(OCTOBER)
It is hardly an exaggeration to say that the tip of a root acts
like the brain of the lower animals.
--_Darwin._
THE BUSY FINGERS OF THE ROOTS
This has been a very busy season for Mr. Root and his family. It always
is, and you can imagine they're all glad when Fall comes and they can
lay by for the Winter.
"There's your apple crop, I helped make that," Mr. Root might say. "And
there's the corn and the wheat in the granary, and the rye and the oats
and the barley; and the hay in the mow; and the pumpkins and the
carrots, and the turnips, and the potatoes in the root cellar; and the
jelly in the jelly-glasses, and the jam, and the preserves--we helped
make them all.
"And we've been working for you almost since the world began; almost,
but not quite--for the earliest plants, the Lichens, for example--didn't
have true roots.
"Yes, and--well, I don't want to say anything--Mr. Lichen has been a
good neighbor--but he never did amount to much; never could. No plant
can amount to much without roots. But with roots and a good start a
plant can do almost anything--raise flowers and fruit and nuts, and help
grow trees so tall you can hardly see the tops of them. And, it isn't
alone what we do for the plants we belong to, but for the soil, for
other plants and roots that come after we're dead and gone. For them we
even split up rocks, and so start these rocks on their way to becoming
soil."
I. ALL IN THE DAY'S WORK
It's a fact. Roots do split rocks. Hundreds of times I've been in the
cracks of rocks that were split in that way. I mean right when the
splitting was going on. This happened oftenest where trees grew on the
stony flanks of mountains. Seeds of the pines, say, dropped in crevices
by the wind, sprout in the soil they find there, and then, as these
shoots grow up into trees, the enlarged roots, in their search for more
soil, thrust themselves deeper and deeper into the original
lodging-place, and so split even big rocks. The tap-roots do the
heaviest part of this pioneer work. After the older and larger roots
have broken up the rock, the smaller roots and fibres, feeling their
way about among the stones, enter the smaller openings and by their
growth divide the rock again and again.
But it's a lot of hard work for little return, so far as these early
settlers are concerned; just a bare living. All these rock fragments, in
the course of the years, become soil, but the amount of decay is small
in the lifetime of the tree that does the breaking.
A root, as you doubtless know, tapers. This enables it to enter a rock
crevice like a wedge. As it pushes its way in farther and farther it is
growing bigger and bigger, and it is this steady pressure that breaks
the rock. Even the tiny root of a bean grows with a force of several
pounds, and the power exerted by the growth of big roots is something
tremendous. At Amherst Agricultural College, one time, they harnessed up
a squash to see how hard it could push by growing. From a force of sixty
pounds, when it was a mere baby, what do you suppose its push amounted
to when it had reached full squashhood in October? Nearly 5,000 pounds;
over two tons!
[Illustration: HOW A LITTLE ROOT SPLIT A GRANITE BLOCK
The little winged seed from which this pine-tree grew was carried by the
wind one day into a tiny crack in that big granite block. As the treelet
grew the tap root split the rock, penetrated to the earth below and fed
the trunk until it became, as you see, a tree 40 feet high and 18 inches
in diameter!]
But don't think because roots can and do split rocks, if need be, that
they go about looking for such hard work. On the contrary. In travelling
through the soil they always choose the easiest route, the softest
spots. They use their brains as well as their muscles, and what they do
with these brains is almost unbelievable.
Yet the roots are such modest, retiring folks, always hiding, that it
was a long time before the wise men--the science people--found out what
all they do. It took a lot of science people and the wisest--including
the great Darwin--to get the story, and they haven't got it all yet, as
you will see. It was Darwin who first thought of having Mr. Root write
out his autobiography--or part of it--the story of his travels; for he
does travel, not only forward--as everybody knows--but around and
around. A regular globe-trotter!
[Illustration: WHY BABY PLANTS BACK INTO THE WORLD
Most plants back into the world out of the seed like that. Why? To
protect their tender first leaves. Suppose you were taking some very
valuable thing, easily injured--baby brother, say--through a swinging
door and you had to use both hands to carry him. You wouldn't open the
door by pushing that dear, little tender head of his against it, would
you? You'd open it by backing through.]
Mr. Darwin was a wonderful hand at that sort of thing--getting nature
people to tell their stories. He was an inventor, like Mr. Edison; only,
instead of inventing telephones for human beings to talk with, he
invented ways of talking for nature people. You saw how he fixed it so
that the earthworms could tell what they knew about geometry and botany.
Well, in the case of the roots, what did he do one day but take a piece
of glass, smoke it all over with lampblack--you'd have thought he was
going to look at an eclipse--and then set it so that Mr. Root could use
it as a kind of writing-desk. In a hitching, jerky sort of way roots
turn round and round as they grow forward. In the ground, to be sure, a
root can't move as freely nor as fast as it did out in the open and over
this smooth glass, but it does turn, slowly, little by little. The very
first change in a growing seed is the putting out of a tiny root, and
from the first this root feels its way along, like one trying to find
something in a dark room. Thus it searches out the most mellow soil and
also any little cracks down which it can pass.
[Illustration: CHARLES DARWIN
The great naturalist.]
"Here's a fine opening for a live young chap," we can imagine one of
these roots saying when it comes to an empty earthworm's burrow or a
vacancy left by some other little root that has decayed and gone away.
Roots always help themselves, when they can, to ready-made openings, and
it is this round-and-round motion that enables them to find these
openings.
But even this isn't all. A root not only moves forward and bends
down--so that it may always keep under cover and away from the
light--but it has a kind of rocking motion, swinging back and forth,
like a winding river between its banks, and for a somewhat similar
reason.
"It's looking for a soft spot!" says the high school boy, "just as the
river does."
NO HIT-OR-MISS METHODS FOR MR. ROOT
Exactly. But not in the sense that this phrase is used in slang. The
root has certain work to do, and it does it in the quickest and best
way. It can get food more quickly out of mellow soil than out of hard,
and so it constantly hunts it up. I mean just that--_hunts it up_. For
it isn't by aimless rocking back and forth that roots just _happen_ upon
the mellow places. It's the other way around; it's from a careful
feeling along for the mellow places that the rocking motion results.
"But how on earth do the roots do this? What makes them do it?"
That's what any live boy would ask, wouldn't he? So you may be sure
that's what the science people asked, and this is the answer:
The roots, like all parts of the plant--like all parts of boys and girls
and grown people, for the matter of that--are made up of little cells.
Well, these cells, first on one side of the root and then the other,
enlarge, and so pump in an extra flow of sap. Now, as we know, the sap
contains food for the plant, just as blood contains food for our bodies;
and more food means more growth. So the side of the root where the cells
first swell out grows fastest and thus pushes the root over on the
opposite side. Then the cells on this opposite side swell, and the root
is turned in the other direction again. So it goes--right and left, up
and down. And when these two motions--the up and down and right and
left--are put together, don't you see what you get? The round-and-round
motion!
Precisely the same thing happened right now when you turned your finger
round and round to imitate the motion of the root. (I saw you!) The
muscles that did the work swelled up first on one side and then on the
other, just as they do when you bend your elbow, when you walk, when you
breathe, when you laugh.
And more than that: You know how tired you get if you keep using one set
of muscles all the time--in sawing fire-wood, for example. Yet you can
play ball by the hour and never think of being tired until it's all
over; because, for one thing, you are constantly bringing new muscles
into action as you go to bat, as you strike, as you run bases. It's the
same way with the roots, it seems. For the theory is that after the
cells on one side have swelled, they rest; then the cells on the other
side get to work.
"But what starts the movement?" you may say. "The idea of moving my arms
and legs starts in my brain."
WHERE MR. ROOT KEEPS HIS BRAINS
Just so again. The root has a brain, too, or what answers for a brain.
And the root's brain, is in its head; at least in the vicinity of its
nose--that is to say, its tip. It's the tip that first finds out which
side of the road is best, and passes the word back to the part of the
root just behind it to bend this way or that. It's also the tip that
feels the pull of gravity and knows that it's the business of roots to
keep under cover. And Mr. Root just _will_ have it that way! You can't
change his mind. Mr. Darwin tried it and he couldn't; although he
finally changed human people's minds a lot.
[Illustration: WHERE MR. ROOT WEARS HIS CAP
A root wears its cap right where you do--over its brain department; that
is to say, the tip. It is called the "root cap" and protects the tip
from injury.]
This is how he tried it on a root. He took a bean with a little root
that had just started out into the world. He cut off the tip and then
set the bean so that the root stuck straight up. It continued to grow
that way for some little time. Finally, however, a new tip had formed.
Then there was a general waking up, as if the tip said to the rest of
the root:
"Here, here, this will never do! Where are you going? You must bend
_down_!"
Anyhow that's what the root proceeded to do. One side seemed to stop
growing, almost, while the other side grew rapidly and so the bending
was done.
"Did you ever! But how does the tip send back word?"
"Don't ask me!" says the science man; say all the science men, even to
this day. "We don't know yet just _how_ it's done. But we're studying
these things all the time, and we'll know more about it by and by.
Meanwhile, perhaps you'll tell _us_ why you say 'ouch' and pull your
finger away when you touch something hot."
"Oh," you reply, "I say 'ouch' because it hurts; and teacher and the
Physiology say my arm pulls my hand away because my head tells it to."
"Yes, but how does the head make the arm do the pulling? What's the
connection?" says the science man.
Well, I guess we'll have to tell him we don't know, won't we?
But all the root's brains aren't in the tip, any more than all _our_
brains are in our heads. Scattered through our bodies, you know, are
_little_ brains, the ganglia, that control different parts of the body.
So it is with roots. For instance, a root at a short distance from the
tip, is sensitive to the touch of hard objects in such a way that it
bends toward them instead of turning away, as the tip does. The result
is that when a root comes to a pebble, say, under ground, the sides of
the root press close up to the sides of the pebble--turn around corners
sharply, by the shortest route--and so get over the obstruction as soon
as possible and resume their course in the soil.
[Illustration: BUT THEY COULDN'T CHANGE ITS MIND
Some sprouting seedlings were attached to a disk like that, and when the
roots started to grow down, the disk was turned to make them point
upwards. But, no Sir! The roots just _wouldn't_ grow upward. They turned
downward. Every time!]
And different parts of a plant's root system respond in different ways
to the pull of gravity, and some don't respond at all. The tap-root, for
example, which always grows down, has roots growing out from it
horizontally. They just won't grow any other way, and yet this is also
supposed to be due to the influence of gravity. Then, from these
horizontal roots, grow out a third set, and they don't seem to pay any
attention whatever to gravity. They grow out in all directions--every
which way--so that if there is a bit to eat anywhere in the neighborhood
they are reasonably sure to find it. You see it works out all right.
When a plant first begins to peep into the world out of that wonder box
we call the seed, it's the root, as we know, that does the peeping; it
comes first. And its first business is to get a firm hold in the soil.
So a lot of fine hairlike fibres grow right and left and all around and
take a firm grip. There is an acid in the root that dissolves whatever
the root touches that has any food in it--including pebbles and old
bones--and so makes a kind of sticky stuff that hardens. In this way
these fibrous roots not only get good meals for themselves and the rest
of the plant, but they hold the plant firmly in the soil, against the
strain of the winds. They also give the tap-root something to brace its
back against, as it were, while it pushes down for water, for the
moisture in the damper portion of the soil beneath.
As you may have noticed, a seed merely lying loose on the ground is
lifted up by its first little root in its effort to poke its nose into
the soil. But Nature makes provisions for covering seeds up. They are
covered by the castings of the earthworms, the dirt thrown out by
burrowing animals and scratching birds. Some seeds fall into cracks
where the ground is very dry and others are washed into them by the
rains; while these as well as seeds lying on the surface are covered by
the washings of the rain. Then come the roots that grip the soil.
Always growing just back of the tip, are thousands of root-hairs, as
fine as down. These get food from the soil. They soon disappear from the
older parts of the root, so that it stops gathering food itself and puts
in all its time passing along to the stem and leaves the food gathered
by the finer and younger roots. This is why plants are so apt to wilt if
you aren't careful when transplanting them; the root-hairs get broken
off. For the same reason, corn, after it grows tall, is not ploughed
deeply. The fine roots reach out between the rows and the ploughshare
would cut them off.
II. MR. ROOT'S PRESENCE OF MIND
All these things and more the roots do in their daily work--in the
ordinary course of business. And it's wonderful enough. Don't you think
so? But there are even stranger things to tell; things that would almost
make us believe roots have what in human beings we call "presence of
mind." That is to say, the faculty of thinking just what to do when
something happens that one isn't looking for; when the house takes fire,
for example, or the baby upsets the ink.
[Illustration: THREE SCHOOLS OF STRATEGY]
A ROOT'S WAY OF CROSSING A ROAD
Take the case of tree roots crossing a country road for a drink of
water. They do it just as you or I would, I'll be bound. Just suppose
you and I were roots of a big tree that wanted to reach the moist bank
of a stream, and there was a hard road-bed between. We can't go over the
top, and the road-bed is so hard we can't go straight through on our
natural level so we'll just stoop down and go under, won't we? That's
exactly what the roots do. They dip down until they get under the
hard-packed soil, and then up they come again on the other side and into
the moist bank they started for.
The roots of each kind of plant or tree have their natural level; that's
one reason, as we know, why so many different kinds of plants--grass,
trees, bushes, and things--get on so well together in the fields and
woods. The tree roots that we have just seen crossing the road only went
down below their natural level because they had to, as if the tip said:
"This soil is too hard. We can never get through. Bend down! Bend down!"
So the roots bent down until they came to softer soil, then forward, but
always working up toward their natural level, and so it was at their
natural level they came out on the other side.
A ROOT'S STRANGE ADVENTURE WITH A SHOE
But here's an example of "presence of mind," that nobody has accounted
for. A good-sized root, working along through the soil, like Little
Brother Mole, to earn its board and keep, came right up against the sole
of somebody's old shoe that had got buried in the soil. In the sole were
a lot of holes where the stitches used to be. The root divided into many
parts, and many of these smaller roots found their way through the
stitch holes. Then, coming out on the other side, these little roots got
together and travelled on, side by side!
[Illustration: HOW THE RAG BABIES TELL THE FORTUNE OF THE SEED CORN
In what is popularly called "the Rag Baby Test" the seed corn is placed
on squares marked on cloth with numbers corresponding to the numbered
ears. Then they are rolled up in one of those moistened rags until they
sprout.]
Isn't that a story for you? But there's no accounting for it. As we have
seen, the men of science know a little bit about how a root manages to
turn round and round and away from the light and so on, but what kind of
machinery or process is it that could tell the root if it would split
up into little threads it could get through the stitch holes in that old
boot? You can't imagine; at least, nobody so far has thought how it was
done. But it's all true. We'll find the story and a lot of other things
about the ways of roots in one of the books we'll get acquainted with
when we come to the "Hide and Seek."
[Illustration: (C) _International Harvester Company_
THIS IS THE ANSWER
The seed from Ear No. 12 came out beautifully, didn't it? That from Ear
No. 13 looks as if they were superstitious in Corn Land; but of course
it was the fault of the seed and not of the number.]
Here's another example of the same thing; what we have called "presence
of mind," resourcefulness, invention. This example is even more
striking, if possible, because, for one thing, it is a case where roots
still more completely altered their habits to save a tree struggling for
its life on a stony mountain cliff. Maeterlinck tells about it in his
picturesque and dramatic style. The subject--the hero, as it were--of
this story was a laurel-tree growing on some cliff above a chasm at the
bottom of which ran a mountain torrent.
"It was easy to see in its twisted and, so to say, writhing trunk,
the whole drama of its hard and tenacious life. The young stem had
started from a vertical plane, so that its top, instead of rising
toward the sky, bent down over the gulf. It was obliged, therefore,
notwithstanding the weight of its branches, stubbornly to bend its
disconcerted trunk into the form of an elbow close to the rock, and
thus, like a swimmer who throws back his head, by means of an
incessant will, to hold the heavy leaves straight up into the sky."
This bent arm, in course of time, struggling with wind and storm, grew
so that it swelled out in knots and cords, like muscles upholding a
terrific burden. But the strain finally proved too much. The tree began
to crack at the elbow and decay set in.
"The leafy dome grew heavier, while a hidden canker gnawed deeper
into the tragic arm that supported it in space. Then, obeying I
know not what order of instinct, two stout roots, issuing from the
trunk at some considerable distance above the elbow, grew out and
moored it to the granite wall."
As if the roots, naturally so afraid of light, had heard a frantic call
for help and, regardless of everything, had come to the rescue.
To be sure, certain roots--the prop-roots of corn-stalks, for instance,
as you have noticed--habitually reach from above ground down into the
soil, and serve to brace the tall stem swaying in the winds, but trees
usually have no such roots and no such habits. Yet, here a tree seems
suddenly to have learned, somehow, that elsewhere in the land of plants
this thing is done. But how did it learn it? Did the brownies or the
gnomes tell it; or was it some of the spirits of the wind that go
everywhere and see everything? It might have been the same wind sprites
that carry the seeds of the laurel and the pine so far up the mountain
flanks. Or it might have been the dryads, those beautiful creatures of
the wood the Greeks knew so much about.
I tell you there are some mighty queer things going on in the plant
world, and perhaps Bud was right!
"Some peoples thinks they ain't no Fairies _now_,
No more yet! But they _is_, I bet!"
HIDE AND SEEK IN THE LIBRARY
And, what is more, real live fairies have been found right down in
the world of roots! The science people call them "Bacteria," but
what of that? The thing about a fairy that makes it a fairy is
that it is always changing something into something else. Isn't
that right? Well, that's exactly what is done by the bacteria on
the roots of certain kinds of plants--clover roots, for one; and
the roots of beans, peas, peanuts, and alfalfa. These plants belong
to the legume family, and if you will look up the word _Legumes_
you will find out all about these fairy factories on the roots.
Among other things you'll learn how small these fairies are. Why,
100,000 of the bacteria that live on clover roots, marching single
file, wouldn't much more than reach across this typed page.[24] And
in their little "villages" on one system of clover roots there are
so many that all of them put together would make a city as big as
London or New York; if the bacteria were as big as people, I mean.
[24] By the way, the funny thing is that, while the bacteria that
live on roots of the legumes are plants and not animals, most of
them _do_ move about.
Of course you have to take a microscope to see them--a very
powerful microscope--and even then some kinds of bacteria you can't
see until you put colored clothes on them. (Every high school boy
who has worked in the "lab" knows how this is done.)
And when you finally see them, a strange thing happens. You've
hardly got your eye on a little Mr. Bacteria before he's two!
"What's this! What's this!" you say. "Am I seeing double?"
You look again and he's _four_! But don't be alarmed, you aren't
seeing double; it's just the little Mr. Bacterias multiplying by
division. How they multiply by division is one of the interesting
things you can learn by looking them up.
But it's a good thing that the bacteria people in the little
nitrogen factories on the clover roots can get more farm-hands in
this way, for they have a lot to do, and their work is one of the
most interesting things that goes on about the place.
The article in the "Country Life Reader" on "The Smallest Plant on
the Farm" will tell you how important these nitrogen farmers are.
You would hardly believe how great their work is, they're so quiet
about it. Do you know what a human nitrogen factory is like? Well,
for one thing, it's the _noisiest_ place in the world. Men, as do
the bacteria, capture the nitrogen out of the air, but they do it
by keeping up continual thunder and rain storms in big barrels.
You will find one of these factories described in an article in
_St. Nicholas_, Volume 45, page 1137.
But what a fuss these human factories make! Why, in growing-time,
out in the clover field, where the loudest sound you hear is the
drone of the bumblebee among the blossoms, the little bacteria
people down among the roots are making nitrogen so much cheaper
than the big noisy factories that it only costs the farmer about
one-fifth as much as the storm-barrel nitrogen. And yet, of course,
it often pays to buy the artificial nitrogen, too.
There are many more striking things about the habits of roots than
I have had room to tell about here, which you will find in such
books as Elliot's "Romance of Plant Life," Coulter's "Plant
Studies," Coulter's "First Book of Botany," Allen's "Story of the
Plants," Chase's "Buds, Stems and Roots," Atkinson's "First Studies
of Plant Life," Darwin's "Power of Movement in Plants," France's
"Germs of Mind in Plants," Gray's "How Plants Behave," Carpenter's
"Vegetable Physiology," Detmer's "Plant Physiology," and Parsons's
"Plants and Their Children."
[Illustration: THANKSGIVING DINNER OF THE DORMICE
They don't sit at the dinner table like that, to be sure, but along in
the Fall and up to nearly the time of our Thanksgiving dinners, the
dormice eat unusually heavy meals and put fat on their little bones to
help them through the long, cold, and barren months of winter.]