(MAY)
It may be doubted whether there are many other animals which have
played so important a part in the history of the world as these
lowly organized creatures.
--_Darwin: "The Formation of Vegetable Mould."_
WHAT THE EARTH OWES TO THE EARTHWORM
Suppose father had a hired hand who would plough his fields, fertilize
them at his own expense, build his own house, board himself, and for all
this ask only the privilege of living on the place, studying Botany,
Geology, and Geometry, and enjoying the scenery.
"Where can I get a man like that?" I imagine father saying.
"You've got him now," you might reply. "He's already working for
you--thousands of him, and has been working for you--millions of
him--for thousands and millions of years."
We have all known him well from boyhood by several names--angleworm,
fishworm, earthworm. He also, as you will find in the dictionary, has a
nice long Latin title. And it is particularly fitting that his name
should be so associated with antiquity, since he belongs to one of the
oldest families in the world; a family far older than the Roman Empire
itself, which his people long ago helped grind back into the dust from
which it came.
And, speaking of Romans, every few years Mr. Earthworm does what Julius
Caesar did, captures the whole of England--all the best parts of it--and
then, unlike Caesar, gives it back to the English, made over again,
better than it was before, as you will see.
I. THE CITIES OF WORMS
If you happen to be a high school boy you, of course, know about a
certain city of Worms and what great things took place there once upon a
time, but there are many cities of worms on any good farm, and each has
more inhabitants than the famous city of Worms of history--something
like 25,000 to the acre; and, in garden soil, 50,000!
[Illustration: ANOTHER "CATHEDRAL OF WORMS"
In the story of the Reformation in your history you will read of a
certain Cathedral of Worms and what took place there once upon a time.
Here is a "cathedral of worms" as interesting to the student of nature
as that famous edifice is to the historian and the architect. It is the
tower-like casting of a big earthworm and was found in the Botanic
Garden at Calcutta. The picture is "life-size."]
Did you ever notice how big boulders in a field are frequently sunk into
the ground as if dropped from a great height? It is the earthworms that
help sink them in the course of their soil-making. They like the moist
shelter of the stones and burrow under them. Finally the weight of the
stones crushes the burrows, and so the stones sink down.
PIONEER LIFE AMONG THE EARTHWORMS
Poor soil, as every boy knows, is a poor place to look for fishworms.
But you have noticed that the mounds the worm throws up on such soil are
larger than those on rich soil. The reason is that the soil, being less
nutritious, the worm must eat more of it and, in so doing, pulverizes
and fertilizes it. But a menu of earth alone not being to the
earthworm's liking, undesirable regions have fewer of these farmers
working underground; and this, for the same reason that these regions
are sparsely settled on the surface--it is so hard to make a living.
So the earthworms may be said to have a decided taste in landscape. They
don't care for desert scenery like Gerome's picture of the lion's big
front yard,[9] but they are very fond of orchards where the soil is rich
and leaves are plenty. The pathways artists are fond of putting in
landscapes would also probably attract the eyes of earthworms--if they
had any, for the worms prefer soil a little packed, as it is in
pathways, because it makes more substantial burrows. And, singularly
enough, the worms also like most the very thing that the artist
emphasizes to lead the eye into his picture--the border lines that
_define_ the path. It is along the edges of a pathway that you find most
worms.
[9] "The Two Majesties." This painting, by a great French realist,
shows a lion getting home rather late, after his night out, stopping
for a look at the rising sun; a thing with which, owing to his
habits, he is not very familiar.
[Illustration: _Painted by F. O. Sylvester._
_Painted by Westman._
THE EARTHWORM'S TASTE IN SCENERY
Two features common to both these pictures--the trees and the
pathways--appeal to earthworms as well as artists, for reasons you have
learned in this chapter.]
The earthworm, in addition to working over and fertilizing the soil
already made, actually helps make soil out of rock. He does this in two
ways: (1) With acids--for, like the Little Old Man of the Rock, he is a
chemist; (2) by grinding up rock in a little mill he always carries with
him.
HOW THE EARTHWORM COOKS HIS MEALS
The earthworm's favorite diet is leaves and he has a way of cooking
them. It is not quite like our way of cooking beet or dandelion leaves,
but it answers the same purpose--it partially digests them. In glands,
in his "mouth," he secretes a fluid which, like our saliva, contains an
alkali. But the earthworm's alkaline solution is much stronger, and when
he covers a fresh green leaf with it--as he is usually obliged to do in
Summer when there are so few stale vegetables, the kind he prefers, in
his market--the leaf quickly turns brown and becomes as soft as a boiled
cabbage.
Of course, there are always dead leaves in the woods, and these, which
even the cow with her fine digestive outfit cannot handle, are a delight
to the earthworm; for he also has a much larger supply of pancreatic
juice than the higher animals, and this takes care of the leaves after
he has swallowed them. He swallows bit by bit; just like a nice little
boy who has been taught not to bolt his food.
The acids in the earthworm's "stomach," acting on the leaves, help make
other acids which remain in the soil after it has passed through the
earthworm's body and help dissolve those fine grains of sand which make
your bare feet so gritty when mud dries on them. And, not only that, but
this coating of soil lying upon the bed rock hastens its decay; for the
earthworm's burrow runs down four to six feet, sometimes farther.
Besides the soil he thus grinds up and fertilizes so well with
leaf-mould--what your text-book on agriculture calls "humus"--the
earthworm does a lot of useful grinding in connection with the building
of his house. He begins, as we do, by digging the cellar; but there he
stops, for _his_ house is _all_ cellar! He makes it in two ways: (1) By
pushing aside the earth as he advances; (2) by swallowing earth and
passing it through his body, thus making the little mounds you see on
the surface.
THE EARTHWORM SYSTEM AT PANAMA
A principle similar to his swallowing operations is frequently employed
in engineering; as in making the Panama Canal, where dredging machinery
dug out swamps and pumped the mud through a tube into other swamps to
fill them up and help get rid of the mosquitoes.
In pushing the earth away the worm uses the principle of the wedge,
stretching out his "nose"--as you have often seen him do when
crawling--and poking it into the crevices in the ground; much as the
wheat roots poke _their_ little noses through the fertile soil the
earthworm makes.
And, as in human engineering and the work of the ant, the earthworm
doesn't throw the dirt around carelessly. He casts it out, first on one
side and then on the other; using his tail to spread it about neatly.
THE TILING IN THE EARTHWORM'S HOUSE
The walls of the earthworm's house are plastered, too. At first they are
made a little larger than his body. Then he coats them with earth,
ground very fine, like the clay for making our cups and saucers, and for
making the beautiful white tiling on the walls at the stations of a city
subway. When this earthworm "porcelain" dries it forms a lining, hard
and smooth, which keeps the earthworm's tender body from being scratched
as he moves up and down his long hallway. It also enables him to travel
faster because it is smooth, and it strengthens the walls.
The burrows which run far down into the ground, as all finally do toward
Autumn, end in a little chamber. Into this tiny bedroom the worm retires
during the hot, dry days of August and there he spends the
Winter--usually with several companions, all sound asleep, packed
together for warmth.
AND RUGS ON THE FLOORS!
Sometimes the Summer and Winter residences are quite ambitious, several
burrows opening into one large chamber and each tunnel having two,
sometimes three, chambers of its own--like a fashionable apartment with
its main reception-room, and still more like the central sitting-rooms
in Greek and Roman palaces. And the earthworm seems even to have some
idea of mosaics, for it is the general practice to pave these chambers
with little pebbles about the size of a mustard-seed. This is to help
keep the worm's body from the cold ground. In addition to the mosaic
floors the earthworms have rugs with lovely leaf patterns like the
Oriental rugs that are so highly prized; and, as in the case of genuine
Oriental rugs, no two patterns are alike. These rugs are leaves which
the earthworm drags into his burrow, not for food but for house
furnishing. When used for house furnishing they are placed in the
entrance-hall; that is to say, they are used to coat the mouth of the
burrow to prevent the worm's body from coming in contact with the
ground. The mouth of the burrow, of course, is just where it is coldest
at night in the Summer, the time of year when the earthworm spends a
great deal of his time in the front of his house. The surface of the
earth, you know, cools very rapidly after sunset and the dew on the
grass in the morning is so cold it makes your bare feet ache. The worm
requires damp earth around him because he breathes through his skin and
must keep it moist, but at the same time he is sensitive to cold.
And to drafts. Ugh!
PEBBLE-FORT DEFENSES AGAINST THE FOE
So he is very careful to keep the front door closed. This he does by
stopping it up with leaves, leaf stems, and sticks. He also protects the
door with little heaps of smooth round pebbles; but these pebbles are of
a larger size than those he uses for paving the floor of his chamber.
Besides helping to keep out drafts these pebbles serve another purpose.
As our ancestors, the cave-builders, barred the door with boulders to
keep out bears and other unwelcome callers, so the earthworms are
protected by the pebbles, to a certain extent, from one of their
enemies--the thousand-legged worm. Because of these little forts, the
earthworms can remain with more safety near the doorway and enjoy the
warmth of the morning sun. (So we might have reproduced Corot's
"Morning" as a kind of landscape the earthworm enjoys!)
II. THE MIND OF THE EARTHWORM
From all of which you can see the earthworm, for what small schooling he
gets, is a very bright boy! If we were as bright, according to our
opportunities, we would probably have answered long ago such puzzles as
the question whether there is really anybody at home in Mars, how to
keep stored eggs from tasting of the shell, and other great scientific
problems of our day.
WHERE MR. EARTHWORM KEEPS HIS BRAIN
Just as we have little brains in the tips of our fingers, the earthworms
have brains in the ends of their "noses." They have neither eyes nor
ears, but, like that wonderful girl, Helen Keller, they make up for the
lack of these senses, to a remarkable degree, by the development of the
sense of touch. They acquire quite a little knowledge of Botany, for
example. They not only know that leaves are good to eat, but they know
which is the "petiole" and which is the "base." They always drag leaves
into their burrows by the smallest ends, because this makes it easier to
get them through the door. And it is not by mere instinct that they do
this. Supply worms with leaves of different form from those which grow
in the region where they live, and they will experiment with them until
they find just the best way in which to pull them into the burrows.
After that they will always take hold of them so, without further
experiment. That is the majority of them will do this; for earthworms
are like other little people--all of them are not equally ambitious or
studious.
And the earthworm also knows something about Geometry. Cut paper into
little triangles of various shapes and pretend to the worms that they
are leaves by scattering them near the mouths of the burrows. Then
remove the leaves with which the burrows are stopped. The worms will
pull in the slips to close the door and they will--most of them--take
hold by the apex of the triangle because that is the narrowest point.
THE EARTHWORM'S TASTE IN MUSIC
So you see the earthworm is a very cultivated country gentleman with his
knowledge of Botany and Geometry, and his taste for landscape. But this
is not all. He also has opinions about music. There are certain notes
that apparently get on his nerves. Put worms in good soil in a
flower-pot, and some evening when they are lying outside their burrows
set the pot on the piano and strike the note C in the bass clef.
Instantly they will pull themselves into their burrows. They will do the
same thing at the sound of G above the line in the treble clef. Although
they cannot hear, they are sensitive to vibrations, and these are
carried from the sounding-board of the piano into the pot. They are less
sensitive when the pot itself is tapped. The music seems to go right
through them.
WHY THE EARLY BIRD GETS THE WORM
Except in rainy weather worms ordinarily come out of their burrows only
at night. By early morning they have withdrawn into their holes and lie
with their noses close to the surface to get the warmth of the morning
sun. Then the early bird gets _them_! The reason a robin cocks his head
in such a funny way--like a lord with a monocle--just before he captures
a worm, is not because he is _listening_, as many people think; for the
worm isn't saying a word and he isn't moving, and wouldn't make a bit of
noise if he did move. The robin's eyes are on each side of his head and
not in the middle of his face like ours, so he must turn his head in
order to bring his eye in line with the hole where he sees the tip of
Mr. Earthworm's nose.
[Illustration: THREE EARLY BIRDS. FIND THE THIRD
Don't they look happy--these two tow-heads? They are evidently going
fishing in the early morning. Another early bird--several of him--that
we are saying a good deal about in these pages is to be found in the
can. Still another, the one at the bottom of the page, is taking
advantage of the earthworm's family habit of warming his "nose" in the
early sun rays.]
[Illustration]
And many people also believe that earthworms come down with the rain.
Even park policemen believe it. At least, one said to me, in Central
Park:
"In dhry spells ye won't see wan. But let there come a little shower an'
th' walks and the dhrives will be covered wid them; like the fairy
stones that fall wid the rain in the ould counthry."
DO EARTHWORMS COME DOWN WITH THE RAIN?
The reason you see so many worms after a rain is that earthworms like
moisture, and the rain seems to make them feel particularly good and
breed a spirit of adventure. So out of their holes and away they go! A
rain is their shower-bath; and you know how a shower-bath makes you
feel. The mornings when the earthworms are apt to be thickest are those
following a comparatively light rain in early Spring when the worms have
recently awakened from their long Winter nap. With the beginning of the
rainy season in the Fall, the worms also do a good deal of travelling
into foreign lands, but in both Spring and Fall you will usually find
more worms after a light shower than after a long, heavy downpour. If
the worms were drowned out it would be the other way around, don't you
see?
To be sure, you will often find dead worms in shallow pools by the
roadside; particularly after Autumn rains. These are sick worms and the
chill was too much for them. But it's remarkable how low a temperature a
good husky angleworm can stand. A professor in the University of
Chicago, near which I live, tells me he has often found the ground in
the neighboring park covered with worms after November rains when his
hands, and those of the students who were helping him gather them for
study, were numb with the cold.
And how much work do you suppose these farmers do in grinding up and
fertilizing the soil? In many parts of England the whole of the best
land--the vegetable mould--passes through their bodies every few years,
and they are doing similar work all over the world.
They not only fertilize the earth by mixing it with the leaves they eat
and those that decay in their burrows, but their castings help to bury
fallen leaves and twigs and dead insects, and they also bring up lower
soil to the surface, thus increasing its fertility. And by loosening the
soil they let in more air. Remember that roots, like people, must have
air.
III. THE MILL OF THE EARTHWORM
For the grinding up of the earth and the leaves, the earthworm has, as I
have already said, a little mill that he always carries with him. Do you
know what a gold mill is? Well, a gold mill is a mill that grinds up
rock and so grinds out the gold. The earthworm's mill, in a manner of
speaking, also grinds out gold, for it grinds the little particles of
stone in the soil, and this soil grows fields of golden grain.
The earthworm's mill is his gizzard. This gizzard is made and works very
much like the gizzard of the chicken. And like the chicken the earthworm
swallows little stones to help his digestion. So these stones, too, are
ground into soil.
Like the chicken's gizzard the gizzard of the earthworm is lined with a
thick, tough membrane, and it has muscles--such muscles! There are two
sets of these muscles and they cross each other somewhat like the warp
and woof of the cloth in your clothes. The muscles that run lengthwise
are not so very strong, for all they have to do is to help the earthworm
swallow, but the muscles that run around the gizzard are wonderfully
strong. They are about ten times as thick as the other muscles. One of
Mr. Earthworm's French biographers[10] calls these muscles "veritable
armatures"; that is, freely translated, "veritable hoops of steel."
[10] When you study French, if you want to read this book--like most
French works on science it is very interesting--ask for Perrier's
"Organization des Lumbricus Terrestris."
I said, in the second paragraph above this, that worms swallow grains
of sand and stones to help their digestions, as chickens do. But the
earthworm saves time, for he takes the stones with his meals; just as
some Englishmen, fat old squires, when they get along in years, or for
any other reason are a little weak in their digestive regions--keep
pepsin on the table with the pepper and salt.
And--believe it or not--the earthworm actually makes his _own_
millstones sometimes! The chalk in the chalky fluid of the glands that
help him digest his meals frequently hardens into little grains in
grinding the food. It's almost as if the saliva in our mouths, in
addition to acting directly on the food, also made a new set of teeth
for us!
Suppose we had a stomach like the earthworm, wouldn't it be fun? We
could digest the biggest dinners at Thanksgiving and Christmas and
picnics and birthdays. We could even eat apples without waiting for them
to get quite ripe. Haven't you done it to your sorrow? And no
stomachache and no mince-pie nightmares!
WHY THE EARTHWORM NEVER HAS NIGHTMARES
By the way, the earthworm, although he has his troubles like the rest of
us, never _has_ nightmares. For one thing he has that stomach[11] and--a
still better reason, perhaps--he never sleeps at night. Like the moths
and the bats and the burglars and members of Parliament, he makes night
his busy day.
[11] Just listen to this: "Worms," says Mr. Darwin, in that
remarkable book of his, "are indifferent to very sharp objects, even
rose thorns and small splinters of glass."
And, in other ways, while he is so much like the rest of us worms of the
dust, his life differs from that of most people. For instance, he not
only works by night while we work by day, and works underground while we
work on top, but he takes his vacation in the Winter while we take ours
in Summer. In that respect Mr. Earthworm is like the millionaires at
Palm Beach; for in Winter he, too, goes in the direction we call south
on the map--that is to say _down_.
But, as you say, it takes all kinds of people to make a world; including
earthworms and millionaires!
HIDE AND SEEK IN THE LIBRARY
Who was that in Mother Goose that went a-fishing "for to catch a
whale"? Anyhow, there are fishworms so big that one might suppose
they were made for catching whales. How long do you suppose they
are, these big fishworms? A foot?
Pshaw! We have fishworms of our own a foot long. Two feet? More.
Three feet? More. You look it up in the article on the earthworm in
the "Britannica."
And how many kinds of earthworms do you suppose there are? You will
be surprised to learn.
Also, you will find that the earthworms have relatives who live in
the water all the time.
The article in the "International" tells why these modest neighbors
of ours don't come to the surface in the daytime. That will be an
interesting thing to know. Don't you think so?
And did you ever count an earthworm's rings? Other scientists have.
(All live boys and girls are scientists; they want to _know_.) Try
counting the rings of an earthworm and then compare your figures
with those given in the article in the "International."
How many hearts do you suppose an earthworm has? You will find in
the "International's" article they have a good many of what are
sometimes called "hearts," and how different the earthworm's
circulation system is from ours.
Does our saliva do for us anything like what it does for the
earthworm; and our pancreatic juice?
Compare the earthworm's method of digging his subway with that of
the armadillo. How do they differ in the way of using their noses?
Do you know how men dig subways; like those under New York City and
Boston, for instance? Books that tell about this phase of human
engineering and tell it in a very interesting way are "On the
Battle-front of Engineering" ("New York's Culebra Cut") and
"Romance of Modern Engineering" ("City Railways"), "Travelers and
Traveling" ("How Elevated Roads and Subways Are Built").
Speaking of the earthworm's wedge and how he uses it, do you know
that all of man's complicated machinery is the result of only a few
simple mechanical principles combined; and that the wedge is one of
the most important? Look up "_wedge_," "_machine_," "_simple
machine_," etc., in the dictionary or encyclopaedia.
How does the earthworm's method of pushing his way in the world
with the end of his nose compare with the way a root works along in
the ground? (See Chapter X.)
The earthworm's neat way of disposing of the dirt he casts out
reminds me of how the beaver handles dirt when he builds a canal,
and the way of the ants in digging their underground homes.
(Chapters VI and VIII.)
We have little brains in our finger-tips just as the earthworm has
on the end of his nose. How much do you know about the little
brains scattered through our bodies (_Ganglia_)?
You see the simple earthworm is the A, B, C of a lot of things; and
even Mr. Darwin's famous book doesn't contain all there is to be
learned about him in books and in personal interviews with Mr.
Earthworm himself. A farm boy to whom the writer read the story of
the earthworm, when asked how he thought the worm could turn in his
burrow when it fits him so closely, said, "Why, he turns around in
that little room at the end of the hall," thereby solving, as I
think, a problem that puzzled Mr. Darwin, and which he left
unsolved.
[Illustration: SINFUL TACTICS OF A SACRED BEETLE
The beetle pushing backward is the owner of the ball and is on his
way--as he thinks--to his burrow. The other is altering the direction
toward his own burrow. Fabre's book on the Sacred Beetle--the tumblebug
of our fields and roadways--tells how the thing came out.]