs as well as of his arms. Nevertheless, he
is not on that account better off than we are, but quite the contrary.
I will explain this to you presently.

To return to our subject. You see that it was necessary, before saying
anything about the mouth, to consider the hand, which is the mouth's
purveyor. Before the cook lights the fires the maid must go to market,
must she not? And it is a very valuable maid that we have here: what
would become of us without her?

If we were in the habit of giving thought to everything, we should
never even gather a nut without being grateful to the Providence which
has provided us with the thumb, by means of which we are able to do
it so easily.

But however well I may have expressed it, I am by no means sure, after
all, that I have succeeded in showing you clearly, how absolutely
necessary our hand is to us in eating, and why it has the honor to
stand at the beginning of the history of what we eat.

It still appears to you, I suspect, that even if you were to lose the
use of your hands you would not, for all that, let yourself die of
hunger.

This is because you have not attended to another circumstance, which
nevertheless demands your notice--namely, that from one end of the
world to the other, quantities of hands are being employed in providing
you with the wherewithal to eat.

To go on further: Have you any idea how many hands have been put in
motion merely to enable you to have your coffee and roll in the morning?
What a number, to be sure, over this cup of coffee (which is a trifle
in comparison with the other food you will consume in the course of
the day); from the hand of the negro who gathered the coffee crop to
that of the cook who ground the berries, to say nothing of the hand
of the sailor who guided the ship which bore them to our shores. Again,
from the hand of the laborer who sowed the corn, and that of the miller
who ground it into flour, to the hand of the baker who made it into
a roll. Then the hand of the farmer's wife who milked the cow, and the
hand of the refiner who made the sugar; to say nothing of the many
others who prepared his work for him, and I know not how many more.

How would it be, then, if I were to amuse myself by counting up all
the hands that are wanted to furnish--

    The sugar-refiner's manufactory,
    The milkmaid's shed,
    The baker's oven,
    The miller's mill,
    The laborer's plough,
    The sailor's ship?

And even now is there nothing we have forgotten? Ah, yes! the most
important of all the hands to you;--the hand which brings together
for your benefit the fruits of the labor of all the others--the hand
of your dear mother, always active, always ready, that hand which so
often acts as yours when your own is awkward or idle.

Now, then, you see how you might really manage to do without those two
comparatively helpless little paws of yours (although there is a thumb
to each), without suffering too much for want of food. With such an
army of hands at work, in every way, to furnish provision for that
little mouth, there would not be much danger.


But cut off your cat's fore paws--oh dear! what am I saying? Suppose,
rather, that she has not got any, and then count how many mice she
will catch in a day. The milk you give her is another matter, remember.
Like your cup of coffee, that is provided for her by others.

Believe me, if you were suddenly left all alone in a wood, like those
pretty squirrels who nibble hazel-nuts so daintily, you would soon
discover, from being thus thrown upon your own resources, that the
mouth is not the only thing required for eating, and that whether it
be a paw or a hand, there must always be a servant to go to market for
Mr. Mouth, and to provide him with food.

Happily, we are not driven to this extremity. We take hold of our
coffee-biscuit between the thumb and forefinger, and behold it is on
its road--Open the mouth, and it is soon done!

But before we begin to chew, let us stop to consider a little.

The mouth is the door at which everything enters. Now, to every
well-kept door there is a doorkeeper, or porter. And what is the office
of a well-instructed porter? Well, he asks the people that present
themselves, who they are, and what they have come for; and if he does
not like their appearance, he refuses them admittance. We too, then,
to be complete, need a porter of this sort in our mouths, and I am
happy to say we have one accordingly. I wonder whether you know him?
You look at me quite aghast! Oh, ungrateful child, not to know your
dearest friend! As a punishment, I shall not tell you who he is to-day.
I will give you till to-morrow to think about it.

Meanwhile, as I have a little time left, I will say one word more about
what we are going to look at together. It would hardly be worth while
to tell you this pretty story which we have begun, if from time to
time we were not to extract a moral from it. And what is the moral of
our history to-day?

It has more than one.

In the first place it teaches you, if you never knew it before, that
you are under great obligations to other people, indeed to almost
everybody, and most of all perhaps to people whom you may be tempted
to look down upon. This laborer, with his coarse smock-frock and heavy
shoes, whom you are so ready to ridicule, is the very person who, with
his rough hand, has been the means of procuring for you half the good
things you eat. That workman, with turned-up sleeves, whose dirty black
fingers you are afraid of touching, has very likely blackened and
dirtied them in your service. You owe great respect to all these people,
I assure you, for they all work for you. Do not, then, go and fancy
yourself of great consequence among them--you who are of no use in any
way at present, who want everybody's help yourself, but as yet can
help nobody.

Not that I mean to reproach you by saying this. Your turn has not come
yet, and everybody began like you originally. But I do wish to impress
upon you that you must prepare yourself to become some day useful to
others, so that you may pay back the debts which you are now
contracting.

Every time you look at your little hand, remember that you have its
education to accomplish, its debts of honor to repay, and that you
must make haste and teach it to be very clever, so that it may no
longer be said of you, that you are of no use to anybody.

And then, my dear child, remember that a day will come, when the revered
hands that now take care of your childhood--those hands which to-day
are yours, as it were--will become weak and incapacitated by age. You
will be strong, then, probably, and the assistance which you receive
now, you must then render to her, render it to her as you have received
it--that is to say, with your hands. It is the mother's hand which
comes and goes without ceasing about her little girl now. It is the
daughter's hand which should come and go around the old mother
hereafter--her hand and not another's.

Here again, my child, the mouth is nothing without the hand. The mouth
says, "I love," the hand proves it.



LETTER III.

THE TONGUE.

Now, about this doorkeeper, or porter, as we will call him, of the
mouth. I do not suppose you have guessed who he is; so I am going to
tell you.

The porter who keeps the door of the mouth is _the sense of taste_.

It is he who does the honors of the house so agreeably to proper
visitors, and gives such an unscrupulous dismissal to unpleasant
intruders. In other words, it is by his directions that we welcome so
affectionately with tongue and lips whatever is good to eat, and spit
out unhesitatingly whatever is unpleasant.

I could speak very ill of this porter if I chose; which would not be
very pleasant for certain little gourmands that I see here, who think
a good deal too much of him. But I would rather begin by praising him.
I can make my exceptions afterwards.

In the history I am going to give you, my dear child, there is one
thing you must never lose sight of, even when I do not allude to it;
and that is, that everything we shall examine into, has been expressly
arranged by God for the good and accommodation of our being in this
world; just as a cradle is arranged by a mother for the comfort of her
baby. We must look upon all these things, therefore, as so many
presentsfrom the Almighty himself; and abstain from speaking ill of
them, were it only out of respect for the hand which has bestowed them.

Moreover, there is a very easy plan by which we may satisfy ourselves
of the usefulness and propriety of these gifts--namely, by considering
what would become of us if we were deprived of any one of them.

Suppose, for instance, that you were totally deficient in the sense
of taste, and that when you put a piece of cake into your mouth, it
should create no more sensation in you than when you held it in your
hand?

You would not have thought of imagining such a case yourself, I am
aware; for it never comes into a child's head to think that things can
be otherwise than as God has made them. And in that respect children
are sometimes wiser than philosophers. Nevertheless, we will suppose
this for once, and consider what would happen in consequence.

Well, in the first place, you would eat old mouldy cake with just the
same relish as if it were fresh; and this mouldy cake, which now you
carefully avoid because it is mouldy, is very unwholesome food, and
would poison you were you to eat a great deal of it.

I give this merely as an instance, but it is one of a thousand. And
although, with regard to eatables, you only know such as have been
prepared either in shops or in your mamma's kitchen, still you must
be aware there are many we ought to avoid, because they would do no
good in our stomachs, and that we should often be puzzled to distinguish
these from others, if the sense of taste did not warn us about them.
You must admit, therefore, that such warnings are not without their
value.

In short, it is a marvellous fact that what is unfit for food, is
_almost always_ to be recognized as it enters the mouth, by its
disagreeable taste; a further proof that God has thought of everything.
Medicines, it is true, are unpleasant to the taste, and yet have to
be swallowed in certain cases. But we may compare them to
chimney-sweepers, who are neither pretty to look at, nor invited into
the drawing-room; but who, nevertheless, are from time to time let
into the grandest houses by the porters--though possibly with a
grimace--because their services are wanted. And in the same way
medicines have to be admitted sometimes--despite their
unpleasantness--because they, too, have to work in the chimney. Taste
does not deceive you about them, however; they are not intended to
serve as food. If any one should try to breakfast, dine, and sup upon
physic he would soon find this out.

Besides, I only said _almost_ always, in speaking of unwholesome
food making itself known to us by its nasty taste; for it is an
unfortunate truth that men have invented a thousand plans for baffling
their natural guardian, and for bringing thieves secretly into the
company of honest people. They sometimes put poison, for instance,
into sugar--as is too often done in the case of those horrible green
and blue sugar plums, against which I have an old grudge, for they
poisoned a friend whom I loved dearly in my youth. Such things as these
pass imprudently by the porter, who sees nothing of their real
character--Mr. Sugar concealing the rogues behind him.

Moreover, we are sometimes so foolish as not to leave the porter time
to make his examination. We swallow one thing after another greedily,
without tasting; and such a crowd of arrivals, coming in with a rush,
"forces the sentry," as they say; and whose fault is it, if, after
this, we find thieves established in the house?

But animals have more sense than we have.

Look at your kitten when you give her some tit-bit she is not acquainted
with--how cautiously and gently she puts out her nose, so as to give
herself time for consideration. Then how delicately she touches the
unknown object with the tip of her tongue, once, twice, and perhaps
three times. And when the tip of the tongue has thus gone forward
several times to make observations (for this is the great post of
observation for the cat's porter as well as for ours), she ventures
to decide upon swallowing, but not before. If she has the least
suspicion, no amount of coaxing makes any difference to her; you may
call "puss, puss," for ever; all your tender invitations are useless,
and she turns away.

Very good; here then is one little animal, at least, who understands
for what end she has received the sense of taste, and who makes a
reasonable use of it. Very different from some children of my
acquaintance, who heedlessly stuff into their mouths whatever comes
into their hands, without even taking the trouble to taste it, and who
would escape a good many stomach-aches, if nothing else, if they were
as sensible as Pussy.

This is the really useful side of _the sense of taste_; but its
agreeable side, which is sufficiently well known to you, is not to be
despised either, even on the grounds of utility.

You must know, between ourselves, that eating would be a very tiresome
business if we did not taste what we are eating; and I can well imagine
what trouble mammas would have in persuading their children to come
to dinner or tea, if it were only a question of working their little
jaws, and nothing further. What struggles--what tears! And setting
aside children, who are by no means always the most disobedient to the
will of a good GOD, how few men would care to stop in the midst of
their occupations, to go and grind their teeth one against another for
half-an-hour, if there were not some pleasure attached to an exercise
not naturally amusing in itself? Ay, ay, my dear child, were it not
for the reward in pleasure which is given to men when they eat, the
human race, who as a whole do not live too well already, would live
still worse. And it is necessary that we should be fed, and well fed
too, if we would perform properly here below the mission which we have
received from above.

Yes, "reward" was the word I used. Now it seems absurd to you, perhaps,
that it should be necessary to reward a man for eating a good dinner?
Well, well, GOD has been more kind to him, then, than you would be.
To every duty imposed by Him upon man, He has joined a pleasure as a
reward for fulfilling it. How many things should I not have to say to
you on this subject, if you were older? For the present, I will content
myself with making a comparison.

When a mother thinks her child is not reasonable enough to do, of her
own accord, something which it is nevertheless important she should
do, as learning to read, for instance, or to work with her needle,
&c., she comes to the rescue with rewards, and gives her a plaything
when she has done well. And thus GOD, who had not confidence enough
in man's reason to trust to it alone for supplying the wants of human
nature, has placed a plaything in the shape of pleasure after every
necessity; and in supplying the want, man finds the reward.

You will hardly believe that what I have here explained to you so
quietly by a childish comparison, has been, and alas! still is, the
subject of terrible disputes among grown-up people. If hereafter they
reach your ears, remember what I have told you now, viz., that the
pleasure lodged in the tongue and its surroundings, is a plaything,
but a plaything given to us by GOD; and that we must use it accordingly.

If a little girl has had a plaything given to her by her mother, would
she think to please her by breaking it or throwing it into a corner?
No, certainly not: she would know that in so doing she would be going
directly against her mother's intentions and wishes. Nevertheless she
would amuse herself with it in play hours, with an easy conscience,
and, if she is amiable, she will remember while she does so, that it
comes to her from her mother, and will thank her at the bottom of her
heart.

It is the same with man, of whose playthings we are speaking.

But, moreover, this little girl (it is taken for granted that she is
a good little girl) will not make the plaything the business of her
whole day, the object of all her thoughts; she will not forget
everything for it, she will leave it unhesitatingly when her mamma
calls her. Neither will she wish to be alone in her enjoyments, but
will gladly see her little friends also enjoy similar playthings,
because she thinks that what is good for her must be good for others
too.

It is thus that man should do with his playthings; but, alas! this is
what he does not by any means always do with them, and hence a great
deal has been said against them. Little girls, in particular, are apt
to fail on this point, and that is how the dreadful word _gluttony_
came to be invented. For the same reason, also, people get punished
from time to time; such punishments being the consequence of the misuse
I speak of.

If people who call to see your mamma were, instead of going straight
up stairs to her, to establish themselves at the lodge with the porter,
and stay there chatting with him, do you think she would be much
flattered by their visits? And yet this is exactly what people do who,
when eating, attend only to the porter. He is so pleasant, this porter;
he says such pretty things to you, that you go on talking to him just
as if he were the master of the house, who, meanwhile, has quite gone
out of your head.

You heap sugar-plums upon sugar-plums, cakes upon cakes, sweetmeats
upon sweetmeats--everything that pleases the porter, but is of no use
whatever to the master of the house. And then what happens? The master
gets angry sometimes, and no wonder. Mr. Stomach grows weary of these
visits, which are of no use to him. He rings all the bells, makes no
end of a noise in the house, and forces that traitor of a porter who
has engrossed all his company, to do penance. You are ill--your mouth
is out of order--you have no appetite for anything. The mamma has taken
away the plaything which has been misused, and when she gives it back,
there must be great care taken not to do the same thing over again.

I have thought it only right, my dear child, in telling you the history
of eating, to give to this little detail of its beginning, a place
proportioned to your interest in it. You see by what I have said, that
you are not altogether wrong in following your taste; but neither must
it be forgotten that this part of the business is not in reality the
most important; that a plaything is but a plaything, and that the
porter is not the master of the house.

Now that we have made our good friend's acquaintance, we will wish him
farewell, and I will presently introduce you to his companions of the
antechamber, who are ranged on the two sides of the door, to make the
toilettes for the visitors who present themselves, and to put them in
order for being received in the drawing-room. You will see there some
jolly little fellows, who are also very useful in their way, and whose
history is no less curious. They are called TEETH.



LETTER IV.

THE TEETH.

When you were quite little, my dear child, and still a nursling, you
had nothing behind your lips but two little rosy bars, which were of
no service for gnawing an apple, as they were not supplied with teeth.
You had no need of these then, since nothing but milk passed your lips,
neither had your nurse bargained for your having teeth to bite with.
You see that God provides for everything, as I have already said, and
shall often have occasion to point out to you.

But by degrees the little infant grew into a great girl, and it became
necessary to think of giving her something more solid than milk to
eat; and for this purpose she required teeth. Then some little germs,
which had lain dormant, concealed within the jaws, awoke one after
another, like faithful workmen when they hear the striking of the
clock. Each set to work in his little cell, and with the help of some
phosphorus and some lime, it began to make itself a kind of white
armour, as hard as a stone, which grew larger from day to day.

You know what lime is; that sort of white pulp which you have seen
standing in large troughs where the masons are building houses, andwhich
they use in making mortar; it is with this that your little
masons build your teeth.

As to phosphorus, I am afraid you may never have seen any; but you may
have heard it spoken of. It is sold at the druggist's in the form of
little white sticks, about as thick as your finger; they have a
disagreeable, garlicky smell, and are obliged to be kept in jars of
water, because they seize every opportunity of taking fire; so I advise
you, if ever you do see any phosphorus, not to meddle with it--for in
burning, it sticks closely to the skin, and there is the greatest
difficulty in the world in extinguishing it, and the burns it makes
are fearful. I give you this caution, because phosphorus possesses a
very curious property, which might attract little girls. Wherever it
is rubbed, in the dark, on a door, or on a wall, it leaves a luminous
trail of a very peculiar appearance, which has been called
phosphorescent, from the name of the substance which produces it. And
in this way one can write on walls in letters of fire, to the terror
of cowards. Now, come; if you will promise to be very wise, and only
to make the experiment when your mamma is present, I will teach you
how to make phosphorescent lights without having to go to the
druggist's! There is a small quantity of phosphorus in lucifer matches,
which their garlicky smell proves. Rub them gently in the dark on a
bit of wood, and you will see a ray of light which will shine for some
moments. But mind, you must not play at that game when you are alone;
it is a dangerous amusement, and one hears every day of terrible
accidents caused by disobedient children playing with lucifer matches.
And while we are on the subject, let me warn you against putting them
into your mouth. Phosphorus is a poison, and such a powerful one that
people poison rats with bread-crumb balls in which it has been
introduced.

"Oh dear me! and that poison makes part of our teeth?"

Exactly so, and it even forms part of all our bones, and of the bones
of all animals; the best proof of which is, that the phosphorus of
lucifer matches has been procured out of bones from the slaughter-house.
One could make it from the teeth of little girls if one could get
enough of them.

Now I see what puzzles you, and well it may. You are asking yourself
how those little tooth-makers, the gums, get hold of this terrible
phosphorus, which is set on fire by a mere nothing, and which we dare
not put into our mouths; where do they find the lime which I also
protest is not fit to eat, and yet of which we have stores from our
heads to our feet?

It is very surprising, too, to think of its being forthcoming in the
jaws just when it is wanted there.

You begin to perceive that there are many things to be learnt before
we come to the end of our history, and that we find ourselves checked
at every step; now listen, for we are coming to something very
important.

In distant country-seats, where people are thrown entirely upon their
own resources, they must be provided beforehand with all that is
requisite for repairing the building; and there is, accordingly, a
person called a steward, who keeps everything under lock and key, and
distributes to the workmen whatever materials they may require. Thus,
the steward gives tiles to the slater, planks to the carpenter, colors
to the painter, lime and bricks to the mason--the very same lime that
we have in our teeth--in fact, he has got everything that can be wanted
in his storehouse, and it is to him that every one applies in time of
need.

Now our body also is a mansion, and has its steward too. But what a
steward--how active! what a universal genius I how inefficient by
comparison are the stewards of the greatest lords! He goes, he comes,
he is everywhere at once; and this really, and not as we use the phrase
in speaking of a merely active man: for the _being everywhere at
once_ is in this case, a fact. He keeps everything, not in a
storehouse, but what is far better, in his very pockets, which he
empties by degrees as he goes about, distributing their contents without
ever making a mistake, without stopping, without delaying; and returns
to replenish his resources in a ceaseless, indefatigable course, which
never flags, night nor day. And you can form no idea how many workmen
he has under his orders, all laboring without intermission, all
requiring different things--not one of them pausing, even for a
joke!--not even to say--"Wait a moment;"--they do not understand what
waiting means: he must always keep giving, giving, giving. By and by
we shall have a long account to give of this wonderful steward, whose
name, be it known, if you have not already guessed it, is Blood.

It is he who, one fine day when he was making his round of the jaws,
found those little germs I spoke of, awake and eager for work; and he
began at once to start them with materials. He knew that phosphorus
and lime were what they needed: he drew phosphorus and lime therefore
out of his pockets,--and, to be very exact, some other little matters
too,--but these were the most important; but I cannot stop to tell you
everything at once.

Now, where did the blood obtain this phosphorus and lime?

I expected you to ask this, but if you want everything explained as
we go along, we shall not get very far. In fact, if I answer all your
questions I shall be letting out my secret too soon, and telling you
the end of my story almost before it is begun.

So be it, however; perhaps you will feel more courage to go on, when
you know where we are going.

The steward of a country-house distributes tiles, planks, paint, bricks,
lime; but none of these things are his own, as you know; he has received
them from his master: and, in the same way, our steward has nothing
of his own: everything he distributes comes from the master of the
house, and as I have already told you, this master is the stomach. As
fast as the steward distributes, therefore, must the master renew the
stores--and renew them all, for unless he does this, the work would
stop. In proportion as the blood gives out on all sides the contents
of his pockets, the stomach must replenish them, and fill them with
everything necessary, or there would be a revolution in the house.
Now, as there can be nothing in the stomach but what has got into it
by the mouth, it behooves us to put into the mouth whatever is needed
for the supply of our numerous workmen; and this is why we eat.

I perceive that I have plunged here into an explanation out of which
I shall not easily extricate myself, for I can guess what you are going
to say next. When you began to cut your teeth, you had eaten neither
phosphorus nor lime, as nothing but milk had entered your mouth.

That is true. Neither then, nor since then, have you eaten those things,
and what is more, I hope you never will. And yet both must have got
into your mouth, for without them your teeth could never have grown.
How are we to get out of this puzzle?

Suppose now, for a moment, that instead of phosphorus and lime,
thelittle workmen in your jaws had asked the blood for sugar to make the
teeth with. Fortunately this is only a supposition; otherwise I should
be in great fear for the poor teeth: they would not last very long.
Suppose, further, that instead of your eating the lump of sugar which
was destined to turn into a tooth, your mamma had melted it in a glass
of water, and had given it to you to drink; you could not say you had
eaten sugar, and yet the sugar would really have got into your stomach,
and there would be nothing very wonderful if the stomach had found it
out and given it to the blood, and the blood had carried it off to the
place where it was wanted. Now, allowing that the lump of sugar was
very small, and the glass of water very large, the sugar might have
passed without your perceiving it, and yet the tooth would have grown
all the same, and without the help of a miracle.

And this is how it was. In the milk which you drank as a baby there
were both phosphorus and lime, though in very small quantities. There
were many other things besides; everything of course that the blood
required for the use of its work-people, because at that time the
stomach was only receiving milk, and yet all the work was going on as
usual.

And therefore, my dear child, whenever in the course of our studies,
you hear me describe such and such a thing as being within us, say
quietly to yourself, "that also was in the milk which nourished me
when I was a baby."

Of course, the same things are in what you eat now; only now they come
in a form more difficult to deal with, and the labor of detaching them
from the surrounding ingredients is much greater. The whole business
indeed of this famous machine which we are studying consists in
unfastening the links which hold things together, and in laying aside
what is useful, to be sent to the blood divested of the refuse. The
stomach was too feeble in your infancy to have encountered the work
it has to do now. It is for this reason that God devised for the benefit
of little children that excellent nourishment--milk--which contains,
all ready for use, every ingredient the blood wants; and is almost,
in fact, blood ready made.

Only think, my child, what you owe to her who gave you this nourishment!
It was actually her blood she was giving you; her blood which entered
into your veins, and which wrought within you in the wonderful way
which I have been describing. Other people gave you sugar-plums, kisses,
and toys; but she gave you the teeth which crunched the sugar-plums,
the flesh of the rosy cheeks which got the kisses, and of the little
hands which handled the toys. If ever you can forget this, you are
ungrateful indeed!

Now, beware of going on to ask me how we know that there are so many
sorts of things in milk, or I shall end by getting angry. Question
after question; why, you might drive me in this way to the end of the
world, and we should never reach the point we are aiming at. We have
already traveled far away from the teeth, concerning which I wanted
to talk to you at this time, but our lesson is nearly over and we have
scarcely said a word about them! One cannot learn everything at once.
Upon the point in question you must take my word; and as you may
believe, I would not run the risk of being contradicted before you,
by those who have authority on the subject.

Let it suffice you, for to-day, to have gained some idea of the manner
in which the materials which constitute our bodies are manufactured
within us. We have got at this by talking of the teeth; to-morrow, it
may be the saliva, the next day something else. What I have now told
you will be of use all the way through, and I do not regret the time
we have given to the subject. If you have understood that well; the
time has not been lost.



LETTER V.

THE TEETH _(continued.)_

My thoughts return involuntarily to the subject I last explained to
you, my dear child, and I find that I have a great deal to say about
it still.

You see now, I hope, that we have something else to consult besides
a dainty taste when we are eating; and that if we are to work to any
good purpose we must think a little about this poor blood; who has so
much to do, and who often finds himself so much at fault, when we send
him nothing but barley-sugar and biscuits for his support. It is not
with such stuff as that, as you may well imagine, that he can be enabled
to answer satisfactorily to the constant demands of his little workmen,
and we expose him to the risk of getting into disgrace with them, if
we furnish him with no better provisions.

And who is the sufferer? Not I who am giving you this information,
most certainly.

Now, when children hesitate about eating plain food, and fly from beef
to rush at dessert, they act as a man would do who should begin to
build by giving his workmen reeds instead of beams, and squares of
gingerbread instead of bricks. A pretty house he would have of
it;--just think!

On the contrary, what your mother asks you to eat, my dear little
epicure, is sure to be something which contains the indispensable
supplies for which your blood is craving; for people knew all about
this by experience long before they could explain the why and the
wherefore. But now that you are so much better informed than even the
most learned men were a century ago, pouting and wry faces at table
are no longer excusable, and I should be sadly ashamed of you if I
should hear you continued to make them.

And this is what I was more particularly thinking of just now, when
I took up my pen again. No doubt it is very amusing to be able to look
clearly into one's frame, and see what goes on inside, but the amusement
anything affords is the least important part of it; you have begun to
find this out already, and you will find it out more and more every
day. What seems to me one of the great advantages of the study we have
begun together is, that at every step you take you will meet with the
most practical and useful instruction, as well as the most unanswerable
reasons for doing what your parents ask you to do every day.

To obey without knowing why is certainly possible, and may be done
happily enough. But we obey more readily and easily when we understand
the reason for doing so; and a duty which one can satisfy oneself
about, forces itself upon one as a sort of necessity. And what can
throw a stronger light on our duties than a thorough acquaintance with
ourselves?

It is upwards of two thousand two hundred years ago (and that is not
yesterday, you must own!) since one of the greatest minds of the
world--Socrates--never forget that name--taught his disciples, as a
foundation precept, this apparently simple maxim, "Know thyself." He
meant this, it is true, in a much higher sense than we are aiming at
in these conversations of ours, but his rule is so practical, that
although you have only as yet taken a mere peep into one small corner
of self-knowledge, you find, if I am not much mistaken, that your heart
has beaten once or twice rather faster than it did before. Was I wrong,
in saying from the beginning, that we become better as we grow in
knowledge? Is it not true that you have felt more tenderly than ever
towards her who nourished you with her milk, since I explained to you
the value of milk; and that you have kissed your mother's hand all the
more lovingly since you heard my history of the hand? To tell you the
truth, if you had not done so, I should have been dissatisfied both
with you and myself.

And wait! While we are talking thus, another thought has come into my
head about hands and nurses, which I must tell you of.

There is something of the nurse, my child, in those who take the best
fruits of their intellect and heart, and transform them, as it were,
into milk, in order that your infant soul may receive a nourishment
it will be able to digest without too much effort. In this way their
very soul enters into you, and it is but fair that you should reward
them as they deserve. Young as you are, too, you have a recompense in
your power: one more acceptable even than Academic prizes--of which
it is indispensable not to be too avaricious--you can give them your
love.

Besides, it is not only hands but heads that are at work for you, and
of these many more than you suppose; and your debt of gratitude is as
much due to the one as to the other.

Perhaps my first letter may have led you to suppose that I was inclined
to laugh at what I called learned men; and they are perhaps a little
to blame for not thinking often enough about little girls; but
nevertheless these men are of the greatest use to them in an indirect
way. You owe them much, therefore, and without them could have known
nothing of what I am teaching you. It is very grand for us, is it not,
to know that there is phosphorus and lime in our teeth? But it took
generations of learned men, and investigations and discoveries without
end, and ages of laborious study, to extract from nature this secret
which you have learnt in five minutes. And whatever others you may
learn hereafter, remember that it is the same story with all. While
profiting, therefore, at your ease, by all these conquests of science,
I would have you hold in grateful recollection those who have gained
them at so much cost to themselves: almost always at the expense of
their fortune, sometimes at the peril of their lives.

There they are, observe, a little knot of men with no sort of outward
pretension. They speak a language which scares children away. They
weigh dirty little powders in apothecaries' scales; steep sheets of
copper in acid-water; and watch air-bubbles passing through bent glass
tubes, some of which are as dangerous as cannon balls. They scrape old
bones, and slice scraps no bigger than a pin's head. They keep theireyes
fixed for hours upon things they are examining through microscopes
of a dozen glasses, and when you go to see what they are looking at,
you find nothing at all. To see them at work, in what they call their
laboratories, you would say that they were a set of madmen. But at the
end, it is found, some fine day, that they have changed the face of
the earth; have worked revolutions before which emperors and kings bow
in respect; have enriched nations by millions at a time; have revealed
to the human race, divine laws of which it had hitherto been ignorant;
finally, have furnished the means of teaching little boys and girls
some very curious things, which will make them more agreeable as well
as reasonable. And this is a benefit not to be despised, since these
children are destined one day to become fathers and mothers, and so
to govern the next generation; and the better they themselves are
instructed, the better this will be done.

But now let us go back to the poor teeth, whom we seem to have forgotten
altogether. However, we knew very well that they would not run away
meantime.

I told you before that it was their business to dress and prepare
whatever was presented to them, but the reception they bestow is not
one which would suit every body's taste, for it consists in being made
mince-meat of And in order to do their work in the best way possible
they divide their labor; some cut up, others tear, and others pound.

First, there are those flat teeth in front of the two jaws, just below
the nose. Touch yours with the tip of your finger; you will find that
they terminate in sharp-edged blades, like knives. These are called
_incisors,_ from the Latin word _incidere,_ which means to cut, and it
is with them we bite bread and apples, where the first business is to
cut. It is with the same teeth that lazy little girls bite their thread,
when they will not take the trouble to find their scissors; and, by the
by, this is a very bad trick, because by rubbing them one against
another in this manner we wear them out, and, as you will soon discover,
worn-out teeth never grow again.

The next sort are those little pointed teeth, which come after the
_incisors,_ on each side of both jaws. You will easily find them;
and if you press against them a little, you will feel their points.
If we call the first set the knives of the mouth, we may call these
its forks. They serve to pierce whatever requires to be torn, and they
are called _canine_ teeth, from the Latin word _canis_, a dog, because
dogs make great use of them in tearing their food. They place their paws
upon it, and plunging the canine teeth into it, pull off pieces by a
jerk of the head. Look into the mouth of papa's dog: you will recognize
these teeth by their rather curved points. They are longer than the
rest, and are called fangs. I do not know, after all, why they have
chosen to name these teeth _canine_, as all carnivorous animals have the
same fangs, and in the lion, the tiger, and many other species, they are
much more developed and sharper than in the dog. In cats they are like
little nails. However, the name is given, and we cannot alter it.

The last teeth, which are placed at the back of the jaw, are called
molars, from the Latin word _mola_, which means a millstone.

You must be prepared to meet with several Latin words as we go on; but
never mind; this will give you the opportunity of learning a little
Latin, and so of keeping your brother in order, if he ever looks down
upon you because he is learning Latin at school. Formerly, all learned
men wrote in Latin, and as they ruled supreme in all such subjects as
those we are discussing, they gave to everything such names as they
pleased, without consulting the public, who did not just then trouble
their heads about the matter. Now they give Greek names, which can
hardly be called an improvement; but if they ever wish to attract the
attention of little girls they must translate their hard words into
our own language.

To return to our grinders: they perform the same office as a miller's
millstone; that is to say, they grind everything that comes in their
way. These teeth have flat, square tops, with little inequalities on
the surface, which you can feel the moment you lay your finger on them.
These are the largest and strongest of the three sets, and with them
we even crack nuts, when we prefer the risk of breaking our teeth to
the trouble of looking for the nut-crackers!

Now, I will answer for it that you cannot explain to me why we always
place what is hard to break between the _molars,_ and never employ
the _incisors_ in the work? And yet everybody does this alike--from
the child to the grown-up man--and all equally without thinking of
what they are doing.

I will tell you the reason, however, if you will first tell me why,
when you are going to snip off the tip of your thread (which offers
very little resistance), you do it with the point of your scissors;
whereas you put any tough thing which is likely to resist strongly (a
match, for instance) close up to their hinge; particularly if you have
no scruple about spoiling the scissors, by the way!

If you were a grown-up lad, and I were teaching you natural philosophy,
I should have here a fine opportunity for explaining what is called
_the theory of the lever_. But I think _the theory of the lever_ would
frighten you; so we must get out of the difficulty in some other way.

I find, however, that I have been joking so much as I went along, that
I have but little space left, and feel quite ashamed of myself. We
seem quite unlucky over these teeth.

I have already been scolded by people who are not altogether wrong in
accusing me of losing my time in chattering, first of one thing and
then of another. They complain that by thus nibbling at every blade
of grass on the way-side we shall never get to the end of our journey;
and there is some truth in what they say. Still, I will whisper to you
in excuse that I thought we might play truant a little bit while we
were on familiar ground, where naturally you were sure to feel a
particular interest in everything. The hand, the tongue, the
teeth--these are all old friends of yours--and I thought you would
like to hear all about them. By-and-bye we shall be in the little black
hole, and then we shall get on much more rapidly.



LETTER VI.

THE TEETH _(continued)._

I left off at the _molars_, which are the teeth one selects to
crack nuts with; and if I remember rightly, we talked about different
ways of cutting with scissors.

Let us look at the subject from a distance, that we may understand it
more clearly. Let us imagine a horse drawing a heavy cart slowly along.
Ask it to gallop, and it will answer, "With all my heart! but you must
give me a lighter carriage to draw." And now fancy another flying over
the ground with a gig behind it. Ask it to exchange the gig for the
cart, and it will say, "Yes; but then I shall have to go slowly."

Whereby you see that with the same amount of strength to work with,
one has the choice of two things: either of conquering a great
resistance slowly, or a slight one quickly.

And it is partly on this account, dear child, that I teach you so
gradually; for young heads, fresh to the work, are less easily drawn
along than others, and have but a certain amount of strength.

Hitherto all has been clear as the day. Now take your scissors in your
left hand; hold the lower ring of the handle firmly between your thumb
and closed hand, so that the blade shall remain straight and immovable:
then with your other hand cause the upper ring to go up and down, and
watch the blade as it moves. The whole of it moves at once, and is put
in motion by the same power--viz., your right hand. But the point makes
a long circuit in the air, while the hinge end makes only a very little
one--indeed, moves almost imperceptibly: and, as you may imagine, a
different sort of effort is required from the motive power (your hand)
according as resistance is made at the point or at the hinge. The point
goes full gallop: it is the horse in the gig; the light work is for
him. The hinge moves slowly; it is the cart-horse, and takes the heavy
labor.

I hope I have made you understand this, for it explains the cracking
of our nut, though you may not suspect it. Move your scissors once
more in the same way. Now, you have before you the pattern of the two
jaws on one side of your face, from the ear to the nose; the upper
one, which never moves (as you may convince yourself by placing a
finger on your upper lip when you either speak or eat), and the lower
one which goes up and down. Two pairs of scissors set points to points
give you the whole jaw. The _incisors_ are at the points, they
gallop up and down, and are worthless for doing hard work; the
_molars_ are at the hinges, and move slowly; and if anything tough
has to be dealt with, it comes to them as a matter of course; hence
they are the nutcrackers. You must own that it is pleasant to reflect
thus upon what we are doing every day, and the next time you see a
stonemason moving stones of twenty times his own weight with his iron
bar, ask your papa to explain to you the principle of the lever. After
what I have told you, you will understand it very readily, or at least
enough of it to satisfy your mind.

But, besides this power of moving up and down, the lower jaw possesses
another less obvious one, by means of which it goes from right to left.
This is precisely what naughty children make use of when they grind
their teeth: not that I mean this remark for you, for I have a better
opinion of you than to suppose you do such things. Those who make such
bad use of their jaws deserve to lose the power of ever moving them
thus, and then they would find themselves sadly at a loss how to chew
their bread--for their _molars_ would be of but little service
to them in such a case; as it is chiefly by this second action of the
jaw that the food is pounded. Try to chew a bit of bread by only moving
your jaw up and down, and you will soon tire of the attempt.

One word more to complete my description of the teeth: that portion
of them which is in the jaw is called the _root_; and the _incisors_,
which cannot work hard because, like the gig-horses, they have but
little resisting power, possess only small and short roots; whereas the
_canines,_ whose duty it is to tear the food sideways, would run the
risk of being dragged out and left sticking in the substances they are
at work upon, if they were not well secured; these, therefore, have
roots which go much deeper into the jaw, and in consequence of this they
give us more pain than the others when the dentist extracts them: those
famous _eye-teeth_, which so terrify people on such occasions, are the
_canines_ of the upper jaw, and lie, in fact, just below the eye.

The _molars_ meanwhile would be in danger of being shaken in the
sideway movement, while chewing: so they do as you would do if you
were pushed aside. Now you would throw out your feet right and left
in order to steady yourself, and thus the molars, which have always
two roots, throw them out right and left for the same purpose. Some
have three, some four, and they require no less for the business they
have to do.

Above the root comes what is called the crown; that is the part of the
tooth which is exposed to the air; the part which does the work, and
which bears the brunt of all the rubbing. Now, however hard it may be,
it would soon end in being worn out by all this fun if it were not
covered by a still harder substance, which is called _enamel_.
The _enamel_ which forms the coating of china plates, and which
you can easily distinguish by examining a broken plate, will give you
a very exact idea of it. It is this enamel which gives the teeth the
polish and brilliancy we so much admire, and it is desirable to be
very careful of it, not out of vanity, though there is no objection
to a little vanity on the subject, but because the enamel is
the protector of the teeth, and when that is destroyed, you may say
good-bye to the teeth themselves. All acids eat into the enamel, as
vinegar or lemon-juice does into marble; and one of the best means of
preserving this protecting armor of the teeth is never to eat the unripe
windfalls of fruit, which I have seen unreasonable children pick up in
orchards and devour so recklessly. They give sufficient warning, by
their acidity, that they are not fit for food, and when this warning is
neglected, they take their revenge by corroding the enamel of the
teeth; not to speak of the disturbance which they afterwards cause in
the poor stomach.

I said that without this coating of enamel, the teeth would be
prematurely worn out, the reason of which is, that the teeth have not
the property of growing again, as the nails and hair have. When those
little germs of which I spoke when we began to describe the teeth,
have finished their work, they perish and fall out, like masons who,
when they have built the house, take their departure forever.

But the "forever" wants explanation. For such stern conditions would
fall hard on very little children, who, not having come to their reason,
cannot be expected to understand the great value of their teeth, and
take all the care they need of them. So to them _a second_ chance
is given.

Your first teeth, the _milk-teeth_, as they are called, count for
nothing: they are a kind of specimen, just to serve while you are very
young.

When you are approaching what is called the age of reason, (and this
word implies a great deal, my dear child,) the real teeth, the teeth
which are to serve you for life, begin to whisper among themselves,
"Now, here is a little girl who is becoming reasonable, and who will
soon, or else never, be fit to take charge of her teeth." No sooner
said than done: other masons set to work in other cells, placed under
the first set, and as the permanent teeth keep growing and growing,
they gradually push out the milk-teeth, which were only keeping their
places ready for them till they came.

This is just your case at present, and you now understand your
responsibility, and how necessary it is to preserve those good teeth
which have placed so generous a confidence in your care of them, and
which, once gone, can never be replaced.

You have no loss by the exchange; you had twenty-four at first, you
will now have twenty-eight. Twenty-eight, did I say? nay, you will
have thirty-two; but the last four will come later still. The last
_molars_ on each side, above and below, in both jaws, will not
make their appearance till you are grown up. They are a fastidious and
timid set, and will not run any risks; and they are called
_wisdom-teeth_, because they do not appear till we are supposed
to have arrived at years of discretion. Some people do not cut them
before they are thirty, and you will agree that, if they have not
become wise by that time, they have but a very poor chance of ever
being so!

There is much more still to be said about the teeth; but I think I
have told you quite enough to teach you the importance of these little
bony possessions of yours, which children do not always value as they
deserve, and whose safety they endanger as carelessly as if they had
fresh supplies of them ready in their pockets. If so many skilful
contrivances have been devised for enabling us to masticate our food
properly, it is clear that this process is not an unimportant one.
Those, therefore, who swallow a mouthful after two or three turns,
forget that they are thereby forcing the stomach to do the work the
teeth have neglected to do, and this is very bad economy, I can assure
you. You will see hereafter, when we speak about animals, that by a
marvellous compensation of nature, the power of the stomach is always
great in proportion to the _in_efficiency of the teeth, and that
by the same rule, it is weakest when the jaws are best furnished. Now,
no jaw is more completely furnished than the human one; it is clear,
then, that it should do its own work and not leave it to be done by
those who are less able: and the little girl who, in order to finish
her dinner more quickly, shirks the use of her teeth, and sends food,
half chewed, into her stomach, is like a man who, having two servants,
the one strong and vigorous, the other feeble and delicate, allows the
first to dawdle at his ease, and puts all the hard work on the other.
He would be very unjust in so doing, would he not? And as injustice
always meets with its reward, his work is sure to be badly done.

Now, the work in question consists in reducing what we eat into a sort
of pulp or liquid paste, from which the blood extracts at last whatever
it requires. But the teeth may bite and tear the materials as they
please, they can make nothing of them but a powder, which would never
turn into a pulp, if during their labors they were not assisted by an
indispensable auxiliary. To make pap for infants what do we add to the
bread after it is cut in little bits? Without being a very clever cook,
you will know that it is water which is wanted. And thus, to assist
us in making pap for the blood, Providence has furnished us with a
number of small spongy organs within the mouth, which are always filled
with water. These are called _salivary glands_. This water oozes
out from them of itself, on the least movement of the jaw, which presses
upon the sponges as it goes up and down. The name of this water, as
I need scarcely tell you, is _saliva_.

When I call it water, it is not merely from its resemblance; _saliva_ is
really pure water with a little _albumen_ added. Do not be afraid of
that word--it is not so alarming as it appears to be. It means simply
the substance you know as the _white of egg_. There is also a little
soda in the water, which you know is one of the ingredients of which
soap is made. And this explains why the saliva becomes frothy, when the
cheeks and tongue set it in motion in the mouth while we are talking;
just as the whites of egg, or soapy water, become frothy when whipped up
or beaten in a basin.

But the albumen and the soda have not been added to the saliva, in our
case, merely to make it frothy; that would have been of very little
use. They give to the water a greater power to dissolve the food into
paste, and thus to begin that series of transformations by which it
gradually becomes the fine red blood which shows itself in little drops
at the tip of your finger when you have been using your needle
awkwardly.

When once minced up by the teeth and moistened by the saliva, the food
is reduced to a state of pulp, and having nothing further to do in the
mouth, is ready to pass forward. But getting out of the mouth on its
journey downwards is not so simple an affair as getting into it by the
_front door_, as it did at first. Swallowing is in fact a complicated
action, and not to be explained in half a dozen words, and I think we
have already chatted enough for to-day. I only wish I may not have tired
you out with these interminable teeth! But you may expect something
quite new when I begin again.



LETTER VII.

THE THROAT.

You remember a certain door-keeper, or porter, of whom we have already
spoken a good deal, who resides in the mouth--the sense of taste, I
mean?

Well, it is a porter's business to sweep out the entrance to a house,
and you may always recognize him in the courtyard by his broom.

And accordingly our porter too has a broom specially placed at his
service, namely, the tongue; and an unrivalled broom it is--for it is
self-acting, never wears out, and makes no dust--qualities we cannot
succeed in obtaining in any brooms of our own manufacture.

When the time has come for the pounded mouthful (described in the last
chapter) to travel forward (the teeth having properly prepared it),
the broom begins its work; scouring all along the gums, twisting and
turning right and left, backwards and forwards, up and down; picking
up the least grains of the pulp which have been manufactured in the
mouth; and as the heap increases, it makes itself into a shovel--another
accomplishment one would scarcely have expected it to possess. What
it gathers together thus, rolls by degrees on its surface into a ball,
which at last finds itself fixed between the palate and the tongue in
such a manner that it cannot escape; at which moment the tongue presses
its tip against the upper front teeth, forms of itself an inclined
plane, and--but stop! we are getting on too fast.

At the back of the mouth, (which is the antechamber, as we said before,)
is a sort of lobby, separated from the mouth by a little fleshy
tongue_let_, suspended to the palate, exactly like those tapestry
curtains which are sometimes hung between two rooms, under which one
is enabled to pass, by just lifting them up.

If this lobby led only from the mouth to the stomach, the act of
swallowing would be the simplest thing in the world; the tongue would
be raised, the pounded ball would glide on, would pass under the
curtain, and then good-bye to it. Unfortunately, however, the architect
of the house seems to have economized his construction-apparatus here.
The lobby serves two purposes; it is the passage from the mouth to the
stomach, as well as from the nose to the lungs.

The air we breathe has its two separate doors there--one opening
towards the nose, the other towards the lungs; through neither of which
is any sort of food allowed to pass. But, as you may imagine, the food
itself knows nothing of such spiteful restraints, and it is a matter
of perfect indifference to it through which of the doors it passes.
Not unlike a good many children who, though they are reasonable
creatures, will push their way into places where they have been
forbidden to go; and who can expect a pulpy food-ball to be more
reasonable than a child? It was necessary, therefore, so to arrange
matters that there should be no choice on the subject; that when the
food-ball got into the lobby it should find no door open but its own,
namely, that which led to the stomach. And that is exactly what is
done.

You have not, perhaps, remarked that in the act of swallowing, something
rises and contracts itself at the same moment in your throat, producing
a kind of internal convulsion which jerks whatever is inside. People
do not think about it when they are eating, because it is an involuntary
action, and their attention is otherwise engaged.

But try to swallow when there is nothing in your mouth, and you will
perceive what I mean at once.

Now, imagine our lobby at the back of the throat as a small closet,
with a doorway in its wall, half-way up, the doorway being closed by
a curtain. In the ceiling is a hole, which leads to the nose; in the
floor two large tubes open out; the front one leading to the lungs,
the one behind, to the stomach.

Now swallow, and I will tell you what happens. The curtain rises up
and clings to the ceiling, and thus the passage to the nose is stopped
up. The lung-tube rises along the wall, and hides itself under the
door, contracting itself, and making itself quite small, as if it
wished to leave plenty of room for the mouthful of food which is about
to pass over it; and, for still greater security, at the very moment
it rises, it pushes against a small trap-door which shuts up its mouth.
No other road remains, therefore, but through the tube which leads to
the stomach; the pulpy mouthful drops straight therein, without risk
of mistake, and when it is once there, everything readjusts itself as
before.

These are very ingenious contrivances, and I will venture to say that
if we would but study the wonders of the marvellous and varied machinery
which is constantly at work in our behalf within us, we should be much
better employed than in learning things from which no practical good
can be derived. Moreover, we should be ashamed to trust, like the lower
animals, only to our instinct, (which, after all, is much less developed
in us than in them,) for blindly escaping the thousand chances of
destruction that beset a structure so fragile and delicate in its
contrivances as the human body. Besides, it is not only our own
machinery that is entrusted to us, we are liable to be responsible for
that of others, whose development it is our duty to guard and watch;
and how can we do this with a safe conscience, if we are ignorant of
the construction, the action, the laws of all sorts which the great
Artificer has, so to speak, made use of in forming our bodies?

When you, in your turn, are a mother, you dear little rogue, who sit
there opening wide your bright eyes, and not comprehending a word of
what I am saying, you will be glad that you were taught when you were
little, how your own little girl ought to be managed. You will find
a hundred opportunities of making good use, in her behalf, of what you
and I are learning together, and in the meantime there is no reason
why you should not yourself profit by the knowledge you have gained.

I am quite sure, for instance, that in repeating to your child the
simple rule of politeness, with which everybody is acquainted, "_Never
talk when you are eating_," you will be very careful to add, "_and
especially when you are swallowing_," for reasons I am about to detail.

When we want to speak we have to drive the air from the lungs into the
mouth, and our words are sounds produced by this air as it passes
through. This is the reason why I advise you to go on gently, and make
the proper stops in reading aloud: to _take breath_, in fact, as
it is called; otherwise, breath would all at once fail you, and you
would be obliged to stop short in the middle of a sentence and wait
like a simpleton till you had refilled the lungs with air by breathing.
It was for this purpose, also, and not for mere economy's sake, as you
may have thought, that the little cross-road of four doors has been
placed at the back of the mouth, enabling it to communicate at pleasure
with either the lungs or the stomach. It is a dangerous passage for
food-parcels making their way to the stomach; but if you could
substitute for it, as it may have occurred to you to do lately, a
simple tube going directly to the stomach,--behold! you would find
yourself dumb;--a serious misfortune, eh? for a little girl! But come,
I am quizzing too much, so console yourself. I know many grown-up
people who would be at least as sorry as yourself.

To return to our subject. We have said that, in order to guard against
accidents, the lung-tube is closed at the moment we are about to
swallow. But if by any unlucky chance the air is coming up from the
lungs at the same moment, it must have a free passage. Its tube cannot
help returning to its place; the little trap-door which shuts up the
opening opens whether or no, and then adieu to all the precautions of
good Mother Nature! The mouthful when it drops, falls outside of its
proper tube--that is to say, into the other, which is exactly in front
of it, and we find that we have _swallowed the wrong way_.

You know what happens in such a case. You cough and cough till you are
torn to pieces, till you grow scarlet, or even blue in the face; till
you lose your breath; till your body trembles; till your eyes start
out of their sockets. Let who will be there, there is no resource but
to hide your face in your handkerchief. The tube, which was only made
for the passage of air, on finding an intruder forcing an entrance,
does its utmost to drive it back through the door. Then the lungs,
which would be destroyed by its getting to them, come to the assistance
of the faithful servant who is struggling for their protection: they
agitate themselves violently, and send forth gusts of air which drive
all before them. Thence arises the cough, and by this means at last
the enemy is thrust out of the mouth, like dust before the wind. And
it is only when the passages are cleared that the storm subsides. But
the commotion is no laughing matter, I assure you; for if one had
swallowed a little _too far_ the wrong way, or if the substance
swallowed had been too heavy for the air-tube, aided by the lungs, to
eject within a certain time, death would have ensued: instances of
which are by no means unknown. Nature does nothing in vain; this is
no case of a man frightened by a mouse. When you find your whole being
concentrating its efforts to one point, and betraying such distress,
at an accident apparently so trifling, you may be sure there is danger,
and real danger too; and if you doubt it, that makes no
difference--happily for you.

Now you have learned why little girls should not attempt to talk and
swallow at the same time, and, I may add, still less laugh; for
laughingis a kind of somersault, performed by the lungs, and is always
accompanied by the ejectment of a great deal more breath than is
necessary in speaking, so that the jerks it occasions derange still
more the wise provisions made to protect life whenever we swallow
anything, and therefore we are more apt to swallow the wrong way while
laughing than while speaking.

Need I say that we ought equally to guard against making others laugh
or talk; or exciting, or frightening them, while they are swallowing;
in short, avoid doing anything to create a sudden shock which might
suddenly force the air out of their lungs, and cause them in the same
manner to swallow the wrong way? Politeness requires this from us, and
what I have now said will fix the lesson still more strongly on your
mind. What would become of you if you were to see a person die in your
presence in consequence of some foolish joke, however apparently
innocent?

Not to conclude with so painful a picture, I will, before we part,
give you the right names of the _curtain_, the _lobby_ or _closet_, and
the _tubes_ of which we have been speaking.

The curtain is called the _Soft Palate_.

The lobby, the _Pharynx_.

The tube which leads to the stomach, the _Aesophagus_.

The tube leading to the lungs, the _Larynx_.

The opening of this tube is the _Glottis_, and the little trap-door
which closes it when one swallows, is the _Epiglottis_.

You must excuse my attempting to explain the meanings of all these
names; it would take me too long to do so. After all, the mere names
are nothing. If I have succeeded in making you understand how all the
different parts act, you may call them what you like.

Here we will rest. We are now on our way to where we shall see the
large apartments, and be introduced to the master, that head of the
house, whom no one can approach without so many ceremonies.



LETTER VIII.

THE STOMACH.

Once in the _oesophagus_ (you remember this is the name of the tube
which leads to the stomach), the mouthful of food has nothing to do but
to proceed on its way. All along this tube there is a succession
of small elastic rings, [Footnote: Properly, _contractile circular
fibres_.] which contract behind the food to force it forward, and
widen before it to give it free passage. They thus propel it forward,
one after another, till it reaches the entrance to the stomach, into
which the last ring pushes it, closing upon it at the same time.

Have you ever observed a worm or a leech in motion? You see a successive
swelling up of the whole surface of its body, as the creature gradually
pushes forward, just as if there was something in its inside rolling
along from the tail to the head. Such is precisely the appearance which
the _oesophagus_ would present to you, as the food passes down it, if
you had the opportunity of seeing it in action; and this has been called
_the vermicular movement_, in consequence of its resemblance to the
movement of a worm.

Here I wish to draw your attention to the very important fact, that
this movement is in one respect of a quite different nature from that
of your thumb when you take hold of a bit of bread, or that of your
jaw when you bite with your teeth, or of your tongue, &c., when you
swallow. All these actions belong to yourself, to a certain extent;
they are voluntary, and under your own guidance; that is, you may
perform them or not, as you choose. There is a constant connexion
between you and them, and you knew what I meant at once as I named
each of them in succession. But in speaking of this other movement we
enter upon another world, of which you know nothing. Here is the black
hole of which I spoke. The little rings of the _oesophagus_ perform
their work by themselves, and you have no power in the matter. Not
only do they move independently of you, but were you to take it into
your head to stop them, it would be about as wise a proceeding as if
you were to talk to them. We will speak hereafter, in another place,
of these impertinent servants, who do not recognise your authority,
and with whom we shall have constantly to do, throughout what remains
to be said on the subject of eating. The truth is, your body is like
a little kingdom, of which you have to be the queen, but queen of the
frontiers only. The arms, the legs, the lips, the eyelids, all the
exterior parts, are your very humble servants; at your slightest bidding
they move or keep still: your will is their law. But in the interior
you are quite unknown. There, there is a little republic to itself,
ruling itself independently of your orders, which it would laugh at,
if you attempted to issue them.

This republic, to make use of another metaphor, is the kitchen of the
body. It is there they make blood, as they know how; putting it to all
sorts of uses for your advantage, it is true, but without your consent.
You are in the position of the lady of a house whose servants have
shut the door of the kitchen in her face that they may carry on their
business after their own fashion, leaving only the housemaid and
coachman at her command. It may be humiliating, perhaps, to be thus
only partially mistress at home; but what can you do, my little
demi-queen? I will tell you: make up your mind to govern the subjects
under your orders as wisely as possible; and, as to the rest, be content
with the only resource left you: viz., that of looking in at the window
of the kitchen to see what goes on there!

The stomach is the head cook: the president of the internal republic.
He has charge of the stoves; the whole weight of affairs is on his
hands, and he provides for the interests of all. Aesop taught us this,
long ago, in his fable of "The Belly and Members." [Footnote: La
Fontaine's translation is quoted in the French original, where the
name of the fable is "_Messer Gaster_," a more correct title than our
own. _Gaster_ is a Greek word signifying stomach; and it is strictly
_the stomach_ which is _meant_ in the fable. From this comes, too, the
medical term _gastritis_, the name of a disease of the stomach.--TR.] It
is a very good fable, and was wisely appealed to once by a Roman Consul
to appease a disturbance in the State. But the application was not quite
fair in one respect; and since I have started the subject, I will
satisfy myself by explaining to you where it was wrong. The time will
not be wasted, for this fable has furnished information to a great many
people about the economy of their insides, and possibly to you; and I
should like you to know the exact truth of all the particulars alluded
to. Whether Aesop understood them all, I cannot pretend to say; but the
application by the old Roman to the quarrel between the big-wig senators
and the people was on one point decidedly unjust; for there was, as far
as facts are concerned, something to be said on behalf of the stomach,
which Consul Menenius seems not to have thought of.

When you come to this part of the Roman history you will learn that
the Roman Senate was a large and fat stomach, which did, it is true,
furnish good nourishment to the other members of the State, but kept
the best share for itself. We may say this now without risk of offence,
it having been dead for so long a time. Our stomach is the leanest,
slightest, frailest part of our body. It is master in the sense in
which it is said in the Gospel, "Let him that is first among you be
the servant of the others." It receives everything, but it gives
everything back, and keeps nothing, or almost nothing, for itself.
Between ourselves, Consul Menenius, the advocate of the Senate, had
no business to talk to the poor wretches at Rome of any comparison
between their government and so careful an administrator of the public
good as a human stomach. He should have taken his subject of comparison
from the families of geese or ducks--animals which have no teeth. These
have strong, well-grown stomachs--true Roman senators--whose stoutness
is in proportion to the work given them to do. But man provides his
with work already prepared by chewing, supposing him to have had the
sense to chew it, of course. It was not from a comparison with man,
therefore, that Menenius ought to have got his boasted apologue, which
was but a poor jest on the subject.

You did not expect, my dear, to come in for a lesson on Roman History
in a discussion on the stomach. But the study of nature is connected
with everything else, though without appearing to be so, and I was not
sorry to give you, incidentally, this proof of the unexpected light
which it throws, as we go along, upon a thousand questions which appear
perfectly foreign to it. Look, for example, at this old fable cited
by Menenius. For the two thousand years and upwards that it has been
in circulation, troops of historians, poets, orators, and writers of
all kinds, have passed it forward from one to the other, without having
troubled themselves to investigate the laws of nature in connection
with the stomach; therefore, not one, that I am aware of, has observed
this small error, so trifling in appearance, so important in reality,
which nevertheless is obvious to the first young naturalist who thinks
the matter over.

But enough of the Romans. Let us return to our master--the head cook,
if you choose to call him so.

I was telling you just now that he managed the stoves, and you may
have thought that I was merely using similes, as I am apt to do. But
not so: it is quite true that he cooks; and so now tell me, if you
can, whence he gets his fire to cook with, or rather, to speak more
correctly, who gives it to him?

Now you are quite puzzled, so I must help you out.

In the mansion we were talking about some time ago, to whom would anyone
who wanted to light a fire, apply for wood?

I think you can answer this yourself, for you cannot have forgotten
our famous steward, who gives everything to everybody. But, you will
wonder, I dare say, how the blood can carry wood in his pockets.
Wood? Ay, and real wood too, as we shall soon see: but it is not wood
we are talking about now. The blood has something more to the purpose
than wood in his pockets, for he has heat ready made. So when the
stomach wishes to set to work, it appeals to the blood, which comes
running from all parts of the body, and heats it so effectually that
everything within is really and actually cooked. This is why one feels
a sort of slight shudder down the back when the stomach has a great
deal to do at once, for the blood being called for in a hurry, comes
rushing along in great gushes, and carries with it the heat from the
other parts of the body.

It is for this reason, too, that it is so dangerous to bathe when the
stomach is at work cooking, because the cold of the water drives
suddenly back all the blood which has accumulated around the little
saucepan, and this causes such a shock in the body that people often
die of it.

Do not ask me, to-day, where this heat of the blood comes from; we
will speak of that hereafter. But I may tell you at once that our dear
steward is not a bit cleverer in this matter than other people, and
obtains his heat, like the humblest mortal, by burning his wood. Do
not puzzle yourself to find out how. Enough that he burns it as we do,
and by a similar process.

Well, in one way or another, the master cook has his fire at command.
You know also, already, what it is he has to get cooked; namely, the
pulpy stew, which has begun in the mouth by chewing, and which it is
his business now to finish perfectly. Now see what a cook does who has
got her stew over the fire. She turns and turns it again and again,
and shakes the saucepan from time to time, that the ingredients may
be more thoroughly mixed up together; and this is precisely what is
done by the stomach; for all the time that the cooking is going on,
he swells and contracts himself alternately, after the fashion of those
rings of the _oesophagus_ we were talking about, tossing and tumbling
the food from one side to another, so as to knead it, as it were.

Again, the cook adds water to her stew from time to time to keep it
moist; and so the stomach pours constantly upon his stew a liquid,
which contains a great deal of water, and which flows in from a quantity
of little holes, sunk in his delicate coats.

What more?

The cook puts in a little salt: and this the stomach takes care not
to forget either, for he is a cook who understands his business. In
the liquid of which I am speaking, there is, if not exactly salt as
one sees it at table, at all events the most active part of salt, that
which possesses in the highest degree the property of reducing
everything we eat to a paste; and this is the real reason why we find
all food so insipid which has not been seasoned with salt. As salt
contains a principle essential to the work to be done by the stomach,
some method had to be devised to induce us to provide him with it, and
this method the porter up above has hit upon. He makes a face if we
offer him anything without a little salt on it, as much as to say--"How
can you expect them to cook you properly down below, my good friend,
if you don't bring them proper materials?"

Upon which hint men have always acted from the beginning; and as far
as we can trace history back, we find them mixing salt with their food,
though without knowing the real reason why. It is the same, too, with
the lower animals. They know nothing of the matter either, but this
does not prevent their having a natural relish for salt, as any one
will tell you who has the charge of cattle; for their stomachs require
for their cooking the very same seasoning as our own, and therefore
their porter above has received the same orders.

Salt is not the only thing, however, that exists in that liquid in the
stomach. Learned men, after making minute researches, have found in
it another equally powerful material, which is also found in milk.
Therefore cheese, which contains this material as well as salt, is
quite in its place at the end of dinner. It furnishes reinforcements
for the stomach in cooking, and this is why you so often hear people
say that a little cheese helps the digestion.

The _digestion_! Yes, that is the word I ought to have begun with.
It is the real name of all this cooking; an operation after which I
would defy you to recognise the nice little cakes you have eaten, any
better than your mamma can trace her pretty rosy-cheeked apples in the
jelly which she left on the fire two hours ago. The stomach, as you
see, is very busy quite as long a time as that, and if we have to be
very careful (as I pointed out before) not to disturb him too suddenly
in his work after dinner, it is also important that we should not,
while at dinner, give him more work to do than he is capable of doing.
Although he is the master, he is but a puny fellow, as I have already
pointed out; nevertheless, he works conscientiously, because he knows
that the life of the whole body depends upon his exertions. Some people
even say that in spite of his leanness he strips himself, at each
digestion, of his interior skin, which he sacrifices to his work, and
the fragments of which tend to increase and improve the stew which is
entrusted to his care. Think of this, my dear, whenever a greedy fit
comes over you, and recollect that such a disinterested public
functionary deserves some consideration. Besides, there is serious
danger, quite apart from any question of injustice, in overwhelming
him with work. If your legs are wearied out, you have it in your power
to lie in bed. If your arm is in pain, you can keep it at rest. But
your stomach is like those poor people who have to support their
families by the labor of each day. He, too, labors for others: he has
no right to rest, no right to be ill, therefore; and when he begins
to fail, woe betide you--you will have enough of it.

Children who have learnt nothing may laugh at all this, but you, my
dear, are beginning to know something, and "science constrains,"
_i.e._ it has its claims and requirements. It requires you, to-day, not
to be greedy, to-morrow, something else, and so on, continually, until
you have become quite reasonable and wise. I am sorry for you if this
vexes you, but it was your own wish to learn, and _science constrains_.
Indeed, I will whisper to you in confidence that this is the best excuse
people who are unwilling to learn have to offer for refusing. They do
not know what learning may lead to, and what a pity it would be if they
could no longer be greedy, or ill-natured, or selfish. What would become
of us all in such a case?



LETTER IX.

THE STOMACH--_(continued)_.

We made a very long story of the stomach last time, my dear child;
and, after all, I see that there was one thing I forgot to tell
you--viz., what it is like.

Have you ever seen a bagpiper, I wonder? A man who carries under his
arm a kind of large dark brown bag, which he fills with air by blowing
into it, and out of which he presently forces the same air into a
musical pipe by pressing it gently with his elbow. If you never saw
such a thing, it is a pity; first, because the bagpipe was the national
instrument of our ancestors the Gauls, and is religiously preserved
as such by the Scotch Highlanders and the peasants of Brittany--(two
remnants of that illustrious race, whose history I recommend to your
careful perusal some day); secondly, and it is this fact which has the
greatest interest for us just now, because that large bag, which is
the principal part of the instrument, gives you a very exact idea of
your stomach; for in fact it really and truly _is_ a stomach itself, and
moreover, the stomach of an animal whose interior formation resembles
yours very, very much.

And who do you suppose is this audacious animal, which presumes to
have an inside so like that of a pretty little girl? Really, I am half
ashamed to name him, for fear you should be angry with me for doing
so. It is--it is the pig! The resemblance is not exactly a flattering
one to you, perhaps, but we are all alike, and it would be worse than
foolish to grumble at being created as we are. Moreover, there is one
difference; the pig, who thinks of nothing but eating, has a very much
larger stomach than we have, which is some consolation, at any rate.

Place the palm of your right hand on what is called the pit of the
stomach, turning the ends of the fingers towards the heart; your hand
will nearly cover the space usually occupied by the stomach, and you
may figure it to yourself as a rounded and elongated bag, bigger above
than below, making a very decided bend inside as it descends from the
heart downward; something like one of those long French pears, called
"Bon-chretiens," if it were bent in the middle, and the big end of it
were placed next the heart. As for the exact size of the bag, there
is no telling it, for it depends upon circumstances. It is a very
convenient bag in that respect; just such a one as you would like to
have in your frock for a pocket; only there would be a danger of your
being tempted to put too many things into it. For as you fill it, it
expands, and enlarges itself like an indian-rubber ball, which, though
only the size of an egg to begin with, becomes as big as your head if
you blow hard into it. Then, as it gets empty, it recovers itself,
diminishing gradually in size in plait-like contractions.

When people remain too long without eating, they have, as they say,
twinges in the stomach. This is because the stomach, becoming by degrees
quite empty, and contracting more and more, the surrounding parts which
were sustained by it, lose their support, and strain at their ligaments,
which now have all the weight to bear. Careless people, who do not
think of such things, are reminded by the twinging pains that it is
time to eat, just as a careless servant is called to order by the bell
of which his master has pulled the string.

In your case, my dear child, such warnings are soon attended to, and
you have not always even to wait till they come. But there are hundreds
of miserable beings who are warned to no purpose, who cannot obey the
master when he calls for his rations, because they have nothing to
give him; and when this forced disobedience lasts too long, they end
by dying of it. In cases like these, when human beings thus cruelly
perish, the stomach is found to be contracted till it is scarcely
bigger than one's finger.

On the other hand, a man once died suffocated from excess of food,
after one of those great public dinners, which last four, six, or more
hours--one can scarcely say correctly how long--and the doctors who
examined him found his stomach so prodigiously enlarged that it alone
occupied more than one-half of his inside. As you perceive, therefore,
the stomach has, properly speaking, no fixed size. Its size depends
upon what there is in it. It is like those men whose manners go up and
down with their fortunes; who seem very grand people when their pockets
are well filled, but become very small ones when their purses are
empty. There is, nevertheless, this difference between them, that such
men are fools, because they are men, and not _bags_; whereas the
stomach is a sensible bag, fulfilling with intelligence the duties of
its character as a bag. It is very fortunate for us that it is ready
to change its size, according to the caprices of our appetite; and
dressmakers would do well if they could get a hint from it how to
improve their style of pockets, which certainly cannot have cost their
inventors any very great effort of imagination!

The way in which this extraordinary pocket empties itself is not less
curious than the rest. As long as digestion is going on, the stomach
is firmly closed at each end; at the upper one by the last ring of the
_aesophagus_, and at the lower by another ring of the same kind,
only stronger; the watchful guardian of the passage which leads to the
intestines. This ring is called the _pylorus_.

For once, here is a name which agrees with our method of describing
the human machine, and I have much pleasure in translating it to you,
although it is a Greek word. _Pylorus_ is the Greek for a porter;
and our ring is indeed a porter like the one of which we have already
said so much, and which I called last time the _porter up above_,
in anticipation of his colleague below.

The porter up above presides at the entrance; the one below at the
exit, and both for the same purpose, namely, to _taste._ [Footnote:
It would be absurd to say so in the common acceptation of the term;
but according to No. 1 of Mr. Mayo's "Classification of the impressions
produced by substances taken into the fauces," viz., _"Where
sensations of_ touch _alone are produced, as by rock-crystal,
sapphire, or ice,"_ the word taste may be applied to the
discriminating faculty of the _Pylorus_.--TR.]

It may well astonish you, that you should have in your inside a taster
who is not accountable to you; who experiences sensations of which you
know nothing, and cannot even form an idea. Yet thus it is. The
_pylorus_ actually tastes the paste which is in the stomach, and
if it is not to his taste, that is to say, if the work of digestion
has not sufficiently transformed it for use, he keeps the door
relentlessly closed.

The porter up above has a thousand different tastes. He makes his bow
to meringues, and admits wings of chickens. Fries, roasts, stews,
things tender or crisp, sweet and salt, oily, greasy, or sour; amongall
kinds he has friends whom he welcomes in succession; and it is
well for us that he does so, for we share in all his pleasures.

The porter below, who works for himself alone, obscure and unknown
down in his black hole, the porter below, I say, has but one taste,
knows but one friend--a gray-looking paste, semi-liquid, with a very
peculiar unsavoury smell, disagreeable enough to any one but himself,
which is called the _chyme_, I scarcely know why, but it is what
everything one eats turns into, without exception, be it delicate or
coarse by nature. The great lord's truffle-stuffed pullet makes, as
nearly as possible, the same _chyme_ as the charcoal-burner's black
bread; and though the palate of the former may be better treated
than that of the latter, the _pylori_ can enjoy but one and the
selfsame sauce. Equality is soon restored in this case, therefore, as
you see.

To be free to pass through then, the contents of the stomach must be
reduced to the condition of _chyme,_ the only substance which finds
favor with the _pylorus:_ and as, in the endless varieties of food which
go to form our nutriment, some sorts turn into _chyme_ much more quickly
than others, it follows, that by the aid of its discriminating tact
(which is not easy to elude) the _pylorus_ allows some to pass, while it
turns back others, until all in succession are converted into chyme. For
example, in the case of a mouthful of bread and meat swallowed at once,
the bread passes away on its travels long before the meat has done
dancing attendance in the stomach, awaiting that transformation without
which the _pylorus_ will never allow it to slip through.

This ought to make you seriously reflect on the danger of carelessly
swallowing things, which, by their nature, are not susceptible of being
converted into _chyme,_ particularly if they are too large to
hide in the general paste, as a cherry-stone will sometimes do, so
mixed up with other food as to pass unperceived by the _pylorus,_
over whose decisions we have no control, remember. It bangs the door
to, be assured, in the very face of anything obnoxious without
hesitation, and the poor stomach would find itself condemned to retain
them for an indefinite period, unless by dint of prayers and
supplications they should contrive to soften the stern guardian, who
may at last get accustomed to their approach, and, perhaps, in a weak
moment, allow them to pass as contraband goods; like a custom-house
officer on a foreign frontier who will occasionally shut his eyes to
a country friend's packet of tobacco. But the poor stomach has had to
suffer a martyrdom meantime, while the dispute was pending, and before
the intruder has been winked at by the porter.

I shall remember all my life the history of a peach-stone, which was
related to me in 1831. I was at the time a youngster at the Stanislaus
College, and (aided perhaps by the Revolution of July, which had
recently occurred), it was just then discovered to be a proper thing
to set about teaching the laws of nature to children. Consequently,
for the first time in the history of schools, a professor of natural
history was added to the instructors of Latin and Greek. I leave you
to judge how we opened our ears to his lessons. When we arrived in the
course of our new studies at the _pylorus,_ of which we had none
of us ever heard before, our professor, in warning us, as I have done
you, of the dangers of imprudent gluttony, related, as an instance,
the case of a lady who had inadvertently swallowed a peach-stone. For
two years she suffered agonies in her stomach without any cessation
or relief. The luckless peach-stone, repelled by the walls of the
stomach, which its very touch irritated, was incessantly thrown against
the entrance of the _pylorus,_ but in vain. As to turning itself
into _chyme,_ such a thing was not to be thought of, it was far
too hard a substance for that. Round and round it went, causing in its
relentless course such renewed suffering to the poor patient, that she
was visibly sinking from day to day.

The doctors, finding all their treatment of no avail, began to despair
of her life, when one fine day she was suddenly, and as if by
enchantment, relieved of her tormentor. The peach-stone had bribed the
porter, with whom, in the course of the two years, it had scraped up
a sort of friendship. It had cleared the terrible barrier, had been
allowed to slip out, and the lady was saved; but it was only just in
time.

I do not know, my dear, that this story, which is certainly well
calculated to cure you of any fancy for swallowing peach-stones,
willmake as much impression on you as it did on me five-and-twenty years
ago. The idea of telling it to you occurred to me quite by chance. It
has carried me back to the time when, as is now the case with you, the
mysteries which lie hidden in our internal organization were beginning
to be revealed to my mind; and you will one day know with what delight
one recalls the remembrance of these first dawnings of the intellectual
life--that delightful infancy of the growing mind--more rich in
recollections, and more interesting a thousand fold than the infancy
of the body. I have allowed myself the little treat of this episode,
and if I have had the good fortune to amuse you at all during our
progress, you must not cavil at this piece of self-indulgence.
And now we have done just what the peach-stone did; we, too, have
passed the barrier, and are out of the stomach, but still we have not
yet come to the end of our tale.



LETTER X.

THE INTESTINAL CANAL.

I venture to hope, my dear child, that more and more light is dawning
upon your mind, as we gradually proceed on our little journey. You
must by this time have some idea how the food, which has been masticated
and softened in the mouth, cooked, kneaded, and decomposed in the
stomach, and transformed into a soft, semi-transparent kind of paste,
will soon be ready to mix with the blood, in order to repair the waste
that the life-stream is continually undergoing in its ceaseless course
through all parts of the body.

You have perhaps thought it a sad degradation for a truffle-stuffed
fowl to turn to _chyme._ But when you consider that by this means
it becomes part and parcel of a human body, the change is not to be
despised. It was necessary, to begin with, that materials destined to
the honor of being incorporated into our frame, should break the links
which bound them to the condition of fowl and vegetable, and thus be
free to engage in new relations; just as a man who wishes to be
naturalized in a new country must first break the ties which hold him
to the old one. Those articles of food we were speaking of lately,
which are so stiff and ceremonious, and want so much coaxing before
they change into _chyme,_ which, moreover, we call _indigestible_
because they tire the stomach so much more than the rest, are merely
those whose component parts being held together by more solid ties than
usual, continue obstinately in the same state as at first, and will not
consent to that dissolution which is the first condition of their
glorious transformation.

Moreover, the transformation which has been described to you now, you
will henceforth meet with everywhere; wherever, that is to say, and
as far as, you choose to pursue the study of nature. God works by one
grand and simple rule so far as we can discover. He destroys to
reconstruct, builds up what is to be, out of the ruins of what has
been, creates life by death, if I may so express myself, and thus,
what takes place in our stomachs on a small scale goes on on a large
one in the universe.

Social communities, like everything else, are subject to this universal
law, and it is not always an advantage to them when they refuse to be
digested in the great stomach of the age!

While we are on this subject, and to show you how wonderfully this
little history of eating, told in this familiar style, applies right
and left, let us reflect on the causes which have produced a great and
mighty nation in one country (as in France), while in another (as in.
Germany), a far more numerous and even more intellectual population
has failed to rise to anything like the same distinction. The
explanation is not difficult. In the one case, the petty tribes among
which the land was originally divided consented to mix, and dissolve,
and be digested as it were together, in order to revive again for a
more glorious career; while in the other, the aboriginal societies
have adhered stiffly to their distinctive characters, and failing to
submit to the regenerating process, cling together in indigested
portions, rather than assimilate into one great whole.

However, we must return to the _pylorus_ or we shall be getting
into a difficulty! What I am now going to offer you though, is rather
hard of digestion, but it will not do to provide sweet pastry only for
your brain; it will be more wholesome for it to have something a little
more solid to bite at from time to time.

The _pylorus_, then, as has been shown, makes way for all sorts
of aliments when they have been converted into _chyme; i.e._,
when they have lost their original form and individuality. They are
dead to their first life, therefore; now the question is, how are they
to be revived into the new one?

Behind the _pylorus_ extends a long conduit or tube--so long as to be
sometimes seven times the length of the whole body, but doubled up
backwards and forwards a number of times, so as to form a large bundle,
which fills the whole cavity of the belly--or as we also call it, the
_abdomen_. This bundle or packet is known to everybody as _the
intestines_, and it is divided into two portions: the _small
intestine_--that is, the slenderer, finer portion which begins at the
_pylorus_, and forms all the doublings of the packet, and the _large
intestine_, which is shorter and thicker also, as its name implies, and
keeps to some extent separate, though it is in reality only a
continuation of the other. This starts at the base of the _abdomen_,
near the right side, goes up in a straight line to the height of the
stomach, below which it passes, making a large bend in front of the
small intestine; after which it descends on the left side to the lower
part of the trunk, where it terminates.

You will perhaps inquire how the _chyme_ continues to make its way
through all these manifold twists of the intestines; but do not trouble
yourself; it has only to let itself go. That _vermicular movement_ which
we noticed in the _oesophagus_ and in the _stomach_ is found here also.
It reigns, so to speak, from one end of our internal eating-machine to
the other; which eating-machine, by the way, we will now call by its
proper scientific name--_the intestinal canal_; and it is by that
movement the food is carried forward from the first moment it leaves the
mouth, and helped through all its journeyings, till it reaches the
termination of the large intestine.

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.

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.

The tubes of distribution, which run out from the machine in all
directions, are called with us _arteries_; the return tubes, which
bring back the water to the machine, are called _veins._

Finally, we have not exactly the _filters_ employed to clear the
water from the impurities contracted as it goes along, for no such
thing exists in us. There are in our case the refuse-chambers of which
I have already spoken, in connexion with the liver, where the blood
disembarrasses itself of any useless materials, and from which it comes
out with clean pockets, so to speak, reverting to the comparison of
which we have already availed ourselves.

As you see, then, everything comes round again; and the bright idea
which our professors hit upon in order to satisfy the caprice of the
banker is exactly carried out in your own body, only a thousand times
more perfectly than could have been done by them all, even with all
their science added to all his money.

I mentioned that the shrewdest of the party boasted about making an
artificial heart. But, let me tell you, there is one thing I would
have defied him to imitate, by any expedient he could devise, and that
is the inimitable construction of the _arteries_ and _veins,_ and the
incomprehensible delicacy of their innumerable ramifications.

Let us talk a little about these marvellous tubes, and begin with the
arteries, which have the most important part to play.

Did you ever see a doctor try the pulse of his patient? Take hold of
your own wrist and search a little above the thumb. You will soon find
the place and feel something beating against your finger. There is an
artery which passes there, and the little beating you feel is the
rebound of the pulsations, of your heart. Every time that the left
_ventricle,_ by contracting itself, chases the blood into the arteries,
these, of which the tissue is very elastic, become distended all at
once, and then contract again, repeating the process whenever a fresh
gush of blood arrives, so that their movement is exactly regulated by
the movement of the heart. It is true the two movements are in a
contrary direction; that is to say, the artery becomes distended, while
the heart contracts, and contracts when the heart enlarges itself; but
that makes no difference to the doctor. What he wants to know is, with
what force and rapidity the heart of the patient beats, and I will
explain why. It is an interesting point in the history of circulation.

When you were very little--very little indeed, my dear child--your
heart beat from 130 to 140 times in a minute. Afterwards the beats
sank to 100 per minute; then to fewer still. At present I cannot tell
you the precise number: perhaps, about ninety. When you are a grown-up
young lady, it will beat about eighty times in the minute; when you
are a mother, about seventy-three times; when a grandmother (if such
a blessing be granted you), only from fifty to sixty times, perhaps
even fewer. People tell of an old man of eighty-four whose heart beat
only twenty-nine times in the sixty seconds.

Observe that in all my calculations I have taken special care to prefix
the word _about_ to the numbers mentioned. And this because, in
point of fact, the heart is a capricious creature, which has no exact
rules to go by. It changes its pace on every occasion--fear, joy, every
emotion which agitates the soul, quickens or retards its movements;
and derangements of health may be detected by its pulsations, which
are infinitely varied in character. In fever, for instance, which is
nothing but a race of the blood at full speed, the hearts of grown-up
people beat as quickly as those of little children; sometimes, indeed,
more quickly still. In certain maladies it goes with great sudden
leaps, like a galloping horse; in others it trots in little jerks;
while in some cases it moves slowly and wearily, and its throbs are
so weak that one can scarcely feel them.

These pulsations, then, afford important revelations to the doctor.
The heart is for him a gossiping confidant, who lets out the secrets
of illnesses, however closely they may fancy themselves hidden in the
remote depths of the body. When the doctor lays his finger on the
patient's pulse, it is precisely the same thing to him as if he had
laid it on his heart, only with this difference, that the one is much
less difficult to do, and much sooner done than the other.

The artery of the wrist is in fact a small heart, not only because it
follows all the movements of the large one, but because it carries
forward the work which the other begins, and assists also in propelling
the blood to the furthest extremities of the limbs, driving it on in
its turn at each of its own contractions. Imagine a fire-engine, whose
pipes should take up and drive forwards along their whole length the
water which is thrown upon the fire, and you will have some idea of
the marvellous machine which is at work in our behalf within us. Nor
are you to suppose that the wrist-artery is a specially privileged
one, because it has been chosen to hold intercourse with physicians.
All the others are equally serviceable; and if they cannot all be
used for "feeling the pulse," it is because they are generally more
deeply buried in the flesh, where it is not easy to reach them.

Observe your mother when she is packing a trunk, and you will see that
whatever she is most afraid maybe spoiled, she is most careful to put
in the middle, so that it may be least exposed to accidents. And this
is what a kind Providence has done with the arteries, which have the
utmost cause to dread accidents; whilst the veins, which are much
better able to bear rough usage, are allowed to wander about freely
just under the skin. But when the bones happen to take up a great deal
of room, and come near the skin themselves, as is the case in the
wrist, the artery is forced, whether he likes it or not, to venture
to the surface, and then we are able to put our fingers upon him.

And there are others in the same sort of situation; the artery of the
foot for instance. But only just think how far from agreeable it would
be to have to take off your shoe and present your foot to the doctor!

The artery which passes to the temple, just by the ear, is another
affair. That would answer the purpose very well in fact, and I even
advise you to make use of it when you want to feel your own pulse. It
is more easily found than the other even, and its pulsations are still
more easily perceptible. Nevertheless, when all is said and done, it
is better for the doctor to take his patient by the hand than by the
head. Merely as a matter of good manners.

I will now make you acquainted with the principal arteries, and the
manner in which they distribute the blood through the body.

The whole of the blood driven out by the left ventricle at each of its
contractions, passes into one large canal called the _aorta_. The
_aorta_ as it goes away at first ascends; then bends back in a curve;
and from this curve, which is called the _arch of the aorta_ (from its
shape) diverge right and left, certain branch-pipes which carry the
blood into the two arms and on each side of the head; and which are, in
fact, the beginning, or upper end, of those whose pulsations we feel
with our fingers in the two wrists and at the temples.

The supply to the upper part of the body being secured, the _aorta_
begins to descend. But now imagine of what importance it must be, that
this head-artery--the foster-father of the whole body--should be
sheltered from every accident. The _aorta_ once divided, death is
inevitable; you might as well have your head cut off at once; and
thus it has been fixed in the best--that is to say, the safest--place.
Of course you know what is meant by the _backbone_ or _spine_, called
also the _vertebral column_, in consequence of its being made like a
sort of column composed of a series of small bones fastened together,
which are named _vertebræ_. Touch it and feel how solid it is, and how
few dangers there can be for anything placed behind it. Well, that is
the rampart which has been given to the _Aorta_. As this descends, it
slips behind the heart and takes up its place in front of the _vertebral
column_ which it follows all the way down the back, just to the top of
the loins. There it is, so to speak, almost unassailable; in fact hardly
any cases are known of the _Aorta_ being wounded; to get at it, it would
be necessary to bestow one of those blows which used to be given in the
time of the Crusades, which cut the body in two. There was an end of the
_Aorta_, as of every thing else then; it was unfortunately not worth
talking about any longer!

The next time you see a fish on the table, ask to be shown the large
central bone. It is the fish's _vertebral column_, and it will give you
an idea of your own, for it is constructed on the same plan. You will
perceive a blackish thread running all along it--that is _the aorta_.

As it descends, the _aorta_ sends off on its passage a great number of
arteries which carry the blood into all parts of the body. Arrived at
the loins it forms a fork; dividing into two great branches, which
continue their descent, one on each side the body, down to the very
extremities of the two feet.

As you perceive, dear child, this is not very difficult to remember.
A large fork, whose two points are at the tips of the feet, the handle
of which curves at the top like the crook of a crozier; from this curve
come four branches, which pass into the two arms and to the two sides
of the head--and this is the whole story. But of course, it would be
another affair were I to enter into the detail of all the ramifications.
Here it is that all engineers, past, present, and future, are baffled,
defeated and outdone! Choose any place you please upon your body, and
run the finest needle you can find into it what will issue from the
puncture?

"Thanks for the proposal," you say; "I have no occasion to try the
experiment, to discover that blood will come out."

You say that very readily, young lady; but have you ever asked yourself,
what is implied by your being so sure before hand that you can bring
blood from any part of your body if you choose to prick it, though
never so slightly? It implies that there is not on your whole frame
a spot the size of a needle's point, which has not its own little canal
filled with blood; for if there were such a one, there at any rate the
needle would pass in without tearing the canal, and causing the blood
to flow out. And now count the number of places from the top to the
bottom of your dear little self, on which one could put the point of
a needle, and even when you have counted them all, do not fancy you
have arrived at the number of the tiny tubes of blood. Compared to
these, your needle is a coarse stake, and tears not one but a thousand
of these little tubes in its passage.

That seems to you rather a strong expression, does it not? But let me
make good my boldness. A needle's point is very fine, I admit; but a
person who could not see it without spectacles must have very poor
sight. Whereas the last subdivisions of the blood-tubes are so
attenuated, that the best eyes in the world, your own included, cannot
distinguish them. You are astonished at this, and yet it is nothing
compared to what follows.

No doubt you have heard of the microscope,--that wonderful instrument
by which you may see objects a thousand, a hundred thousand, a million
times, if necessary, larger than they really are. With the microscope,
therefore, as a matter of course, we can see a good many of those tiny
canals which elude our unaided sight. But, alas! we discover at the
same time that these are by no means the last subdivisions. The canals
invisible to our naked eyes subdivide themselves again into others,
and these into others again, and so it goes on, till at last--the man
at the microscope can see no more, but the subdivisions still continue.

You were ready to exclaim, at my talking of thousands of canals being
torn by a needle in passing through; but had I even said millions, it
may be doubted whether I should have spoken the whole truth.

Besides, when you consider the office of the blood, you can easily
understand that if there were a single atom of the body left unvisited
by him, that atom could never be nourished. Do I say nourished? I have
made here a supposition altogether inadmissible; it could have no
existence at all, since it is the blood only which produces it.

These imperceptible canals of blood have been called _capillaries_,
from the Latin word, _capillus_, which means a hair; because the
old learned men, who had no suspicion of the wonders hereafter to be
revealed by the microscope, could think of no better way of expressing
their delicacy, than by comparing them to hairs. Very likely they
thought even this a great compliment, but your delicate fair hairs,
fine as they are, are absolute cables--and coarse cables too, believe
me, compared to the _capillary vessels_ which extend to every portion
of your body.

Observe further, that each of these arterial _capillaries_ is
necessarily composed (being the continuation of the large ones) of
three coats enclosed one within the other, which can be perfectly
distinguished in arteries of a tolerable size; add to this that within
these coats there is blood, and in the blood some thirty substances
we know of, not to speak of those we do not know; and then you will
begin to form some notion of the marvels collected together in each
poor little morsel of your body, however minute a one you may picture
to yourself.



LETTER XV.

THE NOURISHMENT OF THE ORGANS.

When I said formerly that our dear and wonderful steward the blood,
was everywhere at once, you little suspected the prodigies involved
in that _everywhere_. But you will have a glimpse of them now, when I
tell you it is at the extremities of the _capillary arteries_ that he
carries on his distribution of goods, and accomplishes a mysterious act
of nutrition; a wonder much greater even than that of which we have just
spoken. Here, indeed, the question is no longer mechanical divisions,
whose delicacy, surprising as it may be, is yet within our powers of
comprehension. What is more surprising still, what moreover we cannot
comprehend at all, is the delicate sensitiveness of tact--I would almost
say of instinct--with which each one of the million millions of tiny
atoms of which our body is composed, draws out of the blood--the common
food of all--exactly that aliment which is necessary to it, leaving the
rest to his neighbor, and this without ever making a mistake.

You have never thought about this; for children go on living at their
ease, as if it was the simplest thing in the world to do; never
suspecting even that their life is a continued miracle, and never, of
course, therefore, feeling bound to be grateful to the Author of that
miracle. And alas! how many hundreds of people live and die children
in that respect.

But what would happen, I should like to know, if the eye took to seizing
upon the food of the nail, if the hairs stopped on the way what was
intended for the muscles, if the tongue absorbed what ought to go to
the teeth, and the teeth what ought to go to the tongue! Yet what
prevents their doing so? Can you tell me? They all drink alike out of
the same cup. The same blood goes to furnish them all. The substances
that it brings to the eye are the same as those which it brings to the
nail; and nevertheless the eye takes from it that which makes an eye,
and the nail that which makes a nail.

How is this done, do you think? that is the question.

When the doctors reply to this, that each organ has its peculiar
sensibility, which makes it recognize and imbibe from the blood one
particular substance and no other, they are strangely mistaken if they
flatter themselves that they have really answered anything. They have
done nothing but reproduce the question in other words, for it is
precisely that sensibility which requires explanation, and to tell us
that it exists, does not explain much, you must own. If you were to
ask why you had got a headache, and some one were to reply that it was
because your head ached, you would not be much the wiser I fancy.

Each of our organs, then, may be considered as a distinct being, having
its separate life, and its particular likings. These organs behave
towards the blood like men who recognize some friend in a crowd, and
proceed to seize him by the arm; and when I told you just now that
they never made a mistake, I spoke of their regular course of action
in ordinary circumstances. Like men, they also make mistakes sometimes,
in certain cases; and take one substance for another, or do not
recognize the one they are in need of; an unanswerable proof that at
other times they exercise a sort of discernment, and do not act by a
sort of fatality, as one might be tempted to believe. Look at the
bones, for instance. They are composed of _gelatine_ (which cooks
serve up under the name of meat-jelly, but which would be more properly
called bone-jelly), and of phosphate of lime, a kind of stone of which
we have spoken before, if I remember rightly, and from which they get
all their solidity. Originally, the substance of the bone is entirely
gelatinous, and the phosphate of lime deposits itself therein by
degrees, as time goes on, and always in greater abundance as we advance
in age.

Properly the bones borrow only gelatine and phosphate of lime from the
blood. But when they come to be broken, their texture or _tissue_
inflames in the fractured place; and then it changes its tastes, if
I may so express myself; and, lo and behold, extracts from the blood
that which forms certain little fleshy shoots, which unite together
from the two sides of the fracture, and so mend the broken bone. Here is
one exception to the rule.

Again, in certain diseases, the bones suddenly quarrel with the
phosphate of lime; they will not hear of it any longer, they will not
accept a fresh supply; and as the old wears out by degrees, by reason
of the continual destruction of which I spoke the other day, the bones
become more and more enfeebled, and soon can no longer support the
body. A second exception this.

Finally, when old age comes on, the bones end by being so much
encumbered with phosphate of lime, that they have no room to admit the
fresh supply which keeps coming to them in the blood. What becomes of
it then? It goes to seek its fortune elsewhere; and there are charitable
souls, who forgetting their instinctive antipathies, consent to give
it hospitality, though much to the prejudice of the poor old man
himself, who is no longer served so well as formerly, by the incautious
servants who have allowed themselves to be thus fatally beguiled; but
no one consults him. It is the arteries especially, and sometimes
the muscles, which take this great liberty, and it is not unusual among
old people to meet with these fairly _ossified_--that is to say,
changed into bone, thanks to the phosphate of lime with which they
have consented to burden themselves. This is a third exception, and
I will spare you any others.

What may we infer from all this, my dear child? Well, two things.
First, that we know nothing at all about the whole affair; a fact which
at once places us on a footing with the most learned philosophers in
the world. Secondly, that our body is a perpetual miracle; a miracle
which eats and drinks and walks, and which we must not look down upon
for so doing: for God dwells therein. I should have to come back to
this at every turn, if I wanted to fathom everything I have to tell
you about. Each tip of hair which you grow, is an incomprehensible
prodigy which would puzzle us for ever, if we did not call to our aid
those eternal laws which have made us what we are, and to which it is
very just our spirits should submit, since we could not exist for one
second were they to cease from making themselves obeyed in our bodies.

Reflect on this, my dear little pupil. Young as you may be, you can
already understand from it, that there is above you something which
demands your respect. The good God, to whom your mother makes you pray
every night, on your knees, with folded hands, is not so far off as
you might perhaps suppose. He is not a being of the fancy, secluded
in the depths of that unknown space which men call Heaven, in order
to give it a name. If His all-powerful hand reaches thus into the
innermost recesses of your body, His voice speaks also in your heart,
and to what it says you must listen.



LETTER XVI.

THE ORGANS.

Contrary to my custom, my dear child, I made use, in the last chapter,
of a new word, without giving an explanation of it.

I spoke to you of _our organs_, and we have not yet ascertained what an
_organ_ is.

You probably knew what I meant, because it is a word which is used in
conversation and pretty well understood by everybody. But I am bent
upon giving you a more exact idea of it, for the trouble will be well
bestowed. If I did not do this at once it was because there is a good
deal to tell about, and that would have carried me too far away from
my subject.

_Organ_, comes from the Greek word _organon_, and means _instrument_. It
was used particularly to signify instruments of music, so much so that
our word "organ" comes from it. Our bodily organs then, are
_instruments_, or _tools_ if you like it better, which have been given
to us, wherewith to perform all the acts of life; and as there is not
one part of the body which is not of use to us for some purpose or
other, our body is, in point of fact, from head to foot a compound of
_organs_. Thus the hand is the tool which we make use of to lay hold of
anything--so an _organ_; the eye is the instrument of sight--so an
_organ_; the heart is the machine which causes the blood to circulate--so
an organ; the liver fabricates the bile--it is an organ therefore;
the bones are the framework which support the weight of the body--so
organs; the muscles are the power which sets the bones in movement--organs
also, therefore; the skin is the armor which protects them--so an
organ: in fact everything within us is an organ. If there was any corner
of our body which was not an organ, it would be useless to us, and we
should not, therefore, have received it, because God makes nothing
without a use.

Here lies the secret of that great miracle which is called life. I do
not know whether you will be able to understand me thoroughly, but
open your ears, as if some one was going to explain addition to you;
this is not more difficult.

Life is in reality the total of an addition sum. Each one of our organs
is a distinct being which has its particular nature and special office;
its separate life consequently; and our individual life is the sum
total of all these lesser lives, independent one of the other, but
which nevertheless blend together by a mysterious combination, into
one common life, which is everywhere and nowhere at the same time. It
follows from this, that the more organs a being has, the greater is
the sum total; the more, consequently, is life developed in him.
Remember this when we begin to study life in the lower animals. In
proportion as you find the number of _organs_ diminish, you will
find life diminishing in power, until we arrive at beings who have,
as it were, only one organ apparent, and whose life is so insignificant,
that we have some difficulty in giving an account of it, and are saying
the utmost that can be said in calling it life at all.

But this comparison of life to the total of an addition sum, is too
dry; and, although it has its appropriate side, yet it might give you
a false idea of life; which is what always happens when one tries to
solve inscrutable questions and hidden mysteries by a matter-of-fact
illustration.

Let us try for something more to the purpose.

I told you that the Greek word _organon_ was applied especially
to instruments of music. Well, let us consider our organs as so many
musical instruments. You have, probably, sometimes been at a concert.
Each of the instruments in the orchestra performs its own part, does
it not? The little flute pipes through all its holes; the double-bass
pours thunder from its chords: the violin sighs with his; the cymbals
clash; the Chinese bells dance to their own tinkling; all go at it in
their own fashion, each independently of the other. And yet, when the
orchestra is in good tune together, and well played, you hear but one
sound; and to you the result of all these various noises, each of which
would have no meaning alone, is music composed by some great artist
whom you do not see. It is no longer a flute, a double-bass, or a violin
which you hoar; it is a symphony of Beethoven's, an oratorio of Haydn's,
or Mozart's overture to _Don Juan_.

Life is just like this. All the instruments are playing together, and
there is but one music; music written by God.

But wait! when I say _life is just like this_, let us come to an
understanding. Life is _some_thing like it, that is all, for as
to telling you what life is, I shall not attempt it. I know nothing
about it, do you see, though that is a painful confession to have to
make to a pupil; but in this case it does not distress me, and you are
welcome to hunt the world through for a master, who in this matter
does know anything. I could make a hundred other comparisons, but
theywould all fail in some point or other. Shall I tell you where this
one fails? In an orchestra there is always a musician by the side of
the instrument. Now with us we see the instrument well enough, but we
cannot see the musician.

You are inclined to ask me, perhaps, why I am wasting so much paper
to-day in talking to you about organs, instead of going on tranquilly
with our little history of the circulation. But I told you just now
that the secret of life lies in the organs, and before entering upon
the history of life, I ought to have begun with them. It is there all
the books begin which treat of the subject we are studying together,
and if you had one in your hands at this moment, it would teach you
that all creatures whatsoever are divided into those which have organs
and those which have none--that is, into _organic_ and _inorganic_
beings [Footnote: A lump of iron is the same throughout. Each of its
parts has the same properties and the same uses. It has no organs, it is
an _inorganic_ being. A rose tree has flowers, which are differently
made from its leaves, and serve a different use: a root which sucks up
the precious food of the earth; a bark which is of a different nature
from the wood, and serves a different purpose. It has organs; it is an
_organic being_: all animals and vegetables are _organic beings_.] (_in_
stands here for _not_, as _in_complete means not complete).

This is, in fact, the starting point for the study of nature, and there
are many other things besides which I ought to have told you before
I began. But we went straight ahead, without looking at what we were
leaving behind, satisfied with turning aside from time to time to pay
our debts.

And while I am making my confession, I ought to tell you all. You would
probably only have listened to me with half an ear, if I had begun at
the beginning. There is a proverb which says--"The appetite comes with
eating." I do not advise you to follow this proverb too closely at
dinner, for it might mislead you sadly. But it is always true when
applied to learning; it is what one knows already that gives one a
taste for learning more. If I have been making you bite at the organs
to-day, which is rather a tough morsel, it was because I fancied that
your appetite had begun to come. Was I wrong?

Let us now return to the blood which nourishes the organs.



LETTER XVII.

ARTERIAL AND VENOUS BLOOD.

It is at the extremity of the capillary arteries, as we have said,
that the incomprehensible prodigy of the nourishment of our organs is
accomplished. This done, the next thing is for the blood to return to
its starting-point; and here recommence those infinitesimally minute
wonders of which we have already spoken. Close upon the capillary
_arteries_ follow the capillary _veins_, equally fine and imperceptible
as the others. These take possession of the blood everywhere at once,
without allowing it a moment's respite, and it is thenceforth on its
road of return, travelling back again to the heart.

Where do the veins begin? where do the arteries end? No one can say
precisely, since the last ramifications of each elude the eye of man,
however much it may be aided by the admirable instruments which his
genius has invented. Nevertheless, although no one has ever ascertained
the fact by sight, there is one thing I can tell you--namely, that our
minute veins are a continuation of our minute arteries, and that it
is the same canal which as it lengthens out turns from an artery into
a vein, without any interruption; the substances destined for the
nourishment of the organs passing through its walls, as moisture passes
through our skin when we perspire.

But if nobody has seen this, say you, how can they know it for a fact?

Let me explain. In man, and in the animals which come nearest to man
in structure, it has never been seen; but it has been seen elsewhere.
This requires a little explanation, and you will not regret my giving
it hereafter. It has its interest, I assure you.

When you put your hand on your throat, how does it feel to you?
_Warm_, does it not? And when you take hold of a kitten or a bird,
how do they feel? _warm_ in the same way. Now, then, can you tell
me whence comes this warmth? But to save time I will answer the question
myself. It comes from their and your _blood_, which is itself warm, and
we shall soon see why. You have no idea of all the curious facts wrapt
up in that little phrase, "You are warm-blooded;" your blood is warm.
But it has not got warm of itself; bear that well in mind.

Now if you touch a frog, a lizard, or a fish, how do they feel to you?
Cold, of course, you answer. But I ask why? A question you will answer
in the same way as the other. Because their blood is cold, they are
"cold-blooded."

Precisely; and while you are about it you may add that, if their blood
be cold, it is because it has not been warmed as yours is. Do not be
impatient, we shall make all this clear at the proper time and place.

Now in the cold-blooded animals, such as serpents, frogs, tortoises,
lizards, fishes, and others, the blood circulates as it does in us,
and what is more, it does so, thanks to a machinery very similar to
our own. But, as you may imagine, a machine which produces warmth must
be constructed in a more perfect manner than a machine which produces
no warmth; and to speak truth, without flattering you, there is a
little difference between you and a frog, and it seems natural enough
that the body of a frog should be more clumsy in structure than yours.

It is the old story of the poor man being not so well lodged as the
rich; but putting aside rich and poor, who are all human beings alike,
let us take one of those lovely dolls who walk, and move their arms
and head, and say papa! and mamma! and compare it with a cheap bazaar
doll which you can get for a penny. Both are made, in the main, in one
way. Each has two arms, two legs, a mouth, a nose, eyes, &c.; but what
a difference in the details of the two! and what infinitely more pains
have been bestowed on one than on the other!

Well, cold-blooded animals are, so to speak, _penny doll_ animals,
by comparison with ourselves. Like us they have arteries and veins,
but there is not near so much workmanship in them; and that marvellous
delicacy of the capillary extremities, which in man and in the
warm-blooded animals drives the close observer to despair, does not
exist to trouble us in these others. It is true that with the naked
eye we are still unable to see everything, even in them; but with the
help of the microscope the whole is laid open to us--the extremities
of the arteries and the extremities of the veins; and it was here that
what I was telling you of, just now, was observed and discovered,--namely,
that the end of the artery changes into a vein, without any
interruption in the tube. It was these very observations upon fishes and
frogs, which eventually gained the day in favor of Harvey's ideas on the
circulation of the blood, at which the learned men of his own age had
laughed so much. He was dead by that time it is true, as has happened
but too often in such cases, but do not let us pity him too much! He who
has had the rare good-fortune to lay hold of a new truth, and launch it
into the world, is sufficiently recompensed in advance. If he also
craves after the flattering voice of man's approbation, and the toylike
pleasure of personal triumph, he is after all but a child, unworthy of
the great part God has given him the privilege of playing.

A child, did I say? Then how rude you must have thought me, dear child!
And as a punishment, you are perhaps going to remind me that I have
once more fallen into my old bad habit of wandering away from my
subject. Never mind, I am going to return to it at once.

How can one distinguish--you will ask me--an artery from a vein, so
as to be able to determine which is a vein and which an artery?

In many ways, I reply. First of all, an artery, as I told you lately,
is composed of three coats, of which the principal, _i.e._. the
inner one, is tough and elastic, whereby the artery is enabled to force
the blood forward in its turn, but which is also the reason of arterial
cuts being so dangerous; for in such cases the wounded tube remains
wide open; being held so by the stiffer inner coat; and thus the blood
is allowed to run out indefinitely. Now this inner coat is wanting in
the veins, whose walls sink in together when a cut is made in them,
so that it is much easier to stop the flow of the blood in them.

Furthermore, the veins are furnished inside at intervals with little
doors, similar to those we noticed at the entrance of the _auricles_ and
_ventricles_ of the heart. You remember those important _valvelets_, on
which depends so much of the mechanism; which permit the blood to pass
in one direction, but will not allow it to return back in the
other?--well, the little doors of the veins, which are also called
_valvelets_, do exactly the same work. They open in the direction of the
heart, to allow the blood to pass on, but it finds them fast closed if
it wants to go back; so that as soon as it has forced one passage there
is no longer any hope of its return, and thus by degrees it gets nearer
and nearer to the heart without any possibility of escape. There is
nothing similar to this in the arteries, which the blood traverses in a
single bound from the impetus it receives from the heart.

Finally--and this is most important--the blood which is found in the
veins is no longer the same as that which fills the heart.

No longer the same? you exclaim--have we then two sorts of blood in
our bodies? Most certainly, my dear child; but you would not have
suspected it; for when you accidentally prick or cut yourself, or when
your nose bleeds, it is always the same sort of blood that comes
out--that fine red liquid which everybody knows so well by sight. This
is because the blood flows at once from the small arteries and small
veins, and what you see is a mixture of the two. The same mixture
issues from all wounds, whether small or great, and on this account
people are unanimous in declaring that blood is red; a statement which
is not true of either arterial or venous blood, separately. The last
is black, as you might convince yourself if you had courage enough,
and should happen to be in the room with any one who was going to be
bled,--a rare event, happily, in these enlightened days.

In such a case it is always a vein which is opened, the reason of which
you will understand, after what I said of the danger of cutting the
arteries. You would there, fore see a reddish black jet of liquid spout
from under the lancet; much blacker than red, however--that is
_venous_ blood. When, on the other band, an artery has been accidentally
cut, what comes out is quite different. It is a rosy, frothy fluid,
almost like milk and carmine dissolved in it, which has been whipped up
with a stick; this is called _arterial_ blood.

Nothing is more simple, as you perceive, than to distinguish an artery
from a vein; you have only to ascertain what is inside of it. When the
blood goes out to our organs to nourish them, it is _arterial_; when it
is returning back after having nourished them, it has become _venous_.
But what--you will ask--is it going to do now at the heart, towards
which it is on its road? It is going to seek there a fresh impetus which
shall send it once more into the lungs, where it will again become
_arterial_, _i. e._ and once more capable of affording nourishment to
the organs. Therein lies the whole secret, and the why and the wherefore
of the CIRCULATION.

This is easily said, dear child; but suppose that you do not comprehend
it? Well, you need not be ashamed. There is no possibility of
comprehending it until one has learnt what RESPIRATION is--so here we
are stopped short.

To-morrow, then, when we will begin with the study of this third part
of the History of Nutrition; and if the first two have amused you, I
feel pretty sure you will not find this last one dull.



LETTER XVIII.

ATMOSPHERIC PRESSURE.

When we have been laboring very hard, my dear child, and want to rest
for a minute, we say, _Let us take breath_; because breathing is
an action which takes place of itself, requiring neither effort nor
attention on our part.

But, if it takes place of itself, it does not explain itself;
consequently, when I say to you, _Now, let us take breath_, this
is not a signal for my having a rest, for I have undertaken to explain
Respiration to you.

If you were a German, I would remind you of what so often happens when
you put a fork into a dish of sour-krout. You want to lay hold of a
little bit merely, but the strips of cabbage-leaf are twisted one
within the other, and hang together in spite of you, so that
withoutintending it you get hold of a whole plateful at once.

Now this Respiration affair is something like the sour-krout
story--begging your pardon for the comparison. I should have liked to
give you only a small plateful--a child's plateful--of it; but I feel
the explanations coming, hanging one upon the other; and, whether I
will or no, I must treat you like a grown-up person, and we must give
up for once the nice little doll's dinners with which we began.

In my opinion, you will lose nothing by the change if you will but pay
attention; for about that soft little breath of yours, which is always
coming and going over your pretty lips, there are many more things to
be learnt than you have heard of yet. As I said just now, you will
find you have got hold of a plateful all at once. A good appetite to
you!

To prevent confusion we will divide the subject into two parts. I shall
explain to you first, _How we breathe?_--a very curious question,
as you will see. And afterwards we will examine, _Why we breathe?_--which
is still more interesting.

First, I must tell you that air is heavy, and very heavy too; a thousand
times more so than you may suppose. The air we breathe, through which
we move backwards and forwards, that air is _some_thing, remember,
although we do not see it; and when there is a wind, that is to say,
when the air is in motion, like a stream of water running down a hill,
we are forced to acknowledge its being something, for we see it throw
down the largest trees and carry along the biggest ships. But without
going so far out of the way for examples, try--you who run so well--to
run for two minutes against a strong wind: and then you shall tell me
whether the air is something or nothing. But if it be something it
must have weight, for all substances have; paper as well as lead; with
this sole difference, that the weight of lead is greater in proportion
to its size than that of paper. Now a sheet of paper is very light,
is it not? and you would be puzzled perhaps to say what it weighs. But
many sheets of paper placed one upon the other, end by forming a thick
book which has its undeniable weight; and if some one were to heap
upon your head a pile of large books, like those you see on your papa's
shelves, the end might be that you would be crushed to death.

In the same way, a small amount of air is by no means heavy; but you
can conceive that a great quantity of it gathered together may end by
weighing a great deal. Now get well into your head the fact, that we,
here, on the surface of the earth, are at the bottom of an immense
mass of air, extending to somewhere about forty or fifty miles above
our heads. Let us say forty to make more sure, for learned men have
not yet been able to calculate the precise height to a nicety; and for
my own part, I think we have done wonders to get so near the mark even
as this. But can you picture to yourself the distance which forty miles
high really is? I will help you to form some idea.

One mile contains 5,280 feet, and your papa is six feet high. One mile
high would therefore be 880 times as high as your papa, But this is
a mere nothing--only one mile's height. In forty miles there would be
no less than 211,200 feet; and setting papas aside, of whom it would
take 35,200, one on the top of the other, to go so far into the sky,
let us think of the height of the tallest buildings you know; church
and cathedral towers for instance. Now the towers of many parish
churches are 150 feet high; the towers of York Minister not 300. At
that rate it would take 1,408 ordinary parish church-towers, or upwards
of 704 York Minster towers, piled one above the other, to reach to the
end of the forty miles of air above our heads. I leave you to judge
what would be the weight of a mass of paper piled up as high as that.
You may safely grant then, that this mass or pile, or if you like it
better, this _column_ of air (for that is the proper expression),
must be of considerable weight; as is still further made certain by
the fact of its having been weighed, so that I can even name the weight
to you if you wish to hear it. Bear in mind too, that the weight of
a column of air will be in proportion to its _superficial extent_--to
its breadth and width, that is; for, as you may suppose, a column as
large in extent as one of the towers of York Minster will weigh a good
deal more than one the size of a single brick.

But wait; here is a book on the table which will serve me for a measure,
and as you will probably find the same on your mamma's table, you can
follow my measurement. It is a French Grammar. The back is seven inches
long and four and a quarter wide. That is, there are four and a quarter
rows, each seven inches long. In other words, the back contains
nearly--and let us call it quite, for convenience' sake--thirty inches
side by side. Thirty _square inches_ as it is called. Measure your
mamma's copy and you will see. Now, can you guess the weight of the
column of air forty miles high which this volume supports? Upwards
of four cwt.; 450 lbs., that is to say. If you want to be very exact,
here is the rule. Air presses on all bodies at the rate of fifteen
pounds to every square inch; so now you can make the calculation for
yourself.

But I suspect you had no idea you were so strong; for I see you tossing
up the book, heavily laden as it is, like a feather.

Comfort yourself. There is no magic in the matter. If a very strong man
were to push you on one side, could you resist him? Certainly not. But
if another man of equal strength were to push you at the same time on
the other side, what would happen? Well, you would remain quietly in
your place, without troubling yourself more about one than the other,
the two forces mutually destroying each other. And this is the case
here. While the air above your book is weighing down upon it with a
force of 450 lbs., the air below it presses against it underneath with
an equal weight, and this destroys the effect of the other. From 450
lbs. take 450 lbs., and nothing remains. Your grammar has nothing to
carry after all, and you may toss it about as you please, without
deserving much credit for the effort.

"What are you telling me?" you inquire. "If I put a stone on the top
of my head, I can feel its weight easily enough; but if I put my hand
on the top of the stone I no longer feel anything. How can the air
below the stone press against it? And talking of columns--how pleasant
it would be, for instance, if the people who go up the Monument were
to have the weight of it on their heads when they get to the top!"

Well said, little one. And your objection reminds me of an argument
which distracted my head as a lad, when I first heard the pressure of
air explained by a good fellow who did not trouble himself to be quite
as exact as you and I are in our discussions. I was told that the
surface of the body, or the skin of a large man, measured sixteen feet
square, which is equal to the surface of a table four feet long and
four broad. Now, you know that in four feet there are forty-eight
inches, and on the surface of the table are forty-eight rows, with
forty-eight inches in each, or 2,304 square inches; so that a man's
surface is 2,304 square inches, and the weight his body supports is
34,560 lbs., or upwards of fifteen tons--always at the rate of fifteen
pounds to every square inch, you understand. Now, I was constantly
asking myself how it happened that in entering a house one never seemed
to get rid of this almost fabulous weight, since the roof of the house
must naturally interpose itself between the air-column of forty miles
high and the man who would then only have some few feet of air above
his head. The roof would support the rest, that was clear. From whence,
then, came the 34,560 lbs. which seemed to weigh as heavily as before;
since, whether on the threshold of the door, while still under shelter
of the roof, or two steps outside in the open air, under the tremendous
column forty miles high, one never felt a bit lighter, not even to the
extent of the weight of a single sheet of paper? This was a difficulty
from which I could never extricate myself.

I found out the answer to the riddle afterwards, and a very simple one
it is.

Air does not, in point of fact, _weigh down_ like a solid fifty
pounds' weight, which has no impulse but to descend, and has nothing
to do with anything above it. It _presses against_ rather, like
a spring, which, having been compressed, tries to resume its natural
position with a force equal to that which holds it back. Ask some one
to show you the spring of a watch, and you will understand this better.
Each atom of air is a spring of matchless elasticity, which nothing
can break, which never wears out, which one can always compress, if
one employs force sufficient, and which is always ready to expand
indefinitely, in proportion as the compressing power is withdrawn.

Now, consider the column of air outside the door, where there is a
pile of such springs forty miles high. The lower ones have to bear up
all their comrades, which press upon them with their united weight,
and these make desperate efforts to repulse the tremendous pressure,
and to spread out in their turn. They endeavor to escape in every
direction--to the right, to the left, above, below; but caught between
the earth, which will not give way, and the compact mass of all the
columns of air which surrounds the earth in every direction, and of
which the lower part is equally compressed everywhere, they struggle
unceasingly, but in vain; indefatigable, but powerless. You live in
the midst of those little wrestlers, and naturally bear the punishment
of the injury done to them. They press against you as against every
thing else--before, behind, on all sides--with a force equal to thatwith
which they are themselves compressed, or I would say, equal to
the weight by which they are so horribly squeezed and contracted: so
that, in fact, you bear this weight not only on your head and shoulders,
as you might at first suppose, but also all along your body and limbs,
under your arms, under your chin, in the hollow of your nostrils,
everywhere.

Now we will suppose you to enter the house; and what do you find there?
Outer air, which on its part has got in by the door, the window, and
every little crevice in the wall. The column outside the roof no longer
presses upon it, but what is the gain of that?

It was compressed when it got in, and the little springs will struggle
as a matter of course, quite as much on this side of the door as on
the other. The protecting roof has so little power that were it not
itself protected by the air outside, the pressure of which keeps it
in its place, the air within would shiver it into a thousand fragments
in its efforts to get loose.

You laugh; but wait till I explain myself further. I will take the
case of a miniature house to make the matter pleasanter to you; one
fifteen feet long, fifteen feet wide, and with a flat roof, the most
economical plan as regards space. Fifteen feet are five yards, and as
the multiplication table tells us that five times five make twenty-five,
our roof will in this case be twenty-five square yards (_i. e._
225 square feet) in superficial extent, or _area_; it is not much,
and you will find few as small.

Would you like to calculate the force with which the millions and
thousand millions of little spring imps imprisoned under that poor
unfortunate roof would press against it? We settled before that the
quantity of them brought to bear upon a square inch had the power to
push at the rate of fifteen pounds. Were they to push against a square
yard (a surface 1296 times greater than the square inch) it would
therefore be 19,440 lbs. This being so for one square yard, calculate
for twenty-five square yards, and you will have the amount of pressure
against our roof--viz. 486,000 lbs--merely that! And now tell me what
cottage roof in the world was ever built so as to be able to stand
against such a weight?

Perhaps though, you can scarcely appreciate the amount of heaviness,
486,000 lbs. Well, 486,000 lbs. is nearly 217 tons; and one of those
railway trucks that you see laden with coals at the stations can carry,
perhaps, from eight to ten tons, without breaking down. Say ten tons
as an outside estimate, and then think of piling the contents of
twenty-one such trucks on your roof, and yet you would still be short
of the weight of air which is bearing down upon it. I need scarcely
say now that were you to take away the air from within the roof, theair
without would smash both it and the whole cottage flat, as a giant
at a fair strikes an egg flat with one blow of his fist. To show you
how in another way: take a moderate sized column or pillar, such as
you see sometimes in a nobleman's grounds, of about the weight of the
twenty-one tons, and set it up like a chimney on the roof of our
cottage, then walk away to a little distance and watch what will happen!

There, little Miss Laugher! have you at last learned to value the
weight of the air, or _atmospheric pressure_ as it is more properly
called; since it is the force with which the atmosphere presses against
rather than weighs upon everything on the surface of the globe? It is
no joke, as you perceive, and it affords plenty of subject
forreflection. I have still to prove to you that I have not been making
fun of you with my calculations, and that the weight of air upon a
square inch is really what I have said--viz., fifteen pounds.

Now, there is a very simple way by which we might get to know your
strength, and tell its amount in figures, if one chose; namely, by
putting a weight on your arms--a heap of books, if you please--and
keep adding and adding to it, until those poor little arms were unable
to bear any more. Then weighing what they had borne, whether we should
find it to be ten or thirty pounds--I cannot guess how much it might
be at this distance--one might safely say, without fear of mistake,
"The strength of this young lady is equal to ten, twenty, or thirty
pounds"--in other words, "she represents a weight of ten, twenty, or
thirty pounds" and by a similar plan people have ascertained the
strength of the air--that is, the weight which it represents. They
have weighed what it is capable of carrying.

I told you lately that the whole surface of the earth was covered by
an immense army of little imps--otherwise called little air-springs,
which, compressed by the giant mass of their comrades above, all of
whom they have to carry on their backs, are always trying to protect
themselves, by pushing back everything which comes across them. Imagine
the bottom of a well. Our imps are permanently installed there as a
matter of course, and face to face with the water they push against
it, each one doing his best, on all points at once. As the pressure
is equal everywhere therefore, and always the same, there are no signs
of it to be seen.

Now insert in the water the end of a tube closed below by a cork which
exactly fits the interior, but which can be moved up and down in the
tube by means of a bar of iron or wood which runs through it. This is
called a _piston_, I may as well tell you as we go on.

When the piston rises in the tube, it drives before it, as it goes,
the air which was already there; and which cannot slip away down the
sides because the piston fits so closely to them all the way along.
The result of this is, that just underneath the piston there is a place
in the water to which the air cannot reach, and at that place the water
has no pressure upon it at all.

Now see what happens. Pressed upon heavily by the air in every other
part and place, like a mouse hunted by a cat, who finds at last a hole
through which to escape, the poor water darts at this and ascends the
tube close after the piston.

So far so good; but if the tube is very long, and the piston rises
rather high;--at thirty-three or thirty-four feet above the level of
the water it has to continue its ascent alone. The water parts company,
stopping quietly behind, half-way up the tube.

"What is the meaning of this?" you will ask.

It means that the force which presses on the well-water all round the
tube, and thus drives it up, has done all it can, and that our little
air-imps refuse to supply any more. The water which rises in the tube
has a weight of its own of course, and with this weight it presses,
as it is fair it should, on the water below. In proportion as the
piston rises, the column of water which follows it gets bigger and
bigger, and naturally its weight increases at the same time. At last
there comes a moment when this weight becomes such that its pressure
on the water below is equal to that with which the air-imps are pressing
on the water in the well. Thenceforth they may push as they please;
no more water will go up. They are in the same position now that they
were before, when their comrades (afterwards driven out by the piston)
were pressing upon the same point, which had only a moment's freedom;
and this water column of thirty-three or thirty-four feet holds them
in check, to exactly the same extent as the gay fellows whose place
it has taken.

Nothing is easier now than to calculate, even to a few grains almost,
the force of the pressure of air. One can get at the weight of water,
thank goodness! and it has been ascertained that our water-column will
weigh fifteen pounds if the tube is a square inch in size. You will
comprehend after this that it might be any size you may please to
imagine, without there being the slightest alteration in the height
of the column. The larger it is, the heavier will be the column of
water on the one hand; but on the other, the greater will be the number
of air-imps turned out; so it comes to the same thing in the end.

If you should feel any doubt about the correctness of this reasoning,
you have only to try the experiment over again, in a well, filled with
mercury for instance. Ask to be shown some pure mercury, which is also
called _Quicksilver_, because one wants to express melted silver,
apt to be constantly on the move; it is often to be met with in houses.
Mercury weighs thirteen and a half times more than water: according
to our calculations, therefore, it would take thirteen and a half times
less of it than of water to bring our little air-imps to reason. And
this is just what you will find happens; you will see the column of
mercury stop short exactly at the moment when it has attained the
orthodox weight of fifteen pounds; that is to say, at a height of
twenty-eight inches.

On the other hand, take some ether. You know that delicate spirit,
which smells so strong, which makes your hand feel cold if it is put
upon it, and which we give to sick people to inhale. Ether weighs
one-quarter less than water. In a well of ether you would therefore
see something quite different, and your column would rise without being
asked, to something like forty-three feet, exactly up to the point of
weighing--like the others--fifteen pounds to every square inch. Air
will not be replaced with less.

That, then, is the measure of its strength, or our scales are deceitful.



LETTER XIX.

THE ACTION OF THE LUNGS.

I hope I have told you enough, my dear child, to enable you fully to
estimate the force with which air presses upon everything on the surface
of the earth, and consequently upon our own bodies among the rest.

If you understand this, nothing is easier than to understand how air
comes and goes in our lungs.

When the cook wants to light her fire with two or three hot coals,
what does she do?

She takes the bellows and blows it, does she not?

But if she has no bellows at hand, what does she do? You answer at
once, she blows it herself with all the strength of her lungs.

By which it would seem--does it not?--that we are a sort of living
bellows, being able, in case of necessity, to act as a substitute for
the wood and leather ones of common use. And if we really possess the
power of doing the work of a bellows, may not this be because we have
within us some little machine of the nature of a bellows?

Exactly; and this fact gives me the opportunity of making you understand
the action of the lungs by explaining that of the bellows, which is
in everybody's hands, but which three-fourths of the people use, without
troubling themselves to inquire how it is made or acts.

"A bellows, as you know, is composed of two pieces of board, capable
of being separated and brought together again at will, and united by
a piece of leather so shaped and arranged that it doubles up when the
boards close, the intermediate space forming a firmly-closed box, the
size of which increases or diminishes at every movement of the boards.

"We take the bellows down to use it, and there are the boards, lying
flat upon each other, the box between them quite small. Is there
anything inside, do you think?

"Nothing," you answer; "the bellows is empty."

Do you think so really, my child? Do you think a tumbler is empty,
then, when you have drunk out its contents; and that jelly pots are
empty when all the jelly is eaten? There are not so many empty things
in the world, I assure you, as you suppose. You forget the air--that
monster who is always wanting to stretch himself out, and pushes against
everything he meets. He is an unceremonious gentleman, who takes
possession of every vacant place; as fast as you put a spoonful on
your plate, he takes up the room of the jelly which has been removed,
and at each mouthful you swallow, he slips into the place of the water
which goes away. When you think the glass and pot are empty, they are,
in reality, full of air. You cannot see it; but it is there, you may
rely upon it.

There is air, then, in the bellows-box, because there is air in every
place where there is nothing else to dispute possession with it. The
quantity is small in this case, no doubt, because the box is small and
cannot hold much.

But now, look! I separate the boards, and the box, which was small,
becomes large. For once, then, here is a box which must be partially
empty; for it has just, as if by magic, made a space in itself in which
positively there cannot be anything, since there was nothing there
beforehand.

Ay! but look down at the centre of the upper board. You see a little
hole there, do you not, and below the little hole a small piece of
leather, which seems to close it up? That is a _valve_, one of those
doors, such as we noticed before in the heart, and such as are to be
found, moreover, in most houses, which let people through on one side
but not on the other. This one opens when it is pushed from without, but
lets nothing out which has once got in. Now, the air outside, as I said
before, is always pushing against everything. He pushes as a matter of
course, therefore, against the valve, and as there is nothing behind it
to resist the pressure, in proportion as room is made inside the box, he
enters and fills it with himself.

But presently some one begins to close the bellows, and he finds himself
caught between the boards; on which these invite him to begone, with
the same sort of politeness displayed by the police, when the hour of
departure comes in a place of public exhibition; when, _i.e._,
they spread out on all sides, and force the crowd before them till
they have found the road to the door. But the air cannot get back by
the way it came in, the door being shut. As, however, it must go out
somewhere, whether it likes it or not, it passes through the tube at
the end of the box (the _nozzle_ of the bellows), and comes out
thence with a rush upon the fire. When it is once gone the bellows can
be distended again, and the process be repeated as before indefinitely.

And this is just what goes on inside ourselves. Your chest, my child,
is a box which expands and contracts alternately; making a place for
the air by the first effort, and then driving it out by the second.
It is neither more nor less than a bellows, but of a simpler
construction than that used by the cook. The exit pipe serves also for
a door of entrance, and there is but one board instead of two.

The _exit pipe_ is the _larynx_, of which we spoke before,
when we were talking of swallowing the wrong way, and which communicates
with the air outside, through the nose and mouth at the same time,
allowing us to breathe through either one or the other as we like.

As to the _board_, I said a few words about it when I was describing the
liver. It is the _diaphragm_--that separating partition--that floor
which is placed between the two stories or divisions of the body--the
belly and the chest.

But here especially the infinite superiority of the works of God over
the miserable inventions of man comes out in all its grandeur.

A bellows which was to have the honor of keeping up within us that
miraculous fire--the pre-eminently sacred fire--which we call Life,
required something more than a common board for its foundation. And
accordingly this, of which I am now going to give you a detailed
history, is as marvellous as it is admirable. I fancy that when you
have read my account, you will no longer turn up your nose at the vile
word _diaphragm_.

Let us first take a peep at the construction of the bellows.

On each side of the _vertebral column_, from the neck to the loins,
spring twelve long bones, one below the other, bent in the form of bows;
these are called the _ribs_. The first seven pairs of ribs rest, and as
it were, unite, in front, upon a bone called the _sternum_, which you
can trace with your finger down to the pit of the stomach, at which
point the finger sinks in, for there is no more _sternum_, and the last
five ribs on each side no longer unite with those of the opposite one.
For which reason they are called _false ribs_. On the other hand they
are joined to each other at the ends by means of a strip or band of a
substance sufficiently strong, but at the same time flexible, and
somewhat elastic, which is called _cartilage_ or _gristle_. The next
time you see a roasting piece of veal on the table, look well at it, and
you will see at the end a white substance which crackles under your
teeth; that is _gristle_.

This forms the framework of our bellows, which you may picture to
yourself as a kind of cage, widening towards the bottom and going to
a point at the top, for the arches formed by the upper ribs are smaller
than the others. The whole terminates in a sort of ring, through which
pass, together, the _oesophagus_ and the _trachea_.

The space between the ribs is occupied by muscles which reach from one
to the other, and the whole framework or cage is shut in below by the
_diaphragm_, that marvellous board whose history I have promised to
relate.

The _diaphragm_, as I told you some time ago, is a large muscle, thin
and flat, stretched like a cloth between the chest and the _abdomen_. It
is fastened by an infinity of little threads called _fibres_, to the
lower edge of the cage I have just been describing, and it looks at
first sight as if it must be incapable of moving, since it is fixed in
one invariable manner all round the body.

It moves nevertheless, but not in the same way as the boards of our
bellows.

Ask your brother to hold two corners of your pocket-handkerchief; take
hold of the other two yourself, and turn the handkerchief so as to
face the wind. The four corners remain in their place, do they not?
but the middle, inflated by the wind, curves and swells out in front
like a ship's sail, which itself is only an immense hand kerchief after
all. Then draw the handkerchief tightly towards you, each to your own
side, and it will recover itself and become flat again. Loosen it a
little and it will curve and swell out again in the middle, and this
maneuver you can go through as often as you choose.

Which very maneuver the _diaphragm_ is continually performing, of and by
itself.

In its natural position it bulges upwards in the middle, like a cloth
swollen out by the wind, and thus occupies a portion of the chest at
the expense of the lungs. When air has to be admitted, its _fibres_
tighten and bring it flat again, as you and your brother brought the
handkerchief flat just now by tightening it.

The whole space previously occupied by the arch of the _diaphragm_
is thus given up to the lungs, which, being elastic, instantly stretch
themselves out to it; while air, running in through the nose and mouth,
fills up in proportion the empty place (_vacuum_) created by the
extension of the lungs, exactly as in the case of the bellows.

But soon the fibres of the _diaphragm_ relax. It rises up again into its
old position, driving back the lungs as it does so; and the air finding
there is now no room for it, goes out by the same way the other came in.
I say _the other_, observe, because the air that goes out is no longer
the same as when it came in; and this is the secret of _why we breathe_;
while the up and down movement of the _diaphragm_ is the explanation of
_how we breathe_.

As you perceive, then, the mechanism of these bellows of ours, is of
the most simple, and consequently of the most ingenious character, and
leaves far behind it anything we have ever imagined.

Are you disappointed? Do you feel inclined to exclaim, "Is this all?"
to ask where are the wonders I promised you? to protest that I may
talk as I please about the inflating and flattening of a
pocket-handkerchief? _you_ can see nothing so marvellous in the
matter; nothing worth making your mouth water for.

A little patience, Mademoiselle! Hitherto we have talked only of the
machine; but there is a goblin inside it, and our fairy tale is going
to begin again.

There are in some families certain old servants who belong to the
house, more, it may be said, than their masters, in some ways. They
educate the children, and they serve them till death; they live for
them alone, and know so well what they have to do, both by day and
night, that there is no need to give them any orders. Nay, not only
is it unnecessary to give them directions--it is for the most part
labor in vain. They are so completely at home in their business, that
they will go nobody's way but their own. If you wish them to alter
their habits they may obey you for an instant, but it is only to return
into the old groove directly after; for they know better than you do
what you want.

I was very little when I first read in the story-books of my day, some
bitter complaints of the disappearance of this race of old-fashioned
servants of the good old times. And you very likely may have seen it
said that they are no longer to be met with. Yet there will always be
some, depend upon it, in families, who know how to make and to keep
them. Good old times or not, they have never been found in any other
but these cases.

Still, _I_ have just such a one as I have described--even I who
am talking to you--and so has your mamma; and what is more, you have
one yourself; and what is more still, everybody else has one. This
servant of the good old times, who will never disappear (and this is
more than one can promise of any other) is the _Diaphragm!_ When
you came into the world, my dear child, and were merely a poor little
lump of flesh, without strength, intelligence, or will; incapable of
giving any orders whatever to those organs of yours, of whose existence
you were not even aware, your _diaphragm_ quietly began his duties,
without leave or inquiry from you, and with your first _breath_ your
life began. Since which he has always gone on, whether you attended
to him or not, and his last effort will be your last sigh.

When you go to sleep, careless of all that is to happen, until you
awake again, that servant of yours, indefatigable at his post, labors
for you still, and the light breath which half opens your rosy little
lips as it passes through them; that light breath which your happy
mother watches with such pleasure, is his work. Midnight strikes--one
o'clock--two; all around you are buried in sleep--but he is awake
still. Were it otherwise--were he to go to sleep when you do, you
would never awake again!

This protector of each instant, this faithful guardian of your life,
is, nevertheless, subject to you as a servant to his master. Attend
to him, and he will obey your orders. You can make him go at a great
pace, or slowly, as you choose; or stop him altogether, if the fancy
takes you to do so: but this not for long. The servant of the good old
times is obstinate in the performance of his duties. He will yield to
you in trifles; but do not try to force him over serious matters. I
have read somewhere of a desperate young fellow, chained down in a
dungeon, who killed himself by holding his breath; but I never quite
believed it. Mr. Diaphragm would not allow any one to carry rebellion
so far as that.

But we have not finished yet, and you do not yet know how appropriate
is the comparison I am making.

Should any misfortune, any grief, any trifling annoyance even, befall
his master, a good servant suffers with him, and as much as he does;
sometimes even more. Occasionally the master is comforted, while he
remains still disturbed.

"And the diaphragm?" you ask.

The diaphragm does precisely the same, my dear child. Yours, especially,
shares in all your griefs to such an extent that, truth to say, he is
not always quite reasonable. The other day when your mamma did not
want to take you into the country with her, he was so sorry for you
that he went into perfect convulsions, and you sobbed and sobbed till
she was obliged to say, "Come, then, you naughty child;" whereupon you
embraced your mamma, and were quite happy again, while he remained
still unappeased, and your poor little chest was shaken more than once
afterwards by his last convulsions.

Sobbing, you must know, is merely a convulsion--a great shake of the
diaphragm--which is the reason of its causing such a heaving of the
chest.

It is the same with respect to joy. The joy of the master makes the
servant dance, and so the diaphragm too! Its little internal jumps
are, then, what we call laughter--a thing you are well acquainted with.
Put your hand on your chest next time you laugh (and I hope it will
be soon) and you will feel how it dances--thanks to the diaphragm which
jumps for joy whenever it finds you in good humor.

Please to observe further, that nothing of all this is done to order.
He starts of himself, poor fellow, without waiting to ask if you will
ever know anything about it; and, in truth, you have known nothing
about it up to the present moment.

What say you to the diaphragm now, my child? Does not the very name
please you? You scarcely expected to find there--under your lungs--so
good a servant, one so attached to your person, so strongly resembling
in all points the best specimens we know among men. And still we have
not done. I have reserved as a finale for you a new point of resemblance
which will make you open your eyes very wide indeed.

The old servant is sometimes cross and grumbling. If anything is going
against his grain in the house he has no scruple in saying so; and his
mode of speaking is sometimes rather rude. Nor is it of any use to get
impatient and impose silence on him; he will listen to nothing--it is
his privilege. But let some unforeseen accident happen to his master,
let him see him deeply affected, and in a moment all his anger is over.
He sets himself silently to work again, recalled to order twenty times
sooner by his master's emotion than by his utmost impatience.

You ask what I am coming to now? My dear child, what I have just told
you is the history of the _hiccup_--the history of the hiccup, neither
more nor less.

I must first tell you, however, that the _diaphragm_ keeps up
intimate relations with his neighbor below--the stomach. Every time
he rises in the breast the stomach rises behind him; and not only the
stomach, but also its companions, the intestines. All the officials
employed in the business of digestion travel regularly with him; coming
down as well as going up in company. Put your hand upon your abdomen
and breathe strongly and you will feel the rebound of all the movements
of the diaphragm.

Now, when matters are going on wrongly inside, when too much work has
been imposed on the officials, or work they dislike, or else when they
have been disturbed in their labors, it will sometimes happen that the
_diaphragm_ takes part with his comrades in the abdomen. He gets
angry then, and shakes his master, who cannot help himself a bit. You
must be very well acquainted with these attacks, which are very
fatiguing when they last long. One begs pardon and resists him in vain;
he does as he pleases, without stopping to listen, turning everything
upside down; and do you know the only efficacious plan for calming him
at once? It was a constant source of wonder to me when I was little.
A sudden fright, a start unexpectedly caused by a friendly hand slipping
secretly behind, and laying hold of one, was all-sufficient; disarmed
by the agitation you have undergone, the naughty, stubborn muscle
forgives you, and you are cured.

Having dwelt so long on the truly wonderful resemblance between the
proceedings of two sorts of beings, whom no one that I know of ever
thought of comparing together before, I will now, my dear child, give
you the key to all these comparisons, which seem so whimsical at first,
but are so striking in reality, and which come to my pen of their own
accord, as it were, in the midst of the explanations I have undertaken
to give you. Many people who would not themselves care for them, will
declare that they are too hard for a little girl to follow. But for
my own part, I find that the eye can take in a mountain as easily as
a fly, and that it is not more difficult to lay hold of great ideas
than of little ones. It is short-sighted people, not children, who
cannot see far before them. Who made the heavens and the earth? God,
your catechism tells you. The same God made both; did he not? We do
not acknowledge two. And if it be the self-same God who made everything,
the hand of the universal Maker will be found everywhere; and from the
highest to the lowest portion of His work the same mind will manifest
itself under a thousand different forms. Not only, either, is each man
separately, one by one, the work of God. The whole human race, taken
in the mass, is also His creation; and the laws by which human
society--that great body of the human race--seeks to regulate itself
for the preservation of its existence, are undoubtedly the same as
those which overruled the organization of our individual bodies. It
is not very astonishing, then, if we find, in the life of human society
around us, details corresponding with each detail of the life of the
human body, or, at any rate, closely resembling them. What would really
be astonishing, would be that mankind as a whole should be differently
constituted from man as an individual, and that human society should
have other appointed conditions of well-being than those of each of
its members.

So, while I am on the subject, I should like to advise those who wishto
apply themselves to what is called _politics_--that is to say, social
life--to begin their studies of the body social, by studying the body
human, first. They will learn more from it than from the newspapers!

But you have nothing to do with all this. For the present, take notice
of one thing only; viz., that the hand of the same God has passed over
everything, and that there is neither much presumption nor much merit
in tracing points of comparison between the different parts of His
work. These comparisons are not a mere play of the mind; they really
exist ready made in the very foundations of things.

Now let us come down a little from these heights and return to our
friends the lungs. I have not spoken about them for some time, and I
have not yet told you how they are constructed.

I wish I could show you some, but the cook will do so, if you would
like to see them. The _lights_ with which she feeds the cat and
the dog are the lungs of some animal.

Take up a piece in your hand, and you will find you have got hold of
something _light_ (cooks have not given it its name without a reason),
which is also soft, sinks under your finger if you press it, and rises
again afterwards like a sponge. In fact, the lung, like the sponge, is
composed of an infinity of minute cells, whose elastic sides can be
contracted or expanded at will. They are like so many little chambers,
into every one of which blood and air keep running hastily, each on its
own side, to bid good day to each other, touch hands, and then hurry out
as briskly as they came in. Whether the bit of lights the cat is eating,
comes from an ox, a pig, or a sheep, you may look at it with perfect
confidence; your own lung is precisely like it. You would see nothing
different, could you look into your own chest.

So much for the _substance_ of the lungs. As to SHAPE, imagine
two large, elongated packets, flat inside, descending right and left,
inside the breast, and bearing the heart, suspended between the two,
in the middle. The extremity of each packet descends below the heart,
and it is in the interval which separates them that the arch of the
diaphragm performs its up and down movement.

I have already said that air reaches the lungs through the _larynx_. The
_larynx_ (of which we shall speak further when I have explained another
curious thing very valuable to little girls--the voice), the _larynx_ is
a tube composed of five pieces of _cartilage_ (you know now what
_cartilage_ or _gristle_ is), the firm resisting texture of which keeps
it always open. After these five pieces of _cartilage_, come others, and
the tube is continued; but it then takes the name of the _trachea_; the
_larynx_ and _trachea_ constituting the _windpipe_. At its entrance into
the chest, the _trachea_ divides into two branches, which are called
_bronchial tubes_, and which run, one into the right lung, the other
into the left. You sometimes hear people talking about _bronchitis_. It
is an inflammation of these _bronchial tubes_, which are within an inch
or two of the lungs. It is necessary, therefore, to be very careful in
such circumstances, and do exactly what the doctor prescribes,
because--one step further, and the inflammation extends from the
bronchial tubes into the lungs themselves, with which it is not safe to
play tricks.

Having reached the lungs, the _bronchial tubes_ subdivide into
branches, which ramify again in their turn like the boughs of a tree,
and the whole ramification terminates in imperceptible little tubes,
each of which comes out in one of those little chambers I was talking
about just now. And this is the way in which air gets there at all.

The venous blood which leaves the heart, arrives on its side by one
large canal, which passes out from the right ventricle, and which is
called the _pulmonary artery_. And, to tell you the truth, while there
is no learned man present to be angry with us, it is a very ill-chosen
name, because it is _venous_ blood which flows in this so-called
_artery_. But the doctors have decided that all the vessels which run
from the heart should be called _arteries_, and all those which go back
to it _veins_, whatever may be the nature of the blood which they
contain. We cannot help it, because they manage all these matters in
their own way; but in that case it was scarcely worth their while to
talk about _arterial_ and _venous_ blood. It would have been better to
have said simply, red blood and black blood.

Be this as it may, _venous blood_ arrives from the right _ventricle_
through the _pulmonary artery_. This divides itself, like the _bronchial
tubes_, into thousands of little pipes, whose extremities come creeping
along the partitions of the little chambers in question.

And here, then, takes place, between the air and the blood, that
mysterious intercourse for the account of which I have kept you waiting
so long; and at the end of which the black blood becomes red, or, in
other words, from venous becomes arterial. I have called it
"intercourse," and this is really the proper phrase; for this
transformation of the blood is accomplished by means of an exchange.
The air gives something to the blood, and the blood gives something
to the air--each giving, in exchange, like two people over a bargain
in the marketplace.

With your permission, my dear child, we will stop here to-day. We have
now got to the charcoal market, and it is a little black.



LETTER XX.

CARBON AND OXYGEN.

Here, then, my dear child, we have arrived at the explanation of that
great mystery, WHY _we breathe._ Keep on the alert, for we are now
entering into a region where everything will be new to you.

Here we are at the charcoal market, I said to you just now, and no
doubt you concluded that I was beginning another comparison.

But no such thing; there is no question of comparison or simile here;
I state the fact itself, pure and simple as it stands: it is a
_market,_ for commercial intercourse and exchange are carried on
there, as I told you before, and it is a _charcoal_ market,
because _charcoal_ is, positively, the essential and chief article of
commerce.

You are astonished, I dare say, and are ready to ask me whether I can
possibly mean real charcoal, charcoal such as the cook puts into the
furnace. Surely, say you, we have nothing like _that_ in our bodies?
Surely we don't eat _that_?

But I answer yes; real, true charcoal, and you do not dislike it; you
eat of it even daily; nay, you do not swallow a single mouthful of
food which does not contain its proportion of charcoal.

You laugh; but wait a little and listen.

When you are toasting a slice of bread for breakfast, and hold it too
near the fire, what happens to it?

It turns quite black, does it not?

When mutton-chops are left too long unturned on the gridiron, what
happens to them?

They turn quite black also.

When your brother forgets the apples which he has set to roast, what
happens to them?

They turn quite black, as you have seen more than once.

It is always black, then, that these things turn, is it not? and a
fine rich _charcoaly_ black, as you may see if you please to
observe charcoal closely, for just such is the color of little burnt
cakes, over-roasted chestnuts, and potatoes in their skins, which have
been dropped into the fire.

But there is a common term by which we can express more accurately the
misfortune which has befallen all these various things--slices of
bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not,
when "burnt," "over-toasted," "over-roasted," or "over-baked." We may
call them _carbonized_, or more simply _charred_ or _charcoaled_; though
the word _charred_ is generally used only for burnt _wood_. But _carbon_
being the principal ingredient of _charcoal_, and _charcoal_ being one
of the purer forms in which we get at _carbon_, they are almost
synonymous terms, and you may call your burnt food _carbonized_, or
_charred_, or _charcoaled_, whichever you prefer.

The next question is, how did charcoal or carbon get into the food so
as to justify our talking of its being _carbonized_ or _charred_? Even
when we use charcoal stoves for cooking, the charcoal does not jump out
and get into the mutton-chops, etc., you may be sure. Then it is clear
it must have been in them before they were brought to the fire to be
cooked; and such is indeed the case, only its black face escaped notice
because it was in such gay-looking company, and kept itself hid behind
the others like a needle lost in a match-box. Set fire to the matches,
and you will soon have nothing left but the needle, which will then
strike your eye at once. And so with our burnt food; the fire has
carried off all the other ingredients, and the charcoal is left behind
alone, exposed to everybody's view, as if on purpose to teach them that
it was always there; in the apples, i.e., the potatoes, mutton-chops,
etc., which seemed so tempting when the black rogue was hid, but from
which now, when he is there by himself, they turn away in disgust.

Charcoal is, in fact, a much more generally distributed substance than
you have been used to suppose, dear child. That which comes from burnt
wood is most easily observed, because there is a much larger proportion
of charcoal in wood than anywhere else; but there is not a morsel,
however small, of any animal or vegetable whatsoever, which does not
contain charcoal. In the sugar which you crunch, in the wine which you
drink, there is charcoal. I could even find some in the water you wash
in if I were to try hard. There is charcoal in the goose-quill which
I hold in my hand at this moment, and in the paper on which I am
writing, and in the handkerchief on my knee. If I hold them all three
in the light of my wax taper, I shall soon see them turn black and
betray the presence of our friend. It exists in the wax taper itself,
as also in the candle, as also in the oil lamp. If I were to hold a
piece of flat glass above their flame, I should collect enough of it
to blacken the tip of anybody's nose who presumed to doubt the fact.
There is a portion of it in the air; a portion of it in the earth.
Where is it not? In short, all the stones of all the buildings in the
world are filled with it from top to bottom. _Charcoal,_ under his more
scientific and important name of _carbon,_ may be called one of the
great lords of the world. His domain is so extensive that one might go
round the world without getting out of it; he is even worse than the
Marquis of Carabas.

After this you will never, I hope, want to persuade me you do not
eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of
all the things you see on the dinner-table there is but one in which you
will not find it--viz., the salt-cellar; and even while saying this,
I mean only, in the _salt_ itself, for as to the salt-cellar,
clear and transparent as its glass may be, there is charcoal in it!

Our bodies, therefore, are full of charcoal. Everything that we eat
supplies them with enormous quantities of it, which take up their
quarters in every corner of our organs. It is one of the principal
materials of the vast collection of structures of which I spoke to you
in the early part of these letters, and of which the blood, the steward
of the body, is the universal master-builder. If you remember, I told
you then that these structures fell to pieces of themselves, in
proportion as the workmen went on building, and that the blood, which
brings fresh materials on its arrival from the lungs and heart, carries
away the refuse ones on its return. And, of all these refuse materials,
old charcoal is one of those which takes up the most room, as fresh
charcoal took up a great deal of room in the new materials. The blood,
as he goes back again, has his pockets quite crammed with it, and if
he did not try hard to get rid of it as fast as possible, he would be
disabled from being of any further use.

Now it is in the lungs that he clears himself of it. He gives it up
to the air, which has need of it for a very interesting operation, of
which I shall tell you more by and bye; and in return the air gives
him something which is quite indispensable to him, for without it he
would not dare to return to the organs, as his authority would no
longer be recognised.

In the same way, the charcoal-seller goes to market with his charcoal
and receives silver in exchange.

If he were to go home without money his wife would receive him with
abuse.

But what is the indispensable thing which the blood obtains in his
marketing?

Remember its name well: it is OXYGEN.

And we must speak of it with respect, for we are talking here of a
very great and powerful personage, very superior even to CARBON. If
CARBON be one of the great lords of the world, OXYGEN is its king.

There is a certain substance, my dear child, of which many people,
especially little girls, do not even know the name, but which yet
constitutes of itself alone a good half of everything we are acquainted
with in the world. And this substance is the very thing I have just
named to you. It is OXYGEN.

Ascend into the air as high as you can go, viz., to forty miles or so
from the ground, as we said before; _oxygen_ forms the fifth part
of that vast aerial ocean which surrounds the globe on every side.
There it is free--is _itself_--if I may use the expression; it
is in the condition of _gas_; that is to say, it eludes our sight,
though there is no difficulty in ascertaining its presence, when one
knows how to set about it.

Go down into the depths of the sea. People think they have good reasons
for believing this to be two and a half miles deep on an average, which
would give a pretty little sum total of tons for its whole weight, as
you will be convinced, if you take the trouble of observing the space
it covers on a map of the world;--to say nothing of lakes, rivers,
streams, the water in the clouds, the water scattered throughout the
interior or on the surface of continents, including that with which
you wash your face every morning.

Oxygen enters in the proportion of eight-ninths into the composition
of this incalculable mass. _Eight-ninths_, you understand, which
is very near being the whole nine; in every nine pounds of water there
are eight pounds of oxygen, the remainder being left for another
substance, of which we shall have occasion to speak presently, and
which is called _hydrogen_.

The earth on which you tread is full of oxygen. So far as we have
penetrated hitherto into the interior of the globe, we have found king
Oxygen everywhere: hidden under a thousand forms, connected with a
heap of substances, not one of which could exist without him; imprisoned
in a thousand combinations, and always ready to resume his natural
condition if his prison-house be destroyed. The whole surface of the
earth, plains, hills, mountains, towns, deserts, cultivated fields,
everything you would look down upon, if on a clear day you could be
carried high enough in a balloon to take in the whole earth at a
glance:--all that may be considered as an immense reservoir of oxygen,
out of which we should see it escaping in gigantic waves, if some
superhuman chemist were to take it into his head to put our poor little
globe into a retort of the same kind as chemists use among us. To give
you an example; the stones of our fine buildings, in which we have
already discovered the presence of _carbon_, are almost half made
up of _oxygen_. In a stone which weighs 100 lbs. there are 48
lbs. of oxygen, and the first chemist who passes by could make them
come out of it if he chose, if he were to use a little trouble and
skill.

I enumerated to you last time many of the substances in which _carbon_
is to be found; but as regards _oxygen_ we must give up all attempt at
making a list; it would comprehend the whole dictionary. Touch whatever
lies under your hand--in your room--in the house--wherever you may go--I
will almost defy you to put your finger upon anything--metals
excepted--which is not crammed with oxygen. Your very body, to conclude
with, would become so small a thing, were the oxygen it contains
extracted from it, that you would be perfectly amazed.

So when I told you oxygen was king of the world, I did not say too
much, did I? Between ourselves too, it is a great misfortune that
people live on so complacently in total ignorance of this all-important
material, which is connected with everything, which insinuates itself
everywhere, which we make use of every instant of our lives, which may
almost be said to be in some sort our very selves, since it constitutes
three-fourths of our body, but whose name nevertheless would, I am
certain, make many pretty little mouths pout, if one were to utter it
in a drawing-room.

This is really the case. Many young ladies who are proud to know who
Caractacus was, would be ashamed to know anything about oxygen. There
is a foolish notion that women have no business with such subjects,
probably because children are supposed not to breathe and mothers are
not required to watch over them?

This reminds me that we are on the road to explain _respiration,_
which I had almost forgotten in lifting up this corner of the veil
behind which Nature hides her most valuable secrets from the idle and
ignorant.

It is _oxygen_ then, which the blood carries off triumphantly from his
interview with the air in the cells of the lungs; and, by the way, it
is, thanks to this oxygen that it returns from the lungs to the heart,
and so from the heart to the organs, with that beautiful rosy tint which
distinguishes _arterial_ from _venous_ blood.

Now the blood gives out this oxygen on its road every time it performs
the journey, and the perpetual course it performs from the lungs to
the organs, and from the organs to the lungs, has for its chief object
the perpetual renovation of this previous provision, which is as
perpetually consumed.

Do you ask of what use it is? Does the blood leave it at random in our
organs, and is it one of the materials with which our steward is
constantly providing the little workmen of the body for their various
constructions?

No, my dear child. The proverb _"One cannot live upon air,"_ is
a very true one, although it is equally true that we cannot live without
air. Air does not nourish our organs; on the contrary, it consumes
them, and what we eat, serves to supply in precisely the same proportion
its insatiable appetite. When we leave off eating, from whatever cause,
the air does not leave off too. He goes on always just the same, and
that is the reason why people who are starved to death are so thin.
(The air has consumed the vital parts.)

You did not expect this; but now prepare yourself to go on from one
surprise to another. To begin with, I shall have to stop here and
explain to you before we go any further--can you guess what? Nay, I
am sure you cannot; FIRE.

There is not much connection, you will say, between _fire_ and
_breathing_.

But there you are mistaken. It is precisely the same thing, as I will
prove to you next time.



LETTER XXI.

COMBUSTION.

Have you never, my dear child, whilst warming your little feet on the
hearth in winter-time, asked yourself, _What is fire?_ that great
benefactor of man; fire, without which part of the world would be
uninhabitable by us during at least a third of the year; fire, without
which we could not bake a morsel of bread, and would have to eat our
meat raw; fire, which lights up the night for us, and without which
we should have to go to bed when the hens go to roost; fire, which
subdues metals, and without which we should have neither iron, nor
copper, nor silver, nor anything that is manufactured from those
materials; fire, without which, in short, human industry could not
rise to much higher results than that of the monkey and of the beaver?

We are all of us, it is true, so much accustomed to fire that we do
not pay much attention to it, and have a sort of persuasion that lucifer
matches have existed from all eternity. But the first men, who were
nearer neighbors to that great discovery whence all others have
originated--the first men treated fire with more respect than we do.
It was to them one of the mighty things of the world. The ancient
Persians made a god of it, and told how Zoroaster, their prophet, went
to seek it in heaven, passing thither from the top of the Himalayas,
the highest chain of mountains in the known world.

The old Greeks pretended that Prometheus stole it from the gods, to
make a present of it to man, which came to nearly the same thing as
the Persian account. The Romans had their _sacred fire_, which
the celebrated Vestals were bound to keep lighted, on pain of death
to whoever should let it go out. At the present day we do not stand
upon such ceremonies, but warm our feet at it quite familiarly, without
wishing for anything further. But you would see a terrible revolution
in the world if some Prometheus reversed were, some fine morning, to
steal it from us, and carry it back to its ancient owners. Every branch
of human industry would suddenly stop, as if by enchantment, and in
the course of a very few years the poor little framework of human
society, of which we are now so proud, would totally change its aspect,
and the whole world would be turned topsy-turvy.

But do not be alarmed; there is no danger of the sort. Fire is not a
present once made to man, but liable to be taken away from him at will.
It is a law of nature which existed before the human race came into
being, and which will doubtless continue to exist when the human race
shall have disappeared. The existence of fire is connected in the most
intimate way with that of that great king of the world of whom we spoke
last time--Oxygen. Fire is the wedding-feast of Oxygen with other
substances!

When kings are married, what rejoicings there are! what a commotion!
what illuminations! It is only right and proper, then, that the king
of the world should have rejoicings and illuminations at his weddings
also. And they have never been wanting. The rejoicings are the warmth
which rejoices us; the illuminations, the flame which gives us light.
But man, in his dealings with nature, is an imperious subject, such
as few earthly kings are troubled with--happily for them! Whenever he
wants warmth and light he forces the king of the world to get married,
and then takes advantage of the feast; nothing worse than that.

"How so?" you exclaim. "If I want to make a fire with stones or iron,
I should never succeed. Is this because oxygen never unites himself
with those substances, nor with heaps of others which are equally
useless in lighting a fire? Yet you told me that oxygen was to be met
with almost everywhere."

It is a fair question, my dear child; but my answer is, that what you
said last is precisely the reason why all substances are not fit for
making fire of. When oxygen is already there, as he is in stones, for
instance, the marriage is over--the feast cannot begin again. Kings
are like other people in this respect; their weddings are only
celebrated once. If you had happened to be present at the moment when
oxygen was united to the materials of which stones are composed, you
would have seen a feast of which I should like to have heard some news.
I was not there myself either; but learned men in these latter days
have succeeded in breaking the bonds which united oxygen with the
primitive substances in certain fragments of stone, and with these
substances thus freed, and consequently able to remarry, they have
been enabled to give us, in miniature, the spectacle of the festivities
of a fresh wedding. And I can assure you it is enough to make one
shudder, to think of the time when such a marriage must have taken
place on a large scale.

With regard to _iron_ the case is quite different.

You have without doubt heard tell of Louis XIV. (of France), that proud
king who was called _le Grand_, and who is said to have heard
himself compared to the sun, without smiling. It seems that he one day
took it into his head to marry, it is difficult to say why, with Madame
de Maintenon, the old wife of a poor paralytic poet named Scarron,
who, as such, however, was only known by some few farces. Do you suppose
that the palace of Versailles was illuminated in honor of this marriage?
Not a bit of it. It was a disgraceful marriage, which they were bound
to keep secret. The ceremony was conducted mysteriously and without
lighting a single candle more than ordinary.

I do not pretend to say that oxygen has any of these weaknesses, nor
that he is any more partial to marrying with one body more than with
another. In the good God's great world, outside of the family of man,
they know nothing of our foolish pride, of our little weaknesses. It
is nevertheless a fact that this dear monarch has his preferences, and
that all his marriages are not made in this fashion.

Leave those pretty little scissors of yours, with which you would try
in vain to make a fire, outside your window for two or three days, and
then observe the dreadful, scaly, red stain which you are sure to find
on them afterwards, and which is called _rust._ Have you any idea
whence it proceeds? I will tell you. It comes from the oxygen, which
has been making one of those cheerless secret marriages with the iron
of your scissors. So there have been no pretty sights nor sounds, no
lights nor cheerful noises to entertain anybody, and though people may
have wished for them ever so much, they have had to do without them.

I will tell you the true reason of these marriages _incognito._
It is because oxygen is but feebly attracted by iron, who does not
stand so high in his good graces as many other bodies, and so (to
continue the joke) he unites slowly and languidly with him, as we may
say.

Now tell me, when you set fire to a bit of paper, how long does it
take to burn?

Half a minute, at the utmost, you answer.

Very good. And how long does it take to produce that rust-stain, even
though it is probably not a hundredth part the size of the paper?

Two or three days, is your reply, for so I told you my self.

Here is a strange difference indeed; but from it you may discover why
you have not seen any signs of rejoicing or illuminations at the iron
wedding. These are always in proportion to the quantity of oxygen which
is being married at once--and this was--oh, such a slow affair! When
the quantity is very small indeed, the festal illuminations are very
small indeed too, and in fact escape observation altogether. In the
same way that you would not be conscious of little bits of thread laid
delicately one after another on your back, whereas you would plainly
feel a large sheet, were it to fall on your shoulders. Yet what is the
large sheet but a great quantity of little bits of thread? Only in
that case they would all come upon you at once, like the marriage
illuminations of burning paper.

Wait a little longer and we shall finish.

What is there, then, in the paper which pleases the oxygen so much
that he unites himself to it so readily, and in such large quantities?

What is there? Two substances of high degree, who have actually risen
to the dignity of a royal alliance, by the important part they play
in the world; one of these, charcoal or _carbon_, we know quite
well already; the other I have only mentioned to you in connection
with water, HYDROGEN. Thanks to gas companies, everybody in these days
knows _hydrogen,_ at least by name. But before proceeding, I will
just tell you that it is by far the lightest body that is known. It
is forty and a half times lighter than air, which is not very heavy
itself, although in the mass it has its weight, as we have seen.

The true province of hydrogen is water, where it keeps house with
oxygen, in proportion of one to eight pounds, as you may remember I
stated in my last letter. But beside this, _hydrogen_ and _carbon_ are
in a manner inseparable friends, whom one invariably meets side by side
in all animal and vegetable substances. In wood, coal, oil, tallow, and
spirits of wine; in everything in short that we call _combustibles,_
because the name of _combustion_ has been given to this marriage of
oxygen with other bodies, hydrogen and carbon keep themselves shut up
very discreetly and very quietly; like two children playing at
hide-and-seek. You have sometimes played at hide-and-seek yourself, no
doubt? Now, if some naughty child had come behind you with a lighted
candle, what would you have done? You would have had to turn out, whether
you liked it or not, and be caught. Well! this is what happens to our two
friends, when you bring the paper to the fire. The heat forces them out,
and the oxygen, which is always at hand, seizes upon them. In a
twinkling they are married, and a beautiful flame springs up into the
air, which lasts till everything has disappeared.

Hydrogen and carbon! These, then, are the two great combustibles, the
two parents of fire; and as nature has lavished them upon us in what
we may call inexhaustible quantities; when you hear people lamenting
and saying that wood is disappearing, that coal is diminishing, and
that the human race will end by not knowing how to warm themselves,
do not disturb yourself in the least.

There is more hydrogen in a bucket of water than is wanted to cook a
large dinner. There is as much and more carbon in our stone quarries
than in our coal pits, and when all the woods in the world are cut
down (which I trust will never be!) do you know what we shall do? Why,
we shall take to burning the mountains. The Jura mountains in
Switzerland, for instance, (to take the most favorable case) are great
masses of carbon, without its ever being visible. Everything depends
upon knowing how to make it come out of its hiding place; but that
will de done when it is wanted: more difficult matters have been
accomplished already. As to oxygen, whether carbon comes to him from
a log of wood or from a building stone; whether the hydrogen comes
from a candle or a glass of water, is a matter of perfect indifference
to him. He only considers persons, not their origin, and marries as
willingly in one case as in the other.

So we have returned to the subject of _respiration_, on which I
always seem to be turning my back; but now the question is, what brings
us to it again? And this is the explanation.

When the oxygen picked up in the lungs by the blood has traveled with
it to the organs, he finds there two well-known friends--hydrogen and
carbon.

You smile, and exclaim at once, "Then he marries them, does he?"

Yes, my dear child; and it is only for that purpose he enters our
bodies at all. And this is why I could not make you understand the
nature of respiration until I had explained that of fire to you. As
I have told you before, it is the same thing. Invite air into your
body by the bellows of your chest, or drive it into the fire by the
kitchen bellows--it is always king Oxygen whom you are sending to his
wedding.



LETTER XXII.

ANIMAL HEAT.

Now, then, we have got hold of the secret of respiration; the _oxygen_
within us unites itself to the _hydrogen_ and _carbon._

And for what purpose, do you suppose?

Unquestionably it must be to make a fire, since they never come together
without doing so.

But what do people make fires for? I ask next. Well! surely to warm
themselves, do they not?

And this is the history of your body being warm exactly like a
dining-room stove, where the oxygen in the air forms an alliance with
the hydrogen and carbon of the wood. Nature warms little girls inside,
on precisely the same plan by which men warm their houses in winter.

Imagine, then, a little stove, furnished with little arms for helping
itself out of the wood-basket as it is wanted, and with little legs
to run and refill it when it is empty; the fire must be always burning
there, and the stove must be always warm.

Just such a little stove is your body; your mouth being the little
door, by which there constantly enter--not wood, that would hardly be
pleasant--but--hydrogen and carbon under the forms of bread, mutton
broth, cakes, sweetmeats, and all the good things people have learnt
to make with sugar, fat, and flour. There is hydrogen and carbon in
everything we eat, as I have already told you; but sugar, fat, flour,
and _wine_ are the substances which contain them in the greatest
quantities, and consequently they are our best _combustibles._

You are surprised, perhaps, at _wine_ being a combustible; wine,
which you think would put out rather than make a fire.

And it would. But that is only because in it, what is good for burning
is mixed with a great deal of water, which prevents our being able to
set it on fire. But if part of this water is withdrawn, you have
_brandy,_ which lights easily enough; and if part of the remaining
water is withdrawn from the brandy, you have _spirits of wine_, which
takes fire more easily still. If you have ever seen a _spirit-of-wine_
lamp, you must know something about this. Judge from that what a fire
spirits of wine must make in the body, even when it has a good deal of
water with it; for it is right to tell you that your little stove is
very superior to the one in the dining-room, and that it hunts out for
consumption the smallest portions of combustible matter, in places where
the other would be a good deal puzzled to find them.

This is not all, however. I have much greater wonders to tell you yet.

What should you say to a stove, which, summer or winter, night or day,
in rain or sunshine, amid the ice of the pole, or under the sun of the
equator, was able to keep itself constantly in the same condition;
neither hotter nor colder one minute than another, whether you gave
it much or little fuel, at a given moment, and sometimes when you gave
it nothing for whole days together? It would be worthy of a fairy tale,
would it not? Yet the human body is a stove of this description.

But this requires a little explanation.

It is rather bold in me, you may think, to assert so freely, that all
the year round, from one end of the earth to the other, the human body
is never colder nor hotter than mine is, for instance, at this present
moment. "Hot" and "cold" is soon said, you argue: but the exact
varieties of _more_ or _less_ are not so easy to measure, and especially
not easy to remember, with reference to so many bodies, scattered over
the face of the whole earth. What may be warmth for one in one case, may
not be equal warmth for another; and even supposing that the same
individual learned man could go and inspect every part of the globe in
succession, how could he possibly recall, while touching the body of a
negro in Senegal, in July, the exact amount of animal heat he had found
in a Greenland Esquimaux in January?

Be content. I should not have settled the question so cavalierly, if
people had not discovered an infallible method of estimating accurately,
and always in the same manner, the degree of warmth, in other words,
the _temperature_ of the body.

Let us first see, then, what this method is, though it will oblige us
to digress a little; but you are accustomed to that now, surely; and
besides, if I were to go straight ahead, you would not be able to
follow me.

Do you ever recollect being very cold? Let mammas look after their
little girls as much as they please, to prevent it, it is sure to
happen to every one some day or other. Now does it not seem at those
times as if the whole body were contracting itself--and when people
are shivering with cold, have they not a shrunk, shrivelled look? When
the weather is very hot, on the contrary, our bodies feel as if they
were swelling and stretching, and one seems to take up more room than
before. This is the case with all bodies. Heat swells, or, as learned
people call it, expands, them: cold shrinks or contracts them.
Furthermore, _mercury_ is one of the things most susceptible of this
action of heat and cold, and we have had recourse to it accordingly, in
the construction of the _thermometer_, [Footnote: _Thermometer_ comes
from two Greek words: _thermos_, heat; and _metron_, measure. The
degrees in the Thermometer about to be described are marked on the
_Centigrade_ principle. [Not the one (Fahrenheit) in general use in the
United States.]] a very useful instrument, which you will hear spoken of
all your life.

The _thermometer_, or _heat-measure_, consists of a little hollow ball
filled with mercury, out of which rises a small tube of very thin glass,
in which the mercury can move up and down. When the thermometer is
exposed to heat, the heat causes the mercury to expand, so it goes up
the tube; when the thermometer is exposed to cold, the mercury contracts
and sinks again.

Now suppose you were to melt some ice in the palm of one hand, and try
to dip a finger-tip of the other in a saucepan of boiling water; you
would find a great difference of temperature between the two, would
you not? Which difference of temperature people have succeeded in
measuring with the thermometer, as accurately as your mamma measures
a piece of cloth with her yard measure.

This is how it is done:

You surround the ball of mercury with pounded ice, and while it is
melting make a mark at that point in the tube where the mercury has
stopped in its descent. Then plunge the thermometer into boiling water.
Whereupon the mercury goes up, up, up, till at last it reaches a point
beyond which it will not pass. Here a second mark is made, and the
space between the two marks is divided into a hundred perfectly equal
parts, indicated by so many small lines, which are called _degrees_. But
this word _degrees_ has a double meaning in some languages. It means
_steps_ as well as the degrees of measurement we are talking about;
steps being, as you know, the perfectly equal parts into which a
staircase is divided. Fancy the mercury-tube a staircase, then, rising
from the cellar where the melting ice is, up to the garret where the
boiling water is, and let it consist of 100 steps. The mercury goes up
and down this staircase, according as the temperature it encounters
approaches that of the boiling water or of the melting ice; and if you
wish to know exactly how far it is from the cellar or from the garret,
you have only to count the _steps_. Hence arise those expressions which
you so often hear--high temperature and low temperature. These mean,
temperature according to which the mercury goes up or down this
staircase.

On the actual floor of the cellar where the ice melts, there are yet
no degrees (a floor is not a _step_, you know), so there you find the
word _zero_, which means a cipher or nought. Then you begin to count 1,
2, 3, 4 degrees, marked by lines up to 100, where you reach the garret,
_i.e._ the boiling-water height.

Of course, if the thermometer be exposed to an amount of cold greater
than that of melting ice, the mercury will sink below the cellar.
Accordingly the staircase is carried below it, with steps (so to speak)
of precisely the same size as those above, and you count as before,
1, 2, 3, &c., as it descends; adding however, to distinguish these
degrees from the others, "_below zero_." You may go on in that
way as far as 40; but there you must stop. At that point the mercury
freezes. He sits down there on his last step, and will not go any
further!

In the same way if the thermometer is exposed to a heat greater than
that of boiling water, the mercury will rise higher than the garret.
So the staircase is made to go up higher, and always with steps of the
same size, counting from 101 upwards, as far as 350 if you choose; but
no further, observe! If the temperature were raised beyond that, the
mercury would begin to boil, and then, indeed, good-bye to steps and
measured degrees! The gentleman would dance so fast that there would
be no possibility of seeing anything, to say nothing of his flying
away!

Now nothing is easier than to use the thermometer. You place it in the
situation where you want to measure the heat, and the mercury goes up
or down of itself until it reaches the degree which corresponds with
the temperature of the place. It is much more convenient than your
mamma's yard measure, which has to be moved about over the stuff, and
which is very apt to slip if you do not hold it carefully. Dressmakers
would be delighted to have a measure which only wanted laying upon the
material, and which would unroll itself and stop short just at the
proper point. And this kind of office the thermometer really performs.

We will suppose to-day to be the 30th of November. I have just carried
the thermometer out of doors; the mercury has fixed itself at the
second degree _below zero_. This tells me that it is freezing
cold. My fingers have told me so already; but exactly to what extent
they could not say. Just now in the room, the mercury was at the 15th
degree _above_ zero, thanks to the stove in which we have a good
fire. In summer-time it rises to 25, 26, or 28 degrees. I once saw it
climb as high as 33 degrees: in the shade of course, you understand;
in the sun it would have been quite another affair. Well! there was
a universal outcry against the heat. Grown-up young ladies whom I try
to teach all sorts of things as I do you, pretended that it was
impossible to work. Yet I should find a still greater heat inside my
body, if I could get the thermometer there. Have no fears, however;
I am not going to make a hole in it: luckily there is one already. I
put the ball of mercury into my mouth. And now I can almost tell without
looking. The mercury was on its way up the staircase as soon as I took
the ball in my hand--and now it has reached the 37th step.

You can try the experiment on yourself, but I forewarn you that it
ought to be rather hotter with you than with me: the mercury will
probably rise a degree higher. I will not promise that in your
grandpapa's mouth it may not sink a degree--but that will be all. In
different mouths it has, between the 38th and 36th degree, room for
the play of a little variation, but it can no more go beyond these
than a tethered cow can get beyond the circle made by her cord as she
turns round the stake. Go round the world with your thermometer, pop
it into everybody's mouth, wiping it if you choose as you proceed, you
will always find the mercury on guard. Its tethering cord is somewhat
elastic, like everything else about us; but if by any accident it
should exceed its limit by even one degree above or below, it would
be quite as extraordinary as meeting a giant of eight feet, or a dwarf
of three--which one does see occasionally, although the standard of
human height varies generally round the centre of five feet.

Since there is a fire always kept burning within us, there is no
difficulty in comprehending why our bodies always keep warm. Of course,
however, the fire must be kept brighter in winter than in summer, but
people have no need to be told so. Nature provides for the necessity.
She gives us more appetite in cold than in hot weather; not that we
can perceive much difference in ourselves in this respect from winter
to summer; for our bodies stick to their accustomed habits, and call
out pretty loudly for the same daily rations, though without having
the same need of them. In order to estimate fairly the connexion which
exists between the internal need of food--_i.e.,_ of combustible
matter--and the external temperature, we must compare the Hindoo, who
lives on a pinch of rice a day, between the tropic and the equator,
with the Esquimaux, who, to keep up his 37 degrees of heat, beyond the
polar circle, in a country where European travellers have seen mercury
freeze, sometimes swallows from ten to fifteen pints of whale-oil at
a sitting! Just fancy _whale-oil!_ which is much nastier than
even cod-liver oil, if you ever tasted that; but, on the other hand,
it is a thorough _combustible_, and the poor people are not so
very particular: come what will, the fire must be kept up, and that
briskly. But without going thus into extremes, a friend of mine once
told me that in Portugal, the land of oranges, it is not uncommon to
see gentlemen and ladies (that is to say, those who can eat and drink
what they please) dine standing, in five minutes, on a bit of bread
and whatever else may be handy. Propose this system to the inhabitants
of our colder and damper climate, whose very young ladies, fair and
delicate-looking as they are, need a helping of good roast-beef for
dinner to keep life in them, and they would only laugh at you. But
those who were well instructed could go on to inform you that the
chilly atmosphere of northern countries creates the necessity for a
more active internal fire than is ever needed under the burning sun
of Portugal, and that a mouthful of bread per day will not, in their
case, suffice to maintain the appointed thirty-seven degrees of heat.

For the same reason, Spaniards drink water, and are satisfied; whereas
English wine-merchants add brandy to a good many foreign wines, or
they would be quite unacceptable from being deficient in combustible.
It is for the same reason, also, that Russians can swallow, without
wincing, bumpers of brandy which would kill a Provençal outright: and
that the Swedish Government has no end of trouble to keep the country
people from converting into brandy the corn that ought to go to the
miller; whilst the Mohammedan Arabs accept without difficulty that
precept of the Koran which forbids the use of wine and spirituous
liquors. It is easy for the Arabs, who are kept warm by their climate,
to do without brandy. It is less easy for the Swedes, who are surrounded
by cold.

All this comes as a matter of course, and we do the same thing
ourselves, without being unusually sagacious. In January, when the
thermometer goes down to twelve or fifteen degrees below zero, I put
more fuel into my stove than I am doing to-day, with only two degrees
of cold to bear with. There is nothing surprising in all this.

The wonderful thing is, that when an Englishman goes to India, he takes
his roast beef and his spirits with him, and in a temperature of more
than thirty degrees of heat, quietly heaps up fuel in his stove, just
as if he was in England, or nearly so. You think he will set fire to
the house, perhaps. But no. Send the thermometer to his mouth for
information, and it will only mark down thirty-seven degrees; neither
more nor less than in the mouth of a rice-eater! The stove has more
sense than its owner. It only burns just what hydrogen and carbon it
wants, and takes no more trouble about the remainder than if it had
not been eaten.

How about the remainder, then? you ask; if it is not consumed for use,
what becomes of it? Do you remember, my dear child, that long ago,
after explaining the office of the bile and the liver, I put off telling
you what the bile _consisted of_, until we had talked about the lungs
and respiration? Well, the time has come now; so listen.

The hydrogen and carbon which is not consumed by the oxygen in the
blood, is seized upon by the liver, who employs it in the manufacture
of bile. Therefore the greater the amount of unemployed hydrogen and
carbon there is in the blood, the greater is the quantity of bile
manufactured by the liver--that is all. When once the body has attained
to its proper degree of heat, it is in vain you load it with
combustibles; it will not get any warmer, do what you will. Only you
will have cut out so much extra work for the liver, and the poor wretch
will have to get through it as he can. Accordingly, what happens in
the long run to our great eaters and drinkers, whether in India or
elsewhere? The bile-manufacturer, overwhelmed with work, gets worn
out at last, and kicks; and people come home with that miserable
disease, which is called the "liver-complaint."

This is one explanation of that wonderful uniformity of temperature
which, happily, human imprudence cannot disturb. But the blood has a
second resource for getting rid of its superfluity of hydrogen and
carbon, and herein especially is displayed the beautiful foresight
with which everything about us has been prearranged. We are told that
wolves, when they get hold of a larger piece of meat than they care
to eat at the moment, carry off what they do not want to some corner
and bury it in the ground, whence they get it again when their hunger
returns. Dogs sometimes do the same; and the blood has a similar
instinct. Listen attentively, for this is very interesting.

I light a candle and you see a bright flame, which will last as long
as there is any tallow below the wick. Can you tell me what it proceeds
from?

Nay, do not laugh at the question; it is quite to the purpose, I assure
you.

We know, do we not, that the substances which burn best are those which
are full of hydrogen and carbon? Tallow, then, is one of those
substances. But tell me further, if you please, what is tallow?

Tallow is _mutton fat_, allow me to say, if you never heard it before.

Now comes the question, who provided the sheep's fat with such a
quantity of hydrogen and carbon as to qualify it for making candles?

The sheep's blood undoubtedly, since blood is the purveyor-general of
living bodies--of the sheep's body as well as of our own.

But how came it that the sheep's blood had so large a stock of these
materials?

Undoubtedly, again, because there was more of them in the food the
sheep had eaten than the oxygen was able to consume or the liver to
employ. In short, the sheep has lungs and a bile-manufactory, as we
have; oxygen performs the same office for it as for us. What takes
place in its body in the matter of respiration is an exact counterpart
of what happens in ours, and the history of its fat is simply the
history of our own.

Now do you think it is for our sakes that the sheep's blood deposits
its fat in little pellet-like morsels throughout the body; do you
suppose the poor creature works in this manner merely to have the honor
of providing us with candles? It is not likely. I was talking about
the wolf just now; but there is no need to look beyond ourselves. In
many poor people's cottages there is somewhere an old earthen pot in
which the savings of each day are carefully put by, penny by penny,
as a last resource in time of need. Should a wicked thief succeed in
murdering the owner and laying hold of the treasure, he will squander
in a few hours of brilliant revelry the precious hoard so slowly got
together as a provision for possible needs. And this is what man does,
when he kills the sheep and takes its fat to make candles of! The poor
animal's blood knew well that bad times might come, that grass might
fail, and the combustible matter conveyed into the body become
insufficient to maintain its thirty-nine or forty degrees of heat
(which is the sheep's measure, who is rather hotter than we are). So
it quietly laid up its surplus stock of combustible so conveniently
brought to hand, and destined to be burnt little by little in the
depths of the organs, should times of scarcity arise. But here steps
in man, the universal thief of Nature, and turns it into a beautiful
flame, regardless of cost, and burns in one evening what his victim
had been economizing for so long. To burn for burning's sake, however,
has always been the fate of tallow, the only difference being in the
way it is done. Like the poor man's clumsy pence, which were put by
to be spent some day or other, only in another manner. It is worth
noting here, that some of the Russian soldiers who were in France in
1815 had a very good idea of restoring candles to their original
destiny. As children of the north, driven to get fire wherever they
could, they ate all the candle-ends they could lay hold of, preferring
to burn the tallow, sheep's fashion, inside rather than out!

Fat is, then, the savings' bank of the blood; there it deposits its
savings, and there it can always find them again in time of need.
Witness the fat pig described by Liebig, the great German chemist,
which having been swallowed up by a landslip, was found alive at the
end of 160 days. Fat was out of the question there, of course; the
animal weighed ten stone less than before. We will take the illustrious
professor's word on trust, but were a few days subtracted from the
account the case would still be a splendid example of the resource
which blood finds in fat when other nourishment fails; for the pig had
certainly been breathing during the whole 160 days, and as, in all
probability, he moved about much slower than usual, his hydrogen and
carbon fire was never extinguished for a single instant; of that I am
perfectly certain, and you shall soon know why. It was well for the
poor fellow himself that he had put by his provisions in time of plenty.
And who suffered? Why, the pig's master, who had looked forward with
pleasure to the rashers of bacon he should cut by and by from the
stores of combustibles in his larder. For once Master Piggy ate his
own bacon himself!

You understand now, I hope, by what ingenious management that marvellous
stove, called an animal, never burns too much fuel, whatever be the
quantity it is supplied with, and how, on the other hand, it has always
as much as it wants.

I have now to explain how important it is that it _should_ always
have enough, and that this is not merely a question of heat and cold,
as with dining-room stoves, but one of life and death! Cheer up! I
have only one more word to say about Respiration, and when you have
heard it you will appreciate still better the lesson of economy which
you have learnt from Nature to-day.



LETTER XXIII.

ACTION OF THE BLOOD UPON THE ORGANS.

The first time we talked about the Blood, my dear little pupil, I
introduced him to you as the steward of your body, and what a steward
to be sure! Always awake, as you may remember, always in motion; his
pockets ever full of the materials unceasingly required by the
indefatigable builders of that human edifice in which it has pleased
God to house your dear little self. If you wish really to understand
what follows now, we must carry on the simile a little further.

A steward not only provides the workmen with materials, but gives them
orders as well, and this is part of the blood's business also. He is
not only commissary-general, but _whipper-in_ of the whole household,
and besides the care of giving out all the stores, has the charge to see
that everything is properly done. The unhappy men who purchase
prosperity at the dreadful cost of maintaining slavery, pretend that
their slaves would do no work worth looking at, were there not always
some one behind them with a whip in his hand. Well, our organs are
slaves, and slaves of the worst sort. They would never do anything
at all, if the blood were not everlastingly whipping them up in his
ceaseless rounds. Let him come to a stand-still for one minute, for
a second even, and everything stops short; then we are at once in the
castle of the Sleeping Beauty in the wood. But perhaps I cannot do
better than to compare our bodily machine to a violin--to hit upon
something less dismal than slaves--a violin with blood for its bow.
As long as the bow runs over the strings the violin makes music and
lives; when the bow stops, it is silent and dies.

You have never yet had a fainting fit, my dear child; it rarely happens
at your age. But you may possibly have seen somebody faint; or, at any
rate, you have heard it talked about. Do you know what takes place in
such cases? Now and then, in consequence of some violent emotion, but
how or why I cannot tell you, all the blood rushes suddenly back towards
the heart, as during an earthquake a river will sometimes flow back
towards its source, leaving its bed dry. Thereupon the face turns
white, as if to give notice that there is no longer anything red below
the skin. The organs, no longer stimulated by the blood, leave off
work altogether. The brain goes to sleep, the muscles relax,
consciousness ceases, and you behold the poor body, from which the
soul seems to have departed, give way on all sides, and fall to the
ground like a corpse. This is not exactly death, but it is yet an
interruption of life. It would be death if nature did not get the upper
hand again, and send back the deserter to his post.

I may remark here that it was partly on this account that some of the
ancients thought the soul was seated in the blood; not a bad idea for
people who were determined to pronounce where the soul was, when it
is so easy to say one knows nothing about it. But those who placed it
in the breath, and who have bequeathed to us those beautiful
expressions--_yielding up the last breath--giving up the ghost_--were
not wrong neither.

In point of fact the blood is not the soul of the body; in other words,
does not keep the body alive, otherwise than by keeping up unceasingly
and everywhere that magic fire of which we were talking last time.

The French people, in their picturesque language, have found an
expression, full of energy, to express the action exercised by the
master workman, who knows how to make his people work: "_Il vous met
le feu sous le ventre._" [Footnote: Literally, _he puts fire under
their bellies;_ but here signifying that he makes it so hot that
the organs are compelled to continue in motion.] This is, to the letter,
the process employed by the blood to make the organs work. It makes
a fire under the belly. Unhappily their work only lasts as long as the
fire which causes the heat, and which is so necessary to life that it
is almost confounded with it. It is the sacred fire of the Roman
Vestals, which must be fed night and day under pain of death should
it go out. Now, if to feed the sacred fire of life, it be necessary
that the blood should everywhere find hydrogen and carbon
_unattached_, that is to say, free and ready to unite themselves
to oxygen, it is no less necessary that he should bring oxygen with
him everywhere. Else there would be no marriage, and therefore no fire.
Oxygen is, then, the talisman which brings the organs to obedience.
Without oxygen he would be a slave-driver without his whip; his orders
would be despised. If the organs were to be deluged with _venous_
blood--with that black blood which has lost its oxygen, they would not
stir any more than if they had received so much water. They acknowledge
nothing but _arterial_ blood--red blood--blood rich in oxygen.
That is what they respect, and which has authority over them; the other
is a bankrupt who has lost his credit with his cash; those whom he fed
but lately now laugh in his face. And as our good steward spends all
his oxygen every time he goes his rounds, it would soon be over with
him, and, consequently, with us, too, if he had not some method of
replenishing his purse after each journey. Happily the lungs are the
inexhaustible chest to which he always returns to renew his right of
authority; that is, his power of preserving life. When it comes to the
_last sigh_, the last effort of the diaphragm by which the chest
is closed forever, we must bid adieu to life. In yielding up that, we
have in very truth yielded up the ghost.

This is no joke, as you see, and it would not do to be caught
unprepared, with an inexorable necessity hanging over one, which never
allows a moment's respite. The blood acts like a reasonable being,
therefore, in laying up his stores of combustible in reserve. Moreover,
whether he has done so or not, the fire must go on all the same; that
is absolutely necessary; and if he has no spare fat to feed it with,
when, from any cause, the stomach leaves off working, he makes use of
anything he can lay his hands upon.

I know a story on this subject which will amuse you.

There lived, in the reign of Francis I. of France, an honest countryman,
of Périgord, named Bernard Palissy. At that time everybody could not
afford to have earthenware plates, as they have now. It was a
manufacture of which only the Italians had the secret, and Bernard,
who knew something of the matter, from being a glass-worker, took it
into his head to try and find it out entirely by himself. So, without
asking anybody's advice, he turned potter, built ovens, picked up wood
as he could, manufactured his first pots, whether well or ill, made
a beginning, and waited. He had fifteen or sixteen years of it before
he succeeded; fifteen or sixteen years of ruinous experiments, which
would have discouraged a less sturdy heart than his. But he, after he
had succeeded in picking up some money by his church windows, returned
to his work with unconquerable perseverance, insensible to poverty,
deaf to the ridicule of neighbors, and unmoved by the abuse of his
wife, who was furious, as you may suppose, at being forced to play the
heroine without having the least turn for it. And one fine day there
was a grand uproar in La Chapelle-Biron (that was the name of his
village). "Bernard Palissy has gone mad," said everybody; "he is burning
up his house to bake his pots." And upon my word it was true! Wood
happened to be wanting while a batch was in the oven, and Bernard
having begun by using up the garden palisades, took next the large
tables, and at last the floor of the house! What his wife had to say,
I leave you to judge; as for him he listened to nothing; but, fixing
his eyes on the insatiable furnace, threw in one thing after another,
caring only for the risk to his handiwork. The ceiling would have
followed the floor had not his pots been sufficiently baked without.

And thus, and thus, does the blood, when combustible matter fails him!
He demolishes the house, and throws it, bit by bit, into the fire. The
fat goes into it naturally enough, as I have already explained to you.
It is the fuel-store of the house. It was put by on purpose, and may
be used up without injury. Then comes the turn of the muscles; more
useful without being indispensable. Those are Bernard Palissy's
palisades one may contrive to do without them. They melt away, so to
speak, after a few days' fast, and you find yourself what people call
"nothing but skin and bone." But then, if this condition is prolonged,
and the exhausted flesh cannot supply the demand, the blood does not
hesitate a moment. He boldly falls upon the most important organs,
without stopping to consider; he, too, is devoted solely to his work,
and that, like the baking of pots, never comes to an end by being
completed; if external help does not arrive in time, the house soon
becomes uninhabitable, and life slips away. The man dies of hunger.

But in the same way that poor Bernard Palissy was in reality working,
all the time, for his wife and children, whose future well-being he
strove for as the final end of all his efforts, though at the risk of
letting them sleep under the bare heavens; so the blood was laboring
up to the last moment for that very life which he at last turned out
of doors; and the work of destruction which caused its final departure
has had in reality the effect of prolonging its stay. Without it, all
would have been over long before.



LETTER XXIV.

THE WORK OP THE ORGANS.

Thus much is settled, then. It is the blood which sets everything in
motion throughout the body. The organs are idlers who would do nothing
but for him; they only work when goaded on, if I may use the expression,
by that fire--always on the point of going out--which he is perpetually
coming back to rekindle, thanks to the oxygen he carries with him from
the lungs.

This will enable me to explain many things, which, although not new
to you, you have probably never tried to account for before.

To begin with: do you remember what happened to you the other day,
when you tried to overtake your mischievous brother in running, and
he, taking advantage of his school-boy legs, led you mercilessly through
all the garden walks, without having the grace even to let you catch
him at the end? You were quite out of breath; your heart beat so rapidly
it almost hurt you; and you were so hot that the perspiration poured
in great drops down your face, so that your mamma, quite frightened,
took you up in her arms and carried you to the fire; for the coolness
of evening was coming on, and a little girl drenched with perspiration
is soon chilled.

Tell me now, what connection was there between your overrunning yourself
in a race and the extraordinary degree of heat which came over you so
soon? Your cheeks were cool and fresh when you began to run; what made
them so red all at once, and especially at a moment when the air was
cool and fresh in the garden?

You open your eyes in surprise; you had never thought of this. No!
that is just the way with little girls. They run; they get hot; it
seems as natural as warming oneself in the sun, and they never ask why
it is so.

Yet you could almost tell me the "why" yourself, if you stopped to
think about it, now that you are what your school-boy brother would
say "_up to a thing or two;_" but to save time, I will help you.

You run as a bird flies, without thinking about it. Nevertheless, if
you could see with a magic glass all that takes place in your body
while those active little feet are carrying it like a feather across
the garden, you would be perfectly amazed. One of these days, when we
have finished our present history, I will tell you that other one,
which is equally worth the trouble. It is enough for the present to
know, that a very complicated piece of work is being carried on there,
in which almost all the muscles of the body take part at the same time,
contracting and relaxing in turn, like so many springs, of which each
either drives forward or holds back a part of the machine. In fact,
while your eyes and thoughts are fixed on the butterfly which is
flitting away from you through the air, there is going on within you
such an unheard-of outlay of efforts as could never be got out of our
idlers if the terrible steward did not lash them severely.

Now, his lash, as we have said often enough, is that eternal fire, the
materials of which he conveys to all parts of the body. On those special
occasions, therefore, he is obliged to make his fire burn much more
briskly than usual--exactly like railway engine-drivers, who increase
the heat of their fire to get up steam in proportion to the speed they
wish to go.

From this you will understand that it is no great wonder that your
small frame should get heated from such work as racing and chasing;
and that if you pursue it too long, the perspiration which comes out
all over you is sufficiently explained.

This is not all, however. The fire, whose strength has to be increased,
naturally requires a larger amount of combustible matter than before,
and forasmuch as there is only a certain fixed quantity in each drop
of blood, whenever the muscles want more than usual, the blood itself
must flow to them in greater abundance. Now if it were a question of
supplying only one part of the body (as it is, you may remember, of
supplying the stomach during the progress of digestion), he might
contrive to accomplish his task there by neglecting it elsewhere, and
overflow one organ at his ease, at the expense of all the rest. But
in this case he is wanted everywhere in the same abundance. It is not
a question of taking one muscle's share for the benefit of another.
From one end of the body to the other, all want to be deluged at once.
And remember that these exigencies do not bring a drop more blood into
the body. How is he to get out of his difficulty then, this overwhelmed
steward of ours? Well! just as your mamma manages, my dear, when there
is more to do than usual in the house;--by running quicker than ever
from the cellar to the garret, and from your room to your papa's! That
is called doubling oneself; and this gallant blood doubles itself to
some purpose. He runs and runs and runs, arrives in hurried streams,
and returns full gallop, passing and repassing through the heart, which
empties and fills itself in sudden jerks. Unluckily, the poor heart
is a delicate sort of person, who does not like having his habits
disarranged, and this forced work soon makes him desperate. The other
day, in his despair, he knocked with all his strength against the walls
of his little chamber, to warn his young mistress that he could bear
no more, and that they were both of them in danger. In fact, you ought
to know that if one was infatuated enough to go on running too long,
one might die of it. When you learn ancient history, you will probably
be told of what happened to the soldier of Marathon, who flew like an
arrow from the field of battle to the gates of Athens, that he might
tell his fellow-citizens a quarter of an hour earlier, that his country
was saved; and he fell dead on his arrival.

But it is not the heart only which suffers by this mad career of the
blood. During each journey it performs it passes through the lungs,
which in their turn are forced to play with hasty jerks. And this is
well for our good steward; for the lungs, filling with air at each
descent of the diaphragm (if you remember what we have said before),
more air, and consequently more oxygen, comes in, and the blood has
by this means a larger stock on hand, ready to help him out in the
unusual waste which is just then going on in the muscles. I spoke just
now of railway steam-engines. See how self-supporting ours is! The
greater the amount of fire wanted, the faster the blood flows; and the
faster the blood flows, the oftener does the coffer re-fill itself,
whence comes the supply of oxygen requisite for keeping up the fire.
All this goes on at once, by one impulse, and the balance between the
receipts and expenditure settles itself of its own accord. How thankful
many families would be if their money-chest would but fill itself in
the same way--in exact proportion as they spend the cash! There is
only one slight drawback, which is, that the diaphragm gets tired with
the unaccustomed gallop it is thus forced into. It falls into
convulsions, therefore, like its neighbor the heart, and the breathing
is stopped, from having been driven too rapidly. An excellent example
for people who want to spend too much at once; showing that Nature
herself cries out against it, even when the only thing wanted is
atmospheric air.

Now, run if you dare! And, to tell you the truth, it would be a great
pity if you did _not_ dare; for our good God has made little children
for running. They have nimbler blood than we older grandfathers, more
elastic lungs, and consequently more oxygen to spend at a time. But you
must confess that it is a great pity we should run all our lives as many
people do, without having the slightest idea of these admirable
contrivances, thanks to which we are enabled to do it. We can run all
the same, it is true, without the knowledge, the little child as easily
as the little roebuck, which sets a similar machine in motion. But it is
no use talking about the little roebuck; it cannot learn what God has
done for it, but the little child can, if he will. Furthermore, there is
nothing to be really alarmed about, for those great commotions only
occur when we have committed excess; and it is a very good thing, in a
general way, for the blood to give us a stroke of his lash from time to
time. I told you lately that the fire which sets the organs to work is
life; and it is no misfortune to be a little more alive than usual.
Besides which, this increased activity of the internal fire does not
serve us in running only. Every time that a man makes an effort; every
time he lifts a weight, or handles a tool, the blood rushes forward to
deluge the muscles that are thus called into play; the heart beats more
quickly, and the air streams in greater abundance into the lungs. Look
at a man chopping wood. If the log resists too much, if for a minute or
two the man has to strike blow after blow without stopping, you will
soon see him panting for breath, just as if he had been running a race.
On the other hand, he will have gained something from chopping his log
besides the right of warming himself before it at the fire. Blood does
not carry fire only into the muscles; he supplies them with nourishment
also, does he not? Every drop of blood deposits its little offering as
it goes by, and consequently the greater the number that pass along, the
richer is the harvest for the muscle. Look, accordingly, at the laboring
classes. How much healthier and stronger they are than those who do not
work! I speak, of course, of working with one's limbs generally; for
those poor girls who work from morning to night, sitting on their
chairs, are none the better for it, but, on the contrary, worse. There
are also certain worthy fellows who, like myself at the present moment,
drive a pen over sheets of paper for half a day at a time, whose muscles
never get any bigger for it, that is quite clear. Moreover, one
condition has to be fulfilled, which unhappily is not always done. The
more people labor, the more they ought to eat. To you, who have just
been looking at the drama that is performed in the body every time a
muscle is set in motion, this is obvious enough. There is no fire
without smoke, says the proverb. It would have been much better to
have said,--there is no fire without fuel;--and the fuel for our fire
is, as you know, what we eat. Try if you can get one stove to burn
more brightly than another, if you have put less fuel into it. Yet,
alas! this is what many poor wretches are obliged to do but too often;
and then the blood, instead of feeding their muscles, consumes them,
for the reasons I gave, in telling you the story of Bernard Palissy.
Think of this, oh my dear child, when you are grown up, and never
grudge those who work for you their proper share of food.

Here I see many other lessons crowding up, out of what you have just
learnt.

And first Nature herself, taken as you find her, shows you that manual
labor is, for us, a most beneficial condition of existence; that it
brings about a re-doubling, an exaltation of life; and that
consequently, we have no need to look down upon those who gain their
bread, as we word it, by the sweat of their brows. I told you this
before, in speaking of the hand, which is of so much more use to those
people than to you; and I repeat it now for another reason, viz.:
because labor elevates him who undertakes it, and creates a real
physical nobility. Barbarians in old times, who knew nothing noble nor
grand but war, despised labor, and left it to their slaves; so much
so, that the name _servile labor_, _i.e._ the labor of slaves,
has stuck to it in some places. As for war, the lot of the ancient
nobility, I scarcely dare to say much against it, however much I should
like to do so on some accounts. For, after all, so long as there are
ruffians to trample on the weak, one is only too glad to find brave
men ready to risk their lives in keeping such rascals down: so long
as there are wolves, we must needs keep shepherds' dogs. But in spite
of everything, the best that can be said in favor of war is, that it
remains a sad but inevitable necessity, and that to get rid of it,
more is wanting than the wish. What a contrast to labor--that contest
of Man with Nature;--that merciful and fruitful war, where victories
are not estimated like other victories, by the number of the slain,
but which, on the contrary, scatters fresh life around it as it spreads;
fresh life in the laborer himself, by the very act of work, fresh life
around him without, by the fruits that work produces!

Between the man who dies in slaying others, and the man who keeps
others alive by living longer himself, it seems cruel to make invidious
comparisons; but if it be just to honor the first out of respect for
the cause he has defended, whenever that cause is respectable--it is,
to say the least of it, not less just to do equal honor to the second.

But let us come down from these philosophic heights, and return to
you, dear child; to you, who have nothing to do with war, its massacres
or its laurels.

It is true, however, that you have nothing to do either, with chopping
wood, and I am not asking you to undertake any such thing. But in the
life of a woman, from the time of her childhood upwards, a thousand
things arise for the hands to do, and the question is, how often you
are likely to feel ashamed of not sending for the servants to do them?
Avoid this false and fatal idea as much as possible. The work of the
hands dishonors no one; it is honorable. To cast it aside altogether
is to make yourself smaller instead of greater; to deprive yourself
of one of the glories and the joys of life. If a good thing is set
before you at dinner, do you send for the servants to eat it? If an
occasion arises for making the blood circulate more rapidly in your
veins, and of increasing the strength and life with, in you into the
bargain, why make _them_ a present of it? Especially when it
cannot be an agreeable present considering that good servants have
plenty of such opportunities from morning to night every day.

There was once upon a time a Persian prince staying in Paris, who was
taken to a very fashionable ball, that he might see a specimen of
European civilization. I am not talking about a prince in the "Arabian
Nights;" mine lived, I believe, in the time of Louis Philippe. The
beautiful dancers wheeled round, their eyes brilliant with pleasure,
in the arms of elegant cavaliers; one would have said that the whole
of this airy troop, swaying to and fro in time to the lively flourishes
of the music, was animated by one soul; everything seemed full of joy
in that large and splendidly lit hall, and mothers secretly envied
their daughters as they passed and re-passed before them. Our oriental
alone scanned with a disdainful eye this youthful enjoyment.

When it was ended,--"How is this?" said he to his conductor; "did you
not tell me that I was to see here the most distinguished families of
Paris?"

"Certainly," replied the other; "among those young ladies who were
just now dancing before you, there were at least twenty of the grandest
heiresses of France."

"Young ladies who dance! Come, come! In my country we have dancers,
but they are paid for it. Our wives are never permitted to dance
themselves. That is all very well for the common people!"

Remember, when needful, the contempt of this Persian prince, my dear
child; and let me beg of you, work for yourself. The dance of labor
is worth quite as much as that of the ball-room, when you give your
heart to it. It is even worth more, very often; and next time I will
tell you why.



LETTER XXV.

CARBONIC ACID.

We are going to make acquaintance to-day with a new personage, who
well deserves our attention. It is the child of oxygen and carbon,
[Footnote: This is the name learned men have given to Charcoal.] though
not in the same way that you are the child of your parents.

To tell you how it is made is more than I am able. It is a _gas_,
or if you like the word better, it is an _air_; for when we say
"gas," we mean "air;" only it is always a different sort of air from
the air of the atmosphere, which learned people are not in the habit
of calling _gas_. I cannot, therefore, show you _carbonic acid_ itself,
for it cannot be seen any more than the air which fills an empty glass.
But I can tell you where there is some, and you even probably know it by
its effects, although you have never heard its name.

Do you remember, on your aunt's wedding-day, that there was a sparkling
wine called champagne, at the grand breakfast? You smile, so I conclude
somebody gave you a little to taste; and if so, you will remember how
sharp it felt to your tongue. Do you remember, too, how the cork flew
out when they were opening the bottle, and how the noise of the "pop!"
startled more little girls than one? It was _carbonic acid_ which
sent the cork flying in that wild way; the carbonic acid which was
imprisoned in the bottle, in desperately close quarters with the wine,
and which accordingly flew out, like a regular goblin, the moment the
iron wire which held down the cork was removed. What sparkled in the
glass, making that pretty white froth which phizzed so gently, as if
inviting you to drink, was the carbonic acid in the wine, making its
escape in thousands of tiny bubbles. What felt so sharp to your tongue
was the same carbonic acid, in its quality of acidity, for thence it
has its name; the word _acid_ being borrowed from a Latin word
signifying the sharp pungent taste, almost _fine-pointed_ as it
were, peculiar to all substances which we call _acids_.

It is carbonic acid also which causes the froth in beer and in new
wine when bottled. It is he who makes soda-water sparkle and sting the
tongue, and ginger-beer the same, if you happen to like it; and so far
you have no particular reason for thinking ill of him. But beware. It
is with him as with a good many others who have sparkling spirits, who
make conversation effervesce with gayety, and who are very seductive
in society when you have nothing else to do but to laugh over your
glass, but whose society is fatal to the soul which delivers itself
up to them. This charming carbonic acid is a mortal poison to any one
who allows it to get into his lungs.

You remember what a violent headache your servant suffered from the
other day after ironing all those clothes you had in the wash? She
owed that headache entirely to this work which she did for you. She
had remained too long standing over the coals over which her flat-irons
were being heated. You know already that when charcoal burns, it is
from the carbon uniting with the oxygen of the air; from this union
proceeds that mischievous child, carbonic acid gas, in torrents, and
the poor girl was ill, because she had breathed more of this than was
good for her health. Observe well, that the room-door was open to let
in the fresh air, and that there was a chimney, to allow the carbonic
acid to escape. It was on this account that she got off with only a
headache. Unhappily, there have sometimes been miserable people who,
weary of life, and knowing this, but not knowing or thinking about the
God who overrules every sorrow for good, have shut themselves up in
a room with a brazier of burning charcoal, after taking the fatal
precaution of stopping up every opening by which air could possibly
get in; and when at last, in such a case, uneasy friends have forced
open the well-closed door, they have found nothing within but a corpse.
Then, too, there are those frightful accidents of which we hear so
often, of workmen groping their way down into long disused wells, who
have died as they reached the bottom; or of sudden deaths in coal-pits.
In general these have been owing to the poor victims encountering the
long pent-up carbonic acid gas, whose poisonous breath blasted and
destroyed them at once.

You may well ask why I am telling you such horrible stories, and what
I am coming to with my carbonic acid? But you have more to do with it
than you think, dear child. You, and I, and everybody we meet, nay,
and the very animals themselves, since their machines are of the same
sort as ours, are all little manufactories of carbonic acid. The thing
is quite clear. Since there is a charcoal fire lit in every part of
our body, there always arises from the union of the oxygen brought by
the blood with the carbon it meets in our organs, that mischievous
child we have been talking about; and our throat is the chimney by
which he gets away. He would kill us outright were he to stop in the
house.

This is how it comes about: In proportion as the blood loses its oxygen,
it picks up in exchange the carbonic acid produced by combustion, so
that it is quite loaded with it by the time it returns to the lungs.
There it takes in a fresh supply of oxygen, and discharges at the same
time its overplus of carbonic acid, which is driven out of the body
by the contractions of the chest, pell-mell with the air which has
just been made use of in breathing. You are aware that this air is not
the same at its exit as at its entrance to the body, and that if you
try and breathe it over again it will no longer be of the same use to
you. That is because it has lost part of its oxygen and brings back
to you the carbonic acid which it had just carried off. If you take
it in a third time, it will be still worse for you; and in case you
should continue to persist--the oxygen always diminishing, and the
carbonic acid always increasing in quantity--the air which was at first
the means of your life will at last become the cause of your death.
Try, as an experiment, to shut yourself up in a small trunk, where no
fresh air can get in; or even in a narrow closely-shut closet, and you
will soon tell me strange news. There will be no occasion to light a
charcoal fire for you in there. Enough is kept burning in your own
little stove, and you will poison yourself.

You see now that the dreadful stories I was telling a short time ago
have something to do with you, and that it is a good thing to be warned
beforehand. And now tell me, when a hundred people--or I ought to say,
a hundred manufactories of carbonic acid--are crowded together for a
whole evening, sometimes for a whole night, in a space just big enough
to allow them to go in and come out; tell me, I say, if that is a sort
of thing which can be beneficial to the health of little girls whose
blood flows so fast, and who require so much oxygen; and whether, on
the contrary, it is not one's duty to keep them away from such scenes?

There may be amusement there, I know; but the best pleasures are those
for which one does not pay too dearly. I have seen the very wax lights
faint and turn pale all at once, in the very midst of those murderous
assemblies, as if to warn the imprudent guests that there was only
just time to open the windows.

And this reminds me of a point I had nearly forgotten. Wax-candles arc
like ourselves. In order to burn, they must have oxygen, and, like us,
they are extinguished by carbonic acid. But like us also--and indeed
to a greater extent, because they consume much more charcoal at
once--they manufacture carbonic acid. Hence that very illumination
which affords the company so much pleasure and pride is plainly an
additional cause of danger. Each of those wax-lights which is spread
around with such a prodigal hand, the only fear being that there may
not be enough of them, is a hungry intruder employed in devouring with
all his might the scanty amount of oxygen provided for the consumption
of the guests.

From each of those cheerful flames--the suns, as it were, of the festive
assembly--shoots out a strong jet of carbonic acid, contributing by
so much to swell out the already formidable streams of poisoned gas,
exhaled to the utmost extent by the dancers. And wait--there is still
something else I was forgetting. You dance. And I told you last time
at what cost you have to dance. You have to make the fire burn much
quicker than usual, that is, to consume a great deal more oxygen at
once, and so you double and treble the activity of the carbonic acid
manufacture: and this just at the moment when it would be so convenient
that it should go on as slowly as possible! After this, you need not
be surprised that people should look fagged and exhausted next morning.
What astonishes me is that they are not obliged to lie in bed
altogether, after treating their poor lungs to such an entertainment.
And even if you have spared your legs, you are not much better off,
as you are sure to find out in time, especially if the thing is repeated
too often.

When I told you just now that the dance of labor was worth as much as
the dance of the ball-room, was I right or wrong? What do you say
yourself?

I could repeat the same of theatres--places of entertainment specially
adapted for impoverishing the blood, and ruining the health of the
happy mortals who go there, evening after evening, to purchase at the
door the right of filling their lungs with carbonic acid, not to speak
of other poisons. You must see clearly that such places as those are
not fit for little lungs as dainty as yours; and this may help you to
submit with a good grace when you see people going there without you.
Grown-up people escape moreover, because the human machine possesses
a strange elasticity, which enables it to accommodate itself--one
scarcely knows how--to the sometimes very critical positions in which
its lords and masters place it without a thought. But to do this, it
is well that it should be thoroughly formed and established; for you
run a risk of injuring it for ever, if you misuse it too early in life.
Tell this to your dear schoolboy brother, when he wants to smoke his
cigar like a man. If his lungs could speak, they would call out to him
that it was very hard upon them, at their age, to be so treated, and
that he ought at any rate to wait till they had passed their
examinations!

But I must not get into a dispute with so important an individual, by
throwing stones into a garden which is not under my care. For you, my
dear child, the moral of this day's lesson--which to my mind is much
more alarming than a hobgoblin tale, since it concerns the realities
of every-day life--is clear; and it is this:

Seek your amusements as far as possible in the fresh air. In the summer,
when the lamp is lit, bid your mamma a sweet good-night, and go to
bed. In the winter do not wait till there is a great quantity of
carbonic acid in the room where the grown-up people are sitting, before
you retire to your own like a reasonable girl, anxious not to do
mischief to that valuable and indefatigable servant, the poor blood!
Not to mention that if she were to injure him too much, she would have
to bear his grumbling for the rest of her life. We cannot change him
as we change other servants.



LETTER XXVI.

ALIMENTS OF COMBUSTION.

We have spent a very long time, my dear child, over the little fire,
which goes on burning secretly in every one of us, quietly devouring
what little girls eat with such a good appetite, quite unsuspicious
of what they are doing it for. However, if I mean to finish the history
of our mouthful of bread, I must push on to its last chapter.

The _whole_ of what we eat is not burnt, as you may easily suppose; for,
if it were, what would the blood have left to feed the body with, and to
repair in due proportion the continual destruction or waste which goes
on in our organs? Our food, or "_aliments_" as the general collection of
different sorts of food is called, are divided into two very distinct
sets: some, which are destined to be burnt, and which are called
_aliments of combustion_; others, which are destined to nourish the
body, and which are called _aliments of nutrition_. I have to tell you
now about these last, and you will find their history by no means
uninteresting.

Learned men having detected, beyond the possibility of a doubt, the
existence of these two sorts of aliments, one is tempted to think they
ought to have made it known to the cooks, and that ever since so
important a discovery, the dishes on all well-regulated tables should
have been arranged accordingly; aliments of combustion on one side,
aliments of nutrition on the other. It cannot be enough merely to give
your guests a treat; you ought to provide them with everything necessary
for the proper fulfilment of the claims within; and if you give some
nothing but combustibles, leaving the others no share of fuel, how
will they be able to manage? Nobody thinks about this, however; not
even cooks, to begin with, who, as far as fire is concerned, find they
have had quite enough to do with it in their cooking; and as for the
guests, when they have had their dinner they go away satisfied, as a
matter of course, quite as well provided for as if the mistress of the
house had made her calculations, pen in hand, while writing out the
bill of fare, with a view to combustion and nutrition. Now, how is
that?

It is because the two sorts of aliments are, for the most part, met
with together in everything we eat, so that we swallow them at once
in one mouthful; and have therefore no need to trouble ourselves further
on the subject. There is our bit of bread, for instance. What is bread
made of? Of flour. Bread, then, must contain all that was previously
in the flour. Very good. Now I will teach you how to discover in flour
the aliment of combustion on the one hand, and the aliment of nutrition
on the other.

Take a handful of flour, and hold it under a small stream of water;
knead it lightly between your fingers. The water will be quite white
as it leaves it, carrying away with it a fine powder, which you could
easily collect if you were to let the water run into a vase, where the
powder would soon settle to the bottom. That powder is starch--the
same starch as washerwomen use for starching linen, and which our
grandfathers employed in powdering their wigs. You had some put on
your own hair one day when you were dressed up as a court-lady of olden
time. Now, starch is an excellent combustible. People have succeeded,
by means which I will not offer to detail here, in ascertaining almost
exactly what it is made of, and they have found in it three of our old
acquaintances, oxygen, hydrogen, and carbon, combined together in such
proportions that 100 ounces of starch contain as follows:

                  Ounces.
    Carbon          45
    Hydrogen         6
    Oxygen          49
                   ---
                   100
I give you the calculation in round numbers, so as not to burden your
memory with fractions; and I will do the same with the other sums I
shall have to go through to-day, this being, let me tell you, an
arithmetical day. Besides, I could scarcely take upon myself to warrant
the absolute correctness of those very precise fractions people
sometimes go into. Even our learned friends squabble now and then as
to which is right or wrong over the 100th part of a grain, more or
less, in making out their balance, and you and I will not offer to
decide between them. I always think we have accomplished wonders in
getting even _near_ the mark, and with their permission we will
stop there.

Starch, then, of whose weight carbon constitutes nearly one-half, is
of course a first-rate combustible. Indeed, one may almost consider
it the parent, as it were, of at least half our aliments of combustion,
for if (in consequence of a certain operation, which nature has the
power of performing for herself, in certain circumstances) it loses
a portion of its carbon, so that there remain but 36 ounces of it in
the 100 of starch, our starch is turned into something else; now can
you guess what that something is? Neither more nor less than _sugar_!
Witness the grand manufactories at Colmar, in France, where bags of
starch are converted into casks of syrup by a process of nature alone;
so that the inhabitants of the neighborhood sweeten their coffee at
breakfast with what might have been made into rolls, had it been left
alone. And this is not all. Give back this starch-sugar into the hands
of Nature once more by putting it into certain other conditions, and a
new process begins in it. About a third of its carbon will unite itself,
of its own accord, with the two-thirds of its oxygen, so as to make
carbonic acid, (you are acquainted with that gentleman now) which shall
fly off and away, and there will remain--what do you think?--_Alcohol_,
that other combustible we talked about, and which burns even better than
sugar and starch, since in a hundred ounces it contains as follows:--

                  Ounces.
    Carbon          53
    Hydrogen        13
    Oxygen          34
                   ---
                   100

All this astonishes you. What would you say then if I were to tell you
that your pocket-handkerchief is composed of entirely the same materials
as starch, and in the same proportions too, and that if a chemist were
to take a fancy, by way of a joke, to make you a tumbler of sugar and
water, or a small glass of brandy out of it, he could do so if he
chose. Wonders are found, you see, in other places besides fairy tales;
and since I have begun this subject I will go on to the end. Know then
that from the log on the fire, to the back of your chair, everything
made of wood, is in pretty nearly the same predicament as your
pocket-handkerchief; and if people are not in the habit of making casks
of syrup and kegs of brandy out of the trees they cut down in the
woods, it is only, I assure you, because such sugar and brandy would
cost more to make than other sorts, and would not be so good in the
end. Should some one ever invent and bring to perfection an economical
process for doing it thoroughly well, sugar-makers and spirit-distillers
will have to be on their guard!

But we are wandering from our subject. If I have allowed myself to
make this digression, however, it is because I am not sorry to accustom
your mind early to the idea of those wonderful transformations which
nature accomplishes, and of which I could give you many other instances.

To return to our flour. As soon as all the starch is gone out of it,
there remains in your hand a whitish, elastic substance, which is also
sticky or _glutinous_, so that it makes a very good glue if you choose;
and hence its name of _gluten_, which is the Latin word for glue.

When dried, this _gluten_ becomes brittle and semi-transparent.
It keeps for an unlimited time in _alcohol_, putrefies very soon
in water exposed to the air, and is easily dissolved in a wash of soda
or potash. Finally 100 ounces of it contain as follows:--

                  Ounces.
    Carbon          63
    Hydrogen         7
    Oxygen          13
    Nitrogen        17
                   ---
                   100

Observe the last material named. It is a new arrival, of which I shall
soon have something to say.

But where am I leading you? you will ask, with all these uninteresting
details about glue.

Wait a little and you shall hear.

You have probably never seen any one bled, which is a pity, as it
happens; for if you had, you might have noticed (provided you had had
the courage to look into the basin), that after a few seconds, the
blood which had been taken away separated itself of its own accord
into two portions; the one a yellowish transparent liquid, the other
an opaque red mass floating on the top, and which is called the
_coagulum_ of the blood or _clot_. This _coagulum_ owes its color to an
infinity of minute red bodies of which we will speak more fully by and
by, and which are retained as if in a net, in the meshes of a peculiar
substance to which I am now going to call your attention.

That substance is whitish, elastic and sticky; and when dried becomes
brittle and semi-transparent. It keeps for an unlimited time in alcohol,
putrefies very soon in water exposed to the air, and is easily dissolved
in a wash of soda or potash. Finally 100 ounces of it contain as
follows:--

                   Ounces.
    Carbon           63
    Hydrogen          7
    Oxygen           13
    Nitrogen         17
                    ---
                    100

This substance is called _fibrine_. It goes to form the fibres of those
muscles which are contained in a half formed state in the blood.

You are laughing by this time I know, and I also know the reason why.
I have told you the same story twice over. You have not forgotten my
wearisome description of _gluten_, and here I am, saying exactly
the same thing of _fibrine_! You conclude I am dreaming, and have
made a mistake!

But no, I am wide awake, I assure you, and mean what I say. And if
these details are the same in the two cases, it is for the simple
reason that the two bodies are one and the same thing; _gluten_ and
_fibrine_ being in reality but one substance, so that were the most
skilful professor to see the two together dried, he would be puzzled to
say which came from the flour, and which from the blood. I mentioned
that our muscles existed in a half-formed state in the blood. Here is
something further. The _fibres_ of muscles exist previously in full
perfection, in the bread we eat; and when you make little round pills of
the crumbs at your side, it is composed of fibres stolen from your
muscles which enable the particles to stick together; and I say _stolen
from your muscles_, because they are the _gluten_ which you ought to
have eaten. I hope the thought of this may cure you of a foolish habit,
which is sometimes far from agreeable to those who sit by you.

This, then, is the first great _aliment of nutrition_, and you
may make yourself perfectly easy about the fate of those who eat bread.
If little girls should now and then have to lunch on dry bread, I do
not see that they are much to be pitied. There is the starch to keep
up their fire, and the gluten for their nourishment, and that is all
they require. The porter above is the only one who finds fault. And
in these days porters have become more difficult to please than the
masters themselves.

Then as to babies who drink nothing but milk, you perhaps wish to know
where they get their share of fibrine.

And I am obliged to own there is none in the milk itself; but, I
daresay, you know curdled milk or _rennet_? The same separation into two
portions has taken place there which occurs in the blood when drawn from
the arm; underneath is a yellowish transparent liquid,--that is the
_whey_; above a white curd of which cheese is made, and which contains a
great part of what would have made butter. By carefully clearing the
curd from all its buttery particles you obtain a kind of white powder
which is the essential principle of cheese, and to which the pretty name
of _casein_ is given because _caseus_ is the Latin for cheese. I shall
not trouble you now with details about _casein_; but there is one thing
you ought to know. A hundred ounces of _casein_ contain as follows:--

                    Ounces.
    Carbon            63
    Hydrogen           7
    Oxygen            13
    Nitrogen          17
                     ---
                     100

Exactly like gluten and fibrine!

Now, then, you can understand that no particular credit is due to the
blood for manufacturing muscles out of the cheese of the milk which
a little baby sucks. He has much less trouble than the manufacturers
at Colmar have in turning their starch into sugar; because in his case
the new substance is not only composed of the same materials as the
old one, but contains them in exactly the same proportion also.

We have a second aliment of nutrition, you see, and I must warn you
that it is not found in milk only. It exists in large quantities in
peas, beans, lentils, and kidney-beans, which are actually full of
cheese, however strange this may seem to you. It would not surprise
you so much, however, if you had been in China and had tasted those
delicious little cheeses which are sold in the streets of Canton. They
cannot be distinguished from our own. Only the Chinese (from whom we
shall learn a great many things when we have beaten them so that they
will conclude to be friends with us)--the Chinese, I say, do without
milk altogether. They stew down peas into a thin pulp. They curdle
this pulp just as we do milk, and in the same way they squeeze the
curd well, salt it, and put it into moulds--just as we do--and out
comes a cheese at last--a real cheese, composed of real _casein_!
Put it into the hands of a chemist, and ask him the component parts
of a hundred grains of it, and he will tell you as follows:--

                   Ounces.
    Carbon           63
    Hydrogen          7, etc.

I stop there; for you surely know the list by this time!

Only the third aliment of nutrition remains to be considered, for there
are but three; and I will tell you in confidence, what is stranger
still, viz., that there is in reality but one! But we have had enough
food for one day, and I do not wish to spoil your appetite. We will
reserve the rest for another meal.



LETTER XXVII.

ALIMENTS OF NUTRITION (_continued_).

NITROGEN OR AZOTE.

There is a favorite conjuring trick, which always amuses people, though
it deceives no one. The conjuror shows you an egg, holds it up to the
light that you may see it is quite fresh, then breaks it;
and--crack--out comes a poor little wet bird, who flies away as well
as he can.

This trick is repeated in earnest by nature every day, under our very
eyes, without our paying any attention to it. She brings a chicken out
of the egg, which we place under the hen for twenty-two days, instead
of eating it in the shell as we might have done, and we view it as a
matter of course. Yet we do not say here that the bird may not have
come down the conjuror's sleeve, or the hen may not have brought it
from under her wing. It was really in the egg, and its own beak tapped
against the shell from within and cracked it.

How has this come about? No one can have put that beak, those feathers,
those feet, the whole little body, in short, into the egg while the
hen was sitting upon it, that is certain. It is equally certain, then,
that the liquid inside the egg must have contained materials for all
those things beforehand; and if Nature could manufacture the bones,
muscles, eyes, etc., of the chicken, out of that liquid while in the
egg, she would probably have found no more difficulty in manufacturing
your bones, muscles, eyes, etc., from it had you swallowed the egg
yourself.

Here, then, is an undeniable _aliment of nutrition_.

It is called _albumen_, which is the Latin word for _white of egg_. It
is easily recognized by a very obvious characteristic. When exposed to a
temperature varying from sixty to seventy-five degrees of heat,
according to the quantity of water with which it is mixed, _albumen_
hardens, and changes from a colorless transparent liquid, into that
opaque white substance, which everybody who has eaten "hard-boiled eggs"
is perfectly well acquainted with.

I will only add one trifling detail. 100 ounces of albumen contain as
follows:

                   Ounces.
    Carbon           63
    Hydrogen         --

You can fill up this number yourself, can you not? And knowing the 7
of hydrogen, you may guess what follows! After what we have talked of
last time, here is already an explanation of the chicken's growth. But
let us go on.

You recollect that yellowish liquid I spoke about, which lies underneath
the _clot_, or _coagulum_ of the blood? I will tell you its name, that
we may get on more easily afterward. It is called the _serum_, a Latin
word, which, for once, people have not taken the trouble of translating,
and which also means _whey_. Put this _serum_ on the fire, and in
scarcely longer time than it takes to boil an egg hard, it will be full
of an opaque white substance, which is the very _albumen_ we are
speaking of. Our blood, then, contains _white of egg_; it contains in
fact--if you care to know it--sixty-five times more white of egg than
fibrine, for in 1,000 ounces of blood, you will find 195 of _albumen_,
and only three of _fibrine_; of _casein_, none.

Nevertheless we eat cheese from time to time. And we generally eat
more meat than eggs, and meat is principally composed of fibrine! I
should be a good deal puzzled to make you understand this, if we had
not our grand list to refer to.

                   Ounces.
    Carbon           63
    Hydrogen          7, etc.

_Fibrine_, casein_, _albumen_, they are all the same thing in the main.
It is one substance assuming different appearances, according to the
occasion; like actors who play several parts in a piece, and go behind
the scenes from time to time to change their dresses. The usual
appearance of the aliment of nutrition in the blood is _albumen_; and in
the stomach, which is the dressing-room of our actors, _fibrine_ and
_casein_ disguise themselves ingeniously as _albumen_; trusting to
_albumen_ to come forward afterwards as _fibrine_ or _casein_, when
there is either a muscle to be formed, or milk to be produced.

Know, moreover, that _albumen_ very often comes to us ready dressed, and
it is not only from eggs we get it. As we have already found the
_fibrine_ of the muscle and the _casein_ of milk in vegetables, so we
shall also find there, and that without looking far, the albumen of the
egg. It exists in grass, in salad, and in all the soft parts of
vegetables. The juice of root-vegetables in particular contains
remarkable quantities of it. Boil, for instance, the juice of a turnip,
after straining it quite clear, and you will see a white, opaque
substance produced, exactly like that which you would observe under
similar circumstances in the _serum_ of the blood; real _white of egg_,
that is to say--to call it by the name you are most familiar with--with
all its due proportions of carbon, hydrogen, oxygen, and nitrogen.

I wonder whether you feel as I do, dear child; for I own that I turn
giddy almost when I look too long into these depths of the mysteries
of nature. Here, for instance, is the substance which is found
everywhere, and everywhere the same--in the grass as in the egg, in
your blood as in turnip-juice! And with this one sole substance which
it has pleased the great Creator to throw broadcast into everything
you eat, He has fashioned all the thousand portions of your frame,
diverse and delicate as they are; never once undoing it, so to speak,
to re-arrange differently the elements of which it is composed. From
time to time it receives some slight impulse which alters its appearance
but not its nature, and that is all. As the chemist found it in the
bit of salad, so he will find it again in the tip of your nose, if you
will trust him with that for examination. We are proud of our personal
appearance sometimes, and smile at ourselves in the looking-glass; we
think the body a very precious thing; but yet when we look deeply into
it we find it merely so much charcoal, water and air.

This reminds me that we have not yet made acquaintance with the new
personage who was lately introduced upon the scene. _Nitrogen_ or
_azote_, I mean. He plays too important a part to be allowed to remain
in obscurity.

You have already learnt that oxygen united with hydrogen produces
water. Combined with nitrogen it produces air; but in that case there
is no union of the two. They are merely neighbors, occupying between
them the whole space extending from the earth's surface to forty or
fifty miles above our heads; together everywhere, but everywhere as
entire strangers to each other as two Englishmen who have never been
introduced! I should be a good deal puzzled to say what nitrogen does
in the air: he is there as an inert body, and leaves all the business
to the oxygen. When we breathe, for instance, the nitrogen enters our
lungs together with its inseparable companion, but it goes out as it
went in, without leaving a trace of its passage. Nevertheless, as
sometimes happens among men, the one who does nothing takes up the
most room. Nitrogen alone occupies four-fifths of the atmosphere, where
it is of no other use than to moderate the ardent activity of king
oxygen, who would consume everything were he alone. I can compare it
to nothing better than to the water you mix with wine, which would be
too fiery for your inside if you drank it by itself. This is what
nitrogen does. It puts the drag on the car of combustion; as in society,
the large proportion of quiet people put the drag on the car of progress
(let us for once indulge ourselves in talking like the newspapers!);
and such people are of definite use, however irritating their
interference may appear in some cases. The world would go on too rapidly
if there were nothing but oxygen among men. We have quite enough in
having a fifth of it!

But what in the world am I talking about? Let us get back to nitrogen
as fast as we can!

We must not imagine there is no energy in this quiet moderator of
oxygen. Like those calm people who become terrible when once roused,
our nitrogen becomes extremely violent in his actions when he is excited
by another substance, and is bent on forming alliances. Sometimes the
usually cold neighbor unites itself to oxygen in the closest bonds;
in which case the two together form that powerful liquid, _aqua-fortis_,
of which you may have heard, and which corrodes copper, burns the skin,
and devours indiscriminately almost everything it comes in contact with.
Combined with hydrogen, nitrogen forms _ammonia_, which is still often
called by its old name _volatile alkali_; one of the most powerful
bodies in existence, and one for which you would very soon learn to
entertain a proper respect, if somebody were to uncork a bottle of it
under your nose. Finally, nitrogen and carbon combined, produce a quite
foreign substance (_cyanogen_), resembling neither father nor mother in
its actions and powers, to the confusion of all preconceived ideas, when
Gay-Lussac, a Frenchman, introduced it to the world, where it fell like
a bombshell upon the theory of chemical combinations. This impertinent
fellow, combining with hydrogen in his turn, produces _prussic acid_,
the most frightful of poisons; one drop of which placed on the tongue of
a horse strikes it dead as if by lightning.

You perceive that you must not trust our worthy friend too far. You
have learnt, however, elsewhere, that it is not equally formidable in
all its combinations. Those very substances which, when paired off
into small separate groups, destroy all before them, constitute, all
four together, that precious aliment of nutrition of which we are
formed. Moreover, its real name is "_azotized aliment_" because
it is the presence of nitrogen or azote in it, which, above all,
determines its quality, so that people are in the habit of estimating
the nourishing power of our food by the amount of nitrogen it contains.
In fact, nitrogen seems to be a substance especially inclined towards
everything that has life. His three comrades wander in mighty streams,
so to speak, through every part of creation; but he, except in the
vast domain of the atmosphere, where he reigns in such majestic repose,
is rarely met with, except in animals, or in such portions of plants
as are destined for the support of animal life.

On this point I will tell you the history of his original name,
_azote_, which you will find curious enough. A short time before
the French Revolution, in 1789, the principal properties of this gas
were made known to the world by a learned Frenchman, who may be almost
considered the father of modern chemistry, and whose name I must beg
you to recollect. [Footnote: Dr. Daniel Rutherford (Edinburgh)
discovered the existence of _Nitrogen_, A. D. 1772; but he never
investigated its character.] He was called _Lavoisier_. While
endeavoring to account satisfactorily for _combustion_, which
before his time people explained any way they could, Lavoisier succeeded
in separating our two friends, the neighbors in the atmosphere, one
from the other, and was the first man in the world who managed to
secure in two bottles--on the one hand, the bubbling oxygen freed from
his tiresome mentor; on the other, the sober *azote, snatched away
from his giddy pupil. What he did with the bottle of oxygen matters
but little to us; but in the bottle of _azote_ he plunged, by way
of experiment, an unfortunate mouse, and subsequently a little bird,
both of whom, finding no oxygen to breathe, died one after the other.
Nothing could live in it, as you may suppose; and Lavoisier thought
it must be right to give so destructive a gas the name of _azote_,
which in Greek means "_opposed to life_." Meantime, science went
on progressing by the gleam of the lamp he had lit, and then followed
the discoveries of his successors, who forced their way into the obscure
laboratory where the elements of living bodies are prepared. And at
last it was ascertained that this _azote_, opposed to life as it
was thought to be, was actually an essential property of life; that
it accompanied it everywhere, and that without it the whole framework
of the animal machine would fall to pieces. It is still known by its
old name, which custom had sanctioned; but I imagine no learned man
can ever utter it now without a feeling of humility, and without the
thought that the future has possibly many contradictions in store for
him also. Besides, nitrogen has to pass through many fine-drawing
processes before it attains that post of honor which has been assigned
to it in the animal kingdom. The animal himself can do nothing with
it, unless it has been previously absorbed and digested by the
vegetable, and the vegetable in its turn could get no good from it,
were it to remain isolated and indifferent in the bosom of the
atmosphere. It is only when it has formed one of those combinations
I have been telling you about, and more particularly the second, which
produces _ammonia_, that it fairly enters upon the round of life.
And then, in the mysterious depths of vegetable existence is organized
that wonderful _quadrille_ of the _aliments of nutrition_, the history
of which has now been sufficiently explained to you.

The vegetable kingdom, therefore, is simply the great kitchen in which
the dinner of the animal kingdom is being constantly made ready; and
when we eat beef, it is, in fact, the grass which the ox has eaten,
which nourishes us. The animal is only a medium which transmits intact
to us the _albumen_ extracted in his own stomach from the juices
furnished to him in the fields. He is the waiter of the eating-house;
the dishes which he brings us have been given him already cooked in
the kitchen. But to appreciate properly the service he renders us we
must remember that the dishes to be obtained from grass are very, very
small, and that it would be a great fatigue to the stomach if it could
only get at such tiny scraps at a time; as, alas! has sometimes happened
to the famine-stricken poor, who have tried in vain to support life
from the grass in the field. But these minute dishes are brought to
us in the mass whenever we eat beef, and our stomachs benefit
accordingly. Do not forget this, my child; and when mamma asks you to
eat meat, obey her with a good grace; if, that is to say, you wish to
grow up to be a woman.



LETTER XXVIII.

COMPOSITION OF THE BLOOD.

One word more before we finish. We must not leave off without bidding
a last farewell to the good servant of whom we have spoken so much;
the model steward so exact in giving back everything he receives--the
factotum of the house in short. We have watched him at work long enough,
but I have not yet described him personally to you, nor told you exactly
what he is composed of.

And here I shall be obliged to begin again with figures and
calculations, although I am told young people are not very fond of
them. Nevertheless, none of us can manage our affairs properly without
them. Hereafter, when you are at the head of a family, you will be
obliged to practise arithmetic, if you want to know what is going on
in your house. Never allow yourself to look upon what is necessary as
wearisome; the true secret of being punctual in our duties is to throw
our heart and interest into them.

I choose, therefore, to suppose that you will be interested to know
that 1000 ounces of blood generally contain, (for there are shades of
difference between one sort of blood and another) 870 ounces of the
_serum_ I have been talking about, and 130 ounces of _clot_. At first
sight one would take the quantity of _clot_ to be much greater than it
really is; but in the state you see it, in the basin, it contains a
considerable amount of water, which belongs by right to its companion
_serum_, and which has to be drained away from it before it can be
weighed.

Now, in our 870 ounces of serum, we shall find, to begin with, 790 of
water; do not be astonished at the quantity. Most of the weight of all
animals is produced by water; they weigh comparatively nothing after
being thoroughly dried in a stove--when they are dead of course--for
neither animal nor plant can live unless saturated with water. This,
by the way, may serve to explain the ease with which we can keep
ourselves floating in water; we are not much more than water ourselves!
Were it not for those abominable bones which are a little bit heavier
than the rest, we should never sink unless a stone were hung round our
necks.

I repeat then; 790 ounces of water in 870 of _serum_, which leaves 80.
Of this, _albumen_ furnishes seventy, and the ten others, with the
exception of a small portion of fat which floats here and there
ready-made, are _salts_. It would take too long to explain what _salts_
are here, but there is one sort of salt you know perfectly well; viz.,
that which is put on the dinner-table in a salt-cellar. And it is the
most important of all. More than half the ten ounces of salts consist of
it alone, which will make you understand better than before, what I
explained with reference to the stomach; that is, why we put salt in our
food. The porter above is quite up to his business when he asks everyone
who enters to produce his little bit of salt. It is an attention which
the blood appreciates very highly, although table-salt is of no great
use to him in his building operations; but it evidently keeps him in
good humor, and he would work badly without it. It is the same with all
the animals man makes use of, and even the plants he cultivates, find
that salt gives them an appetite. And it would almost seem as if nature
had purposely dealt with us in this matter on a magnificent scale. She
has made salt-magazines of the sea and the bosom of the earth, where it
exists in prodigious masses which cost nothing but the labor of stooping
to pick up, except in countries where a gentleman called a tax-gatherer,
stands by to count the lumps and allow them to pass on by paying a
duty. For my part, if I were the government--this is a secret between
you and me, mind--I would look out for something else to stand in the
place of the salt-tax. It is not well to interpose between man and the
gratuities of Dame Nature, and to make him pay more heavily for the
blood's chosen friend than she meant him to be charged.

But to proceed, the kitchen-salt being deducted from the ten ounces
of salts-in-general, there remain altogether from four to five ounces,
which contain----. But here I stop, for it puzzles me very much how
to go on! Enough, that to enable you to follow me, you would require
at least as much knowledge of chemistry as will be expected of a young
man who has to pass an examination in medicine. Fancy the contents of
a whole druggist's shop! I will tell you a few names, that you may
have a specimen of the style in use, but I forewarn you that they are
not inviting: _hydrochlorate of ammonia; hydrochlorate of potash;
carbonate of lime; sulphate of potash; phosphate of lime; phosphate
of magnesia; lactate of soda._ I spare you the others, for many
others there are, without counting those which have not yet been
discovered I All these things are to be found, I must tell you, in
fibrine and albumen, but in such minute quantities that it is scarcely
possible to recognize them.

In the serum, for instance, the gentlemen are so very small, and so
completely entangled one with the other, that it is startling to think
of the skill and patience requisite for making them all out, to say
nothing of affixing the right name--uncouth as it may seem--to each
grain of this almost imperceptible dust! He who first called man an
epitome of creation, scarcely knew how truly he was speaking, for man
bears about in his veins, ascertained samples of at least half the
primitive substances from which all others are made, and if the whole
of them should some day be found to be there, I for one should not be
surprised.

This is well worth knowing, is it not? and I have not come to the end
of my story yet.

We have still the 130 ounces of _clot_ to speak about. But their
contents are easily reckoned. Three ounces of fibrine and 127 of
_globules_.

Here, however, we enter upon such a world of wonders, that I am quite
delighted to be able to finish with it. It will be the masterpiece of
our exhibition!

You feel quite sure blood is red, do you not? Well! it is no more red
than the water of a stream would be, if you were to fill it with little
red fishes. Suppose the fishes to be very very small, as small as a
grain of sand; and closely crowded together through the whole depth
of the stream: the water would look quite red, would it not? And this
is the way in which blood looks red: only observe one thing; a grain
of sand is a mountain in comparison with the little red fishes in the
blood. If I were to tell you they measured about the 3,200th part of
an inch in diameter, you would not be much the wiser, so I prefer
saying (by way of giving you a more striking idea of their minuteness)
that there would be about a million in such a drop of blood as would
hang on the point of a needle. I say so on the authority of a scientific
Frenchman--M. Bouillet. Not that he ever counted them, as you may
suppose, any more than I have done; but this is as near an approach
as can be made by calculation to the size of those fabulous
blood-fishes, which are the 3,200th part of an inch in diameter.

These littlest fishes are called _globules_; but they are not
exactly shaped like _little globes_, as the word would lead you
to suppose. They are more like little plates slightly hollowed out on
both sides. The central nucleus is surrounded by a flattened margin
rather bladdery in appearance, of a beautiful red color, formed of a
sort of very soft and very elastic jelly. I scarcely need tell you
that all this was discovered through the microscope, and moreover, by
examining the blood of frogs, in which the globules are much larger
than in ours. [Footnote: Authentic portraits of these globules drawn--so
to speak--by Nature herself, are to be seen on the admirable Photographs
obtained by Bertsch, with the aid of the solar microscope, invented
by himself and Arnaud. There you see them magnified 250,000 times, and
may study them at your ease, and verify my description for yourself
without any fear of being deceived. You must persuade your father to
procure one. This result of photography is among the wonders of modern
science.]

It was in 1661--rather more than two hundred years ago--that an Italian
and a Dutchman discovered, each by himself in his own country, the
microscopic population of the blood. The name of the Italian is not
very difficult--_Malpighi_. As to the Dutchman's, you must pronounce it
in the best way you can--he was called _Leeuwenhock_. You smile, but he
was nevertheless one of the first men who really comprehended what a
wonderful auxiliary human science had just got hold of in the
microscope, and he has helped to open the eyes of the world to the
marvels of miniature creation. So content yourself, young lady, with
mis-pronouncing his name, and beware of laughing at it! Names are
something like faces, one may live to be ashamed of ridiculing
the wrong one.

This discovery of the globules of the blood, was destined to throw
great light upon the way in which the _nutrition of the organs_
was carried on. Modern chemists, who are always fond of investigation,
have examined what they are made of, and can find little else in them
but _albumen_. Out of our 127 ounces of globules, 125 are albumen;
and these, with the 70 ounces which we found before in the serum, make
up the 195 ounces (of albumen) which I told you were contained in the
1,000 ounces of blood. Forgive me all these ounces and figures. Exact
accounts give exact information.

These globules, then, are composed almost entirely of albumen. Nearly
two-thirds of all the albumen in the blood is concentrated in them;
and you know now the use of albumen, viz., that it is the foundation
of all the buildings of which the blood is the architect. Everything
leads us to believe that the formation of globules in the blood is the
last touch given by nature to that magical provision begun in
thevegetable, continued in the stomach, and finished in the veins, to
which, in combination with carbon, hydrogen, oxygen, and nitrogen, we
are indebted for the subsistence of every portion of our body. Thus
the blood-globules may be considered as albumen which has finished its
education, and is ready to go into the world; while the albumen of the
serum is, like our young friends, the generations in reserve, who are
still at school awaiting their turn.

This is more than a mere supposition. Scientific men have taken to
themselves, on their own authority, all sorts of rights over animals,
and we profit basely enough by their crimes--I will not withdraw the
word--in order to increase our knowledge. Accordingly, they conceived
the idea of opening the veins of animals, and allowing the blood to
flow until the victim was prostrate and motionless as a corpse. This
done, they proceeded to fill the exhausted veins with blood, similar
to that which had been withdrawn, and with the blood, life was seen
gradually to return, till the animal rose from the ground, walked, and
resumed its disturbed existence, as if nothing had happened. The
interesting part of the experiment to us is, that if serum only, without
globules, be restored to the unfortunate animal, it is of no use
whatever, and the corpse does not revive.

It is evident, then, that all the power and virtue of the blood lies
in the globules; and according as their number is great or small it
is "rich" or "poor," as it is called; and where their number is not
up to the mark, the blood acts more feebly on the organs, life is
calmer, and people are no longer troubled with emotions--in other
words, with violent heats of the blood. Hence the impassible character
of _lymphatic_ people, who often get on in the struggle of life
better than others, because they are never in a hurry, and know how
to wait for opportunities. You will occasionally hear the word
_lymphatic_, for it has become the fashion, and it is time for
me to explain it; but unluckily the explanation is not in its favor.

You remember those little scavengers we spoke about formerly, who came
from the depths of all the organs, carrying away with them the worn-out
building materials, and covering the surface of the body with an
inextricable net work of tiny canals. These canals are called
_lymphatic vessels_, in consequence of being filled with a liquid
which is called _lymph_ (_water_, in Latin), but why I cannot
tell you, for it is, in fact, simple _serum_. There was a very
simple way of ascertaining this by making out an inventory of the
contents of the _lymph_ liquid, and when this was done, they were
found to consist of water, albumen, and the salts of serum; there was
even a little fibrine; the only thing wanting was _globules_.

How the truant serum finds its way into the lymphatic vessels is
probably as follows:--I have already mentioned the inconceivable
delicacy of the capillary vessels, those last ramifications of our
arteries and veins. It needs all the impulsive power of the heart to
enable the blood to force its way through these narrow passages; and
minute as are the globules, it would seem that they have but just room
to pass, for in examining under the microscope a corner of the tongue
of a live frog, the globules have been seen doubling themselves up to
pass through the capillaries, resuming their natural form afterwards.

It was this, indeed, which made me tell you just now that their margins
were elastic. During this momentary crush, part of the serum being
forced on too fast, oozes through the wall of the over-filled
capillaries, as water oozes through the leathern pipes of a fire-engine,
and hence probably the appearance of serum or _lymph_ in the organs,
where it is immediately sucked up (i. e., _absorbed_) by the lymphatic
vessels. Now, you will easily understand that the larger the proportion
of serum in the blood, the greater will be the quantity to be expelled
in passing through the capillaries, and the more will the lymphatic
vessels swell. In such cases the temperament or constitution is said to
be _lymphatic_. If, on the contrary, the globules are in excess, the
lymphatic vessels receive less serum, and diminish in size. The
temperament is then called _sanguine_, as if there were no serum in the
blood. You shall be judge yourself, knowing what you now do, whether it
would not be more reasonable to call such temperaments _serous_ and
_globulous_. At any rate those names would give people an idea of the
real state of things, and teach them that there were such things as
globules in the blood.

[Footnote: Here is a summary of the contents of 1000 oz. of blood:--

                                  Ounces.
           Water................... 790
    Serum. Albumen...................70  870
           Salts.................... 10

           Fibrine................... 3
    Clot.  Globules Albumen..  125       130
           Coloring matter...... 2  127
                                        ----
                                        1000
                                        ----]

To conclude, I must give you an account of the two ounces which still
remain of the 127 of globules, albumen taking up only 125, as you know.
Those two poor little ounces--the remainder of the thousand with which
we started--would you believe it?--they alone have the honor of
conferring upon the blood its beautiful red color. They constitute the
coloring matter of the globules, and you will never guess its chief
element. It is iron; ay, actually iron, young lady--the iron of swords
and bayonets. We often accuse it of tingeing the earth with blood; and
you may now know further, that it reddens blood itself by way of
compensation. Do not trouble yourself as to where it comes from. Our
fields are full of it, our very plants have stores of it. It sometimes
happens that our digestive apparatus, put out of order by other
occupations, fails to make use of the amount of iron offered to it;
in which case the blood is discolored, and the face turns pallid as
wax: this is an illness requiring great care. If it should ever befall
you, you will not be surprised, after to-day's lesson, to hear the
doctor say that you must have some iron. But be easy--you will not
have to swallow it whole! If you will take my advice, you will obey
the doctor's orders as soon as you can.

Not that looking pale signifies any thing: indeed, some young ladies
think it an advantage. But it is no advantage to any body when the
blood-globules are distressed for want of their proper supply of iron,
and do their work grudgingly, like ill-fed laborers. Nothing can go
on without them, you know, and they are people whom it is not well to
leave too long out of sorts. Else languor comes on; languor which is
the beginning of death: and pray remember that iron, which so often
causes death, is equally useful for keeping it at bay. By sending it
to the discolored globules, you give them back their energy and
brilliancy together.

I have come here to the end of all that is known with any certainty
about these wonderful globules which are to us the medium of life.
Shall I go further, is the question, and take you with me into the
fields of supposition, so full of noxious weeds? And yet why not?
Science owes its present position to the praiseworthy rule of never
adopting any theory which is not supported by well-established facts;
and I would be the last to advise a change. Were I to tell you, what
I am now going to say to you, at a meeting of the British Association
of Science, they would turn me out of the room, and with very good
reason. Nothing ought to be taught there but what can be proved. But
this is of no consequence to you and me, and we have a right to amuse
ourselves a little, after having worked so hard.

Well, there is an idea which nothing shall ever drive out of my head,
however imperfectly it may be proved as yet; namely, that each of our
globules is an animated being; and that our life is the mysterious
result of these millions of lesser lives, each of them insignificant
in itself; in the same way that the mighty existence of a nation, is
a compound of crowds of existences, each, for the most part, without
individual importance. Take our own or any other country as an instance;
where millions of brains, many of them by no means first-rate in power,
go to form a national character, the highest (as each _nation_
is apt to think of itself) in the world. According to this idea, you
must be a sort of nation yourself, my dear child, which is gratifying
to think of on the whole.

This is much more extraordinary than what I told you some time ago,
of the individual life of the organs, each of which on this new system
would be a province in itself! Do not exclaim too hastily. Whether the
globules are animated or not, it is very certain, let me tell you,
that your life depends entirely upon them; that it is weakened if they
are weakened; that it revives with them; and that whether you attribute
individual life to them or not, makes no alteration in the fact: their
action upon you remains the same. And he must be a very clever man who
can show me the exact difference between action and life. Hereafter,
when we have descended the scale of the animal world together, and are
arrived at the study of what are called microscopic animals, you will
better understand the words which appear so strange to you now. What
little our feeble instruments have revealed to us so far, of the history
of those globules, places them almost on a level with those strange
creatures, inexplicable to us, which are found in innumerable
multitudes, in a variety of liquids. We trace in them the beginning
of organization; their form and size are alike in all individuals of
the same species; and species vary enough to induce one to believe,
that there is a necessary relation between an animal's way of life and
that of its globules. If the microscope has not yet caught them in any
overt living act, who can be surprised? it is only dead blood which
has been submitted to the test. They ought to be observed in the
exercise of their functions, in the living animal itself, as has been
done to some extent in the frog; and if our foolish chat could influence
scientific observers, I would say to them what M. Leverrier said years
ago to the astonished astronomers: "Look yonder; you ought to see a
light there with which you are not yet acquainted!"

I am carrying you a long way on the wings of my fancy, my dear child;
but have no fears; I will not let you fall. This life of our globules,
which would, after all, be only one mystery the more among many, opens
before our eyes a magnificent vista of the uniformity in the scheme
of creation; which goes on repeating itself, while enlarging its circles
to infinity. We may, all of us, be only so many globules of the great
invisible fabric of humanity, in which we go up and down one after
another; and those vast globes which our telescopes follow through
celestial space, may be but globules of one, as yet unknown, to which
the Almighty alone can give a name.

Take this page to your father, my dear child, if you do not understand
it rightly; and now, shake hands, my history is ended!



PART SECOND--ANIMALS.

LETTER XXIX.

CLASSIFICATION OF ANIMALS.


'It is dangerous to show man how much he resembles the beasts, without
at the same time pointing out to him his own greatness. It is also
dangerous to show him his greatness, without pointing out his baseness.
It is more dangerous still to leave him in ignorance of both. But it
is greatly for his advantage to have both set before him.'--_Pensées
de Pascal_.

The man who wrote that, my dear child, did not trouble himself much
about children. He was one of the gravest specimens of literary
genius--a man who can scarcely be said to have ever been a child
himself; for as the story goes, he was found one day, when only twelve
years old, inventing geometry, and his father only saved him from
trouble, by putting the great book of Euclid into his hands; and, at
sixteen, he wrote a treatise on _Conic Sections_, which was the
wonder of all the learned men of the day. I have not a very clear idea
of what Conic Sections are myself; but I tell you this to show that
Pascal was a very profound and learned man, under whose authority,
therefore, I am very glad to take shelter, now that I am going to set
before you the very startling points of resemblance which exist between
you and the beasts.

As to your greatness, it delights me to explain it to you. It is not
due to the handsome clothes you wear when you are going out, nor to
the luxurious furniture of mamma's drawing-room, but to the possession
of that young soul which is beginning to dawn within you, as the sun
rises in the morning sky, and pierces through the early mists; in that
growing intelligence which has enabled you to understand so far all
the pretty stories I have told you; in that fresh unsullied conscience,
which congratulates you when you have been good, and reproves you when
you have done wrong: all of them gifts which are not bestowed on the
lower animals, or certainly not to the same extent as upon you--gifts
by which you rise more and more above them, the more they are developed
in yourself. Your baseness--but, begging Pascal's pardon, I cannot
call it baseness--your connecting link with the brute creation lies
in those other gifts of God which you and they share in common--in
those wonders of your organization, which we shall now meet with in
them again, in full perfection at first, and that in every respect;
by which fact you may learn, if you never thought of it before, that
the lower animals come from the same creating hand as yourself, and
ought to be looked upon to some extent as younger brothers, however
distasteful such a notion may seem at first. Societies have been
established of late, both in France and England, for the protection
of animals; and a noble and honorable task they have undertaken, in
spite of the jokes that have been made at their expense. It is a
mischievous cavil to tell people who are doing good in one direction,
that more might have been done somewhere else. Everything hangs together
in the progress of public morality, and you cannot strike a blow at
cruelty to animals without at the same time making a hit at cruelty
to man. And the best argument in favor of the rights of beasts to
protection, will be found in the tour you and I are now going to make
together through the different classes of the animal creation.

Let us begin with the horse--one of the beasts which oftenest needs
our protection. Give him the mouthful of bread whose history we have
just finished. He accepts it as a treat, and needs no pressing to eat
it. And if it could tell you all its adventures afterwards, you would
find that you were listening to precisely the same story as your own
over again; that nothing was different, nothing wanting. First of
all--teeth to grind it, and a tongue to swallow it with, as a matter
of course. Next a _larynx_, which hides itself to avoid it, and an
oesophagus,* which receives it, just as in your case; a stomach with its
_gastric juices_, the same as yours, in bagpipe form, and its _pylorus_,
like your own; a _lesser intestine_, into which bile pours from a liver
like yours; _chyliferous vessels_ which suck up a milky chyle, as with
you; farther on a _large intestine_; and so on to the end. Nor is this
all:--the horse has also a heart, with its two _ventricles_, and its
double play of valves; a heart which the little girl in our tale might
confidently have exhibited to the engineers as her own, but that it
would have been somewhat too big, of course; into which heart, as into
ours, comes _venous_ blood, to be changed afterwards to _arterial_; in
lungs to which the air keeps rushing, forced thither by the see-saw
action of a _diaphragm_, as faithful a servant to him as to you.
And those lungs like our own, are a charcoal market: the same exchange
takes place there, of carbonic acid for oxygen, as in ours, an
unanswerable proof that the stove inside the horse burns fuel in the
same way as our own: and if you were to place the thermometer inside
his mouth (for we are polite enough to call it his mouth), it would
mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves
not worth mentioning. Finally, if you examine his blood, you will meet
with the same _serum_ and _clot_, the whole company of _hydroclorates,
phosphates, carbonates, &c._, from which we shrank before, and globules
made like your own; having the same construction, and the same life, or
action, if you like it better. I need scarcely add that 100 oz. of its
_fibrine_ and _albumen_ contain:

    Of carbon......... 63 oz.
    Of hydrogen........ 7

This is understood all along as being the case everywhere, from man
down to the turnip; so that, like you, this noble animal, as the horse
is called, is in point of fact only so much carbon, so much water, and
so much air, joined to a handful of salt, which represents the earth's
share in the bodies of animals.

You must confess that, if we cannot quite call the horse a
fellow-creature, he is nevertheless very like us. And it is the same
with all those animals which man makes use of as his servants, and
which have really a sort of right to the protection of society, since
they form, to a certain extent, a portion of the human family. I do
not speak here of the dog, who pays his taxes, poor fellow, in his
quality of friend to man.

When I think of the almost identical organization of man and his
next-door neighbors, I am astonished how it could possibly have come
into the head of a certain learned individual (I will not mention his
name), when drawing up a plan of natural history, to give to man a
separate kingdom, as a sequel to the three kingdoms already
established--the mineral, vegetable, and animal. One might have forgiven
Pascal if such an idea had got into his head after writing his treatise
on Conic Sections; there being nothing in them to throw light on such
a subject. But in a naturalist, an observer who had spent his life in
the study of living creatures, the thing seems almost incredible.
Possibly he had reasons for what he did, but he certainly did not find
them in the subjects of his studies.

Forgive me, my dear child, for forgetting you in this fit of indignation
upon a point you cannot care much about. It leads me naturally enough
to my present business, which is none of the easiest, but you must
help me by paying attention. I am going to describe the _classification
of the animal kingdom_.

There are a terrible number of animals, as you know; and if we wish
to study them to any real purpose, we must begin by introducing some
sort of order into the innumerable crowds which throng, pell-mell,
around us for observation. We should otherwise never know where to
begin, or when we had come to an end.

There are many ways of setting a crowd in order, but they all go upon
the same plan. The individuals composing the crowd are parcelled off
into companies, each company having a distinguishing mark peculiar to
those who compose it. Thus the first division is into a few large
companies, which are afterwards subdivided into smaller ones, and those
into others still less, until the divisions have gone far enough. And
this is what is called a _classification_.

Let us imagine, as an example, a large crowd in a public garden; I
will soon classify it for you. I shall put the men on one side and the
women on the other. Then--to begin with the women--I shall subdivide
them into married and single. Then among married women I shall make
a company of mammas, and another of those who have no children. Among
the unmarried I shall have a group of those who have never been
married--girls, that is--and another of widows--those who were once
married, but are so no longer. Then, following the girls, I shall
separate them into tall and short. And among the short ones I shall
divide the brunettes from the blondes, and so I shall get at last to
a little blonde girl, whose classification (were she a soldier) in
military rank would be as follows:--_squadron_ of blondes; _company_ of
shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_
of women. The division of men could be carried out in the same manner;
and thus we should classify our mob into complete military order. This
is easy enough, however; but the classifying of animals is a very
different affair, and I will tell you why. We ourselves require a
classification to study them by, though none was needed for their
creation. The Almighty has formed them all on one uniform plan, around
which He has, if I may so express it, lavished an infinity of
modifications separating species from species, yet without placing
between the different species those fixed barriers which we should
require now to enable us to classify them strictly. You who are learning
the pianoforte have perhaps been told the meaning of a _theme_ of
music--the first idea of the composer who follows it throughout the
piece from one end to the other, embroidering on it, as on a bit of
canvas, a thousand variations melting one into another. Such is pretty
nearly, if we may venture the comparison, the way in which we can
picture to ourselves the Almighty moving through the work of animal
creation. Step in afterwards and divide away into regiments and
battalions, if you please. Nature permits it, but she will never,
to accommodate your classifications, separate what in her is really
united.

There is still a way, however, and that is to do as I did just now in
the case of the crowd. To take, viz., only one _character_ (as we call a
distinguishing mark in natural history), and to throw together all the
individuals which possess it, the blondes, the shorts, the girls, &c. In
this way it may soon be done; but what is the result? You are in one
class, your eldest sister is in another, your mamma in a third, and your
brother in a different division altogether, a long way from you all.
Such a classification is called _artificial_, and you can see at once
that it is worthless.

The most natural plan is to put together those that are of the same
family; and the classifications made on this principle are called
_natural_ classifications.

It is a classification of this sort which has been adopted for the
animal kingdom. People have taken all the animals which possess in
common not one character only, but a collection of characters of the
most important kind, _dominant characters_, as they are called;
and of these animals they have formed, to begin with, large primary
groups; subdividing these afterwards according to the secondary
differences, which distinguish different species in the same group
from each other.

In this manner all the different sorts of animals are included in
different systematic divisions of one vast whole, through which it is
easy to find one's way, because there is a beginning and an end; and
in which animals of the same family are always grouped side by side.
Were I to mention all the divisions of this immense classification at
once, you would find the account a little long, and not very amusing.
We will go through them by degrees therefore, and, to simplify matters,
will, throughout the whole, only consider those particular characters
which are connected with our special study, the nourishment of life,
that is to say: so that you will always find yourself on well-known
ground.

I must tell you once for all, however, that it is with this as it is
with grammar. Here and there are--and it cannot be avoided--certain
exceptional cases which keep protesting timidly against the
arbitrariness of rules; but no matter; we must be contented with what
we can get, and be grateful into the bargain to those who have given
us this skillful classification, at once so ingenious and useful, in
spite of its inevitable imperfections. What is impossible is expected
of nobody. You could not understand, even if I wished to explain it
to you, the amount of science, labor and genius requisite for making
out that long list, which, tiresome as it may seem to children, is
absolutely beautiful in the eyes of learned men; too beautiful, perhaps,
and I will tell you why when we have finished. Meantime, as the best
reward we can give to those who have done us some great service is to
teach their names to children, I will tell you, before bidding you
good-bye, to whom we owe this classification, the details of which I
do not enter upon to-day.

In the first place, we owe the method employed in its establishment,
the method of _natural classification, i.e._, to a learned man
of the last century--a learned Frenchman, Bernard de Jussieu--who tried
it upon plants; another large flock by no means very easy to put in
order, as you may convince yourself any day by studying botany. The
man who applied this system to animals was also a learned Frenchman,
the clearness of the French mind adapting them peculiarly for that
sort of work. And he, too, is one of the glories of that nation. His
labors and discoveries gave a perfectly new impulse to the study of
nature. It was George Cuvier, whose statue you may see at Montbéliard,
if you should ever go there. Not that Cuvier carried through this
gigantic work alone, though the credit of it is justly his due, he
having directed and inspired it. He was assisted by many. But among
his assistants there was one, Laurillard, the most modest, yet the
most active of all, whose name I will mention also, because, like the
others, more or less celebrated, he has never had his reward. [Footnote:
In the earlier editions of this work, there was, in this place, a
severe reproach upon Cuvier for not having given proper credit to
Laurillard. This reproach I have since learned was unjust. M.
Valenciennes himself, one of the most illustrious of the collaborators
of the great Cuvier, has written me a letter in which he defends the
reputation of his friend with a warm indignation which does honor to
both of them; and cites passages in which Cuvier has spoken of
Laurillard, and among others, in the third volume of the _Ossements
Fossiles_, p. 32, ed. of 1822.]

It only remains for me, therefore, to let the lash, which I was laying
upon the shoulders of another, fall now upon my own, and to deplore
the too great facility with which I had credited, without sufficient
proofs, an assertion which I had otherwise good reason to believe to
be exact--coming to me, as it did, from Montbéliard himself, on the
testimony, it is said, of the family of Laurillard. From this avowal,
a little painful, I confess, my young readers may learn the
inconvenience of rashly condemning others! As I said in the concluding
passage, which truth, only too late, now compels me to suppress--"The
truth is sure to come out at last."



LETTER XXX.

MAMMALIA. (_Mammals_.)

Do you remember of my talking of the _vertebral column_ when I was
describing that great artery, the _aorta_, to which it forms a rampart
of defence? I should not have named it without explanation, but that you
had only to pass your hand down your back to find out what it was. Now
the _vertebral column_, or backbone, is one of those _dominant
characters_ which always carries along with it a train of other points
of resemblance in the animals where it is found. It has been chosen,
therefore, as the rallying-point of the first great group. I must tell
you beforehand that there are four of these groups, four large
companies, _i.e._, which naturalists have called by various names; as
Groups, Sections, Primary Divisions and even Branches; in this case
comparing them to four great branches of a tree, going off in different
directions from the same trunk.

And, first of all, we have to begin with the group of the
_Vertebrata_--vertebrata animals--vertebrata being a word which
explains itself.

Of course we ourselves belong to this group. In fact, we are at the
head of it; but it descends far below us. It goes on to the frog and
the fish, and includes the monkey, the ox, the fowl and the lizard;
for all these creatures possess the vertebral column. The frog does
not appear to be very much like us at first sight; and yet, by virtue
of its vertebra, it has its points of resemblance to us, which are
worth the trouble of considering. Vertebrated animals are all furnished
with a head, containing a brain, which gives its orders to the whole
body; they have all an internal skeleton, that is to say, a system of
bones linked together, forming a solid base by which all the organs
are supported. I was going to add that they have all four limbs; but
here the serpent glides in to call me to order, and to hiss at our
childish craving for fine-drawn divisions, in perfect order, where
there is an exactly proper place for everything. However, each has,
without exception, a heart, with its network of blood-vessels; red
blood, under its two conditions of arterial and venous; and also a
digestive tube, acting, on the whole, pretty much like our own. I do
not insist, mind, upon this last point, viz., that of the digestive
tube; for we shall see, by-and-by, that it is a character beyond the
pale of the primary groups. It is the fundamental character of the
trunk itself, which necessarily exists, therefore, in all the groups;
and, as I told you in my first letter, you will find it everywhere.

This is--to let you into the secret at once--the theme on which the
Great Composer has based all His infinite varieties of animal life;
and herein lies the uniformity of the animal creation, that startling
uniformity which has given so much offence to many learned men, and
which is so obvious that it will strike you of itself, I feel sure.
But I reserve this subject to the end of my letters, when you will
have heard all, and be able to judge for yourself.

It would be plunging back into confusion to attempt to examine all the
vertebrated classes at once. After making a division you must go on.
The groups have, therefore, been subdivided into _five classes_, which
we will study in succession, only naming each now: viz. _mammals_,
_birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at
this last name: it is a Greek word, meaning simply frogs.

The mammals are our immediate neighbors. Mammalia are the animals which
produce milk. They bring forth their young alive, and give suck to
them as soon as they are born. This was your first nourishment, my
dear child, so you yourself are a little mammal.

What I said to you in the last letter about the horse, applies pretty
nearly as well to all mammals. We shall not, therefore, have any great
variations to notice here. Nevertheless, as these are the animals which
interest us most nearly, as they are in fact our nearest of kin, so
to speak, and those with whom we have the most to do, we will now pass
in review the different orders of which their class is composed. I
must explain to you that the _classes_ are subdivided into
_orders_, the orders into _families_, the families into
_genera_, the genera into _species_; as in armies divisions
subdivide into regiments, regiments into battalions, &c. It became
necessary, moreover, to make use of special names, in order to make
these subdivisions comprehensible, and the following are those which
have been adopted.

ORDER 1. _Bimana (two-handed)_.

Here we may pass on at once, for we have discussed this order enough
already. We are _bimane_ ourselves, since we have the distinction
of possessing two hands. Yes; that is the pretty title which the
professors have been so polite as to give us, instead of leaving us
simply our proper name of man. Yet it would have been very easy to do
this, seeing that we are the only family, the only genus, and the only
species of the order. In railway travelling, people of distinction
have a reserved carriage to themselves: so we decidedly deserve an
order to ourselves; but that is not quite the same as a separate
kingdom. In short, you are a _bimane_; so make the best you can of it.

ORDER 2. _Quadrumana (four-handed)_.

These, as their name indicates, have four hands: two at the end of the
arms, and two at the end of the legs; such are the monkeys. There is
nothing to remark; they are all alike. Stay; I am wrong, though: there
is something, insignificant it is true, but still pointing to deviation.
In some the canine teeth are set forward, _i.e._ project, and are
longer than the rest, and some species, as the ape, for instance, have
just under their cheeks convenient little pockets, which open into the
mouth, and in which they can deposit a reserve of nuts to be devoured
at leisure; these are called _pouches_.

It is a trifle in itself, but we have here a first example of the
eccentricities of nature in the construction of animals. At one time
she adds a detail; at another she suppresses one. Sometimes she is
pleased to enlarge an organ, as in the canine teeth of the monkey;
sometimes she reduces it; or perhaps here she makes its construction
more simple; there again more complicated: but still it is always the
same organ. So the dressmaker shapes the sleeves of a dress, sometimes
open, sometimes closed, flat or puffed, plain or ornamented,
pagoda-shaped or gigot-formed: but still they are all of them sleeves.

ORDER 3. _Cheiroptera (wing-handed)_.

I am quite ashamed of offering you such a word as this, my dear child.
It was a Greek fancy of the learned men, who would not condescend to
use the vulgar name Bats. In the Greek, _cheir_ means hand, and
_pteron_ wing. The Cheiroptera are animals with winged hands; in
fact, the fingers which terminate the fore-limbs of the bat lengthen
as they spread out to an extravagant extent; and are connected together
by a membrane springing from the body, with which they beat the air
as with a wing, and which enables them to fly with such ease that
theyare often taken for birds.

But, so far from really being a bird, this curious little creature has
the same internal organization as ours, and indeed comes so near us,
though without looking as if it did, that a scientific man, and a very
distinguished one too, placed the bat in the first family of the animal
kingdom, with the monkey, and, you will hardly believe it, with man.
It is found that the bat, like man and the monkey, suckles its young
at the breast; and it was this very character which Linnæus, the leader
of artificial classification, thought of selecting as the distinguishing
mark of his first family in the animal kingdom. It is true that in
honor of the human race he had given that first family a much more
sonorous name than our usual one of _man_--viz. _primates_, the first in
rank--that is, the princes. But, alas! we were to be princes on an
equality with bats; and, for my own part, I prefer being a _bimane_, and
alone. I really believe that it was to put this saucy little creature
back into its proper place that, at the time of the great revolution in
favor of natural classification, the conclave of professors assembled at
the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera
on the bat, ejecting it contemptuously from the overthrown dynasty of
the _primates_.

I have not been sorry to make you acquainted as we went along, with
this little trait in the history of classification; but beyond it there
is really nothing particular to say about the apparatus for the
nourishment of the deposed bat-princes, which is a plain proof how
nearly it must be like our own. By-the-by, there is one trifling remark
to be made with regard to her teeth. The bats we have in our country
(France), for there are many varieties of species in the world, live
on insects, which they catch in their flight by night. These insects
are often enveloped in a very hard outer case, which molars like ours
would have some difficulty in chewing properly; consequently the molars
of our little friend are fringed with conical points, and with these
she grinds down her prey without difficulty.

In America there is a large bat, the vampire, which lives on the blood
of animals, and nature has armed it accordingly. It has at the
extremityof its muzzle two sharp beak-like incisors, like the lancets of
a surgeon. The vampire bat, which roams by night like other bats, goes
straight at the large animals it sees asleep, delicately opens a vein
in the throat without waking them, and sucks their blood in long
draughts, taking care, by fanning them with its wings, to lull them
into a cool and balmy slumber. It does not, as you see, make a savage
attack on its victim: it merely inflicts a bite like that of the leech,
but the result may be death. This is the best emblem I know of the
sycophant, who undermines your soul while he fans your vanity; and
observe, while we are on the subject, that this species has always had
the art of insinuating itself among princes.

ORDER 4. _Carnivora (flesh-eaters)_.

When translated into English, this word needs no explanation. And here
we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers,
lions, of all the fighting animals, _i.e._, those which steep
their muzzles in blood, and live by devouring others. These have a
similar apparatus for nutrition to our own; especially the bear, who,
with the monkey, is the animal most nearly resembling man, seeing that
he has feet like ours, with scarcely any tail, while the monkey has
our hands, without specifying any other points of resemblance. Like
ourselves, too, the bear is omnivorous; that is to say, it eats
everything, vegetables and fruit as well as meat; and nature, which
has given it our diet, has furnished it with molars almost exactly
like our own. Its canine teeth alone differ from ours: they are more
prominent even than those of the _quadrumana_; and this is the
case with all the members of the order, in whom we find them sometimes
developed into actual daggers. But those of them which are purely
carnivorous have molars peculiar to themselves. The lion, for example,
who does not share the bear's taste for carrots, and who would die of
hunger surrounded by the honey and grapes of which the bear is so
fond--the lion, who never takes anything but raw meat between his
teeth, has molars furnished with sharp cutting edges, intended to slice
the meat like the chopping knives used by cooks for making a hash.

The lion offers another peculiarity, which is common to him with all
the _Carnivora_. Place your finger close to the lower end of your
ear, and work your jaw; you will feel something hard moving backward
and forward against your finger. This is where the lower jaw is set
into a bone of the skull, called the _temporal_, if you care to know its
name; in other words, the bone of the temple. The extremity of the jaw
bends, and forms a kind of little knob, called _condyle_, which fits
into a cavity of the temporal bone. With us the cavity is not very deep,
nor the knob very large, so that it can play very freely; and it is this
which allows us that second movement from side to side, of which I spoke
to you formerly, and thanks to which, our little mills reduce a mouthful
of bread into paste. But this freedom of action has also its
inconveniences. You must never attempt to force too large an article
into your mouth at once--an apple, for instance--the efforts you would
then be obliged to make might easily cause the _condyle_ to slip out of
its little cavity, where its hold is but slight, and to get under the
_temporal bone_; and there you would be with your mouth wide open until
the doctor arrived. The lion, whose voracious jaw opens like the door of
an oven, so that the tamers of wild beasts have no scruple in thrusting
in their whole heads, a mouthful a good deal larger than an apple; the
lion, who has no doctors, would often be liable to this accident--an
irremediable one in his case--if nature had not made a special provision
for him. In order to secure greater firmness and strength, the second
movement is in his case sacrificed by embedding the _condyles_
deeply in their cavities, where they are fastened in such a fashion
that they can only move up and down, like the handles of a pair of
pincers. This is a restraint which enables the jaw to be safely thrown
open as wide as the fiery impulse of its terrible proprietor impels
it. Less freedom, in exchange for more power, is a bargain which any
one would gladly accept who plays the part of a lion!

I have here a remark to make. We have now passed in review three orders
besides our own, and have only had to point out a change in the
fastenings of the jaws and in the teeth; and you will find that the
same sort of modifications take place in the whole class of mammals.
This is in fact the essentially movable and variable point in their
apparatus for nutrition. The jaw and its weapons vary their character
from one species to another, according to the nature of their food;
but the modifications generally terminate there, _i.e._ on the
threshold, as it were. The interior arrangements of the house remain
otherwise much the same in all.

Here, however, in the lion, there is an interior change to be described;
but not in the arrangement of the parts, only in their size; the stomach
in this species being even smaller and weaker in proportion than ours,
and the digestive tube more than twice as short. The digestive tube
of an ordinary sized man is about seven times the length of his body,
whilst that of the lion only measures three times the length of the
animal. This is a natural consequence of the kind of nourishment he
takes. Flesh and blood, on which he lives entirely, is concentrated
_albumen_, prepared beforehand in the bodies of his victims; so
that no great preparation is needed here to convert it into lion's
blood. A professor of chemistry, who has a good assistant, does not
need a very large laboratory. This is the case with the lion; and
nature, which makes nothing in vain, has here economised space. Tame
the monarch of the forest into a domestic animal, and change his food,
and I will wager anything you please that, in the course of a few
generations, his digestive tube will lengthen itself. Examine the
inside of the cat, his little cousin, formed originally on the same
pattern as himself, and, without having ascertained the fact myself,
I am sure that, by dint of feeding it daily on sops and milk from
generation to generation, its digestive tube has become more than three
times the length of its body.

Here you ought to be told at once a very important fact relative to
the organization of the lower animals, one which places them all very
far below the order of _Bimana_, since there is such an order.
In bestowing intelligence and freedom of action on man, the Almighty
has given him the unspeakable privilege of working in His footsteps--if
I may presume to use the expression--of following up His work of
creation as it came from His hand. Now especially that man begins to
see a little more clearly into the laws of life, he has entered more
directly into the possession of this almost divine privilege, which
the Almighty has graciously vouchsafed him. You can even now have an
ox or a sheep made to order in England, giving your dimensions, as if
you were ordering a cabinet; and in a few years, if you have not asked
actual impossibilities, your commission will be executed to within an
inch. This is not said in reference to the _Carnivora_. But in
bidding you good-bye, my dear little mammal, I could not bear to leave
you under the weight of that debasing title: I wanted also to show you
your greatness.



LETTER XXXI.

MAMMALIA. _(Mammals)--continued_.

Let us continue to pass in review the different orders of the class
Mammalia. We may meet elsewhere with facts more important to science,
but nowhere with any so personally interesting to ourselves.

ORDER 5. _Insectivora (insect-eaters)_.

This order devours insects, as their name tells you plainly enough.
They feed in the same manner as the bats; consequently they have molars
like theirs, as was necessary. It is an unimportant little family, and
we will not waste much time upon it. The chief of the order is the
hedgehog, a native of our country--not very large, about nine inches
long--which lives in the woods, and which when rolled up into a ball,
with all its quills standing out, looks very much like an enormous
horse-chestnut in its shell. Its canines have not much work to do,
consequently they are very small; but, on the other hand, its two front
incisors are prolonged beyond the others, the better to seize its prey,
which creeps upon the ground. Internally there is nothing to remark
upon.

Next to the hedgehog I will mention as a curiosity the shrew or
sand-mouse, which, in spite of its name, is no mouse at all, but has
the honor, if honor it be, of being the smallest animal known of the
class Mammalia.

It is about two inches in length altogether; and if you carefully
examine its little body, you will find that it contains all the organs
you possess yourself--oesophagus, stomach, liver, intestines, veins,
arteries, heart, lungs--nothing is wanting: the machinery is absolutely
the same.

ORDER 6. _Rodentia (rodents)_.

Were we to translate this word into its meaning, namely, the _Gnawers_,
there would be some comfort in it, for we would at once know what it
means: but no matter. Rodents, or Gnawers, are rats, hares, rabbits,
beavers, marmosets, squirrels, in fact all the creatures which _nibble_.
To _nibble_, if you do not exactly understand the word, means to chew
with the points of the teeth. The rodents have no other way of eating
but by filing, if one may so say, their food with the points of two
incisors with which both the jaws are provided; these incisors are very
long, much longer even than those of the hedgehog. The next time you see
a rabbit at table, ask to see the head; and you will find that it has
four pretty little teeth, very sharp, shaped like a joiner's chisel;
that is to say, with a "bevelled edge," to use the received expression;
in other words, with one edge thinner than the other.

Here, then, we begin to diverge from the old model. First, there is a
different fastening, or _articulation_, as it is called, of the jaw. Its
_condyles_, which we saw just now in the _Carnivora_ enlarged
transversely and deeply embedded in the _fossae_ or cavity of the
temporal bone, extend here longitudinally; an arrangement which enables
the jaw to move backward and forward at pleasure, like the arm of the
locksmith when using the file. Furthermore, those little teeth, which
are constantly rubbing against each other, would be very soon worn out,
if, like our own, they were made once for all; accordingly their germ,
or _pulp_, to use the proper term, instead of perishing, as with us,
when the tooth has once come, retains its life, and works on throughout
the life of the animal. They sometimes say of a man who has not eaten
for a long while, that his teeth have grown long. This is a joke with
us; but in the case of a _rodent_ would be too serious a matter to be a
joke; for, as their incisors are always growing, like our nails, they
would soon become too long if the animal ceased for any length of time
to wear them down by eating. It is for this reason that rats and mice
have such incessant appetites, and that with them "all is fish that
comes to the net;" old books, rags, and even planks of wood, which they
will gnaw for want of something better. Come what may, they must keep up
at an equal rate the wear and tear of the incisors, and the internal
growth of the pulp beneath, which is always pushing the tooth forward.
This dull continuous work might otherwise have a terrible result, which
you would never suspect. It is very disastrous for a young lady to lose
a front tooth, as it is called, for it sadly spoils a pretty face; but
for a _rodent_ such a loss is much worse; in fact, it is a
death-warrant. The corresponding tooth, having no longer anything to rub
against, ceases to wear out; and as it does not stop growing on this
account, it lengthens indefinitely, until at last it pushes out beyond
the mouth, and places itself like a bar between the two Remaining teeth
and the food of the animal, who, poor beast, being unable to eat,
ceases to live.

The canines, whose duty it is to pierce the food, have, of course, no
use in a jaw that grinds, nor are they to be found there. Between the
incisors and the molars there is a large vacant space, which you will
easily detect if you examine a rabbit's head.

Finally, animals which can fall back in time of need on a plank for
their dinner, require a very different-sized cooking apparatus to that
of the _Carnivora_. Thus the rat, the most perfect sample of the
rodent order, possesses a digestive tube of a prodigious length, through
which the scrapings of wood have plenty of time for travelling, while
the minute nutritive particles they contain are being thoroughly
disengaged; and as every part of the animal organization tends towards
keeping our insatiable rodents in the constant state of voracity
required by its inexorable pulps, nature has given it an enormous heart
whose size exceeds even that of its stomach.

Perhaps you do not catch at once the connection which exists between
the size of the heart and of the appetite; yet it is very simple. Large
barrels are requisite for those who brew a great deal of beer, and
large hearts for those who make a great deal of blood. Now, it is the
blood, as you know, which carries heat; in other words, life, throughout
the body; when it pours in in torrents, the fire goes twice as fast,
and, consequently, the feeding must be kept up. A medical friend of
mine told me that he once had some rats sent to him--a boxful in
fact--for one of those scientific experiments which one would venture
to condemn more earnestly if their results were not sometimes
beneficial. Next morning there were only two or three animals to be
found, and these had eaten up the others. See the consequence of having
too much heart!

ORDER 7. _Pachydermata (thick-skinned)_.

In Greek _pachus_ means thick, and _derma_ skin. _Pachyderms_,
therefore, are thick-skinned animals. It is rather a vague denomination,
as you perceive, and does not tell us much about them; but it appears
that it was not very easy to find a better term. For my own part I
should be very much puzzled to find a name really suitable for such an
irregular company as this, in which all the huge beasts of the
earth--the elephant, the rhinoceros, the hippopotamus--are heaped one
upon the other, side by side with the horse, the ass, and the hog;
begging your pardon for an ugly word.

All these creatures live on vegetables, with the exception of the hog,
to whom nothing comes amiss; or who, in other words, is _omnivorous_,
like the bear, and also another member of the class _Mammalia_, which I
do not name for fear of making you blush at your companionship. This
assures you that, in the order of the _Pachydermata_, the digestive
apparatus is very fully developed. The horse, for instance, has a very
voluminous stomach, which extends much farther back than the point at
which the oesophagus empties itself; and in which, on close examination,
a sort of contraction is observed which appears to divide it in half,
producing the false effect of there being two stomachs. But, after all,
we do not find, even in this case, any essential difference to remark
upon in the internal arrangements; it is always the teeth we must look
at if we want to have something to say. There, indeed, we have only to
choose; nature has indulged herself in all manner of fantastic freaks.

To begin with the elephant, the grand master of the order, he presents
us with one of the most oddly-furnished jaws in existence. Every one
knows those two enormous tusks which protrude from his mouth, and which
furnish human industry with nearly the whole store of ivory it has
need of. Those two teeth are the largest, beyond comparison, of any
in the animal kingdom; yet they are two merely ornamental teeth,
perfectly useless in the operation of eating, and very ruinous into
the bargain to the proprietor. All those stores of the blood which
furnish the materials for ivory pass into these tusks, and, as often
happens to people who give way to a taste for luxuries, there is nothing
left wherewith to provide the animal with serviceable teeth. Those
tusks of the elephant are nothing but his upper incisors, the only
ones, observe, which curve in coming out of his jaw. In the lower jaw
he has no incisors at all; canine teeth are entirely wanting; and by
way of dental apparatus, this meagerly-furnished mouth possesses on
each side of either jaw one or two molars, enormous in size, but not
of ivory. They are composed of a number of enamelled upright layers
of tooth-substance (_dentine_), soldered together with a bony
cement; and these are our giant's only resource for chewing the grass,
young shoots, and leaves of trees, which are his natural food.
[Footnote: These teeth are nevertheless very efficient grindstones.]
As a consolation, he has the glory of knowing that he possesses the
very finest teeth in the world, the terror of all who approach him;
and I can compare him to nothing so well as to a vain woman, who is
contented to live on potatoes that she may wear fine clothes and excite
the envy of her neighbors.

The hippopotamus also has incisors in the upper jaw, which curve as
they come out of the mouth; but these never attain anything like the
size of the elephant's tusks, neither do they hinder the development
of the other teeth, of which this animal has a very respectable
collection. The upper incisors bend downward; those in the lower jaw
stand out horizontally, and terminate in sharp points like
plough-shares; and indeed the hippopotamus uses them for tearing up
the ground in order to get at the roots which form its nutriment. These
are, besides, formidable weapons, with which when enraged the animal
can tear even boats in pieces; for, as you are aware, the hippopotamus
is almost amphibious, and browses on water-plants, and lives in the
great rivers of Africa, its native country. Its name alone would have
told you this had you understood Greek; [Footnote: _Ippos_, a horse, and
_potamos_, a river. The Greeks, who had seen the hippopotamus in the
Nile, in Egypt, named it the river-horse; as afterwards the Romans
called the elephant the ox of Lucania, because they first saw it in
Lucania during the war with Pyrrhus.] but I have no complaint to make
this time, for it was the Greeks themselves who gave it. You would find
it very awkward, would you not? if you had to breakfast at the bottom of
the Thames, and could not swallow a morsel without having your nose
filled with water? But the hippopotamus labors under no such
inconvenience. Its nostrils are provided with two little doors, which it
closes at will, and behind this screen the lungs keep quite quiet while
the animal goes backwards and forwards in the water. There is generally
a hippopotamus in every large menagerie. The next time you visit one
look at him. You will see him with a large stomach almost trailing on
the ground: and no wonder; he needs plenty of room in which to stow away
all the canes, reeds, and water-plants from the bottoms of rivers, which
are not very nutritious food. Accordingly the stomach of the river-horse
presents the appearance not only of two compartments, like that of the
true horse, but looks as if it were divided into three or four.

To conclude my account of this animal, I must add that the ivory of
its teeth is even more beautiful than that of the elephant's tusks,
and that dentists carve it into very magnificent teeth for their
patients. This is not a matter to interest you much at present, but
we never know what may happen. I advise you, however, never to make
use of hippopotamus's teeth; they turn yellow very quickly, and, when
people are driven to buy teeth, the least they can try for, is to get
good-looking ones for their money.

I should like to say something about the rhinoceros while we are on
the colossal tribes, but it is a very unsatisfactory subject. The
animal has no canines, sometimes no incisors even; sometimes it has
as many as thirty-six teeth, according to the species, as naturalists
aver; and this is all I have to say about this great lump of flesh,
so misshapen outside, yet so regularly formed within. He it is who
especially deserves the title _pachydermata_, his skin being so
hard and thick that bullets glance off its surface. But this has nothing
to do with our present subject, any more than the horn upon his nose,
whose turn for description may come if I ever give you the history of
the skin and all connected with it.

The hog also has canines, and very strong ones; but it is in the wild
state, when it is called a boar, that these appear in their real form.
There we find them projecting out of the mouth with a curve, as is so
commonly seen among the _pachydermata_, forming those terrible,
sharp, and pointed tusks which have been so often fatal to the hunter.
The wild boar of the forest is supposed to be the original ancestor
of the domestic pig; and if, as is probable, this is really the case,
we have here a remarkable instance of the effect of man's treatment
upon the organisation of the animals he collects around him. The wild
boar lives only on fruits and roots, which, like the hippopotamus, he
tears up with his tusks, those safeguards of his, amid the many perils
of his life in the woods. In the service of man, on the contrary, he
becomes lazy, cowardly, and greedy; unlearns his energy and
combativeness, eats all that is offered to him in the trough, even
meat, when it happens to be thrown in; and, in order to do this
moreeasily, has recalled toward his mouth those formidable war-tusks of
his, so tremendous as weapons, so useless as teeth; has, in fact,
turned his sword into a fork. It is the case of a Tartar degenerated
into a Chinaman. [Footnote: China, about which we have heard a great
deal of late years, has been several times invaded by the warrior
hordes of Tartary. But at each time, unto the second and third
generations, the vanquishers have taken the effeminate manners, the
costume and the usages of the vanquished, and so many conquests have
only resulted in converting millions of Tartars into Chinese.]

This suggests to me an idea relative to the horse, the last important
member of the _pachydermata_ which remains to be spoken of. It
also has its canines, but very small ones; they disappear, so to speak,
in a large vacancy between the incisors and the molars, where man
inserts the bit, by means of which the animal has been subdued. Small
as these are, however, these canines indicate that the horse might eat
flesh, canine teeth being the distinctive attribute of the carnivorous
mammals. I have read somewhere, but I do not remember where, that an
unusual development of strength could be produced in the horse by
feeding it on flesh; and the old Greek poets write of a king [Footnote:
Diomed, King of Thrace] in the barbarous ages who gave his horses,
men for food. If I knew some rich professor who was inclined to spend
money in the investigation of a curious fact, I would advise him to
set apart a sum for putting horses on a meat diet, from sire to son,
gradually increasing the quantity; and I would boldly warrant that in
the course of successive generations the canines would become so large
as to impede the entrance of the bit into the mouth, and, moreover,
would make it rather a ticklish office for the groom to place it there.
But let us set aside the teeth the horse might possibly have, in order
to examine those it has already. There are six incisors in each jaw;
these are long and rather projecting teeth, by examining which, the
age of the horse can be detected from certain marks which appear in
them from year to year. The molars are flat, square, furrowed with
bars of enamel, marking out more or less distinct crescents; perfectly
constructed, in short, for chewing hay and oats. Nevertheless, I should
never be surprised to see the enamel crescents become sharp-cutting
in our rich professor's stable; so skillful is the unseen Architect
who created animals, in altering the house when the tenant changes his
habits.

ORDER 8. _Ruminantia (ruminants)._

I shall retain through life a pleasant recollection of the
_ruminants_. Through them I obtained the first prize for natural
history which was ever given in France to the pupils of the learned
university. It is thirty years ago since this happened, and I own,
without any false modesty, that even now the word _ruminant_ rings
very agreeably in my ear. It reminds me of one of the proudest moments
of my life, of the honor done to me by the illustrious Geoffroy St.
Hilaire, when he called me, a little college urchin, up to him, that
he might have a nearer view, as he said, of the baby-professor who had
spoken so well on ruminants. Yes, it is more than thirty years ago, for
alas! it was in 1831. There needed no less an event, as I have told
you before, than the revolution of 1830 in France to induce the big-wigs
of education to sacrifice two hours per week in one class to the study
of natural history. Yes, my dear child, it is only that short time ago
since natural history became one of the subjects of study in French
colleges; and the gray-haired men of the present day finished their
education, as it is called, without having learnt a single word of
what I am now taking the trouble to teach you, a mere child. You see
you have come into the world just at the right time, and will be able
to instruct others in your turn. But before giving lessons to other
people you must first finish learning your own. Forgive me this
involuntary reference to a happy time when I was not much more rational
than you are. And now, let us return to our ruminants--those dear,
good beasts, the nourishing fathers of the human race.



LETTER XXXII.

MAMMALIA--_continued_.

ORDER 8. _Ruminants--continued_.

Every created thing has an appointed part to perform; but there are
some mysterious parts of which we cannot understand the drift. That
of the ruminants, however, is so clearly marked out, that we detect
it at a glance.

To qualify myself for supplying your young mind with the food I am
going to offer it to-day, I have been obliged, my dear child, to browse
in a good many books of which you could have understood but little
yourself; and I have been forced to ruminate a long time upon what I
have read, and to digest it slowly in my head, which I may say, without
vanity, is of larger capacity than yours; no great wonder at my age.
Now, if I have succeeded in my undertaking, you will benefit by all
the work which has been going on in my mind for the purpose of feeding
yours without over-fatigue to it; and I shall almost have the right
to say that its nourishment has been derived from me. My lamp could
tell you what it has sometimes cost me to supply a single page which
might instruct, without repelling you.

Now, this is precisely what the _ruminant_ does. The part he has
to perform is to collect in the meadows a sort of food, which would
disgust less well-organized stomachs than his own, to work it well up
within him, and to give it back in a more palatable and less
indigestible form. The little flesh-eaters (_carnivora_) come
afterwards to the feast, and the feast is himself!

The whole history, then, of the ruminant is to be read in his stomach.
His real office is to digest, and in fact he devotes the best hours
of his days to the perfecting of that beneficent labor, on which the
life of so many weak stomachs depends. Have you ever amused yourself
by watching a large ox lying down in a meadow? Long after he has
finished grazing, his jaw continues to work, turning round and round
like the grindstone of a painter when he is rubbing down his colors.
Look, and you will see that he will remain there for hours together,
motionless and contemplative, absorbed in this incomprehensible
mastication, rolling about in his throat from time to time some
invisible food. Do not laugh at him, however. As you sec him there he
is performing his part in life, he is _ruminating_.

To ruminate is to chew over again what has been already swallowed;
and, however droll this may seem to you, it is the business which all
ruminants are born to. You remember the monkey's pouch, which serves
him as a larder, whence he takes out his provisions as he wants to
eat. The ruminant has an immense pouch of the same kind, into which,
while he is grazing, he hastily conveys large masses of half-bitten
grass. You probably think he is eating when he has his head down in
the grass; but you are mistaken. This is only a preparatory work; he
is hastily heaping up in his larder the food he intends to eat
by-and-by; only his larder, instead of being, like the monkey's, in
his cheeks, where, indeed, there would not have been half room enough
for those great bundles he tucks in, is in the middle of his body,
close to the extremity of the oesophagus, whose lower wall, being slit
at that part, becomes an imperfectly secure tube, ready to burst open
under pressure, and allow the food to escape between the edges of the
slit; these, otherwise, remaining naturally closed. As soon as the
large bundles of grass come to this part, they press against the walls
of the tube, which they by this means separate, and fall into the
provision-pouch, which bears the name of paunch, or grass-pocket, in
fact. As soon as the paunch is well filled, and the animal sure of his
dinner, he lies down in some quiet corner, where he proceeds gravely
with the important act, which is the real object of his existence. A
little below the entrance to the paunch, and communicating both with
it and the canal of the oesophagus, is a second receptacle, which old
French naturalists, not being much acquainted with Greek, named the
_cap_, on account of its fancied resemblance to the caps worn on
the head, and which we call 'king's hood' or 'honey-comb bag.' This
second stomach now contracts (at least so it is supposed), and thus
retains, as if with a closed fist, a portion of the grass accumulated
in the paunch: of this it forms a pellet, which it sends back into the
oesophagus, and the oesophagus, by continued contractions from below
upwards, returns it to the mouth, where at last the grassy lump is
chewed in good earnest, and to some purpose. There is no necessity for
hurry; the ruminant has no other business on the face of the earth but
this, and thus hour after hour passes away, the food pellets rising
one after another to the onslaught of the teeth. Nor do they go back
again until they have been reduced by long mastication into an almost
liquid paste, which glides through the oesophagus without forcing open
the slit, and falls straight into a third pouch, called by old Frenchmen
the _leaf_, on account of certain large folds, some what like the leaves
of a book, which line the interior; and known to us as the _manyplies_.
From this stomach, No. 3, this grass-pap passes into a fourth and last
bag, which is the real stomach, and where the final work of digestion is
accomplished. This fourth pouch also has a pretty little name of the
old-fashioned sort, like the three others; it is called the _reed_ or
_rennet-bag_, from the property it possesses, in the calf, of turning
milk into curds: and of his four stomachs this is the only one which the
ruminant makes use of at first. As long as the young animal is nursed by
its mother, the other compartments remain inactive and small in size;
they neither grow nor exercise their functions until it begins to eat
grass. Indeed, they would probably entirely disappear, if any one would
go to the expense of keeping the animal on milk all its life. If it
ceased to have anything to ruminate, nature would certainly lose no time
in relieving it of its useless workshop of rumination.

As it is right to give every one his due, I will mention that we owe
our accurate knowledge of this simple and ingenious mechanism of
_rumination_ to the labors of Flourens, a scientific Frenchman,
who is still alive, and who has made a great many interesting inquiries
into the subject we are now considering, _i. e._, the life of
animals. He is a very clever man into the bargain--so perfect a master
of his own language, that the French Academy has felt itself justified
in opening its doors to him--an unheard-of honor for a member of the
Academy of Sciences. And yet, in spite of all this, I heartily
congratulate you that the discovery of the _paunch_, the _cap_, the
_leaf_, and the _rennet-bag_, was not delayed for his arrival. He is
just the man who might have been tempted, in his capacity of profound
scholar, to have hunted up for them in the _Jardin des racines grecques_
[Footnote: Your brother can tell you about the _Jardin des racines
grecques_. It is a charming little book, of which every generation of
collegians has learnt, by heart, the commencement; but I have never
known one, even among the most intrepid, who had ever been to the end of
it.], four magnificent names, which would only have bewildered you.

Beyond the rennet-bag there is no change of conformation to note,
except that the intestinal tube is naturally much longer than ours,
on account of the difference of food: as a general rule, it is ten or
twelve times the length of the body. The sheep, who is able to pick
up a living in the poorest pastures, is indebted for this inestimable
power, which makes him the special blessing of dry and barren countries,
to a still further peculiarity of organization; with him the intestinal
tube is twenty-eight times the length of the body.

We have seen among the _Carnivora_, whose jaws have so much work
to do, that the condyles of the jawbone are sunk deeply into the fossa
of the temporal bone. The ruminant, whose peaceful mouth is formed for
contending only with grass, is organized quite differently.

Here the condyle is flattened, and the fossa of the temporal bone very
shallow, presenting to the condyle an almost flat surface, so that the
jawbone is enabled to revolve with ease for the better mastication of
the pellets of grass. This conformation is also to be seen in the
_pachydermata_ who feed upon vegetables. In the horse, especially,
whose food is almost the same as that of the ox, the _articulation_
(as this joining of the condyle to the temporal bone is called) of the
jaw, is also nearly identical; and it is the same with the teeth, with
very trifling variations, those of all ruminants are constructed on
the same plan as in the horse. The canines only require a separate
notice.

But first I must tell you that, by some special privilege, the reason
for which I do not undertake to explain, the order of ruminants is the
only one containing animals with horns on their foreheads. Stags,
goats, reindeer, chamois, gazelles, roebucks, oxen, buffaloes, all the
beasts with horned foreheads, belong to the ruminants. Indeed, this
fact would form a very convenient mark of distinction between them and
other animals, were there not exceptions to it. Some ruminants have
no horns; and then, as if in compensation for the deficiency, we find
them provided with canines in the upper jaw, in addition to those
below.

The ruminant which has the most beautiful canines is the musk-deer,
a pretty little animal inhabiting the highlands of Central Asia, like
the chamois of the Alps. But now that you know who he is, you will
probably often be tempted to wish he had never existed; for it is from
a small pouch below his belly that people obtain that odious musk of
which Oriental beauties are so fond, and which even certain
strong-nerved ladies of our own country are guilty of using in public,
to the great detriment of general health. But enough of this; our
business is with the canines of the musk-deer. They project with a
descending curve from the upper jaw, and would give the animal the
very false appearance of a small wild boar, but for the great delicacy
of its legs, which are more slender than even those of our roebuck,
to whom, with the exception of the horns, it bears a close resemblance,
as its name implies.

After the musk-deer comes the large family of camels and llamas, which
represent--the former in Asia and Africa, the latter in America--the
irregular groups of ruminants which have canines instead of horns, and
which seem to be placed as intermediates between true ruminants and
the pachydermata. They form the connecting link between the horse and
the ox, and men prefer employing them as beasts of burden to using
them as butcher's meat; though one could eat them in their own country
with less disgust than Europeans feel in making a meal of horseflesh;
so that they might be a very acceptable resource in many cases. The
real fact is, that ruminants with horns and without upper canines have
more delicate flesh than the others, and seem more especially destined
to be eaten. Yet if one had only to look at the stomach, which is,
after all, the distinctive characteristic of the order, camels and
llamas would stand in the first rank as ruminants. Besides the usual
character of four stomachs, their paunch and honeycomb-bag are furnished
with large cells which act as reservoirs, and fill with water whenever
the animal has the chance of drinking freely, and from whence in time
of drought he draws it up into his mouth and swallows it. This is what
makes the camel so valuable to the wandering tribes in the great deserts
of Africa and Asia. He is the only animal who can pass several days
under the burning sun of Sahara without drinking--or rather without
appearing to do so--for he carries his provision of water concealed
from all eyes in the recesses of his body. I dare say you have often
heard stories of Arabs dying of thirst who have opened the stomachs
of their camels in search of a last draught of water. It must be a
terrible thirst to drive a man to such an extremity; for, as you may
imagine, one could not expect the water there to be either fresh or
clear, to say nothing of the great risk there would generally be of
finding the reservoir empty. Such an extreme is never resorted to till
water has failed for a long time, and all the goatskin bottles have
been emptied; and in such a ease it is but too likely that the camel
has followed his master's example, and emptied his water-skins for his
own use. But this is only half the internal fittings of the "ship of
the desert," as the Arabs call him. In the desert it is often as
difficult to find food as water; and nature has equally provided for
this. The hump you see rising upon the camel's back in your
picture-books is his safeguard against starvation. It is a huge mass
of fat. I need say no more. You will remember Mr. Liebeg's pig, which
lived 160 days upon its own bacon. Without going quite such lengths
as that, the camel can keep up his fire for a long time upon the fuel
which the blood obtains from this blessed hump. Since we are talking
of this animal, and he takes a remarkable place in a history of
nutrition, I ought to tell you that camels are classed into two families
by their hump: there is the camel, properly so called, which has two
humps, and the dromedary, which has but one. This latter did not require
such a supply of provisions as the other, for he is very much swifter
of foot, and consequently his journeys are more speedily performed.

I have nothing particular to say to you about the other ruminants, in
the matter of their organs of nutrition; but I will not quit the subject
without reminding you of one thing which concerns nutrition, not theirs,
however, but ours. It was by the taming of the domestic ruminants--that
unfailing dinner-material which now follows everywhere at the heels
of his master--that human civilisation began. Before that event, man,
driven to depend for his living upon the hazards of the chase, spent
his whole time in seeking for food, and had none to spare for the
pursuit of any other branch of industry.

Far as we may ascend in the history of ages we shall find shepherd
races. Beyond them there is no history at all, nor could there be. The
first leisure hours of man, and, consequently, his first efforts in
art and literature, date from the period when the ruminant animals,
those special fabricators of nutritive aliments, were gathered around
mankind, and worked out their destiny under the shadow of his tent,
by his direction, and for his benefit. But all this is so distant from
us now, that it is scarcely worth the trouble of thinking about. The
human race is somewhat like those old people who have lost all
recollection of their childhood; and young people are not required to
know what their elders have forgotten. It is well, however, that they
should not be quite ignorant on the subject. When you hear that the
Society for the Prevention of Cruelty to Animals has taken up the cause
of some barbarously-used ox or sheep, do not turn it into ridicule.
Those humble species have supported ours from the first; and you should
recollect, now and then, that human society made its first step forward
when it began to keep flocks and herds.



LETTER XXXIII.

MAMMALIA--_continued_.

We come now to animals less familiar to you, and none of which inhabit
Europe. We shall therefore pass more quickly over them.

ORDER 9. _Marsupialia (pouched)_.

_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials
are distinguished from other animals by a pouch which the mother has
under her belly, and in which the little ones take refuge at the
slightest alarm. You would be very much interested with their whole
story; but it has nothing to do with our present subject, which we
should soon lose sight of if we once began to wander away. This order,
so easily distinguished otherwise by that singular pouch, unfortunately
for us, offers nothing new for observation. It includes several species,
differing entirely from one another on the subject of nutrition, and
closely resembling some already described. Some are both carnivorous
and insectivorous, and are therefore armed with powerful canines, and
with molars like those of the hedgehog. Others are herbivorous, like
hares, and have almost the jaws of a rodent. Among the former we have
the opossum, celebrated by Florian in one of his prettiest fables. The
opossum inhabits South America. Charming little marsupials are to be
found in the Molucca Isles, whence come the nutmeg and the clove; these
are very like our squirrels, and live as they do, in trees, hunting
after fruit and insects. But the greatest number of marsupials belong
to Australia, the real native land of the order. They form by far the
larger portion of the mammalia with which that country is enriched;
the most celebrated amongst them being the kangaroo; an animal which
is now becoming common in European menageries, and which, excepting
in the matter of its pouch, is nothing but a magnified rabbit, as tall
as a man, and with a tail almost as long as itself. As a rabbit, you
know what its eating apparatus must be; and some day, no doubt, the
French Acclimatisation Society will enable us to judge of its flavor.
It is a kind of meat very likely to be seen on our dinner-tables
by-and-by; and, as you have plenty of time before you, probably you
may eat of it before you die.

ORDER 10. _Edentata (toothless)_.

These come more directly within our limits. They are classed according
to their teeth; yet if their name were to be trusted, they ought to
have no teeth at all. Whereas, alas! almost all of them have some, and
I am heartily ashamed of their scientific designation; but how can we
help it? The only really _Edentata, i. e_. toothless animals, amongst
them are the ant-eaters, who, considering the nature of their food, are
not much in want of teeth. They feed among the ant-hills, whence they
get their name; and as they are a tolerable size (from two to three feet
in length), it would really have been quite a hardship upon them to have
been forced to crunch the ants one by one at every meal. To get on
rapidly they catch them with their tongue; but what a tongue! Imagine a
kind of long earthworm, lodged in a snout which is elongated like a
bird's beak, and has a very small opening at the extremity. The ant
eater inserts this long, string-like tongue into the crowded ranks of
its victims, and, as its surface is glutinous, they stick to it by
hundreds at a time, and are swallowed at one gulp without a chance of
escape. This tongue, perfectly unique in its character, stretches out in
its murderous exertions to nearly three times the length of the animal's
long head. What a distance there seems between such a tongue as this and
your own little doorkeeper! But no wonder: we have now reached the
confines of the kingdom of _Mammalia,_ and the face of nature is
beginning to change.

The Armadillo, for instance, which comes next to the ant-eater, looks
far more like the tortoise or lizard than its noble mammalian brethren.
It is covered with scales; and, to look at it, you would say it was
a reptile, in spite of its higher internal organization. As for teeth,
it has certainly enough of them to give the lie to its name of
_edentata;_ but they are not very serviceable ones. They are called
molars, however, because they are situated in that part of the mouth
which is always assigned to molars; but they are miserable grindstones,
very unlike any of which we have hitherto treated. They are all of them
flattened cylinders, with no enamel bars to strengthen them; are small
and poor, and are placed at rather wide intervals from one another. The
poor armadillo munches with these, as best he can, slugs, tender roots,
and other prey of the same sort, with which he is obliged to content
himself, and which do not require very formidable tools.

The most questionable member of this class is the Unau, or Two-toed
Sloth. It only wants incisors to be as toothless as ourselves! and the
first time I saw it I took it for a little bear. It is true I was then
younger than you are now; for the bear, who is one of our nearest
neighbors, ought not to have been confounded with the unhappy being
before us, one of the drudges of the animal creation; though M. de
Blainville (who had not my excuse) proposed placing it still nearer
to us, namely, amongst the _Quadrumana_. Observe that instead of hands
it has at the end of its fore-limbs only two enormously curved claws,
which have somewhat the appearance of a gigantic fork accidentally
twisted. Accordingly its illustrious sponsor offered it to the world as
an _irregular quadrumane_. I believe so, indeed! This _quadrumane_
without hands--this _edentate_ whose molars are preceded by magnificent
canines--this enigma of nature, created for the confusion and despair of
all classification--does, I must in all humility confess, completely
upset the rule I laid down so stringently when speaking of the horse, as
to the objects for which canine teeth were framed. The canine teeth of
the sloth are more developed than its molars, and yet I cannot tell you
what they are there for at all. It feeds upon the leaves of trees; and
old travellers in South America, where it inhabits, have told us that,
when it has once hoisted itself up a tree, it will strip it to its last
leaf, and afterwards drop to the ground to avoid the trouble of crawling
down. This was what first obtained for it the villanous name of sloth, a
title which is certainly justified by its gait when on the ground; for
it is so ill-made that it cannot stand upright on its legs, but moves
clumsily forward by dragging itself on its elbows. It seems, however,
that when once in a tree it is a different creature altogether, and
can scramble lightly from branch to branch. Moreover, if its claws
cannot reasonably be reckoned as hands, they are at all events excellent
hooks; and when it is springing about thus in the forest, suspended
to the branches by its long arms, one might be tempted, while watching
it from below, to decide in favor of M. de Blainville's opinion. I saw
it originally myself in a cage.

As to the sloth's relationship to the armadillo, this rests upon a
detail which bears directly upon our subject. The molars in both animals
are cylindrical and smooth, this is a trifle, but what would you have?
The animal had to be classed somehow; since naturalists have not had
the wit to make detached companies, as they do in regiments of soldiers.
ORDER 11. _Amphibia (two-lived)_.

We are going farther and farther away. Here are animals who are nearly
half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have
two lives: one in the water, which is their true life, and where they
are in their element; the other upon land, where they can only crawl;
for their paws, which are but half developed, are destined to perform
the office of fins, and the hinder ones are extended flatly behind them,
and act like a fish's tail. They are divided into two families, the seal
and the walrus. The first feed on fish, and have the same internal
organization as the _Carnivora_, as well as the same dental
conformation. Some species have even exactly thirty-two teeth, as we
have. The jaw of the walrus is the least regular, and the incisors are
generally wanting, especially in the full-grown animal; for it appears
they lose them very young, as you lost your milk teeth, only, unluckily
for the walrus, his never grow again. On the other hand, he has two
canines in his upper jaw, which, next to the elephant's tusks, are the
largest we have yet met with. They are sometimes as much as two feet
long, and incline downwards with a curve, like the two bars of a
pick-axe. They would play the walrus the same trick that the incisors of
rodents are apt to do when they have not work enough to wear them down;
that is, stop up the entrance of its mouth, were it not that the lower
jaw is contracted in front, in order to fit into the space between the
two canines, which thus form a sort of passage in which it manoeuvres
freely. As you may suppose, the walrus cannot insert prey of any great
size into this contracted passage; but that is no matter, as he lives
partly on seaweeds, and partly--indeed principally--on shell-fish; his
molars being specially adapted for breaking shells. They are short
massive cylinders--the upper ones fitting into the lower as a pestle
into a mortar.

After the walrus comes a strange animal which has been ranked among
Cetaceans (we shall see why presently), but which it would be better
not to separate from the Amphibians, since an Amphibian order has been
made, for it crawls from time to time upon land: this is the Manatee,
or Sea-cow. It comes still nearer a fish than the others. Its forelimbs
are absolute fins, with mere vestiges of nails at their edges; it has
no hind ones, and its body, which is quite cylindrical, ends in a fin
tail in the shape of a shovel. The sea-cow feeds on plants and herbage,
and lives at the mouths of great rivers, going up them occasionally
to great distances, their banks serving it for pasture ground. In some
respects it is half brother to the hippopotamus and the great grass
eating _Pachydermata_, to whom it comes so near in internal
organization, and above all in the structure of its molars, that M.
de Blainville seriously proposed ranking it among the elephants, though
as an _irregular elephant_, as you may suppose. But then Cuvier
had even placed the seal among the _Carnivora_, by the side of
the cat, whose whiskers it possessed, and of the dog, whom it resembled
in the formation of its head. A naturalist's office is sometimes very
perplexing, I assure you; and as we are touching on this subject, I
cannot resist telling you that the sea-cow laid claim to, on so many
sides, had by right a free admission to the celebrated order of
_Primates_, although it looks exactly like a large barrel elongated
at the two ends. It suckles its young at the breast like man and the
monkey; and if Linnæus flinched from this rather too absurd parentage,
old navigators were less scrupulous. Observing this creature in the
distance, sporting on the waves, the upper part of its body quite out
of the sea, the sailors, whose eye is not of the most refined, and who
have no objections generally to the marvellous, imagined they saw a
new species of human beings; and hence arose those stories of mermaids
and sirens which have been told from the days of Homer downwards, and
the traditions of which have not yet quite died out in seaport towns.
To have been passed from man to the whale, touching the elephant on
the road, is a long way to travel, especially when, after all, one is
only a huge barrel of amphibious fat; and you may judge from this that
it is not always an easy thing to classify animals.

ORDER 12. _Cetacea (whale-kind)_.

Cetaceans are whales; and if I had been consulted on the matter, I
should have joined this order and the last together, under whatever
name was thought most appropriate. The passage from the seal to the
whale through the walrus and the sea-cow is an easy and natural one,
the two latter being obviously the connecting links; and in spite of
certain diversities of food, they form in reality one family-party,
as do the marsupials.

But it is too late in the day to talk of this, my dear child, and you
and I cannot pretend to alter what is taught in the schools.

But you are astonished, are you not? to hear that the whale is not a
fish: and no wonder. It is with it, however, as with the armadillo;
it is a fish with a higher organisation inside. The interior of this
enormous mass is a faithful reproduction, as a whole, of that of the
shrew-mouse; and when we come to talk of fishes you will have some
faint idea of the prodigious distance which this places between the
whale and his countrymen of the ocean.

As far as we are concerned, the chief difference is in their way of
breathing. The cetaceans breathe like ourselves, and are obliged to
come to the surface of the water to take air; while fishes have a
special apparatus, which I will explain to you presently, which enables
them to breathe in the water. This is a disadvantage to the cetacean
in his fish life; nevertheless, of all the mammals (as may easily be
imagined) he is the one who can remain longest under the water. With
us, for instance, the best divers one ever heard of, those who go to
the bottom of the sea after the pearl-oyster, can scarcely stay below
longer than two minutes; and even during that short time the veins of
the head become so overcharged with the blood, which cannot return to
the lungs owing to its forced inactivity, that when the diver comes
back to the surface it is by no means unusual to see him streaming
with blood from both nose and ears. The cetaceans remain under water
for half an hour at a time without seeming to suffer in the least; and
Breschet, a clever French naturalist, has given a very satisfactory
explanation of this wonderful faculty. In dissecting a cetacean, he
discovered all along the vertebral column an extensive network of large
veins, which are not found in other mammals, and which seemed designed
to serve as a refuge place for the blood during the time the animal
remains submerged. According to him, this network would act as a
reservoir, to which any overplus in the head or important organs would
flow through vessels communicating therewith, and which might swell
out as it pleased, without any risk to the inert bed of fat against
which it lies. From thence the blood rushes to the lungs, as soon as
the animal's return to the air enables them to play as usual. It must
be admitted, at the same time, that all this involves the necessity
of a much less active life than that of land mammals, that is to say,
a consumption of oxygen much smaller in proportion than theirs; for
were you to be furnished down your back with the finest network
reservoir in the world for venous blood, it would still not enable you
to remain half an hour without breathing.

There is nothing remarkable in the digestive apparatus of the cetaceans
except about the mouth, which is, as you know, the essentially variable
point among animals. To begin with, the cetacean tongue has the most
original appearance possible. Indeed, it is not a tongue, but a large
carpet, spread over the floor of the animal's mouth, and bears not the
faintest trace of resemblance to that nimble delicate porter, who does
you such good service. Imagine a thick soft lump absolutely crammed
with fat, and completely immovable, because it is glued down along its
whole length to the bottom of the mouth, and you will have a good idea
of this strange tongue, which in the whale, the largest of the
cetaceans, attains to the length of twenty-five feet and the width of
twelve, and of itself alone furnishes the whale-fishers with from five
to six tons of oil. This is a great deal farther from us than even the
long string which serves as a tongue to the ant-eater; and you feel
at once that we are getting among strangers.

With respect to teeth, I have now a melancholy piece of news to tell
you. We have done with them; we have seen the last of incisors, canines,
and molars, henceforth you will hear no more about those valuable
instruments. The teeth of the cetaceans, with whom this painful
falling-off begins, are no more teeth than his tongue is a tongue.
They are like so many nails set in a row in the jaw, and can only be
of use in retaining prey, not in grinding it; so that of the many
processes your bit of bread has to go through before it becomes a part
of yourself, there is one which is dispensed with here altogether,
namely, mastication. Cetaceans swallow their food without chewing it.

Besides, they have not got a whole set even of these unmasticating
teeth. Dolphins and porpoises, those faithful companions of the sailor,
around whose vessel they come playing and tumbling in the seas of all
countries, are the only ones who have them in both jaws. And these are
the small fry of the order; they do not usually exceed six or ten feet
in length.

The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals
the true whale in size, and whose head alone forms nearly the half of
its body, has teeth in the lower jaw only. This lower jaw, whose two
sides are joined together for half their length (a new deviation, very
unlike anything we have found before), is so little proportioned to
the gigantic head which contains it, that it is almost lost to sight,
and seems like a small plank slipped under a great square block.

Such as it is, however, it possesses many very respectable teeth, of
which some weigh as much as two pounds; and with these the cachalot,
whose ferocity is tremendous, tears in pieces everything that comes
near it, sometimes even the boats of the fishermen who risk their lives
in the dangerous pursuit of capturing them. By a singular arrangement,
of which this is the only known instance, there is, opposite each of
the cachalot's teeth, a corresponding cavity in the upper jaw, into
which they fit closely, turning the monster's muzzle into the most
formidable pair of pincers to be found in the animal kingdom. Another
curiosity in the order is the tooth of the Narwhal, a modest cetacean,
who is not much more than twenty feet long!

I speak of _the tooth_, because the creature has commonly but
one; a cylindrical-pointed tooth, spirally furrowed, whose length
varies from six to ten feet, and which comes straight out from the
extreme front of the upper jaw, like a soldier's pike. There are two
sockets at this extremity of the jaw, each furnished with a tooth-germ;
but as a general rule the germ on the left side is the only one which
develops, the other lying asleep in its socket, where it is choked up
and never appears. Behind this long pike, which, like the tusk of the
elephant, attracts to itself all the ivory in the body, lies a
completely unfurnished mouth; so that the owner of this magnificent
weapon, invaluable as a war-tool, but quite inapplicable to the purpose
of supporting life, is obliged to feed on small fishes and
_mollusks_. We have not yet spoken about these latter, but if you
have ever seen slugs and snails you will know what a _mollusk_ is.

The same wretched food falls to the lot of the whale also, that giant
of the ocean, whose open mouth forms an aperture twenty feet in extent.
Geoffroy St. Hilaire, in his indefatigable endeavors to trace out
points of resemblance connecting together animals the most unlike in
outward appearance, discovered, along the lower jaw of a young whale,
certain traces of teeth, indicating a last effort on the part of nature
to carry out her usual plan in furnishing the jaws of mammals; but,
like the right-hand tooth of the narwhal, these vain attempts soon
disappear, overgrown and lost in the tissue of the bone, so that the
whale offers us a true type of an _edentate_, classable with the
ant-eater, if one dared, and some people have dared, which by this
time will not surprise you. A classifying professor is utterly
merciless, whether he gets hold of the poor beasts by the mouth or by
the paw: they may protest with all the rest of their body against the
peg on which they are hung; so much the worse for them! If one were
to listen to what they have all got to say, it would be impossible to
classify even one.

To return to the whale. As a compensation for the teeth which she found
herself unable to give him, nature has manufactured on the two sides
of his upper jaw the most extraordinary apparatus without exception
to be found in the mammal mouth. You know what is called the
_whalebone_ used in stay-making, &c. The name is quite correct;
for those little flexible black strips, which support the figure so
nicely, began life in wandering over the polar or Australasian seas,
fastened to the palate of some monstrous whale.

On the two sides of the upper jaw the membrane which covers the palate
sends out rows of broad, thin, horny plates, which are from eight to
ten feet long (they have sometimes been seen twenty-five feet) in the
centre of each side, but which decrease gradually towards the
extremities. These are plates of whalebone (sometimes called whale's
whiskers), and the industry of man has turned them to a thousand
different uses; and you will open your eyes in astonishment when I
tell you that 800 or 900 of them have been sometimes counted on each
side of one mouth. Think of the number of stays that could be furnished
from the whalebone plates of one whale! It is true, they were not
exactly designed for this purpose originally. At the tips and on the
edges of these plates, the elastic fibres of which they are composed
unravel and peel off, and hang down from the lip like tufts of
horsehair. The Arctic seas, which the whale inhabits, are, like other
seas, full of innumerable troops of various little sea-animals, and
it is these which are destined to the honor of nourishing this gigantic
mass of flesh. When the colossus wishes to take a meal, he stretches
his mouth to its utmost width, and the salt water rushing in as into
a gulf, carries with it the imprudent little fry, who disappear then
and there for ever, being retained by the fringe-like sieve of the
whalebone. But as, in this way of eating, the stomach of the whale,
however large, would be terribly overgorged with water, he is furnished
with another apparatus for preventing the inconvenience. All the
superfluous water is rejected by the _pharynx_, and springs up
in spouts of fifteen or twenty feet high, through the nostrils,
_i.e._ the nasal openings, sometimes called "vents," sometimes
"blow-holes," which are pierced exactly at the top of the head. This
is a peculiarity common to all cetaceans, who have thence received the
name of "blowers," alluding to the powerful blast which is necessary
to send those majestic columns of water into the air; but it takes a
much milder form with the lesser cetaceans, such as dolphins and
porpoises. There is but a slight jet with them: the water escapes
comparatively quite quietly from the nostril-vents, trickling away
down the animal's sides.

I hope you consider that I have told you something new this time, my
dear child, and that our machine is beginning to change its appearance
very materially. I told you before that we had reached the outskirts
of the mammal kingdom. When we got to the armadillo we were within a
stone's throw of the reptiles, and here, one step more would take us
to the fishes. But we must first consider the birds, who are a very
superior set of animals to either of the latter; and we have accordingly
an order of mammals (Monotremes) which, as you will now find, opens
the road on that side also.

There are but two sorts, and both of them are natives of Australia,
which is, as you may have heard, the land of the wonderful in natural
history, and their existence was unknown to the learned men of Europe
till within the last sixty years. The most extraordinary of the two
is the _Ornithorhynchus_, or, to translate the hard Greek word
into English, the _Duck-bill_. Its mouth is a true duck's bill,
a downright horny beak, and its short paws sprawling sideways with a
membrane joining the toes together below, and coming a good deal beyond
them in front, seem intermediate between the flippers of the seal and
the webbed feet of a water-bird. The first naturalist who had anything
to do with the ornithorhynchus, Blumenbach the German, who gave it its
pretty name, did not think it was able to suckle its young, so much
did it differ from mammals in some respects, though looking so like
them on the whole. And presently a report arose in the learned world
that the new animal which had been classed at all risks among mammals
(it having the close fur and almost the body of the otter), a report
arose, I say, that this ornithorhynchus of Blumenbach laid eggs like
a real duck. The uproar in the Academies was tremendous. As early as
1829, indeed, a learned Englishman, Sir Everard Home had sent over to
France an authenticated drawing, as he said, of an ornithorhynchian
egg, to the delight of the hunters after analogies among animal races;
while Cuvier looked sadly askance at the intruder, whose arrival threw
his animal outlines into confusion, there being no place in them for
such a beast. Happily for the poor animal, he has ended by almost
settling the matter for himself. The ornithorhynchian egg has never
turned up. But in the animal's nest have been found baby
ornithorhynchuses, newly born, under two inches long (the full-grown
animal being more than a foot and a half), and not a trace of eggshells
near. Further investigations showed that the mother ornithorhynchus
nursed her young with milk, for curdled milk was found in their
stomachs; so the Australian phenomenon has been restored triumphantly
to the Mammalian order, whence Geoffroy St. Hilaire had excluded both
it and its companion, the _echidna_, a sort of hedgehog, provided
like the ornithorhynchus with a bird-like bill, only more of the
canary-bird sort; and like it, also, approximating to the bird tribe
by other details which do not belong to our subject. And so the matter
stands at present; and all we venture to say is that classification
had a very lucky escape.

And now, my dear child, that I have made you acquainted in detail with
your nearest neighbors, the last of whom, nevertheless, are strangely
unlike you outside, however they may resemble you within, I shall take
the liberty of going more quickly over the ground, and shall point out
in the mass only the more important changes which lead from one class
of animals to another. I should be found fault with if I tried to make
you too learned, and you yourself might be tempted to tell me, to my
sorrow, that you had heard about enough.



LETTER XXXIV.

AVES. (_Birds._)

Tell me, my dear child, when you have seen birds taking their flight
into the air, and going boldly to their object, without a thought of
all the barriers, ditches, rivers, and mountains, which hinder man at
every step in his travels, did it never strike you to wish for their
wings, and imagine how you would fly off if you had them? If you ever
dreamt this dream, do not apologise for it; it is one as old as the
world. 'Oh that I had wings like a dove!' cried the Prophet, nearly
3,000 years ago; and the dialogue of the swallow and the prisoner, so
often sung by poets, has been repeated in prose behind all the
prison-bars on the globe since prisons were first invented.

Now you will not think it kind on my part, but I must undeceive you
about this fancy, as you will be undeceived some day about many others.
The wings of a dove or swallow would be of no use to you if you had
them, any more than the formidable swords of the middle ages would be
to our modern gentlemen, were any one to put such into their hands.
We are not adapted for them, nor they for us.

You saw, some time ago, what an amount of muscular exertion was required
for running--what a violent flow of blood, what hurried play of the
lungs. Now in flying it is still worse; for the earth, at any rate,
holds us up quite naturally, whereas the air will not hold up the bird
unless it is beaten vigorously and unremittingly by an untiring wing.
If we men, constructed as we are, had to do such work, we should be
out of breath at once; the heart would cry out immediately for quarter,
and the diaphragm turn red with anger. And only just imagine in what
a critical position a poor wretch launched into the air on the wings
of a swallow would find himself when, at the end of five minutes, his
servants should refuse point-blank to go on working at a height of 500
feet above the ground!

But a bird has not these internal rebellions to fear. In the first
place, it has no diaphragm; so here is another friend to whom we must
say good-bye. We shall not meet with him again anywhere. The journey
we are taking together, my dear, is somewhat like the journey of life.
One sets off, surrounded by friends and acquaintances, but whoever
travels on to the end is apt to find himself alone at last; this is
what is happening to the digestive tube, which we shall see losing all
its accessories, one by one, as we gradually advance in our study.
Even now here is one essential fundamental difference in the internal
machinery. The body has only one compartment instead of two; and the
lungs, masters of the whole space, extend freely to its utmost depths.
When a fowl is cut up at table, look along the body, and you will find
lodged in the cavity of the ribs, a long, blackish, and spongy mass:
this is the lungs. There is not, therefore, the same danger of a bird's
getting out of breath as with us; that delicate board which is found
in our bellows is wanting in his. His is set in action solely by the
to-and-fro movement of the ribs, which is produced by muscular
exertions, which are greatly increased during the action of the wings.
From which it follows, that the rapidity of flight itself regulates
the arrival of air, and consequently the expenditure of strength, or,
if you like better, the activity of the fire, since the energy of the
muscles depends, as we have seen, upon the quantity of oxygen that
feeds the internal stove.

This is not all. These elongated lungs are still not sufficient to
furnish the blood with all the oxygen demanded by this excessive labor
of flight. They are pierced with holes, through which issue pipes which
carry the air all over the body. You know what is said of
spendthrifts?-that they burn the candle at both ends. It is so with
the blood of birds. That fillip which in our case it receives in the
lungs, and which sends it back full of vigor into the arteries, is
repeated in the bird at the other end of the arteries as well. The
capillaries, those delicate vessels at the end of the arteries, plunge
from all sides into little reservoirs of air-lungs, therefore-where
the blood renews its provision of oxygen, and relights its
half-extinguished fire, so that it sends the combustion afresh into
the muscles on its return back to the heart, and sets them going a
second time.

The natural consequence of this prodigality of combustion is, that
there must be, in proportion, much more oxygen in birds than in us;
and that of all animals a bird is the one most quickly poisoned by his
own carbonic acid when the air is not renewed around him. Therefore,
let me beg you never to think of putting a poor little bird under a
wine-glass, as a child of my acquaintance once did, that she might
examine her little friend more closely. In the twinkling of an eye he
would consume all the oxygen inside his prison, and you would soon see
him fall upon his side and die.

On the other hand, the temperature of these flying machines, which
consume so much oxygen, is very much higher than ours. It rises to
41°, 42° (centigrade), and sometimes to 44°, 7° higher than with us.
If ever you have taken hold of a little bird, you will have remarked
how warm it makes your hand: this is quite natural, since there is
always a double fire going on within him, to meet the extraordinary
expenditure of strength that is required of him whenever he takes wing.
Besides, do but look at the poor little creature when you have
imprisoned it in a cage! How it goes up! How it comes down! How it
hops from one perch to another, with a quick sudden movement, like
that of a spring when it unbends. There is no apparent cause for this
state of continual agitation; and yet there is a cause, and only too
serious a one. Its fire is not slackened because you have put it into
a cage, and its muscles, lashed furiously on by the double-oxygenized
blood, drive it hap-hazard into a thousand movements, in which it
expends, as best it can, a superabundance of power, which no longer
finds natural employment. Little children, who are the real
singing-birds of our homes, and whose blood also drives much more
energetically along than ours--little children I say--often fare no
better than caged birds in those larger cages we call schools; and
schoolmasters and governesses would scold rather less if they thought
rather more about this. It is right, I do not deny it, that the
rebellious young rogues should be taught in good time not to abandon
themselves, like wild birds, to the mere animal impulses of the blood:
but, in dealing with them, one must also make allowances, as they say,
for the fire within, and know how to open the cage now and then. It
is not for you, however, that I say this, young lady: you are no longer
a little child; but it may happen that you may have some to take care
of some day. Believe me, then, you must not expect too much wisdom
from them, and you must allow them to change their perch every now and
then. It is a law of our Almighty Father that little children, and
little birds, should not stay too long in one place.

The mechanism of the circulation is here the same as with us, and does
not offer any important peculiarity. Only the left ventricle of the
heart has walls of extreme thickness, which enable it to launch the
blood into the members with greater vigor and rapidity; and the blood
itself, although it is composed of precisely the same materials as
that of the mammals, differs from it nevertheless as regards the
globules. In the first place, they are more numerous; secondly, they
are larger; and finally, instead of being round like a plate, they are
drawn out ovally, and are almost shaped like those long dishes on which
fish is usually served. I shall not attempt to give you the reason of
their size and form. This is hidden from us in the same mystery which
envelopes all the microscopic population of the blood; but is it not
a curious thing, this strange persistency of form in the globules ofall
animals of one class? In all birds they are oval; in all mammals
they are round. In all? Nay, I am wrong. As if the better to hide from
us the key to this riddle, nature has amused herself by making an
exception. Camels and llamas, I forgot to tell you, have also globules
in the form of long dishes, like the hen and the chaffinch. Find out
why, if you can. As to the reason of the number, it is a very simple
one. Since the energy of the blood resides in the globules, it follows
that the most energetic blood will contain the largest amount of
globules. Looking at you, for instance, little monkey, running and
jumping about the garden, I would lay a wager, without counting first,
that there are, in one drop of your blood, some millions more globules
than in one of mine.

Let us now go on to the digestion, with which, properly, we ought to
have begun; but I preferred pointing out to you, first, the particular
character which is the chief mark of distinction in the organization
of the bird.

'When hens grow teeth,' says a shrewd proverb, meaning of course,
_never_. Birds have no teeth, and in this respect there is no
variety among them. All, from the first to the last, have uniformly
the same tool to eat with--the bill, that is--which is, in all cases,
composed of the same elements, two jawbones elongated to a point, and
clothed in a horny armour, which makes their edges sharp and cutting.
At the same time were we to review the birds in detail, as we have
done the mammals, you would see that there are almost more modifications
to be observed in this one single instrument than in our thirty-two
teeth. All birds have a beak, but each has his own, organized expressly
with reference to the kind of food needed by its owner. The eagle's
beak, which mangles living prey, is pointed, bent, and hard as steel;
the bill of the duck, which laps up water from ponds and puddles, in
order to get worms and half-decomposed refuse out of it, is soft, and
flattened like a shovel. The woodpecker's, which has to pierce the
trunks of trees, is like a pickaxe; that of the humming-bird, which
has to suck up the juice of flowers from the bottom of their corollas,
is slender as a needle. The swallow feeds on flies, which it snaps up
on the wing, and has a soft bill, which opens like a little oven. The
stork picks up reptiles in the mud of the marshes; its beak is
straight-pointed, cutting as a knife, and resembles a long pair of
pincers. The sparrow feeds especially on hard grains, difficult to
break; accordingly its beak is stumpy, short, and thick, and is arched
on the upper side for still further solidity. But I should never end
if I began to enumerate all the thousand varieties in the bills of
birds. Each variety, too, corresponds with some peculiar sort of life,
and consequently with a general conformation (easily ascertained) of
the animal in which it appears. Give a naturalist the bill of a
bird--only its bill remember--and he will tell you half its history
without fear of being mistaken.

On the other hand, we must not deceive ourselves as to the real value
of this complaisant bill. Let it transform itself as it pleases into
all manner of forms for the better fulfilment of its task, it makes,
at the best, but a very poor instrument for mastication; nay, to say
the truth, it breaks, cuts, and tears, but it never masticates at all.
Thus the bird's mouthful is far from undergoing as perfect a preparation
as ours does. It is no sooner taken in than it is swallowed, and the
salivary glands, which are still to be found under the tongue, seem
only to be there as a matter of form; what little saliva they produce
is thick and sticky, and has none of the qualities necessary for making
that liquid paste which our tongue sweeps up from every corner of the
mouth. Besides, it must be owned that a bird's tongue would be a very
awkward implement in such a task. Open a hen's bill and you will see
therein a very inferior sort of porter. It is merely a dry hard lance,
as it were, armed with prickles at the point, as ill-qualified for
tasting as for sweeping. So the hen does not waste her time in finding
out the flavor of what is thrown to her. She picks up and swallows
over and over again, without appearing to experience any other pleasure
than that of satisfying her appetite. Birds of prey, it is true, have
rather more convenient tongues, capable, moreover, of tasting up to
a certain point; and the parrot, who is a complete epicure, and chews
his food philosophically, has a charming-little black one, thick,
fleshy, and susceptible--a true porter, in fact-who enables Polly
thoroughly to enjoy her breakfast. But certain birds who live on insects
surpass even the hen in the dryness and hardness of their tongues.
That of the woodpecker, especially, is a model of the kind, and deserves
a few words more than the others. Picture to yourselves a long pin,
terminated by an iron point with barbs like those of fish-hooks. An
ingenious mechanism enables the bird to dart it out with the rapidity
of lightning, far beyond his bill, upon the insects to which he gives
chase. The point pierces them, and the hooks retain them, without any
need of assistance from the bill. I have just told you that this bill
pierces the bark of trees; but it only plays the part of gamekeepers
on grand sporting occasions, who beat the bushes to make the game rise.
The woodpecker's bill routs up the insects by destroying their shelter;
but the real sportsman is the tongue. Good-bye to any notion of a cosy
little chat in such a porter's lodge as that! What could a harpoon
have to say for itself?

Do not, however, let this miserable entrance-hall alarm you, at the
same time, for the fate of the mouthful thus presented half-dressed
to the œsophagus. You will find it only so much the better treated
within. In the first place, the œsophagus, when half-way down to the
stomach, swells out suddenly and forms a pocket, which is generally
particularly well developed in birds who feed on grain; this is called
the _crop_ in English, in French _jabot_; whence comes the application
of that word to those full shirt-frills which have sometimes been the
fashion. It is the pigeon's _crop_ that gives him the rounded chest over
which he bridles so prettily. The crop is a receptacle where the food
makes a halt: it is something between the pouch of the monkey and the
paunch of the ox; a preparatory stomach, which does not, it is true,
send back the grain to the bill, for the bill could do it no good, but
in which that grain lies until there is room for it further on.

Prom thence it resumes its journey; but, before reaching the true
stomach, it passes through a second enlargement of the oesophagus,
whose walls are pitted with numberless little cavities, from which
pour over it the juices destined to supply the place of the saliva
that was wanting above.

It reaches its destination at last, but still hard, and generally
whole. No matter, however. The stomach which receives it, and which
is called the gizzard, is quite a different sort of thing from a useless
membrane, thin and delicate like ours. It is a thick muscle of enormous
power, lined inside with a kind of horny skin, so tough that nothing
can break through it. You may form some idea of the prodigious strength
of this organ, when I tell you that turkey-fowls have been made to
swallow hollow balls of glass, so thick as not to break when dropped
to the ground, and that at the end of a few days they have been found
reduced almost to powder in the uninjured stomach. No fear of
indigestion with such an apparatus as that. Though the grain may not
have been masticated in the bill, what does it signify? There is a
power here, as you see, quite equal to carrying the whole work through.
Thanks, indeed, to the invaluable horn which lines it, fowls which
have no teeth of their own can safely present themselves with as many
and as hard ones as they please. They swallow small pebbles, which rub
against the grain, during the contractions of the gizzard, and act
just as effectually as if they were fixed in the jawbone. Well, this
terrible gizzard performs its crushing work with such energy, that not
only the grain but the pebbles themselves are ground down there, and
end by being pounded into fine sand. When you rear fowls, do not forget,
if you keep them shut up, to put within their reach a store of small
pebbles, so that they may have teeth to run to in time of need.

You remember the _pylorus_--the porter down below, who keeps the
door of egress from our stomach? He is as badly provided for here as
his fellow-workmen up above; worse in fact. It is a gaping hole, and
we cannot expect a very strict supervision from it. Birds who feed on
fruits profit by this fact to carry vegetables from one country to
another. With such an easy opening, seeds have a good many chances of
passing from the stomach unaltered; and then they drop from the clouds,
as is supposed, hap-hazard, and germinate afterwards, when circumstances
prove favorable, to grow up before the astonished eyes of the natives
into plants of which they have never even heard. The French
Acclimatization Society, which I spoke of lately, and which, though
so modern, has correspondents all over the globe, is at this moment
laboring to effect an exchange between all countries of the natural
productions of their soil. But here you see that nature had thought
of this before, and established her acclimatization society long ago.

To complete the internal work of digestion, so feebly begun in the
bill, an extremely large liver pours torrents of bile into the duodenum,
and the manufacture of chyle proceeds with that wild rapidity which
characterizes all the living actions of birds. But speaking of this
liver, I think I ought to give you an account of a celebrated dish,
considered a great dainty by epicures, called _pâtés de foies
gras_--_fat liver patties_, to translate it into its meaning.
Very likely you will not care to eat them after hearing my story; but
that will be no great loss to you, for it is a very indigestible sort
of food, and not at all good for children.

You remember my telling you about Englishmen going to India and coming
back with a liver-complaint, from having eaten and drunk more than the
climate allowed? By an imitation of this process, human
ingenuity--occasionally so cruel--has created the _pâtés de foies
gras_, the glory of Strasburg. I have been in the country, and can
tell you how it is managed. They shut a goose up in a square box, where
there is just room for his body. They open his bill at feeding-time,
and cram down with the finger as much food as can be got in. This is
throttling rather than feeding it. The poor beast, who can use no
resistance, since it cannot move, and who is kept in the dark to prevent
excitement; the poor beast is quite unable to burn all the mass of
combustibles with which the blood soon finds itself loaded. This carries
them to the liver to be turned into bile; but the liver is not equal
to the work, becomes loaded in its turn by unemployed materials, and
grows and grows, till at last, having filled up all the space around
it, it stops the play of the heart and lungs. When the animal is
nearly suffocated they kill it; and this is how we come to have _pâtés
de foies gras_ to eat! If they give us a fit of indigestion
afterwards, it is a vengeance we richly deserve. At Toulouse, where
the same trade is carried on on a large scale, they used formerly to
go even beyond this. They fastened the goose by the feet before the
fire-place, after having put out its eyes. The imitation of the
Englishman's proceeding was still more perfect here, for the fire acted
the part of the Indian sun to perfection. I do not know that part of
the country well enough to tell you whether they have quite given up
this piece of wicked ingenuity; all I can say is, I devoutly hope so.

The intestine of birds is much shorter than that of mammals. Here
everything is done at full gallop, and the chyle has not to go far
before it is absorbed. I have before me a book, in which I am told
that the wagtails eaten in France can be fattened in twenty-four hours,
if you only know how to set about it, and these birds are not rare;
they belong to the same family as the red-breasts, the tomtits, and
the nightingale. Thrushes and wheatears (ortolans) require, for the
same purpose, four or five days in the same country, left to themselves
to roam about, when the vine keeps open table for them.

This incredible quickness, not only in digesting, but, what is much
more, in transforming food into fresh living material
(_assimilating_ it, as it is called), has often a fatal result
for the bird. He is prohibited from fasting; his life is a fire of
straw, which must be replenished unceasingly, or it will die out in
the twinkling of an eye. Our own little birds--children--eat oftener
than grown-up people, and if by any accident they are kept waiting
awhile, they soon cry out with hunger. You know this, do you not? Well,
then, if any one should give you a bird to keep in a cage, remember
that you have undertaken a great responsibility, and that it will not
do to be careless with him. To neglect feeding him for one day is to
run the risk of finding him starved to death next morning. With this
warning, I will conclude my chapter on birds. I hope I have not spoken
in vain in behalf of those poor little captive songsters, whose fragile
lives are at the mercy of their young masters and mistresses.



LETTER XXXV.

REPTILIA. (_Reptiles_.)

Passing from birds to reptiles is like falling from a torrent into
still water. Life drags on as sluggishly with the second as it dashes
furiously forward with the first.

I spoke to you just now about a fire of straw: now we have a fire such
as Frenchwomen make in their _chaufferettes_, or foot-stoves. A
handful of charcoal-dust, and a few live embers between two layers of
ashes, is enough for the whole day; which is economical, is it not?
but then it throws out only just warmth enough to keep one's feet
comfortable. And so it is with reptiles. They live at very small
expense. If you feed them once a month they will not complain, for so
slow a fire does not often need replenishing with combustibles. It is
even said that the experiment has been carried so far with tortoises
that they have been made to fast for more than a year, and still the
charcoal fire kept up its languid pace. Of course, on the other hand,
there is not nearly so much oxygen consumed at once upon such a diet
as this. Where a bird would perish twenty times over in five minutes
for want of oxygen, a lizard can remain whole hours with impunity.
Moreover, the animal heat of reptiles is in proportion to their
expenditure of it. Graceful as is the snake (that living jewel so often
copied by bracelet-makers), you feel on touching it an instinctive
horror, caused by the thrill of cold it produces. All the animals we
have considered hitherto have warm blood, and bear within themselves
the source of their heat, which is pretty nearly always the same. But
reptiles are cold-blooded, and heat comes to them chiefly from without.

If, at the end of a cold winter, we go to some favorable corner to
catch the first rays of spring sunshine, we feel ourselves almost
re-born, as it were, as if a new life had come into us with the
sunbeams. Look at the little lizard you see frisking on the white
stones of the wall; upon him decidedly the sun is darting actual life
from its rays. While the cold lasted he staid squatting in his
hiding-place--not asleep, but annihilated--congealed, so to speak,
like water caught by the frost; no longer digesting, and hardly
breathing, he had ceased to live in reality: and it is no imaginary
regeneration which the return of warmth brings to him. Like those
helpless people who have not the power to carve out their own destinies,
reptiles have within them only an insufficient source of animation;
their life is at the mercy of the sun, and is high or low, according
as that rises or sets in the heavens. At Martinique, where at noonday
it darts its devouring rays perpendicularly upon the cane-fields, and
every one flies into the shade to escape its scorching heat, the
rattlesnake traverses the country, monarch of all he surveys; he strikes
rapidly with a vigorous tail upon the calcined ground; and woe then
to any one who receives his bite! All the fire of the atmosphere has
passed into his frame. Now go to the Zoological Gardens, and see him
there: he crawls languidly under the coverings that shelter him; if
by chance he bites any one, it is with an idle tooth that no longer
knows how to kill; his life was left behind with the sun of the tropics,
and it is little more than a corpse that you are looking at.

And so among ourselves, my dear child: we meet with people whose whole
power comes from without, who are brilliant and haughty in the sunshine
of good fortune, but crest-fallen, cowardly, and cringing in the cold
days of adversity. Nevertheless, they are constituted originally like
other people: they are neither greater fools as a general rule, nor
less gifted than their neighbors; where they fail is in the heart, but
that is enough to spoil everything. And so with reptiles: the heart
is their weak point also. Like us, they have lungs into which the air
pours without any difficulty, and a heart to send the blood to them;
so it seems at first sight as if there could be nothing to prevent
their resisting the changes of external temperature just as well as
ourselves. There is only one small trifle wanting, and that is a
partition in the middle of the heart; but this one defect is enough
to disorder the whole machinery.

You know that, with us, the heart is divided into two compartments:
the right ventricle, which receives the venous blood from the organs
and sends it to the lungs; the left ventricle, which receives it (now
become arterial) from the lungs and returns it to the organs. Hence
the double system of veins and arteries, the one going from the heart
to the lungs, the other from the heart to the organs. All this is found
the same in reptiles: except that the partition, which separates our
two ventricles from each other, does not exist in them; and the heart
has only one common room, in which, therefore, arterial and venous
blood become mixed together. It follows from this that, at each
contraction of the heart, it is a mixture of arterial and venous blood
which is sent in the two opposite directions at the same time, and
that the organs receive some which has been used before, while the
lungs have some returned to them which has been regenerated already.
Now, on the one hand, this mixed blood can only keep up an imperfect
combustion in the body (like the live embers between two layers of
ashes that we spoke of lately), and, on the other hand, the air in the
lungs can only act upon a part of the blood it meets with there, the
rest having already undergone the regenerating process. And this
accounts for both the feeble animal heat and the small consumption of
oxygen in reptiles.

Added to which the lungs of a reptile are coarsely constructed, and
composed of cells enormous in comparison with ours, so that the blood
does not find nearly as many little chambers to rush into for a taste
of air as with us. Moreover, you must understand that there is no such
thing as a diaphragm here: the lungs float loosely in the form of
elongated bags in the one only cavity of the body, and the slight
movement of the ribs does not allow them to dilate sufficiently to
take in much air at a time.

All these things, taken together, make the reptile a very poor stove,
and render him incapable of any prolonged exertion. The serpent darts
like an arrow upon his prey; but he could not pursue it for half a
mile without stopping, not even over the burning soil of the equator.
The lizard is very nimble, is it not? and the quickness of its movements
rather reminds one of the agility of a bird. But watch it, and you
will see it only moves in jerks, and keeps stopping every minute; it
cannot escape you if there is no hole near into which it can disappear.
In France there is a large green lizard that runs among the vine trees.
If you pursue him he is off like lightning for a second; then he stops
suddenly short. You return to the charge, and he starts afresh, but
only to stop again. At the fourth or fifth attack he is quite out of
breath; you poke him with the stick with which you have been hunting
him, but in vain; there he lies motionless, in spite of his alarm. A
few steps have brought him to the end of his powers, like a man whose
heart is diseased and who cannot go far. This, however, is a peculiarity
common to all reptiles. Each of the three orders of which this third
class of Vertebrata is composed has its own particular history besides.
You must excuse my mentioning the barbarous names that have been given
them, and allow me to call them _tortoises_, _lizards_, and _serpents_,
like other people. The hard names mean no more than these; but they are
Greek, which is always more imposing.

The slowness of the tortoise has passed into a proverb, which is not
to be wondered at; for they cannot inhale the air, because their ribs
(which are a reptile's only resource for breathing) are condemned to
absolute immobility. The _carapace_, or shell, which the tortoise
carries on his back, and under which it retreats upon the least alarm,
as under a shield, is really formed of its ribs, each of which has
widened itself so as to join on to its neighbor, like the boards of
an inlaid floor, which run one into another. Of course there is no
question of moving up and down with such ribs, and the poor bellows
cannot work at all. How does the tortoise get out of this difficulty
then, you will ask? I answer, it swallows air, as we should swallow
a glass of water. You see its mouth open and then shut again, thereby
taking in an actual mouthful of air, which the sides of the mouth, by
contracting themselves, send straight to the lungs. These, which are
very large, get filled in this way by degrees, and, when they are quite
inflated, they expel the overplus by collapsing, like an over-stretched
spring. You may imagine that this does not produce a very active
respiration, and that a tortoise would be puzzled to run at even a
moderate trot. To be sure, when he has once filled his great lungs
with air, he has enough for a long time. Most tortoises are aquatic,
and, as divers, leave the cetaceans far behind. Méry, an obscure French
naturalist of the days of the Empire, pretended that he had kept in
his house, _for a month_, some tortoises, whose breathing he had
completely stopped. Only imagine from this how far their life must be
below ours, although it is the result of similar actions, performed by
organs which after all are copies (imperfect ones, it is true) of our
own.

Some tortoises feed on vegetable substances, and some upon fish or
small soft-bodied animals. Like birds, they mash their food with
difficulty, by means of a real bill. Their jawbones are generally
arched forward toward the front, and are furnished with sharp horny
plates, in which a fairly-marked denticulation or notching may sometimes
be traced, as in the bills of birds of prey. Indeed there is one, the
_caretta_, whose hooked and notched beak so completely recalls
the warlike bill of a hawk, that it is usually known by the name of
the "Hawk's-bill Turtle." You ought to know about this tortoise, for
it is the one which furnishes tortoise-shell, that nice material which
is so smooth to the touch, so pretty to look at, and so very fragile,
that it seems only fit for the use of ladies' hands. I could hardly
speak of tortoises without saying something of this one, out of
whose back was carved the handle of your own pretty little penknife.

Behind this bill of the hawk's-bill there is a tongue, but of the
character of a whale's tongue, and it is fastened underneath to the
bottom of the mouth. At the base of it there is a sort of fleshy pad
or cushion, which serves instead of a soft palate, that being another
detail which is about to disappear from our history. We are now really
entering upon the simplification of the digestive tube, which will,
I forewarn you, end by being nothing more than a perfectly straight
pipe, without any appendages whatever. In tortoises the intestine is
still tolerably long, and is doubled up backwards and forwards many
times in the abdomen; but it is already beginning to lose that variety
of form which its different parts assumed in the higher animals. The
large intestine can no longer be clearly distinguished from the smaller
one, nor this from the stomach, which itself seems to be a continuation
of the oesophagus, without any very distinct boundary line between them.
The porter, who with us keeps the door of the stomach, does his duty
here so badly, that there are certain kinds of tortoises whose
oesophagus is covered with spines, the points inclined backward, to
prevent the food from rising up into the mouth whilst the oesophagus is
driving it down by its contractions.

In the gray lizards of our walls we find teeth again, but very different
from any that we have hitherto seen. In the first place, they are not
content with their usual place on the edge of the jaws, but encroach
upon the surface of the palate, where they stretch out in close lines.
Besides, they are even still less like teeth than the great nails in
the jaws of the cetaceans. They are little ivory prongs, with the
points turned inwards, analogous to the thorns of the oesophagus in the
tortoise, and serve the lizard solely to retain and bruise his prey.
He lives on insects, especially flies, which he seizes on the wing
with the greatest skill, hastily catching and engulphing them in his
open jaw; they pierce themselves on the little prongs, and are swallowed
promiscuously. The tongue of the lizard has also a curious peculiarity,
which is shared by that of the serpent: it is divided at the end into
two threads, which dart in and out of its mouth, and by means of which
it laps, like a dog, the few drops of water it requires to satisfy its
thirst. I have seen lizards which had been tamed by children greedily
sucking up the saliva from their lips by drawing across them those
little forked tongues of theirs, which, after all, are very soft, and
perfectly inoffensive.

The tongue of the chameleon, another species of lizard, is still more
curious. You must know that the chameleon is a lumbering lazy animal,
who feeds on flies and other swift insects, and who would, therefore,
be constantly liable to go without his dinner but that his tongue
serves him for a hunting weapon, like those of the wood-pecker and the
ant-eater. When at rest, it is an oval spongy mass, lying comfortably
in the mouth, with nothing formidable in its appearance; but let the
prey come frisking round the chameleon, as if despising so helpless
an enemy, and this great soft tongue is transformed into an active
dart. It shoots forth like an arrow, and will sometimes seize the rash
intruder at half a foot's distance, transferring it with equal rapidity
to the motionless mouth. The blow is so soon struck, that it is very
difficult to see how it all happens. Some say that the chameleon curves
the tip of his tongue by a sudden effort, and then catches his flies
with it, just as you would catch them with your hand. Others maintain
(and this is the general opinion) that the tongue of the chameleon is
terminated by a sort of sticky cushion, on which the flies are caught,
like birds with birdlime. This singular dart is always out-jerked with
such force that, if it strikes against a glass (the experiment has
been tried with chameleons in captivity), it makes a sound as loud as
that of a pea from a pea-shooter; so you may judge if it is not strong
enough to stun a fly. Besides this, too, the chameleon (who is
by-the-by, a hideous little beast) has given endless trouble to
naturalists on another and very different point. It is he who is
so celebrated for his faculty of changing color when any emotion
agitates him; and ever since the days of Aristotle, who lived more than
two thousand years ago, people have been trying to explain this, without
any one being able to flatter himself that he has found out the exact
answer to the riddle.

But there is a lizard more interesting still, and that is the crocodile.
He stands alone among reptiles. His heart has two ventricles, and you
would think that he ought to be included in the class of warm-blooded
animals. But, no. The separation of the two kinds of blood takes place
in the heart, it is true, and it is really true arterial blood which
the aorta carries away from the left ventricle. But the right ventricle
has two doors of exit. One communicates with the lungs, the other with
the aorta; and the latter has hardly performed its distribution in the
upper part of the body when it meets, as it descends, with a treacherous
tube bringing to it a current of venous blood. In this way only half
the blood that comes from the veins passes on to be regenerated by
contact with the air, and all the hinder part of the body receives
nothing but the mixed blood common to reptiles, while the head and
fore members enjoy the privilege of the superior orders. After this
go and lay down your laws of classification! Nature, while maintaining
amongst all animals the same principle of life--the regeneration of
the blood by oxygen--has in their construction followed many systems
leading to the same result by different combinations, and which seem
to permit the establishment of essential distinctions among them. Here
is an animal who, if I may so express myself, is climbing up from one
system to the other, and you would have to cut him in two before you
could classify him properly, since his fore-quarters have risen to the
warm-blooded animals, while his hind ones are left behind among the
cold-blooded reptiles!

But there is something which even outdoes this.

On dry land the crocodile is timid, faltering, a bad walker, incapable
of regular combat, and a man can manage him with a stick. One feels
that he is betrayed by the hinder half of his body, through which
circulates the only half-oxygenized blood. But when once he has plunged
into the water his whole behavior suddenly alters; he is a ferocious
being, high-mettled, indomitable, a savage enemy, redoubling his
exertions, as if the entire mass of his blood had suddenly become
arterial. Geoffroy St. Hilaire, who followed Bonaparte as a scientific
explorer when he set out for the conquest of Egypt, the country of
crocodiles, was deeply struck by studying on the spot this double life,
which seems in a way to maintain two beings in the same body. He
afterwards gave an extremely curious explanation of it in his work on
the crocodiles of Egypt. Here it is; but I forewarn you that you will
not understand it:

"The crocodile, when it is under water, receives by two canals into
the cavity of the abdomen, a considerable quantity of water, which the
animal can renew at will."

You are not much the wiser, are you? But wait a moment. We are soon
coming to the fishes, and you will then see what an unlimited scope
nature has allowed herself here. Not satisfied with two systems in one
animal, she appears to have got hold of three.

If we continue the examination of this privileged reptile, we shall
find many other infractions of the usual rules of his class. His tongue,
certainly, is fastened to his mouth like that of the tortoise, so much
so that the ancient Egyptians told the Greeks he had not got one; but
his set of teeth clearly approach those of the lower mammals. You have
probably heard a great deal of the strength of the crocodile's
formidable teeth. Travellers have given them this reputation; but we
have nothing to do with that now. They stand in battle array, in a
single line, along the whole length of the jaws, into which they are
sunk with genuine fangs, whilst the prongs of our little lizard are
merely fastened to the surface of the bones which support them. Indeed,
in one way, the crocodile is even better provided than the mammals.
He possesses under each tooth one or two germs, the life of which lasts
as long as that of the animal, and which are always there ready
toreplace the previous one should it chance to fall out. There are many
ladies, and (not to be rude) gentlemen as well, who would, I am sure,
give a great deal to have as many teeth at their service. Indeed, they
may possibly think Dame Nature very unjust to have selected this great
villanous beast rather than us as the object of a gift which they would
have been so well able to appreciate. But we must not blame nature too
quickly: she had her reasons. We, during our infancy, have teeth in
reserve. Now, a reptile may be considered as an imperfect rough draft
of a mammal; and the crocodile gives one thoroughly the idea of a
mammal half-finished and fixed for life in a state of childhood. I am
sorry that I cannot enter into full details, that you might see how
far the idea is a just one. Moreover, in his character of a perpetual
child, he is always growing bigger all his life long, and never seems
able to die but by accident, hardly ever, I may really say, from old
age. By specimens kept in captivity, it has been ascertained that
their growth is very slow. Well, imagine their being only from seven
to eight inches long when they come out of the shell, and that
full-grown crocodiles have been found thirty feet in length, and
calculate accordingly. You will not account for it under a century;
and I should like to know what would become of this venerable child
of more than a hundred years old if kind Mother Nature had not left
him our system of milk-teeth to the end?

A curious peculiarity of these persistent teeth is, that they are
hollow inside, so much so, that the bowls of tobacco-pipes are said
to be made from them in Europe. I mention the fact, although of no
great interest to you, for the benefit of any pipe-merchants who have
not yet thought of sending for such things to Cairo.

But let us return to the efforts perceptible in the organization of
the crocodile to raise itself to a higher level. The soft palate, as
we called it (Letter VII.), is wanting in other reptiles; but here
there is one which completely closes the entrance of the windpipe (the
larynx). I announced, too, the disappearance of the diaphragm; and we
bewailed together the loss of that servant of the good old times, whose
touching history you must, I am sure, remember. But I reckoned without
this wretched crocodile, who seems determined to give the lie to all
we have been saying. He has a diaphragm, and one which acts well enough
in the main, although it is pierced right through the middle, as if
it were rather ashamed of being there, and wished to make up for
dividing the body into two compartments, against all proper reptile
regulations, by opening a door of communication between them. What
shall I tell you besides? The lungs, not to be behind the rest of this
aristocratic reptile's organization, are hollowed into cells much more
complicated than those of his fellows. You find here no end of nooks
and corners, which multiply opportunities of contact between the air
and the blood, and so give the crocodile almost the respiration of the
mammals, as he has already got pretty nearly their system of
circulation.

With serpents, again, we fall very low. When we were speaking of the
tortoises I told you that, in proportion as we come down in the scale,
the digestive tube has a tendency to get rid of its accessories, and
to assume the appearance of a perfectly straight tube. If any one were
to cut open a serpent before you, you would see this final condition
almost reached already. In the first place, the soft palate is entirely
suppressed, and the mouth extends straight into the oesophagus, whose
tube seems to run through the whole length of the body without
interruption, with just four or five doublings towards the base, in
that part which represents the intestines. An imperceptible swelling
indicates the place where the real stomach lies within; but in another
sense one may call the oesophagus, and I might almost add the mouth
itself, its stomach. You shall see how.

The jaws of serpents are even in a more unfinished state than those
of other reptiles. Nature has not taken the time to weld the different
parts of them together; but these begin by not being very firmly joined,
remember, in young mammals. The bones of the head, which support the
jaws, are themselves movable, and can be detached from the skull if
necessary, so as to allow the throat to open extraordinarily wide;
thus it is not uncommon to see a serpent swallow animals much larger
than itself. You will be horrified when I tell you that the anaconda,
one of the giants of the family, swallows large quadrupeds at a single
mouthful. What are our mouthfuls in comparison with his? however, it
must be confessed, that his often take several days to go down. When
the animal has rolled up his prey in his terrible folds, he pounds and
kneads it till it is reduced to a kind of long roll, which he moistens
with a copious slaver to make it slip down more easily. Then, attacking
it at one end, he fastens this very expansive jaw upon it, and the
gigantic mouthful slowly begins its journey; what was left outside the
mouth, advancing little by little, in proportion as the digestion
reduces what has entered to pulp, and sends it farther down. This is
on great occasions; but in the case of more modest prey--a rabbit, for
instance--the mouthful goes in whole at one gulp and remains stationary,
partly in the oesophagus, partly in the stomach, while the powerful
juices distilled by the walls of the latter are dissolving it.

You can see that a soft palate would have been quite useless here, and
that the serpent has not much need of teeth to chew his food.
Accordingly, his are nothing but simple prongs, like those of the
lizard, and, like his, they extend over the palate, the more effectually
to cut off the return of the swallowed masses of food. About a hundred
and twenty have been counted in the throat of the boa-constrictor; but
their number varies considerably in the different species. They are
not organs of the highest order, and nature is not very particular
about the quantity.

There is only one tooth among serpents of which she takes any particular
care, and that is the venomous tooth which she has bestowed on certain
species, and which serves them for striking down, as it were, the
animals on which they feed. Let us study it in the rattlesnake, the
most celebrated of this odious race. On each side of the upper jaw you
may see, isolated from the others, and exceeding them all in length,
a very sharp fang pierced through by a tiny canal, which opens into
a gland placed at the root of the tooth. The bone which supports this
little apparatus is very flexible, and when at rest, the fang, falling
back, hides itself in a fold of the gum. When the animal wishes to
bite, it springs up again, and the gland, compressed by the action of
biting, sends into the little canal a jet of poison, which runs through
it into the wound. As far as can be ascertained, this poison paralyses
the victim and disorders the blood, which at once loses its power,
and no longer acts upon the organs as before; still it is only injurious
when it has been carried by the current of circulation into the mass
of the blood; if swallowed, it has no effect whatever on the stomach.
Now do not look at me with such incredulous eyes, as if it were quite
impossible any one should think of swallowing such a thing. You have
no idea what a scientific man is capable of when he comes to close
quarters with nature, for the purpose of extracting one of her secrets.
He has his own fields of battle, where very often as much courage is
displayed as on any other.

These two fangs, in which lie all the power of the animal, are of the
greatest importance to him, and their want of solidity makes them
liable to remain in the wounds which they have made. In consequence
of this, they enjoy the same privilege as the teeth of the crocodile,
and in a still greater degree even. Behind each poison fang lie in
wait, not one nor two, but several sentinel germs, ready at the first
alarm of a loss to set to work and re-supply the disarmed serpent with
his venomous needle. So the serpent also lives in a state of perpetual
childhood: he is always growing; and I could not tell you the exact
natural limits of his life any more than of that of the crocodile.
They are gentlemen who do not allow themselves to be very closely
studied in a state of freedom. But these also grow very slowly, and
some have been met with whose size had extended quite enormously from
their first start. I ought to tell you, once for all, that this
indefinite growth, joined to extreme longevity, is found in many of
the inferior species whom we have yet to consider. It seems the portion
of these unfinished creatures, in which nature has only as it were
sketched in her work, and who seem vowed to endless youth, in testimony
of the state of childhood they represent, a state transitory among the
superior animals, but permanent with them. It belonged of right,
therefore, to the serpent, which is the most unfinished animal we have
yet met with, and who, at the first glance, seems almost reduced to
a mere digestive tube, lodged between a vertebral column and a series
of small ribs, whose number sometimes reaches three hundred. The liver,
which, with us, presents such a distinct and bulky mass, is here
elongated into a thin cord, which runs the whole length of the
oesophagus
and intestine, to the walls of which it is, to some extent, attached.

It is the same with the lungs. There is rarely room for the full
development of two in this narrow conduit, where everything has to
follow the shape of the master of the house: one, therefore, is often
merely indicated by a very slight protuberance; the other, presenting
the appearance of a long tube, which extends nearly half-way down the
body, and whose feeble action halts periodically at each of those
monstrous repasts, after which the torpid animal becomes nothing but
a huge digesting machine. We have now reached the extreme limits of
that organization, the most perfect model of which we find in man, and
which is no longer to be recognized in fishes.



LETTER XXXVI.

PISCES. (_Fishes._)

We are becoming terribly learned, my poor child, and I am half afraid
you will be getting tired of me. When I was little myself, I had rather
a fancy for breaking open those barking pasteboard dogs you know so
well; to see what was inside them. Why should you not, then, feel a
certain amount of interest in looking with me into the insides of real
animals? Still I cannot conceal from myself that the subject grows
very serious at last, and that while I am busied in struggling to make
myself intelligible through the endless crowd of facts which surround
me, I am apt to neglect chatting with you as we go along. Happily,
however, here is an opportunity for so doing.

Up to the present time we have lived, as it were, upon the explanations
I gave you whilst studying the action of life in yourself, and all the
organs we have met with since, have been only, properly speaking,
reproductions, more or less exact, of those which you yourself possess.
But, in passing over into the kingdom of fishes, we find ourselves in
the presence of something altogether new, and I must go back to our
old familiar style of talking to open the subject.

Take a water-bottle half-filled with water, and shake it well, and you
will see a quantity of white froth come to the surface of the liquid.
This is the air which having been drawn in by the water, as it went
up and down in the bottle, is now struggling to fly off again in bubbles
as fast as it can. But the whole of it does not get away; a small
portion remains behind, and melts, as it were, into the water, as a
morsel of sugar would do, taking up its abode therein. This seems odd
to you, but I will tell you how you may convince yourself of the fact.
Get a small white glass bottle, slightly rounded, and thin at the
bottom, if possible; fill it with water, and hold it for a short time
over a lighted taper. If you do this carefully there is no danger. You
will soon see tiny little balls, looking like drops of silver, rise
from the bottom of the bottle, come up to the surface, and burst. This
is the air which was installed in the water, as I described above, and
which is now running away from the heat of the candle, as the
inhabitants run away from a house on fire. After a time the whole will
have passed off, and the little balls will cease to rise.

But what has all this to do with fishes? you ask.

A very great deal, I assure you, dear child. If there had been a little
fish in your bottle, before it was exposed to the flame, it would have
found means to make use of that air, whose original presence in the
water you cannot refuse to believe after having seen it come out. It
is with this air that fishes breathe in the water. They do so rather
feebly, I admit; but, as if to make up to them for the small amount
of the air placed at their disposal, it contains more oxygen than that
we breathe ourselves, because oxygen, dissolving more readily in water
than nitrogen, is there in greater proportion. Of course, you do not
suppose that fishes have lungs like ours? I dare say you know the two
large openings on each side of their head, called _gills_, by which the
fishermen string them together to carry them away more easily? It is
there you will find their lungs, to which the name of _branchiae_, or
gills, has been given, because they are so different from other organs
of respiration that it was impossible to use one word for the two. The
arrangement of the gills varies considerably in the different species,
but their general form is the same everywhere. They are composed of a
number of plates, consisting of an infinitude of leaflets, arranged like
a fringe, and suspended by bony arches, into which plates and leaflets
the blood pours from a thousand invisible canals.

First of all, then, we must see how blood circulates in fishes.

Like reptiles, their heart has only one ventricle, and yet the arterial
and venous blood go each its separate way without the slightest risk
of being mixed; but this is because fishes have not that double system
of veins and arteries which hitherto we have always met with. The
venous blood goes to the heart, which drives it into the gills, from
whence it passes forward of its own accord, as arterial blood into the
organs, under the remote influence of the original impetus from the
heart, the newly-arrived blood incessantly driving the other before
it into the vessels of circulation. It does not flow very quickly, as
you may suppose; and as the heart is close to the head, its action is
but very feebly felt at the extremity of the body, when this happens
to be very long. Nature has, in consequence, taken pity on the eel,
whose tail is so far from its heart, and provided accordingly. Dr.
Marshall Hall has discovered near the tip a second, reinforcing heart,
so to speak, which has its own pulsations, independent of the pulsations
of the one above, and gives a fresh impetus to the sluggish blood,
[Footnote: Many observers refer this to the lymphatic system.--TR.]
which otherwise, as it would seem, would scarcely be able to accomplish
the long return journey. Finally, even with an additional heart in
thetail, the circulation among fishes is quite on a par with their
respiration. They have a melancholy steward, whose legs are very heavy,
and his pockets very light, and their life comes down a peg lower in
consequence. It is always the same life nevertheless--you must never
lose sight of that fact: it gets low in consequence of the imperfection
of the machine, but without changing its nature, any more than the
light in our different sorts of lighting apparatus. You remember that
comparison of the lamp with which I began my story, and which you could
not at the time see the full value of? From a dungeon lamp up to a
candle, you have always grease burning in the air at the end of the
threads of a wick. It does not burn equally well everywhere, and does
not always give the same amount of light; but that is all the
difference. From the mammal to the fish, it is always hydrogen and
carbon (as we have said of the grease) which oxygen sets on fire in
the human body at the fine-drawn extremities of the blood-vessels;
only the fire is lower in some than others, and the life with it. Let
us now look at the circulation of water in the fish's body.

The gills communicate with the mouth by a sort of grating, formed by
the bony arches to which the gill-plates are suspended. The fish begins
by swallowing water, which then passes through the grating and
circulates round the innumerable leaflets of which each plate is
composed, and among which creep the blood-vessels. It is through the
thin coats of these leaflets that the mysterious exchange is made of
the unemployed oxygen in the water and the carbonic acid in the blood.
When this is over, the cover which closes the gills opens to let out
the water, and a fresh gulp takes its place; and so on continually.
When the fish is out of the water its gills fall together and dry up;
the course of the blood, already so weak, is interrupted by the breaking
down and shrinking of the vessels, and the animal can no longer breathe;
so that we have here the curious instance of a creature breathing
oxygen like ourselves, who is drowned, if we may use the expression,
in the air in which we find life, and lives in the water in which we
are drowned. While he is in the water matters take another course, and
his gills, moistened and supported, accommodate themselves perfectly
to the contact of the air, which desires nothing better than to give
up its oxygen to the blood, through the coats of the capillaries.
Accordingly you will often see fishes--carps, for example--come to
the surface of the water to inhale the air like a mammal or a reptile.
This is a valuable resource, which supplements the parsimonious
allowance of air given out to them by the water. There are even certain
fishes whose gills, more firmly closed than those of others, have, in
addition, a number of cells, which retain for a considerable time a
sufficient quantity of water to preserve the gills in their natural
state. These fishes can easily take an airing on land, where they
breathe the air as you or I do, and are downright amphibians.

The most celebrated of these is the _Anabas_, or "climbing-fish."
an Indian fish, which not only can remain many days out of the water,
but also amuses itself by climbing up the palm trees--it is hard to
say how--and establishing itself in the little pools of water left by
the rain at the roots of the leaves. But we need not go to India to
find those wandering fishes. There is one of them living among ourselves
who can walk about in the grass, and I was talking to you about him
only just now--that is the eel. If you ever put eels in a fish-pond
you must, I assure you, try to make it agreeable to them, otherwise
they will have no scruple in setting politeness at defiance and moving
off to seek their fortune elsewhere. In a country walk, when the dew
is on the ground, you yourself may chance to come across one or two
of these gentlemen, who have had their reasons for changing their
residence, and whom you will see gliding so briskly along that they
will deceive you into taking them for snakes if you have not a very
experienced eye; so much so, that in certain parts of France where the
peasants ate snakes formerly, they reconciled themselves to the sickly
idea by christening them _hedgerow-eels_.

On the other hand, fishes may be drowned in water just as easily as
ourselves if it does not contain air. The little fish who could have
lived very well in the bottle we were just now talking about before
you exposed it to the flame of the taper, would have died in it after
all the air-bubbles had gone off; and I hope I need not tell you why.
In the same way, if you leave fishes too long in a small quantity of
water without renewing it, they suffer exactly as we do if the air
which we breathe is not changed often enough. As soon as they have
consumed what oxygen is in the water, it can no longer keep them alive.
It is then, especially, you will see them come gasping to the surface
to call upon the air for help. Those who keep gold fish in a glass
bowl ought to know this, and to change their water oftener than is
generally done. When we take poor little creatures from their natural
way of life, and set a human providence over them in the place of the
Divine one which has hitherto been their safeguard, the least we can
do is to acquaint ourselves with the laws of their existence, so that
we may not expose them to the risk of suffering by our ignorance.
Finally, there are fishes whose gills, still more greedy of oxygen,
will not act well except in thoroughly aerated water, and who would
soon die in our tanks. This is the case with the trout, who is only
happy in the waters of hilly countries; rich with all the air they
have carried along with them as they fell from rock to rock. Now that
people are beginning to do with fishes what has long since been done
with sheep and oxen--keep them in flocks to have them always ready for
use--you may perhaps hear a good deal said about vessels made expressly
for the carriage of trout, with a thousand inventions besides for
sending air into the water, and you will not have to ask the meaning
of this now.

I promised last time that I would revert in the chapter of fishes to
that marvellous transformation of the crocodile which has been explained
by the torrent of water he draws into his stomach. You could understand
nothing about it the other day; but after what we have just seen the
explanation suggests itself. Just as the extraordinary activity of
life in birds is explained by that double oxygenization of blood, of
which part takes place in the lungs and part in the reservoirs of air
placed everywhere in the way of the capillaries, so this sudden increase
of energy in the crocodile the moment it plunges into water may be
explained by a second respiration suddenly established in the vast
cavity of the abdomen, by the contact of the capillaries with the water
which penetrates there. Hence the crocodile would then have, like the
bird, a double respiration: only with him the one would be permanent
and from the lungs, the other temporary and from the stomach. By this,
on the one hand, he would rise up to the birds, since the blood
encounters air twice over in its course, while, at the same time, he
would plunge into the world of fishes, since the blood has to seek air
in the water. The above, be it remembered, is only a supposition, and
I ought to add that in this case there would be a good deal of danger
in observing nature at work, for in front of the laboratory, where she
is toiling in secret, stands on guard a row of teeth, by no means
encouraging to indiscreet intruders. At the same time, if there ever
were a legitimate conjecture, this is it. Everything seems to confirm
it; and if it be true, we should have in the crocodile a specimen of
each of the four systems adopted by nature for the mammal, the bird,
the reptile and the fish. At first I spoke of two, then of three; so
that even in my addition I was modestly below the mark, and had really
some grounds for recommending our friends the classifiers to beware
what they asserted in this case.

Talking of puzzling classifications, this is just the place for
mentioning the _batrachians_, who have been made into a class by
themselves, but who most distinctly belong to two classes at the same
time; not like the crocodile by details borrowed from each, but by a
fundamental change which takes place at a certain period in their
organization. The batrachians are in reality reptiles, but they are
reptiles which begin by being fishes, and real fishes too.

If you have ever strolled about in the country, you must have often
come across those great pools of water which collect at rainy seasons
in the ruts of deep lanes. Amuse yourself by looking into them in
early summer, and unless the land is too parched and dry, the chances
are that you will see quantities of little black fishes, almost entirely
composed of a long tail joined to a large head, playing jovially in
the muddy waters, and looking as if they had dropped there from the
skies. These are young frogs--_tadpoles_, as we call them--and
they are beginning their apprenticeship of life. Enclosed in each side
of those great heads, they have gills, and they breathe in the same
manner as fishes. Presently the two hind feet begin to bud out and
grow, little by little; then the fore feet; finally, the tail wastes
away till it disappears; and thus insensibly the tadpole is transformed
into a frog. Observe here that the tadpole's gills share the same fate
as his fish-tail; they wither and disappear by slow degrees, and
gradually as they do so, his lungs are developed. The animal changes
his class very quietly, and without ceasing to be genuinely the same,
although it would be impossible at last to recognize the old individual
in the new if you had not heard its history beforehand. This is one
of the most striking exemplifications I know of the mysterious process
by which nature has insensibly raised animals from one class to another,
always improving upon her original plan without ever abandoning it.

On the shores of certain subterranean lakes which exist in Carniola,
a country subject at this time to Austria, there are to be found
batrachians far more ambitious than our frog--namely, the _proteans_.
These cumulate rather than change: they become reptiles without ceasing
to be fishes, if I may so express it; they develop lungs as they grow
up, and yet keep their gills. I could tell you a thousand other
particulars about these batrachians if I were to examine them all in
succession; for it is a very motley family, in the bosom of which the
transition from reptiles to fishes is in some imperceptible manner
accomplished; from the frog, which the unanimous consent of mankind has
always ranked among reptiles, to the axolotl or siren, who lives in
Mexican lakes; and who, feature for feature, is exactly like a carp,
with four little feet fastened under him. To be quite in order, the
batrachians ought to have followed the reptiles, for their interior
organization is the same; but how could I tell you about their gills
without explaining that there was air in the water? and I did not want,
for the sake of these intruders, whose babyhood-gills only just appear
and disappear, to rob the history of the fishes of its most interesting
points.

Let us be satisfied, then, with this passing glance at a dubious class,
whose history is only a repetition of two others, and let us return
to our friends the fishes. We have seen how they breathe, now let us
look how they eat.

The modifications of the digestive apparatus are endless among fishes.
The lampreys, who are placed in the lower ranks of the class, carry
out to its fullest extent the type which we have already seen indicated
in the serpent. The digestive tube is quite straight, without any
perceptible swelling, and does not even go the whole length of the
body. It comes to an end at some distance from the tail. Among some
fishes an odd tendency begins to display itself, which we shall meet
with again farther on. The digestive tube, after going downwards towards
the bottom of the body, as we have seen it do so constantly hitherto,
doubles back, and comes up again to the throat, under which it empties
itself. In most cases the stomach is distinct; but it assumes a thousand
different forms; as if nature had wished to try her hand in all sorts
of ways in the construction of these imperfect vertebrates, before
adopting the definite model which was to serve for the others.

The liver is enormous, and generally contains a great quantity of oil,
the taste of which you will know if you have ever swallowed a spoonful
of cod-liver oil; but in most fishes its old companion, the
_pancreas_, has disappeared. In its stead you will find, close
by the outlet of the pylorus, the open ends of certain small tubes,
which are shut in at their upper extremity like a "blind alley," and
through which descends into the interstices a thick glairy fluid, given
out from their sides or walls. The result is the same, you see, although
the organ is different; and, remarkably enough, these little tubes are
wanting among fishes, which, like carp, have a species of salivary
glands in their mouths, of which the others show no trace; from which
one may fairly conclude that these glands and tubes mutually supply
each other's places. Here, then, you see an instance of the light which
different animal organisations throw upon each other when they are
compared together. In fact, this one establishes pretty clearly the
real office of the pancreas in the higher races, exhibiting it to us
as an internal salivary gland, intended to complete the work only begun
by those in the mouth, in the case of lazy people who swallow their
food too quickly.

There is the same diversity in the mouth as in the intestine. Some
fishes, like the skate, have no tongue at all. Others, instead of a
tongue, have a hard dry filament, very nearly immovable, and which one
would think was put there like a stake, to show the place where the
tongue is to be found in the more perfect organisations. There are
even fishes, like the perch and the pike, whose tongue is furnished
with teeth, or rather fangs; an evident sign that it has forfeited the
confidential position occupied by your own good little porter. You
must know also that the perch and the pike, like many other of their
fellows, have teeth all over the mouth. This invasion of the palate
by teeth, which began in the lizard and the serpent, assumes alarming
proportions here. It is not merely the roof of the palate which is
spiked with teeth: above, below, at the sides, everywhere to the very
limits of the oesophagus, the little fangs triumphantly stick out their
slender points. It is impossible, therefore, to state their number.
Nature has scattered them broadcast without counting, just as she has
done with the hairs of the beard round the human mouth; and the
comparison is not so impertinent as you may think. They sometimes form
an actual internal beard, even thicker than our outer one, and which
sprouts from the skin into the bargain. There is one fish whose teeth
are so delicate and so close together that, in passing your finger
over them, you would think you were touching velvet. This does not
refer to the shark, mind. His teeth are sharp-cutting notched blades,
hard as steel, arranged in threatening rows round the entrance of his
mouth, and cut a man in two as easily as your incisors do a piece of
apple. Others, such as the skate, have their mouths paved--that is the
proper term--with perfectly flat teeth. The first time your mamma is
sending to buy fish beg her to let you have a skate's head to look at.
You will be interested to see the small square ivory plates laid close
adjoining each other, like the tiles of a church floor. It is in fact
a regular hall-pavement, over which the visitors glide untouched, and
are then swallowed down in the lump; thus entering straight into the
house without having been stopped by the inscription nature has placed
over your door and mine--"Speak to the Porter."

But all this is nothing compared to the lamprey's entrance-hall, which
differs from ours in quite another way. The lamprey, as I have already
told you, ranks almost lowest among fishes, and consequently among
vertebrate animals, of which fishes form the rear-guard. Indeed, it
is almost stretching a point to consider her worthy to bear the proud
title of a vertebrate at all; for the vertebral column, so clearly
marked in other fishes, where it forms the large central bone, is only
faintly indicated in certain species of lampreys, by a soft thread (or
filament), which is rather a membrane than a bony chaplet, and at the
top of this mockery of a vertebral column is the creature's mouth. If
you ever had leeches on, you will remember the sharp sting you felt
when the little beasts bit you. Well, the lamprey feeds herself just
in the same way as the leech does. Her mouth forms a completely circular
ring, which sticks to the prey, and through which runs backward and
forward a small tongue armed with lancets. This darts out to pierce
the skin, and draws in the blood as it retreats. Round your lips well;
dip them so into a glass of water, and draw back your tongue, and you
will at once feel the water rise into your mouth. It is by a similar
sort of proceeding that leeches relieve people of the blood they want
to get rid of; and in the same way the lamprey draws out the blood of
the animals upon which she fastens.

What a long way we have come already! How very far we find ourselves
here from the little mouths we first talked about as chewing their
eatables so prettily! With the lamprey we bid adieu to the class
Vertebrata--the nobility of the animal kingdom--among whom nevertheless
we must distinguish between the peer, who approaches nearest the person
of his sovereign, and the inferior provincial lords who live at a
hundred miles' distance. There is only one step from the lamprey to
the _mollusks_ or soft-bodied animals, and this is the course
which animal organisation seems really to have taken in its progress.
But nature never moves forward in a single straight line. In passing
from the mollusk to the fish to get thence to the higher vertebrates,
she turned aside in another direction toward a class of animals which
rises far above mollusks, but which leads to nothing beyond.

One would think there had been a check here, as if the creative power,
having discovered that it was going in a wrong direction, had retraced
its steps; if it be allowable to apply common ideas and expressions
to our conceptions of that Great Intelligence which has arranged the
plan of the mysterious ladder of animal life.

The animals we must examine next, on account of their superiority to
the rest, are insects. Small as the ant is, it would not be right to
let her be preceded by the oyster.



LETTER XXXVII.

INSECTA. (_Insects._)

Before speaking of insects, my dear child, it will be necessary, in
the first place, to tell you to what primary division they belong and
on what characters this division has been established. And here I find
myself in a difficulty. We have been but too learned already, and now
we run the risk of becoming still more so, if we commence an attack
on the three primary divisions which follow the vertebrates. We shall
have to encounter terrible names and tedious details, besides having
to take into account a thousand things of which we have not yet spoken.
We are going on quietly with the history of the feeding machine which
occupies the middle of the body, and learned men never looked in that
direction for the establishment of their divisions; between ourselves,
it was not accommodating enough. They have fallen back upon the
locomotive apparatus (_movement machine_) which affects the body
all over, and which they have proclaimed to be the leading feature of
the animal organization, without noticing however that it is, after
all, but the servant of the other. It is true that the great divisions
are more easily established upon this point than the other, because
the differences are more decided. It separates what the other unites,
and thus it is that nature carries on that beautiful combination which
the Germans have so accurately named "_Unity in Variety_" that
is to say, she is always at work, as I have already told you, on the
same canvas, but always embroidering it with a different pattern.
Wait! I have something to promise, if you are very good, and if this
history (that of the feeding machine) should have given you a taste
for inquiry. I will tell you another time the history of the movement
machine, and there the classification of our learned men will come in
naturally very well. In the meantime we will do as they do, and just
shut our eyes to their divisions, in which the feeding machine can
have no interest, because they were established without reference to
it. We will content ourselves, then, without further pretension to
science, with modestly examining the last transformations of our pet
machine in the principal groups of the inferior animals; of which
groups I will now tell you the names in their proper order. They are
as follows: Insects, Crustaceans, Mollusks, Worms, and Zoophytes. You
must take these names on trust; those which you do not understand will
be explained in their places.

1. _Insects._--I know not where it was I once read that there are
said to be something like a hundred thousand different species of
insects; and I verily believe this is not all. Of course we shall not
attempt to review the whole of this formidable battalion. Let us take
one of those you are most familiar with--the cockchafer, for
instance--and examine what goes on in his inside. The history is nearly
that of all the others.

"Fly away, cockchafer, fly!" says the song; and surely it is a bird
that we have here, and a bird which will appear to you even more
wonderful than those of which I have already spoken, when you have
considered the simplicity, and at the same time the strength, of his
organization. His mode of flight is rather lumbering, it is true; he
is, in comparison with the large flies, what the ox is to the deer;
but when you contrast the weight of his thick body with the delicacy
and narrow dimensions of the two membranes which sustain him in the
air, you may well ask yourself how those little morsels of wings, thin
as gold-beater's skin, can carry such a mass along. In fact, they only
accomplish this feat of strength by dint of an excess of activity
almost startling to think of. When you run as fast as you can, how
many times, think you, do you move your legs in one second? You would
be somewhat puzzled to say; and so should I: but I defy you to count
ten. Now the bird makes his wing move much oftener when he beats the
air with rapid blows as he flies; but even he does not strike a hundred
strokes in a second: and what is this to the feats of the cockchafer's
wing? It is not hundreds but thousands of times that he flaps his wings
in a second; and here let me hint, by-the-by, that when people seriously
wish to find out a method of travelling in the air, they will lay aside
balloons, of which they can make nothing in their present condition,
and will set to work to fabricate machines with wings which shall beat
the air as fast as those of the cockchafer. This sounds extravagant,
but I have seen an electric pile fixed in a stand with glass feet,
which caused a little hammer to beat thousands of times in a second:
and surely the hammer could have been made to communicate its movement
to a small wing! Forgive me this little castle in the air! The idea
came into my head a long while ago, and the cockchafer has just reminded
me of it. I will not, however, pursue the subject, neither will I offer
to explain the method used for counting the beats of an insect's wing.
That would carry us farther than would be desirable.

To return to our little animal. I leave you to imagine the enormous
amount of strength required for such precipitate motion. We have spoken
of the rapid course of the blood in birds during flight: who shall
calculate its comparative rate in this fabulously wonderful locomotive,
the cockchafer? And if we lift up the cuirass which encases it, what
do we behold? Not a single trace of all the complicated
circulation-apparatus you have learnt to know so well; neither heart
nor veins nor arteries; only a quantity of whitish liquid, equally
distributed throughout the whole internal cavity. Not a trace of lungs,
nor any apparent means of renovation for this seemingly motionless
blood; for blood it is, in spite of its color, or, at any rate, blood
in its first stage of formation. It also has its globules--ill-formed,
it is true, and altogether in balls--like those found in the chyle
with us; which chyle, be it observed, is the same color as the blood
of insects, and may also be considered blood in its apprenticeship.
By what magic, then, is this raw, imperfectly-formed steward, who seems
altogether stationary, enabled to accomplish exploits which would
stagger his higher-bred compeers, agile and perfected as they are?
Where does he pick up the oxygen necessary for such repeated movements,
it being an established fact that no animal can move at all without
consuming oxygen, and that the quantity consumed is in proportion to
the rate of motion? Look under his wings for an answer. There, all
along his body, you will observe a number of small holes, pierced in
a line, at regular distances, and furnished with shutters of two kinds.
They are the mouths of what are called _tracheæ_, or breathing
tubes: and from them branch out a multitude of little canals, which,
spreading in endless ramifications through every part of the body,
convey to the whole mass of the blood, from all directions, the air
which makes its way into them through the tracheal holes. In this case,
you see, it is not the blood which seeks the air, but the air which
seeks the blood; whence arises a new system of circulation, whose
action is all the more energetic because it is unintermitting, and
makes itself felt everywhere at the same time. A little while ago we
were wondering at the twofold respiration of birds; yet this is far
less surprising than the universally-diffused respiration of insects,
who may well be able to do without lungs, seeing that their whole body
is one vast lung in itself.

For the rest, do not trust to appearances, nor imagine that the blood
of our friend the cockchafer in reality remains motionless around the
air-tubes, idly drinking in the oxygen which is brought to it. Though
not flowing in enclosed canals, it is not the less continually displaced
by regular currents, which sweep through and renew this apparently
stagnant pool. Nor is this the only instance of such a current presented
to us by nature.

Guess, however, if you can, where you will have to look for the
counterpart to the circulation of the cockchafer. In ocean itself!
But, remember, nothing is absolutely little or great in nature, who
applies her laws indifferently to a world as to an atom. The blood of
our world is water, which contains in itself all the germs of fertility,
and without which, as I have already told you, life is impossible
either in the animal or vegetable kingdom. The water of brooks, streams,
and rivers, flows along in channels, which, when figured in a map,
present to the eye of the beholder an exact picture of the system of
circulation found in the vertebrated animals. But the waters of the
sea are borne along, like the blood of insects, by a secret circulation,
which cannot be represented on the map; _i.e._ by immense currents
everlastingly in action, some on the surface, some in the mid-heart
of the ocean, which drive it in ceaseless course from the equator to
the poles, from the poles to the equator; so that the Supreme
Intelligence, in His overruling providence, has ordained the same law
to set in movement the immensity of ocean, and to effect circulation
in the cockchafer's few drops of blood. In the latter we find the
moving agent to be a long tube, which runs the whole length of the
back, and is called the dorsal vessel (from the Latin _dorsum_,
back). I told you that the cockchafer had no heart under his cuirass,
but I spoke too hastily. The dorsal vessel is a _true heart_, but
a heart devoid of veins or arteries, and thrown into the midst of the
blood. It dilates and contracts like ours, sucks in the blood by means
of side-valves, which act as our own do, and drives it back again into
the mass by that valve at its extremities, which opens near the head.
From thence arises a continued to-and-fro movement, which sends the
blood from the head to the tail, and brings it back again from the
tail to the head. But who would recognise, in this simple primitive
organisation, where all seems to go on of its own accord, as it were,
the same machine, with all its complicated movements, that we have
been so long considering?

Well, in this apparently universal shipwreck of all the organs we know
so well, there is yet one which survives, and remains the same as ever,
namely, the digestive tube. I began by saying the insect is a bird.
His digestive tube is formed upon the same pattern as that of birds,
so that naturalists have bestowed the same names on the various parts
in each of them. After the oesophagus comes a crop (_jabot_), very
distinctly indicated; then a gizzard with thick coats, in which the
food is ground down. The hen, if you remember, swallows small pebbles,
which perform in her gizzard the office of the teeth in our mouths.
The cockchafer has no need to swallow anything. His gizzard is furnished
with little pieces of horn; real teeth, fixed in their places, which
have a great advantage over the chance teeth picked up at random by
the hen. I pointed out to you in birds, between the crop and the
gizzard, a swelling or enlargement of the digestive tube, pitted with
small holes, where the food is moistened by juices. The same enlargement
is found here, covered all over with a multitude of small tubes, which
might easily be mistaken for hairs, from which also falls a perfect
shower of juices. The only difference is, that it comes after the
gizzard, instead of before it, as in birds. Some naturalists,
considering that the manufacture of chyle takes place here, have called
it the _chylific ventricle;_ [Footnote: The corresponding
protuberance of the birds bears a name, somewhat similar, but stillmore
barbarous. I had passed it over in silence, because, I make the
confession in all humility, I do not understand it; but a remorse now
seizes me: it is called the _Ventricule succenturie._] a somewhat
barbarous name, but one which explains itself, and might with truth
be applied to the _duodenum_ of the higher animals. Bile is poured
in close to the hinder end of it, but you must not look for the liver;
it has disappeared, or rather its form is entirely changed. You remember
what the _pancreas_ had become in fishes; _i.e._ a row of tubes giving
out a _salivary fluid._ Such is exactly the appearance of the liver in
the cockchafer.

Instead of that fleshy substance on which hitherto the office of
preparing the bile had devolved, you see nothing but a floating bundle
of long loose tubes, which, opening into the intestines, pour in their
bile. The organ is transformed, but we recognise it again by the office
it performs, which continues the same. As to the _pancreas_ it is
wanting here, as in the fish with salivary glands; but in its place
in many insects other tubes, acting also as glands, pour saliva into
the _pharynx; i. e._, the cavity at the back of the throat.

As you see, therefore, everything is found complete in this tube of
a few inches long; and you can also distinguish there a small and a
large intestine. We are speaking of the cockchafer, which feeds on the
leaves of trees; and it is for this reason I name some inches as the
length of the digestive tube. This would not be longer than the body
itself, had it been destined, as in the case of many other insects,
to receive animal food. In fact, the law which we have shown to exist
with regard to the ox and the lion, rules also over the insect-world;
and whilst a radical change seems to have been made in the rest of the
organisation, here everything is in its place, and we find ourselves
in the same system.

Was I not justified in asserting that the unity of the animal plan is
to be found in the digestive tube? and that this is the unchanging
basis upon which the Creator of the animal world had raised his varied
constructions?

How would it be, then, if we were to take the insect from its
starting-point when it is only a worm, that is to say, merely and
simply a digestive tube? for I am only telling you a small portion of
its history here; a history you must know, which reveals a miracle
still more wonderful than the transformation of the little tadpole
into the frog! There is a brilliant-colored fly which comes buzzing
about the meat-safe--the bluebottle--do you know her? It is on her
account that we put large covers of iron wire over the dishes of meat;
but, perhaps, you never troubled yourself to think why.

But the truth is, she only comes there to deposit her eggs in the good
roast-meat; and if she could get near enough to do so, you would soon
afterwards see it swarming with little white worms, which would entirely
take away all your appetite. These worms are only flies out at nurse,
and they will find their wings by-and-by if you only give them time
enough. Disgusting as they may appear on a dining-table, I assure you
they deserve more interest than you may think. When we come to speak
of worms, we will ask of them to let out the secret of the mysterious
transformations of animals.

In the meantime, let us finish the observations we were making on the
_perfect insect_, as this little creature is called when he has
passed through the intermediate stages which separate him from the
undeveloped condition. Forgive me, my dear child, here I am speaking
to you as if you were a grown-up woman! This is because it is so
difficult to explain things of this sort in any other way. And now
that you have been introduced into the midst of the wonders of creation,
you ought to familiarise yourself with the ideas and terms they have
suggested to mankind. I began with you as a child, and great would be
my triumph if I could leave you a grown-up girl! And I flatter myself
that I have so far set your brain, to work, under pretence of amusing
you, that this hope is not altogether unfounded. I found it necessary
to say this to you in confidence, because I have just read over our
first conversations, and perceive that I have insensibly put you on
a different diet from the one I began with. I am obliged to comfort
myself by remembering that you have grown older since, and that you
are now acquainted with a great many things which you had never heard
spoken of then. And this is the secret of all transformations. We crept
on at first over ground that was quite unknown to us; but as we went
along, our wings must have begun to grow, and we are now able to fly
a little!

Do not be afraid, however; I will exercise your tiny butterfly-wings
very carefully just at present. We have only to examine what becomes
of the _chyle_ of the cockchafer after it has been prepared in
the pretty little tube so finely wrought. We men have _chyliferous_
vessels which draw up chyle from the intestines and throw it within
a short distance of the heart, into the torrent of blood, where its
education is completed. But the cockchafer, who has no other vessels
than his air-pipes, and the _dorsal tube_, which has no communication
with the intestines, what is he to do? Do not distress yourself about
him. Make a tube of a bit of linen, well sewn together, and fill it with
water. Sew it together as firmly as you may on all sides, the water will
have no difficulty in escaping through the meshes. And this is just what
happens with the little tubes found in animals, the coats of which are
formed of interwoven fibres. By-the-by, from thence comes their name of
"_tissue_," which they share in common with all the solid substances of
the body, for all were once supposed to have the same general structure.
The intestine of the cockchafer floats, did I not say? in the lake of
blood which fills the whole cavity of the body. Well, then, the chyle
has only to penetrate through these coats, to go where it is wanted.
Hence it is not at all surprising that this blood should be white; and I
have very good reasons just now for comparing it to our _chyle_. It is,
indeed, chyle arriving directly from the place of its manufacture,
without undergoing any other process; by which you may see that this
little machine (of the digestive organs of the cockchafer), though
differing in appearance so entirely from our own, is reducible to the
same elements of construction, and that life is maintained by the same
process as with us; namely, by the action of the air upon the albumen
extracted from food. The cockchafer, it is true, is much further removed
from being a fellow-creature of ours than even the horse; but the
principle of life is the same with him as with us. And this is quite
enough to cause children, who can feel and reason, to think twice before
they begin to torture, by way of amusement, a creature whose life the
God of goodness has subjected to the same conditions as our own. I speak
this to those miserable little executioners who make toys of suffering
animals: but the case is different with agriculturists, who have
necessarily to contend with the devourers of their harvests, and whom,
I admit, it would not be reasonable to bind down by the maxim of Uncle
Toby.

[Footnote: I have introduced my Uncle Toby, who really has nothing
to do here, in order to make you acquainted with a few lines of Sterne,
which I wish I could place before the eyes of every child in the world.

"Go!" said he, one day at table, to an enormous fly which had been
buzzing around his nose and had cruelly tormented him all dinner time.
After many attempts, he finally caught him in his hand. "Go! I will
not do thee any harm," said my Uncle Toby, rising and crossing the
room with the fly in his hand; "I would not hurt a hair of your head.
Go!" said he, opening the window and his hand at the same moment, to
let the fly escape; "go, poor little devil; away with you; why should
I do you any harm? the world is certainly large enough to contain both
of us!"]

But now to finish with the cockchafer. We have got to examine one very
important part of his body, that which in other animals has been the
one most talked about ever since we began our study: I mean the mouth.
You know that this is the essentially variable point in the digestive
tube; so that you will not be much surprised, should we find he has
something altogether new. The mouth of the cockchafer is composed of
a great number of small pieces placed externally round the entrance
to the _alimentary canal_; but the names of these, as they would
not interest you, I will not enter upon with you; more especially as
they refer to such tiny morsels, that you would have great difficulty
in finding them again on the owner. Of these pieces only two are worth
our attention. These are two bits of extremely hard horn, placed one
on each side of the animal, which are called "_mandibles_" and
which serve the cockchafer to cut up the leaves which he eats. Fancy
your share of teeth being two huge things fixed in the two corners of
your mouth, each advancing alone against the other till they meet under
the nose! You would then attack your tarts with the weapons of the
cockchafer! You would not, however, be able to bite them straight
through from the top to the bottom, as is done by all the animals whom
we have yet seen. It is this which so peculiarly distinguishes the
insect's manner of feeding; for we have already been taught by the
bird and the tortoise, that it is possible to eat with two pieces of
horn. The cockchafer now shows us how to eat sideways; but this is
merely an accessory detail. It does not affect what happens after the
mouthful is swallowed. All insects, however, have not this peculiarity.
The cockchafer belongs to the category of grinding insects as they are
called, who bite their food: but there is the category of the sucking
insects (or suckers), whose food consists of liquids; and these insects
are furnished in a different manner.

In the innocent butterfly, who lives on the juice of flowers, the
digestive tube terminates externally in a sort of _trunk,_ twisted
in several convolutions, which is nothing more than an exaggerated
elongation of the two jaws, which become hollow within, and form a
tube when joined together. When the insect alights on a flower, he
suddenly unrolls this trunk, and sucks in the juices from the depth
of its "corolla," as you would drink up liquid with a straw from the
bottom of a small vial. Amuse yourself some summer's day by watching
a butterfly in his labors amongst the flowers: sometimes he stops
still, but oftener he is contented to hover over them; and, as he does
so, you will see a little loose thread, as it were, move backwards and
forwards as fast as possible: this is his trunk, which he darts out,
while flying, into the corolla of the flowers, but which scarcely seems
to touch them, so delicate is its approach.

Less inoffensive far is the trunk of the mosquito-gnat, and of all the
detestable troop of blood-sucking flies. It is always a tube; but this
tube is no longer a simple straw, but a sheath furnished with stilettos
of such exquisite delicacy and temper, that nothing is comparable to
them; and these, as they play up and down, pierce the skin of the
victim, like the lancets of the lamprey, and, like them, draw in blood
as they retreat.

Finally, amongst the _parasites,_ the last and lowest group of
insects, the stiletto-sheath is reduced to the size of a kind of little
tube-shaped beak, which, when not in use, folds down like the fangs
of the rattlesnake.

You do not know, perhaps, what a parasite is. The word comes from the
Greek, and signifies literally, "_that which moves round the
corn._" The Greeks applied it to those shameless paupers who, to
escape honest labor, made their way into the houses of the great, and
enjoyed themselves at their expense. These parasites are little animals
which settle themselves on large ones, to suck in, without having
worked for it, the blood which the others have manufactured. The wolf
hunts, fights, and tears its victim in pieces; and then, by means of
that interior labor which I have spent so much time in describing,
transforms it into nourishing liquid: and when all this is accomplished,
the little flea, who lives hidden among his hairs, coolly draws out
for his own use the valuable blood obtained with so much effort. There
are many parasites in the world, my dear child--yourself, for instance,
to begin with--who are perfectly happy to chew your bread without
asking where the corn comes from which made it. But you have heart
enough to see plainly that this indifference ought not to last, and
that it is not honorable to go on living in this indefinite manner at
other people's cost only.

You will some day have duties to fulfil, which you should accustom
yourself to think of now, in order that you may prepare yourself for
them beforehand, so that it may never hereafter be said of you that
you passed through the midst of human society, taking from it all you
needed, without giving it back anything in return, I advise you to
conjure up this idea when the time comes to leave off playing and begin
preparing to be of use. The sort of thing is not always very amusing,
I admit, but you must look upon it as the ladder by which you will be
enabled to rise from the degradation of a parasitical life. If you
were in a well, and some one were to let down a real ladder for you
to get up by, I do not think you would complain of the difficulty of
using it. It is for you, then, to consider whether you would like to
remain for ever in your present condition; for those who learn nothing,
who _submit_ to nothing, who are good for nothing, but to show
off and amuse themselves--these remain parasites all their lives in
reality, however little they may sometimes seem to suspect it.

At your age, however, there is still no disgrace in the matter. God
shows us by the insects that little things are allowed to be
parasitical; but on this subject I must return to a point in the history
of animals which I touched upon before. I told you, in speaking of the
crocodile, that the perfect state of the inferior animals is found
represented in the infancy or less perfect state of those above them:
and I may say the same again with regard to insects. All the young of
the mammalia begin life as parasites, at least, as sucking animals:
for they all live at first on their mother's milk, which is nothing
more than blood in a peculiar state. But the name of parasite among
insects is generally confined to those which take up their abode on
the bodies of their hosts; though in common justice it might equally
well be applied to the gnat and his relations, who, when once full,
make their bow and are off, like the kitten when he has finished
sucking. Well, without meaning to find fault, if we descend to the
lower ranks of the mammals, we shall find among them many parasites
in the received sense of the word. You remember the pouch to which the
marsupials owe their odd name. The young kangaroo remains hidden for
months in the pouch of its mother, feeding continually all the time;
and it is then a strict parasite. During the four following months it
goes in and out, and strolls about between meals, like other young
ones of its class, and is then an animal at nurse affording thus a
twofold example of the tendency of the great Creator to repeat Himself
in His conceptions, here using for the infancy of the mammal the system
invented for adult insects--elsewhere repeating the butterfly in the
humming-bird, who may fairly be called a vertebrated butterfly, and
reproducing the gnat in the vampire-bat, which I look upon as an
enlarged and perfected revise of the original pattern, whence comes
the scourge of our sweet summer nights.

And now, surely, I have said enough about these parasites, whose very
name, I suspect, will make you shudder after my impertinent application
of it. Never mind: it depends entirely upon yourself to get rid of
whatever you find humiliating in the position I have hinted at. Do all
you can to bring happiness to the parents on whom you live at present,
and who give their life-blood so willingly for your good. God has made
you very different from those little animals who have neither heart
nor reason to guide them. Do not be like them, then, in conduct. By
a little obedience and love--child as you are--you can pay them back
what you owe, and they will never complain of the bargain.



LETTER XXXVIII.

CRUSTACEA--MOLLUSCA. (_Crustaceans and Mollusks._)

_Crustaceans._

Crustaceans consist of cray-fish, crabs, lobsters, and prawns, who may
be considered cousins-german of insects, among which more than one
naturalist has thought they ought to be placed. Like them they are
divided into _grinders_, having the same action of the mandibles;
and _suckers_, who are also parasites, and have tubular sheaths
containing stilettos. Mammals and birds are the victims of parasitical
insects; fishes have been reserved for the crustaceans, who do not
disdain also to fasten upon their humble neighbors, the mollusks; and
even among themselves the little ones settle down on the great. A few
live on land, but an immense majority in water, and seem destined to
represent, in the aquatic world, the aerial class of insects, from
whom, however, they differ in many ways.

The first difference is in that stony crust with which they are
enveloped, like the cockchafer in his horny cuirass, and which you
must know well enough if you have ever eaten lobster. Wherever we meet
with horn in insects, we find stone in crustaceans. The jaws are stony,
and the teeth of the stomach also. They are constructed on the same
plan, only the materials are changed.

The digestive tube is less complicated, and consists merely of one
large stomach, instead of that series of stomachs by which insects
approach the organisation of birds. On the other hand, if among some
of them the liver is reduced to simple tubes, floating loosely in the
body, as we have just seen it in the cockchafer among insects, these
tubes are generally so profusely multiplied, and press so closely
against each other, that they form a large compact lump--a true liver,
to sum up all--from which issues, as from ours, a _choledochian
canal_, a bile duct, _i. e._, which passes out into the intestine at the
entrance of the pylorus.

You recollect that canal of the liver which I was afraid to tell you
the name of because it was so ugly? Well, this is that formidable name!
Now that you have swallowed so many others, you must be strong enough
to digest this.

No chyliferous vessels have been found in crustaceans, whence one may
conclude that the chyle leaves the intestine by oozing from it, just
as it does in insects. There it gives rise to an almost transparent
sort of blood, a kind of sap, or lymph, which is put in motion by a
genuine circulation-apparatus; a real heart, with all its canals. This
heart has only one ventricle, and only sends blood in one direction,
as in the case of fishes; but there is an essential difference between
them, which we must point out. The heart of fishes may be called a
venous heart, since it only receives venous blood, which passes thence
to the gills, while that of crustaceans is an arterial heart. It
receives the blood directly it leaves the respiratory organ, and sends
it, not into one aorta, but into several arteries, which set out at
once, each in its own direction, to nourish the various quarters of
the body. This greatly resembles the system of circulation, with which
we are already acquainted. The veins only are unsatisfactory. They
form a kind of transition between the uncertain currents which convey
the blood of insects from one end to the other of the cavity in which
these strange organs lie bathed, and the closed canals of the higher
animals. But they are not canals, properly speaking. The irregular
intervals which separate the organs, more numerous here, are enclosed
by membranes, between which the venous blood pours, and naturally the
chyle also. The whole thus arrives at certain excavations formed at
the place where the legs are jointed on to the body--reservoirs, so
to speak--where the real canals come to carry it off and convey it
away into the gills.

It is, in fact, by means of gills that crustaceans breathe in their
character of aquatic animals. These gills are made nearly upon the
same model as we have already seen in those of fishes; and although
their form and arrangement differ in different species, yet the
principle is always the same: they are tufts of leaflets springing
from stems, up and down which run two tubes; one which brings the blood
from the venous reservoirs, the other which carries it to the heart.
Crabs, lobsters, and crayfish, who are the "file-leaders" of the
crustacean tribe, have gills enclosed in the body, as fishes have; but
the circulation of the water goes in a contrary direction to theirs,
as does that of the blood. Instead of entering at the mouth and going
out at the sides, as we have seen, it enters at the edge of the bony
shell which covers over the body and comes out near the mouth--a merely
accidental detail which does not in any way alter the play of the
apparatus. All these animals are equally adapted for swimming and for
walking, crabs especially, their gills accommodating themselves without
difficulty to contact with the outer air, as we have seen among certain
fishes; so that one might class them with amphibians. There is even one
crab who has acquired the name of _land-crab_, because, although he has
got gills, he dies in water, the small amount of air he can get out of
it at a time being insufficient for him, and who, therefore, lives
constantly on land. It is true that he seeks out damp spots, for his
gills would also fail him if they became parched, and, like the fishes
who make excursions on dry land, he is provided with an internal
reservoir, which is always filled with a certain quantity of water.

Some aquatic crustaceans have the labor simplified by external gills,
which hang down into the water, sometimes depending from the stomach,
sometimes from the legs. In France you sometimes see at a table certain
little animals, very like shrimps (_squillæ_), the bases of whose
hinder legs are fringed by slender tufts, which are in fact their
gills. They find themselves placed there just within reach of the
venous blood; for in the body opposite the bases of the legs are little
cavities in which it accumulates. Now these gills can only act when
under water, and so the squillæ dies as soon as he is removed from
that protecting element. For the same reason they cannot be kept long,
nor travel far, much to the regret of those who like them and live at
some distance from the sea.

There are other crustaceans, next-door neighbors of the squilla, whose
gills are still more simplified. Here the legs themselves are turned
into extremely thin plates, which play the part of gills, and are thus
organs for two purposes, serving at the same time to swim and breathe
with.

We have in our house one little crustacean, the only one I know of who
associates with men, and that is the wood-louse. You must know the
little grizzly beast, which rolls itself up into a ball whenever it
thinks itself in danger, and who would be taken for an insect by anyone
who was not taught otherwise. The wood-louse has neither gills hanging
down outside, nor anything inside her body which resembles the breathing
apparatus of her great relations. But, on examining her closely, you
will perceive all along her stomach a series of little plates, which
are her breathing-organs, and which come under the class of gills,
because, like other gills, they require a certain degree of moisture
to make them act properly. You will never, therefore, see a wood-louse
strutting about in the sunshine, where he would dry up far too quickly;
but if ever you get into a dark, damp corner, there you have every
chance of finding one.

Animals who breathe through their legs and through their stomachs! You
are astonished, and ask, What are we coming to? What would you say,
then, if I were to go really to the depths of the crustacean world?
We should find there such extraordinary beings as you can form no
notion of, for they all live down below in the sea, and have no special
breathing-organ at all, inasmuch as they breathe through the whole
surface of the body. Do not exclaim yet! I will soon show you one whom
you know perfectly well, and who has no other way of breathing.

But we must keep to the higher crustaceans, if we want to judge of the
class. By going too low, we run the risk of not seeing clearly. Animal
creation is here on a system of experiments: and they are so endlessly
multiplied, and exhibit such a profusion both of deceptive resemblances,
and of differences which disappear by transformations, that
classification no longer knows which way to turn. Worms, crustaceans,
mollusks; to which group do these and those belong? To which ever we
like to refer them, for these groups represent nothing definitely
determined in the plan of creation; and though easy to be distinguished
from each other in the higher branches, they become confused together
in the lower, like mountain summits which spring from a common base,
at the foot of which they are all united together.

On this account, my dear child, you will, I am sure, excuse me now and
henceforth, from entering into details of all the horrible beasts which
swarm in the shallows of the animal world, and whom learned men have
in their wonderful wisdom muffled up in terrible names, in order to
prevent children from coming near them! What would you have thought
of the poor little squilla, so prettily baptised by the fishermen, if
I had taught you that it belonged to the order of _Stomatopoda_?
You will scarcely be able to pronounce the word; but that is no fault
of mine, it is spelt so.

We will content ourselves, then, with having taken a glance at the
most clearly marked individuals; and as I said to you just now, it is
by them that we will arrange our inventory of the groups. Here, as you
may have already remarked, instead of continuing to wander from the
original model whose gradual deterioration we have been following all
this time from one class to another, it would seem that we are retracing
our steps, and regaining some portion of the lost ground. This is
because insects, as I have already stated, are an exceptional case--an
idea apart from the great general plan--a by-lane turning off from one
side of the great line of animal creation.

The crustacean, less perfectly worked out than the insect assuredly,
but more regular, forms, so to speak, the connecting line between that
tiny masterpiece of fancy, so incomplete in its exquisite organisation,
and the shapeless but better constituted lump of the mollusk, who
conceals under his heavy shell the sacred deposit of real organs, those
which we expect to find always and everywhere. An insect outside,
though less refined it is true, a mollusk within, the crustacean reminds
me of what among us is called an _amateur_--that mild lover of
the arts who holds a middle place, as it were, between the artist and
the common citizen.

I regret that you are not at present quite able to appreciate my
comparison fully: but put it by, in reserve, if possible, in your
memory; you will find out hereafter how just it is, and it will,
perhaps, help to prevent you from always setting the lively, noisy
artist, above the quiet and silent citizen. Let this, however, be
between you and me. If they could hear us talking, neither artist nor
citizen would forgive me, and the amateur still less.

_Mollusks._

There is one mollusk universally well known--namely, the oyster--so
we will choose him for discussion. To look on one's plate at that
little mass of soft, compact substance, one feels inclined to ask what
there can possibly be in common between it and us; and if you were to
declare that there was not the faintest trace of resemblance between
the organization of the oyster and our own, I should not be surprised.
Wiser people than you have been caught tripping there; not that they
were ignorant of the points in which the oyster resembled us, but they
paid no attention to them. Viewing it in other respects, they declared
that it was of a structure completely different to our own; and that,
in the construction of this machine, the Creator had worked upon a
particular plan, laid aside afterwards as useless for any other purpose.

I should like to get hold of one of those Academicians, with thirty-six
plans, and confound him before you, in proof of his relationship to
the oyster, by showing you at one sitting that there is an oyster in
himself; nay, further, that he is nothing but an oyster, revised,
amended, and considerably enlarged. And do not imagine that I am only
using a figure of speech here, as the professors of rhetoric call it;
which would be in bad taste: I am speaking literally, and to prove the
existence of the oyster in question in our Academician, I shall only
ask permission to perform a slight operation upon him. You exclaim at
this; but do not alarm yourself, for it is only an operation on paper,
he will not die from it. See now, I cut off his head, his two arms,
and his legs; I take out of his body the vertebral column and the ribs;
I gently place what remains between two shells; and ... there is my
oyster. I willingly admit that it is more carefully elaborated and
richer in details than its sisters in the oyster beds; but all the
principal organs are to be found in them also, and they positively are
beings of a similar construction: you shall judge for yourself.

The mouth--for there is a mouth, though one must look closer than the
oystermen do to discover it--the mouth is exactly what the gullet
(oesophagus) would be in a man whose head had been cut off; that is,
a truncated tube. Then comes the stomach, situated in the very midst
of the liver; which latter may easily be distinguished, even by the
most cursory glance at luncheon, from its dark color. The intestine
also goes right through the liver, doubling backwards and forwards
several times: and thus the digestive tube supplies itself with bile
from the cask (to borrow a commercial expression); and this saves the
expense of a bile-duct (choledochian canal), which would be an
unnecessary mode of conveyance in this case. The animal lives in water;
consequently, instead of lungs he has gills: [Footnote: The land-snail
has lungs.] these are those thin, finely-streaked plates which make
a fringe at the very edge of the shell. Finally, on leaving the gills
the blood is received by an arterial heart, with only one ventricle
like that of the crustaceans, in the shape of a small pear, similar
to ours, having an auricle, and an aorta, branching out so as to
distribute the blood throughout the whole body. And now what do we
find here, let me ask you, in this mutilated man, reduced to the soft
portions of the trunk, whom I have been imagining? A heart, with its
arteries; lungs; a liver; an intestine; a stomach and an oesophagus:
that is to say, merely and simply the organs of nutrition. That is
all, or very nearly so.

As you perceive, then, all the elements of our own feeding-machine lie
between the two shells of a mollusk; in a rough state as yet, it is
true; incomplete, and unruly; as in the case of the intestine, for
instance, which in many of these creatures passes without ceremony
through the heart: but even so they are quite sufficiently indicated
to prevent their being mistaken. Now this machine, it is in vain to
deny it, is the animal itself; but it lives at first, and it is this
which dies in it last. The other matter (the locomotive power),
important as it may seem to us in higher races, only holds a secondary
position in reality: the proof of which is, that here is an animal
reduced absolutely to a mere feeding-machine, who still lives, whilst
there yet remains to be found one who has nothing left but his
movement-machine, and who can yet exist. We cannot disown this primitive
animal, for we have it within ourselves; lost, so to speak, in the
midst of the accessory organs which are successively added to it in
proportion as we rise in the animal scale, but still preserving its
own life, its personality, if I may use the expression. Listen to this,
for here is a history well worth hearing.

I will explain to you, hereafter, how all the actions of the
movement-machine are performed by means of a network of nervous threads
(filaments), whose centre of impulsion is in the brain. How our will
acts upon the brain, and gives its orders to the muscles through the
nervous fibres, I will not offer to explain: it is a fact, let that
suffice us. You say to your foot, "Forward!" and off it starts; "Halt!"
and it stops. Here is an organ under command, a servant of the brain,
where we rule ourselves: with or without explanation, no one will ever
dispute this. The oyster, who has neither head nor brain, has, as his
only instrument of action, certain little masses of nervous substance
scattered right and left, which are called _ganglions_. These
communicate with each other and with the organs by nervous cords, which
are interlaced in all directions, without having any common centre,
and which give the impetus to all parts of the animal.

Well, the human oyster presents to us exactly the same nervous
organisation. It has its ganglions and its nerves to itself, which are
put into communication with the brain by some threads strayed among
his own, but which are not under its orders, and which treat with it
on equal terms. You remember, perhaps, the little republic talked about
when we first entered the digestive tube; you have now the explanation
of it. This republic is the original animal; it is the feeding-machine.
I cannot describe it, and the kingdom of which you are queen, better
than by comparing them to two States having diplomatic relations with
each other, who exchange dispatches and reciprocal influences; and as
to the importance of these respective influences, if one were to compare
them I scarcely know to which side the balance could incline.

We shall return elsewhere to this detail, one of the most interesting
of our organisation, and which here finds its natural explanation. For
the present I will content myself with reminding you that, since the
earliest days of human civilisation, all philosophers, all poets, and
all moralists, whether sacred or profane, have borne witness to that
double life within us, that inward being, blind and deaf, whose
disordered impulses so often carry trouble into those higher regions
where will and reason sit enthroned. Behold him taken in his lair at
last, this mysterious being. I have just unveiled his origin to you.
And here, dear child, I must shelter myself behind a profession of
faith. There will not be wanting people to tell you that it is degrading
man far too much to look so low for the sources of his organisation,
and that this sentence--_the human oyster_--which expresses my
idea so well, is neither more nor less than blasphemy. Let them talk,
but adopt their opinion only when they have proved to you that man had
a special Creator, and that the oyster came from a different hand from
ourselves. I should like to know with what face we could venture to
complain, poor worms that we are, because it has seemed good to our
common Father to carry forward in us his previous creations, and in
what respect human dignity would suffer from this contact with a being
who, like us, is one of the works of God. That human pride may suffer
thereby, I admit, and I am glad it should; but if God has included all
creation in His love, we may well include it all in our respect. Whence
comes our superiority at all, but from the gratuitous gifts of Him who
has made us what we are? Is it to lose it, then, to find ourselves
side by side with inferiors whom the Divine benevolence has visited
like ourselves? Surely not. But enough of the oyster, who has never,
that I am aware of, heard such strange discussions sounding in his
ears before. I have no time nor courage now to speak of the other
mollusks, who offer more or less the same system of organs which I
have just described. I must hasten on to the Worms, who give us the
last clue to the great enigma of the animal machine.



LETTER XXXIX.

VERMES--ZOOPHYTA. (_Worms and Zoophytes_).

_Worms._

The worm of worms, the one you know best, is the earthworm: so he shall
have the honor of representing his group.

He will not take much time to describe. He is, in brief, a tube, open
at both ends, so as to allow food to come in and go out. That is all.

I talked to you before about the ruminants, those food-manufacturers
who are employed in cooking victuals for the stomach, and in disengaging
albumen from the coarse materials among which it is apparently lost,
so as to give it out again in a more acceptable form. The ruminant has
other workmen under him, whom I keep in store for you as the last of
the eaters, and who prepare the raw material for him*. These are the
vegetables, who seek out the elements of albumen in earth, water, and
air, those final sources of all alimentation. The earthworm also is
a _preparer_, but in a peculiar way. Look along the garden-walks
in summer-time, after rainy weather: you will see here and there,
little heaps of earth moulded into small sticks, like dough which has
been passed through a tube. [Footnote: M. Mace's account of the
earthworm's life seems founded on the assumption that it extracts its
nourishment from the earth itself, i.e., from inorganic matter, as
_vegetables_ do, to use his own words. But this notion is so
entirely at variance with present received opinions, and also with the
fact that the animal possesses a gizzard for digesting, as well as an
intestinal canal, that it has been necessary to make considerable
alterations in the description. To dismiss his theory of the primitive
animal, etc., altogether, was, however, impossible, without omitting
the whole chapter; but as young heads are not likely to trouble
themselves about it, and it is very innocent in itself, it will do no
harm; subject to this warning, that M. Macé has taken the earthworm
for a more simply organised creature than it really is.--TR.] This is
the damp soil which the worm has passed through his tube, after
extracting from it, during its passage, the various elements of
fertility he requires for the support of his life. This is what makes
him so particularly fond of garden soil, because it is richer in animal
and vegetable matter than common earth, and proves therefore more
nourishing food. The worm, then, feeds on the fat of the earth, which
he converts into azotic aliment for the use of moles, hens and Chinese.
It only figures, it is true, for want of something better, in Chinese
cookery, so profusely hospitable for all that; but the hen doats upon
it, and you do not despise it yourself when it comes back to you in
the form of a chicken's wing, that second transformation of the matter
of which the soil of your garden is composed. It is told of certain
savage tribes, the victims of constant scarcity, that they swallow
little balls of clay in order to keep down their hunger; and during
the great famines in India the distracted inhabitants may, we are told,
be seen digging up the banks of the rivers to feed on the fertile clay
in which the splendid vegetation of their country is developed. This
is a desperate trial of that primeval system of alimentation which
answers perfectly with the worm, but becomes a cruel mockery in the
case of an organisation as exacting as that of man. Let us examine a
little more closely, then, this wonderful tube.

At first sight one notices, to begin with, that it is composed of
perfectly distinct rings, all quite alike. Inside as well as out each
of these rings is an exact repetition of the other. They are all formed
of circular muscles, enclosed between two coats, which extend from one
to the other. A series of ganglions, arranged in the form of a necklace
along the whole length of the body, set in motion the muscular system
of the rings, each of which possesses its local centre of impulsion.
Each feeds itself in its place from the nourishing juices with which
it is in contact, the interior coat enjoying the double property of
distilling digestive juices and absorbing digested ones. These juices
pass through the muscular partition, and proceed to bathe the outer
coat, which plays, at the same time, the part of coat and lung, and
affords a passage to the air through its soft, damp surface, like that
of gills. From all this results a fine red blood, such as we have not
met with since we left the reptiles, and which is manufactured in all
parts of the body at once.

Each of these rings, then, the worm's only organs, is a little eating
machine to and for itself, and at the same time a little movement
machine also; in fact, a complete animal. Each one could, if necessary,
nourish itself and live apart; and this is what he really does. Learn
hence, to despise nothing in nature. One tramples an earthworm under
foot, and there below one's heel lies a little revealer of secrets,
whose organisation throws the most unexpected light upon one of the
greatest mysteries in our own life.

I said to you before, and I felt at the time that it was rather beyond
you, that "each one of our organs is a distinct being, which has its
particular nature and special office, its separate life consequently;
and our individual life is the sum total of all these lesser lives,
independent one of the other, but which nevertheless blend together,
by a mysterious combination, into one common life, which is diffused
everywhere, but can be apprehended nowhere in particular."

The study of the worm admirably explains this out-of-the-way sentence.
And here observe my adjective--my out-of-the-way--for it is a case in
point. We may call it a literary worm; a worm of four rings, each
perfect in itself, but yet compounded together into a whole with its
own idea.

That which makes this idea of life most difficult to comprehend is,
that one cannot prove it by a direct experiment, since there is not
one of our organs which could exist separately from the others. Although
independent in their special action, yet these multiplied lives are
nevertheless in a state of absolute and mutual dependence, from the
imperative need they have of each other to make them act, each having
for its share only one particular function, the effect of which extends
to all the others. This is called the division of labor; and if you
still do not understand me clearly, I will explain it in another way.
The heart sends to all the organs--does it not?--the blood, without
which they could not live: separated from the heart, the lungs would
die immediately. It is to the lungs the blood goes to find the air,
without which it could not maintain life. Separated from the lungs,
the heart would die immediately. There is nothing belonging to us which
can avoid the inexorable requirements of blood and air;
consequently, there is nothing which can live an isolated life.

I will borrow a simile from human society which you will understand
at once. In civilised countries, where division of labor is established,
the tailor makes clothes, the mason makes houses, and the baker makes
bread. If you could throw them each alone by himself into a wood, the
mason would not be able to dress himself, the baker would sleep in the
open air, and the tailor would not know how to make bread. Or rather,
as not one of them can carry on his trade without the co-operation of
a multitude of hands, they could none of them do anything at all. Each
completely independent in his work, yet each dependent upon the others,
both for living, and even for being able to work, our workmen can only
act when they remain bound in close union with the vast society of
which they form a part; and our organs--those other laborers whom you
have seen working for so long--our organs are just in the same
predicament. But in the primitive societies, among savage tribes, where
each man can make his clothes, his house, his bread (when he has any),
and everything else for himself, you might take such an individual if
you liked, and separate him from the rest of the tribe, and he would
go on living as before. And so with the rings of the worm, that
primitive society of organs. Each of them is a universal workman, who
knows how to make everything. Separate him from his fellows, it will
not disturb him at all, and he will go on living as if nothing was
thematter.

I still remember some profound reflections I indulged in one day some
years ago whilst leaning on my spade and looking at a worm that I had
just cut in two, and whose two halves were walking off one on each
side.

"There was only one creature here just now," I said to myself, "and
now there are two! Have I had power, then, to create one with a stroke
of the spade?"

I had not then got hold of the key which I now give you, and to which
no possible objection can be raised. If there are two beings after the
stroke of the spade it is because there were two before. Nay, there
were even many more, if we may trust to the "Manual of Zoology" by
Milne Edwards, a very good book, excellent for an old scholar like
myself, and which I have found very useful in my country-home, as it
has enabled me to relate to you one after another the mysterious wonders
of life.

He says that, "if one cuts an earthworm across into two, three, ten,
or even twenty morsels, each of these morsels will go on living in the
same way as the whole, and will form a new individual."

Twenty! that seems to me a great many, because, as far as I can trust
to my brief observations as a gardener, it is necessary that some of
the rings should remain united together and afford each other mutual
support, in order to succeed in repairing the bleeding breaches; but
I would much rather believe it than try the operation. My mind is easy
when I am defending the plants that I have sown in my garden from the
gluttonous worm who would rob them of their food; but it would not be
so if I were cutting them up on my table to learn something about them.

Besides, there is no need of an operation to convince oneself of the
particular life of each ring. There is one worm, well known by name
at least, though happily not to be met with every day, and that is the
tape-worm, who establishes himself in the intestine of man, and lives
on the chyme, as the other worm does on garden-mould. They call him
the _Solitary_ worm in France; and if ever one might suppose a
creature appropriately named, it would surely be him; for certainly
there is not much society to be looked for in the dwelling he chooses
for himself! But it happens that this pretended _solitary_ worm,
with his unlimited chain of rings, is only a long row of perfectly
distinct beings, so distinct indeed that, from time to time, some of
the rings let themselves go, fall off like ripe fruit, and go away to
live elsewhere, ready to become the nucleus of a new set, if a happy
accident carries them into another intestine, the only place favorable
to their development.

At last, then, here is a corner of the curtain raised; here we see the
associated organs which constitute an animal, living for once a life
positively and in all respects their own. We are now satisfied about
this; and when at another time we find them bound together in the
chains of a union too ingenious to be severed with impunity--which we
shall discover by seeing their action stop at the moment of
separation--we shall know the cause.

Do not think, my dear child, that a wretched earthworm can prove nothing
as regards other creatures. The worm is the starting-point of all the
organisations which come after him. Of what is he composed? Of a
tubewhich is itself composed of rings. Well, it is upon this very tube
that the whole animal machine has been founded: and these rings, as
they expand and modify themselves in a thousand different ways, give
birth to all those varieties of being which drive classifiers to
despair, because they will not understand that there ought only to be
one animal, since there is only one Creator of animals. Now, this
animal is a digestive tube served by organs; it is a worm, _i.e.,_
which goes on constantly embellishing itself. I said to you long ago,
and at a time when you scarcely knew anything, "Have you ever observed
a worm or a leech in motion? You see a successive swelling up of the
whole surface of its body as the creature gradually pushes forward,
as if there was something in its inside rolling along from the tail
to the head. Such is precisely the appearance which the oesophagus
would present to you as the food passes down it, if you had the
opportunity of seeing it in action; and this has been called the
_vermicular_ movement, in consequence of its resemblance to the
movement of a worm."

And afterwards, in speaking of the intestine:

"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 have now got hold of the secret, namely, that from the beginning
to the end of the digestive tube, its movements are those of a worm.
What a wonder! and that the worm is a digestive tube which can walk.
This worm, or this tube, whichever you please to call it, has never
ceased crawling under our eyes since we began this study. Lost sight
of in man in the midst of the riches he has picked up on his road,
invisible and coiled backward and forward in his palace like an Eastern
despot who leaves everything to be done by his slaves; behold him here
in his first stage naked, shivering in the air, forced to go off himself
and alone to his pasture--ground! But in the coarse earth with which
he fills himself I can already see the delicate chyme which his numerous
servants will prepare for him later on, and into which the heart-tree
will one day send down its roots--the chyliferous vessels.

A short time ago I called the oyster the primitive animal, but I was
in too great a hurry. The worm is the real primitive animal. He is to
be found in the oyster, as the oyster is to be found in us; and that
poor little beast is, by comparison, an animal of high pretension, who
would be shocked, I am sure, if he could understand what we are saying,
and heard us assert that he is nothing but an embellished worm.

_Zoophytes._

Two centuries ago it was believed that below the worm, animal life,
properly so called, ceased, and the creatures whom I am about to
introduce you to were supposed to be animated plants rather than living
organisms. Hence their name was especially chosen to express that
double nature by which they were thought to have a share in two kingdoms
at one time--viz., the animal and vegetable--_zoon_ in Greek
meaning animal, and _phuton_ a plant. Zoophytes were set down as
animal plants.

And although later discoveries have long ago established the fact of
the complete animality of zoophytes, the old name is still in general
use. But you must not let it deceive you. Zoophytes are animals every
inch of them, however low in the organic scale, and although many of
the compound ones imitate the growth of plants and shrubs so exactly
in their mode of spreading that it is only by the closest observation
we can persuade ourselves they do not belong to the vegetable kingdom.
Of these there are the delicate buff-colored, prettily-branched, horny
specimens found on the shore, which make so beautiful a variety in
seaweed pictures among the red and green colors of the real seaweed;
but of these also are those wonderful stony shrubs which grow on the
submerged rocks of islands in warm seas, and the material which you
know so well by the name of coral--the very coral of which the necklaces
and bracelets in the jeweller's window are composed.

In all cases of compound zoophytes, however, there is one great point
which they have in common with the worm, viz., that there is an
association of distinct lives acting unanimously; or, rather, to the
same end. Plainly as this is seen in the worm, it is still more obvious
in the zoophyte. There is no need here either of cutting them up
yourself or of taking other people's dissecting operations upon trust.
It is enough to use your eyes, with the help, it is true, now and then,
of the microscope's clearer sight.

You know the old oak-tree which stands on the outskirts of the wood,
and is called among the country folk _the patriarch_? Now, this
is clearly not an individual, but a nation. It is not a tree; it is
a forest. Nay, may I not call it a green field? For this trunk, so
truly venerable from ages of growth that one feels inclined to bow to
it as one goes by, is, in fact, a collection of structures, accumulated
by countless generations of fleeting herbs, _i.e.,_ leaves, not
one of which has lived for the space of a whole year round. Every
spring some thousands and thousands of buds open to the sun; each one,
therefore, affording a passage to a little green point; and this point
is an oak, who comes into the world, like the first oak, the grandfather
who formerly came forth from an acorn, under the form of an herb or
tender leaf, which a sheep might have browsed upon. Yet it is so
thoroughly an oak, that you have only to take out the bud carefully
before it has expanded and fasten it into another one's place upon a
tree of the same family, though of a different species, and it will
produce an oak of the same sort as its old companions, and which will,
as it progresses, look quite a stranger among the indigenous branches.
This is the secret of what the gardeners call _grafting_, and I
advise you to try the operation upon rose-trees, for nothing is more
amusing. When the autumnal frosts set in, all these troops of new
little oaks die, and deliver up their leaves to the wind; but they
leave behind, as their summer's work, a tiny morsel of new wood, upon
which, if you look carefully, you will see a fresh bud dawning--the
hope of the coming season. And thus the great life of the tree is
perpetuated from century to century by an uninterrupted succession of
transient lives, reminding one in all respects of the life of a nation;
and the similitude is complete in the evergreen trees, where the new
leaf makes its appearance before the old one has quitted the stem.

And such is the life of the great stone trees and shrubs of various
kinds which grow under tropical seas, and whose makers and inhabitants
are the coral polyps, the undoubted heads of the Zoophyte race.

But before considering the _polypidom,_ or external dwelling
(otherwise called the _coeneciun,_ or "common house"), you must
learn something of its originator, the little _polyp,_ who lives
inside, and belongs to a family so widely spread over the face of the
earth, that there are scarcely any waters, whether salt or fresh,
without them.

In your own neighborhood, if you know how to look for them, are to be
found on the banks of ponds, or along the borders of streams which lie
sleeping in roadside ditches, extraordinary beings which, a hundred
years and more ago, completely bewildered the good Dutch naturalist
Trembley, who had taken it into his head to study them. Picture to
yourself some very tiny bags made of a kind of jelly; gray, brown, or,
most commonly of all, green in color, always transparent, and fastened
by their base to the stalks of _carex,_ water-lentils, or the
confervas, which grow in still water. A hunter on the watch, this bag
shoots out on all sides a number of slender threads, like so many
whip-lashes, arranged within a circle round the edge of its opening
or mouth; and with these whip-lashes all the animalcules which come
within reach are entwined, stifled, and carried away to the ever-yawning
little gulf, where they are digested in less than no time. Whatever
will not digest comes out afterwards by the way it went in. Of what
becomes of the results of this digestion it is impossible to form an
idea. Were you to cut up the bag and put little morsels of it under
the best microscope possible, you would see positively nothing but
solid jelly, without the least sign of any organisation whatever. But
this is not all. Replace these morsels in the water, and come back
tolook at them at the end of five, twenty, or thirty hours. Each one of
them will have become a perfect bag, ready to multiply itself afresh
if you submit it to the same operation. Sometimes, on some part of the
original bag, there suddenly appears a little raised spot, like that
which came on your baby brother's arm the other day after he had been
vaccinated. What would you have said, if this ugly spot had grown
larger and larger without stopping; if it had assumed legs, arms, and
a head, and so become another baby, growing from the arm of the first
one? Yet this is just what the spots do which come on the bag I have
been telling you of; and people have come across bags of a larger
species still--between one and two inches in size, in fact--which in
this way carried twelve young ones on their backs, if one is allowed
to talk of stomachs having _backs_. You perceive at once that
this commencement of animal life is not even a digestive tube, and
that nothing in it can be found but a stomach, opening straight to the
air above and closed up below.

It was Réaumur, the originator of the famous thermometer, who gave a
name to the wonderful bags discovered by Trembley. Aristotle had
previously bestowed the title of _polypus_ (many feet) upon a
mollusk outwardly formed upon a similar model [Footnote: This is the
cuttle-fish, called _polypus_ by old naturalists. We shall speak
of it fully hereafter in the history of the movement machine.] with
large whips disposed regularly in a circle round the mouth, and intended
for a similar use, only that they have another function besides; that
of carrying the body along in the capacity of feet by clinging on to
the rocks with their suckers as they go. Réaumur transferred this name
to the newcomers, and called them fresh-water polyps, to the infinite
amusement of Voltaire, who had declared that they were only blades of
grass; a new proof, among many others, that in natural history all the
intellect in the world is not worth a pair of good eyes.

But it was soon found out that, in collecting these bits of living
jelly near the Hague, Trembley had laid his hands on little beings of
immense importance on the surface of the globe, and that he had
discovered under his microscope the explanation of a mystery which had
spread itself, setting human science at defiance, over some thousands
of square miles.

I talked to you just now of the jeweller's coral, of which ornaments
so becoming to dark-haired people are made. That is one of the stony
polypidoms I spoke of as stone trees found at the bottom of the sea,
where it grows attached to the rocks in the form of a charming little
shrub, stretching its red branches in all directions. The Greeks, who
were never at a loss, relate that Perseus one day laid down upon the
sea-shore the famous head of Medusa, the sight of which had the property
of turning everything to stone, and that the nymphs, in sport, showed
it to the coral shrubs; a fact which explained everything quite
naturally. Without exactly holding this mythological explanation,
modern philosophers had not got much farther, and coral was still a
puzzle to them, which they were not fond of troubling themselves about;
till, roused by Trembley's revelations, they examined it more carefully,
and discovered in its soft extremities (hitherto unnoticed) those same
living jelly-bags or sacs, with their circlets of legs, or rather arms,
charged with supplying them with food. These were marine polyps, which
grow, like those in fresh water, one upon another, but each in its own
crusty cell; and like the buds of the oak, these buds of the stony
tree form each its special deposit, which it bequeaths in dying to the
general mass. In short, as the tender shoot of the oak is filled by
degrees with the wood which forms within it, and hardens into a branch,
that goes on increasing by perpetually new growths, so the jelly polyp
of the polypidom hardens below into stone and dies incessantly at the
base, while it lives on indefinitely above in its constantly-renewed
summit.

Do not get tired of all this phantasmagoria, my dear pupil: it is a
matter of the highest interest. Here is the point of junction--the
bond, as it were, between the three kingdoms: an animal growing
vegetable-wise produces a mineral mass, extracted from the waters of
the sea by an infinity of little living crucibles, who carry on under
our eyes the work begun in the first ages of the globe, and quietly
manufacture continents for the use of future generations. This ought
to console you, my dear child, for being little. It is by little things
that God loves to effect what is truly great. He did not seek out the
elephant or the whale to form these worlds; He chose workmen no bigger
than a pin's head. I have spoken to you about jeweller's coral, which
is made into toys or presents for ladies to adorn themselves with; but
its brethren, the madrepores of the Pacific Ocean play a very different
part. They have formed in front of the shores of New Holland a barrier
of reefs three hundred leagues in extent and twenty wide. What are all
our buildings after this?--those pyramids and cathedrals which seem
so gigantic to us? This ever-increasing wave of coral polypidoms will
one day shut against navigators the entrance to one part of the sea's
tropical region; and lands not to be found on the map to-day will then
lie stretched out under the sun, covered with plants and animals; and
this in places where ships now plough the ocean. Know, also, that a
great portion of the soil which we tread under foot has no other origin.
It was manufactured formerly in the sea by infinite myriads of beings,
often infinitely small. Each one, whether polype or shell, produced
its grain of stone, and from all these grains God, who directed their
work, has made our country.

But it is time to bring this chattering to a close, for it will never
end if I do not force myself to stop. I leave it with regret; but all
these paths through which I have threaded my way one after another
without counting them, have already made a volume which may possibly
be considered too large for you. There are many other zoophytes besides
the coral polypes, and all of them beautiful and curious. They all
inhabit the fertile depths of the waters where God has deposited the
first germs of life. I cannot describe them to you now. But to make
amends, I will give you a piece of advice which will perhaps make some
people stare. Ask your papa to lend you Michelet's book, _The Sea_,
and look there for what is said about the mysterious animals which lie
hid beneath the waves. His book was not written for you as this one
is: and if, in spite of all my good intentions, I have not always
succeeded in being as comprehensible as I meant to be, Michelet, who
never thought about little people when he took up his pen, will
certainly startle you now and then. But do not be disheartened by a
word. You will find there, that which will be forever plain to you,
the poesy of nature, and children comprehend that better than learned
men.



LETTER XL.

THE NOURISHMENT OF PLANTS.

One more word before we part about the last of the eaters, about
Vegetables. They will furnish you with a new and very clearly marked
proof of the uniformity of the fundamental conditions to which the
Author of life has subjected all organised beings.

Let us look once more at this oak, of whose manner of growth I was
obliged to give you a sketch beforehand, in order to show you the ties
which unite it with its immediate neighbors in the animal kingdom. How
does it feed? I need not tell you this. It feeds by its roots, which
suck up in the bosom of the earth the water charged with the juices
which form its nourishment. Are you aware that every large branch had
its subterranean fellow or representative, and that the annual shoot
at the top of the tree is reproduced at the base by fresh fibres, which
extend themselves in the soil of the earth, in proportion as their
sisters above make their way in the air? And thus, by means of organs
ever young, the life and progress of the great association is kept up,
while those members whose day of work is over still remain there as
the supports of the edifice. It is the same with human societies. They
are sustained by what is old, but they live and progress only by what
is young. The sap, then, which is the name given to the moisture or
water sucked in by the young roots, having once got into the cells of
which the tissue of the fibres is composed, passes from one to another,
and travels thus to the top of the tree, where it is wanted by the
leaves.

There is no obvious machinery here, however, to impel it forward. It
journeys on of itself, as it were, under the action of laws which have
never been satisfactorily explained, but all of which are dependent
on the vital force or life-power of the tree, inasmuch as without it
there is no circulation. One agent, but by no means the principal, or
it would act as well in a dead tree as a living one, is _capillary
attraction_; and, if you wish to know what that is, you have only
to think of what happens to a towel, if you hang it upon a peg, and
leave the end of it soaking in water. Does not the "wet" seem to climb
up it thread by thread, till it is damp from one end to the other? A
little in this way--but these similes are very imperfect, and will not
bear close application--the sap rises in a tree, stealing up branch
by branch; and it is then called _ascending sap_. [Footnote: M. Macé
speaks of this sap as the _blood of the tree_, and of the leaves only as
_lungs_. These statements have been modified so as to meet the fact that
_ascending sap_ consists of, and conveys the raw elements of _food_ to,
the leaves; that in the leaves this food is _digested_, as well as
brought in contact with the air, and that it is thus converted into that
nourishing fluid, the _descending sap_, which certainly plays the part
of steward to the tree as our blood does to us, and therefore may now be
called the blood of the tree. It must be remembered, however, that each
tree has its own sort of steward, as the case of the _Euphorbia_ (quoted
afterwards) plainly shows. The analogy with the more general substance
of blood is therefore not very complete.-TR.]

It arrives at last at the leaves, which it enters as our food enters
our stomachs, and for the same purpose; for in them takes place, as
in all true stomachs, that process of digestion by which the elements
of the crude sap-food are decomposed from their first condition, and
converted into a nourishing chyle; in each tree of a sort "after its
kind."

But more than this. Like the outer coat of the earthworm, the coat of
the leaf affords a passage to air and moisture through its surface;
and here, therefore, takes place that mysterious exchange which is
everywhere the essential condition of life. Here is the charcoal-market
as before, only the bargainers have changed parts. The air, which in
the other case received the _carbon,_ delivers it up, now, and
receives oxygen in exchange; exactly the reverse of its traffic with
animals. In other words, the tree inhales through its leaves the
carbonic acid gas thrown into the atmosphere by our lungs. On its own
responsibility it breaks through the alliance between the carbon and
oxygen contracted in our organs; keeps the carbon for its own use, to
restore it to us another day under the form of wood, or, by the aid
of the charcoal-burner, in the pure and simple state of charcoal; and
sets at liberty the oxygen, which once more goes off in search of new
lungs and a fresh alliance. Thus a constant equilibrium is maintained
in the atmosphere; and thus, by a system of perpetual rotation or
everlasting merry-go-round, the same substances serve, indefinitely,
to support life of every opposite description.

Now there are two things to be remembered in this inverted respiration
of vegetables. In the first place, it occurs only in the parts which
are _green_. Flowers, fruit, the root, and every part of any other
color, do as we do when we breathe; _i.e._ deprive the air of its
oxygen, charging it with carbonic acid instead. For which reason,
by-the-by, we ought not to keep flowers in a bedroom at night. Charming
as they are, they are _poisoners_, and a headache is what we may
fairly expect after sleeping shut in with them in the same room. It
is almost as bad to allow green boughs to remain there either, for,
in the dark, even the green parts cease to purify the air, and begin
like the others to manufacture carbonic acid, at the expense of course
of their carbon, which thus by degrees is used up. Now, as it is the
carbon which constitutes the solid fibres of plants and produces their
green color, they soon become yellow and limp when deprived of light.
You may, perhaps, have wondered why the gardener amused himself with
smothering his poor lettuces by tying them up at top like a knot of
"back hair," instead of letting them grow freely in the air and
sunshine. It is, my dear, to make them more tender and delicate for
you to eat; and those beautiful, crisp, yellow leaves, so delicious
to the tooth, would have been green and tough, had they not slowly and
quietly let out a great portion of their store of carbon in darkness
during the last few days, before being gathered. Even without playing
the gardener, you may assure yourself of this fact in a still more
simple manner. Put a flat board upon the lawn and leave it there for
three days; then take it up again, and you will find just where the
board has prevented the light from reaching the grass, a yellow mark
so distinctly traced as to be seen from the other end of the garden.

But to return to the sap, which we left undergoing a change from air
and solar influences in the leaves. The ascending sap was to all
appearance only clear water. When it returns from the leaves, charged
with carbon, it is a thick juice having almost the consistency, and
sometimes even the color of milk, and is possessed of properties
altogether new. The most striking example that I can give you of
thedifference of the two states of sap is the Euphorbia of the Canary
Islands, whose digestive or descending sap is a violent poison. When
the natives of the country are accidentally pressed by thirst, they
carefully remove the bark in which the fatal juice circulates, and are
then able to refresh themselves safely by sucking the stem, which
yields only the watery sap sucked from the ground, and as yet unaltered
and harmless.

Each of these two saps, in fact, has its path distinctly traced for
it: the first rises through the wood, the second descends through the
bark, whence it is called descending sap. If you wish to satisfy
yourself of this, fasten a rather tight knot of pack-thread round a
young branch, and after a time you will see it pine below the knot and
become swollen above it, an unanswerable proof that the nutritive
juices flowed downward through the bark; for the wood inside the branch
will have been uninjured by the strangling pressure. Remember this,
my dear, when you are playing in the garden, and do not injure the
bark of the young trees your father likes so much to see flourishing.
It is by the bark that they are nourished, and you might even kill
them by treating it too roughly.

And now I must show you how the nutrition is carried on, or, if you
like better, how the tree grows by means of this descending sap. See:
here is a fir tree, which has just been cut down to the ground. Now,
if you like, I will tell you in a moment how old it is. I will even
tell you the age of every branch, little and big ones both, without
making a mistake in a single year; and you know as well as I do that
I am no conjuror. You see these small circles so delicately drawn, as
it were, upon the face of the sawn trunk, each wider than the last,
as if they were composed of a set of tubes, of unequal sizes, fitting
exactly into each other. Now count them; and you will perhaps find
twenty-five; and as each of these circles represents the work of one
year, you will know that the tree is twenty-five years old. In spring,
when the sap begins to move more briskly, it deposits everywhere between
the wood and the bark, from the trunk to the farthest boughs of the
tree, a uniform layer of a thick liquid, which moulds itself exactly
upon the wood already formed. This layer stiffens during the year; it
gets filled with the carbon left in it atom after atom, by each drop
of the descending sap as it goes by, and thus insensibly becoming
organised and hardened. When winter arrives to interrupt the work, it
will have formed two _ligneous, i.e._ woody layers, as they are
called. Of these, one belongs to the wood, and will never move again
so long as the tree lasts, for it will be covered over, and as it were
buried, by the successive layers yet to come; while, on the contrary,
the other (layer) belongs to the bark, and is doomed to find itself
perpetually forced outwards by the fresh layers, which will after a
while insinuate themselves between it and the wood.

It is for this reason that the bark of old trunks of trees is so deeply
furrowed, and that the dry scales may be picked off the surface without
the slightest injury to the tree. It is part of the original bark,
dead long ago. The old wood also is dead inside, and even when it is
altogether gone, the glad youthful branches growing green in the
sunshine will scarcely find it out! This accounts for those oaks which
time has hollowed without destroying, as those of Allonville in
Normandy, in which mass is said, and which is moreover the greenest
tree in the country. But without going so far, who has not seen those
hollow old willows, sometimes pierced with holes letting in daylight,
yet proudly crowned above by a forest of young boughs, as green and
full of vigor as if the trunk were still in its prime? What was dead
has departed, but all that has life in it remains, and that is enough
for the tree.

Need I add that the descending sap, this steward of the vegetable, has
also his workmen to supply with materials, as in our case, and that
he is always falling in on his road with organs, all of which want
different things from him? That here a flower has to be formed, there
a fruit, there a leaf, or a bit of wood, and so on: and that a
mysterious intelligence--the same that we have found everywhere
else--presides over all these varied constructions, the materials for
which are mixed together pell-mell, in the imperceptible thread of sap
which oozes from the leaf to the bark? I recollect just as I am about
to conclude, my dear child, that I once told you, you were a small
temple in which God perpetually attests His presence, by a permanent
miracle. You may now henceforth look upon a tree as something more
than a bit of wood, yielding a pleasant shade. God is in it also.


CONCLUSION.

And now, my dear little pupil, to what conclusion do we come from all
this? To that which I announced to you from the first. Throughout the
length and breadth of creation, from the highest to the lowest grade,
every living thing is subject to the same law. Everything eats, and
eats nearly in the same manner, since everywhere the same substances
furnish the feast. I laid down in my first letter that our feeding
machine was reproduced even to the farthest limits of the animal
kingdom, though always becoming more simple as the species descends
in the scale. And afterwards, where we began the study of animals, I
told you that in this machine lay the uniformity of their construction.
Was I not right? and what could I add to all the proofs which have
developed themselves one after another, to establish the fact of this
uniformity of plan in the animal machine, in all its essential points?
And it will be to the lasting renown of the illustrious Geoffroy St.
Hilaire that it was, in the face of all the Academies and under the
fire of very learned indignation, he proclaimed this truth, which one
cannot lose sight of without losing one's way in a crowd of arbitrary
fancies.

I return, then, to the definition which I gave you in speaking of the
worm, and which is the final word of the ideas I have been endeavoring
to make you understand. _An animal is a digestive tube served by
organs._

In the first place it must eat, and for this therefore the Creator
provided first. All the rest came afterwards in order to enable it to
eat more readily, to secure its prey more easily, and to make the most
of it when eaten. The movement machine, therefore, whose history I
have promised you, is only an assistant, and not the principal feature
of the organisation, and it is not by it, therefore, that the question
can be decided, whether God has made three, four, or five animals, or
whether he has only made one.

And now, my dear little pupil, I will bid you adieu, or rather say as
the French do, "Au revoir," which means "Good-bye till we meet again,"
begging you to excuse any awkward expressions that may have escaped
me, as also my having now and then talked about things because they
have interested me, without perhaps sufficiently considering whether
they might have an equal interest for you. Yet, while the pen is still
in my hand, I will not leave you my concluding definition of an animal
without adding a word of explanation. You know nothing about such
matters yourself, but to some people my words might have the air of
a parody upon another definition, applied by those grave gentlemen the
Philosophers to man, whom they have denominated _An intelligence
served by organs_. My definition is applicable only to the animal,
and not to man, observe. Man in the natural, physical machinery of his
body, is very decidedly an animal; yet as certainly is he, by the
divine reflection which shines within him, something much more and
greater; but _what_, is so far beyond the reach of definitionthat I
shall not attempt to give you one. "Man," as Jesus Christ has
said, "lives not by bread alone, but by every word that proccedeth out
of the mouth of God." What it is that is nourished in us by that word,
is precisely what I cannot attempt to define for you; yet I think you
have understood my meaning.

Go, then, and eat your food in peace, like the pretty little animal
that you are; but do not forget to nourish also the other part of your
being; that indeed which is of the most importance, and which enables
you to ascend to your Creator.

THE END.



POSTSCRIPT.

In going through the preceding pages (Part II) with a comparative
anatomist, it became evident that some few popular and other errors
and misconceptions had crept into this portion of M. Macé's usually
clear and accurate work.

Naturally it was not in his power to verify all the statements he had
to make on so many and such varied subjects, and he appears occasionally
to have trusted to works of old-fashioned or doubtful authority.

In these cases I have considered it desirable to make such corrections
as should secure the trustworthiness of the descriptions as far as
they pretend to go.

It would not, however, have been in my power to accomplish this, but
for the kind and efficient aid I have received from a scientific student
of these subjects; and I am glad of this opportunity of acknowledging
how much I am indebted to him for his assistance in making the necessary
alterations, as well as for confirming the correctness of the greater
portion of the work.

MARGARET GATTY.

January, 1865. January, 1865.





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