of them became by the splitting in halves of an older cell; each of
these in turn by the splitting in halves of a still older cell, until
we get back to the egg which is the great-great-great-grandfather of
them all. But the egg itself arose by the splitting of still another
cell, which, of course, was part of the parent’s body. This came from
yet another, and so on back to the beginning of life on this earth, tho
nobody knows how long ago that was.
So the living flesh of us has always been alive. Most of it will
die; but some of it will live on in our children and our children’s
children, until the and of the world.
VII
How Much of Us Is Alive
How much of a tree is alive? Certainly not the outer bark. That
falls off in dry scales, or can be scraped off down to the white
layers within, and the tree be none the worse. Certainly not the
wood. One often comes across old trees that have lost limbs or been
carelessly pruned, which are entirely decayed out on the inside, so
that nothing is left but a thin shell next the bark. Yet these trees
grow as vigorously as ever, and bear leaves and fruit like a solid
tree. The bark is dead; and the wood is dead. Between the two is a
thin layer, perhaps a quarter inch thru, which is alive. On one
side, it is changing into dead wood. On the other side, it is
changing into dead bark. The new wood is alive, and the new bark.
Between them is something neither wood nor bark, but just living
tree-stuff. The green leaves also are alive, and the green twigs,
and the blossoms, and the growing buds. But at least half of every
living tree is already dead; while the larger and longer lived a
tree is, the smaller proportion of it is alive at one time.
How much of a hen’s egg is alive? Not the shell, for that is mostly
just chalk. Not the white, for that is merely the little chicken’s
pantry shelf where it keeps the food on which it is to grow. The
living part of the egg is the yolk—unless somebody boils the egg and
so kills it. Sometimes, too, the egg dies, as any living thing may;
then we usually find it out.
Even we ourselves are not all alive. I have already pointed out that
our hair and nails are not alive at all, and that our outer skin,
the thin skin, that is, which we tear off when we bark our shins, is
fully alive only on the inside. Our “bark” in fact, is very like a
tree’s. Each has a soft, thin, living layer on the inside, which
grows, hardens, dies, forms a water-tight layer over the rest of the
body, cracks into scales, and drops off. Where one forms cork, the
other forms horn. Indeed the cork stoppers of our bottles are made
from nothing more than an especially thick corky bark of a certain
kind of oak, like the especially thick and homy soles of all
bare-footed savages and some bare-footed little boys.
“The blood,” we say, “is the life.” And yet the blood itself is
dead. The watery part is just soup; water and salt and fat and
jelly. The minute, coin-like, red blood corpuscles carry the oxygen
of the air from the lungs all over the body. But there are similar
oxygen-carriers, likewise dead, in bottles in the drug-stores. The
corpuscles are dead cells alive once, and like the hard skin cells,
a great deal more useful dead than alive.
As for our teeth, the hard white enamel on the outside is just about
as much alive as a clam shell. The baby tooth, as I have already
explained, is formed in a little pocket in the gum. The inner part
of the tooth grows up from the cells at the bottom, very much as a
hair grows out from the bottom of the still smaller pocket where it
starts. In fact, the tusks of pigs and the long front gnawing teeth
of squirrels and rats are still more like hairs, for they keep
growing from the root, and wear off at the outer end. The tooth
pushes thru the gum; and as it goes by, the cells at the sides of
the pocket and on top plaster it with a coating of enamel.
Therefore, as most of us find out to our cost, this enamel once
destroyed, can never grow again. Once clear of the pocket where it
was formed, it has to last us the rest of our lives; and little boys
and girls who don’t keep their teeth clean when they are young, have
to put up with something not nearly so good when they are grown up.
The inside of the tooth is not quite so dead as the outside—one
sometimes gets the impression during a visit to the dentist that it
isn’t dead at all. The tooth, inside the enamel, is mostly bone; and
bone is mostly lime, like clam-shells, mortar and chalk, plaster,
and the great boulders and ledges of rock in a limestone country.
The rest of the bone is living substance, scattered cells far apart
from one another with long roots, that look as if they had grown out
into the bone like tree roots into the soil. Really, however, it is
the other way. Before there were bones, there were bone cells. These
build themselves round with the hard bone substance, pushing their
neighbors away and leaving only the long root-like strands of living
substance. It is thru these root-like living strands that we feel
the dentist’s auger bore into the solid tooth. But cutting the outer
enamel does not hurt at all simply because no part of that is alive.
We are, then, built of living bricks, but of living bricks set in
dead mortar. We saw that the great trees, complex and long lived,
have more wood and bark and other dead substances in them than the
shrubs, herbs, and grass. These in turn are less alive than the
lowly water plants and yeasts and molds which have no wood or bark
at all. The same is true of animals. The jelly-fishes and infusoria
have neither skin, hair, bones, nails, nor blood, and are pretty
much all alive. So the more a creature’s life is worth, the less of
it is alive.
Even the living cells themselves are not wholly alive. The thin
living jelly always contains water and salt, which are—just water
and salt. Fat cells contain drops of oil, which are simply stored up
food material, no more alive than the oil in an oil can. Plants, on
their side, store up their food largely as starch, no more alive
than that in a package from the grocers. Besides oil and starch,
some cells contain gum or rosin or saliva or milk or sweat, which
they pour out from time to time. These substances, too, can hardly
be considered more alive while they are in the body than when they
are outside.
So the living substance is the cell jelly. Everything outside the
cell is dead; many cells even are dead, while not a few, even while
alive, contain so much dead stuff within them, that there is more
oil in a young hen’s egg than there is chick, and more starch than
corn-plant in a grain of corn.
VIII
How We Grow
By “we” I mean all living things, trees and grass and dogs and cats
and boys and girls. For as you, my reader, have I hope already
discovered, we who have the breath of life in us are a good deal
alike, whether we are oaks or men. We don’t look much alike, to be
sure. But when we consider the things that are not alive—the stones
and stoves and bats and balls and such—and see how very different we
are from these, then we get some idea of what being alive is, and
understand how being alive makes us blood-brothers with everything
else that is alive also.
Now things that are alive usually do more or less growing. We have
already learned something of this growing of little creatures in the
egg—how the eye buds out as a ball and afterwards folds into a cup,
how the limbs sprout out from the body as shapeless lumps which only
gradually turn into hands or feet or wings. We have learned
something of the way the bones grow, and the skin, and the hair, and
the nails. Now we have to learn something more about the way a
little child or a little tree grows up to be a big one.
The tree, we already know, grows larger round only between bark and
wood. It grows taller only at the tips of its branches. The solid
wood, once formed, does not change. If then, you drive two nails
into the trunk of a little tree, say a foot apart and one above the
other, even if that tree should grow to be a hundred feet high,
those two nails would remain just where they were, a foot apart and
just the same height from the ground as before. The little tree
looks so much like the big one, that one cannot help thinking that
it has simply grown thruout, so that the same branch which was once
at the height of one’s head has now been lifted to the height of the
house eaves. But this is not the fact. The lower branches of the
little tree have died and dropped off; what are now the lower
branches of the large tree, were once the top twigs of the little
one, which have always been at the same level where they now are.
The top branches of the large tree, as the tree grows still larger,
will in their turn become, first the middle branches, then the lower
ones, then will drop off entirely.
Now this growing at one end which looks like growing thruout is
pretty common in our own bodies. We have seen how the hair grows at
the inner end only, and the nails likewise, and the skin. Ignorant
people will tell you that cutting off the ends of your hair, or
singeing the ends; and that smearing various messes on the outside
of your skins will change the quality of either. Don’t you believe
them. After wood and skin and hair and teeth are once grown, all we
can do is to protect them. Really to affect their growth for good or
ill, we have to do something to the growing end.
The bones also grow in spots. The child’s leg bones and arm bones
and finger bones do not simply swell up to become the man’s. The
head of each bone, the rounding end, that is, where it touches the
next, grows on the outside. But the shaft does its growing chiefly
at two spots, one at each end where the shaft joins the head.
The bony part of the tooth, on the other hand, starts as a
paper-thin sheet, but full sized. The living cells which build the
hard bone, lie on the inside of this shell. They keep building on
more bone on the inner surface, pushing themselves toward the middle
of the tooth, until the tooth wall is so thick that only a narrow
space is left in the center. But their long roots which they leave
behind, still reach thru to the outer surface of the bone, ready to
ache when there is occasion. Meantime, the outside of the tooth
pocket, as we have learned, has been plastering on enamel on the
outside of the shell, and pushing itself farther and farther away.
A plant’s roots, like its branches, grow at the tips; and the nerves
in our own bodies grow in somewhat the same way, beginning at the
inner end, and somehow finding their way thru and around the other
tissues of the body, till they find the place to which they were
sent. But the muscles and the fat grow thruout their mass, like
dough being raised for bread. Most of the hollow tubes of the
body—the blood vessels, for example, and the red lane down which our
breakfast goes—grow in this way. But the hollow bones, as they grow,
are taken down on the inside to enlarge the hollow, and built up
again on the outside with old material and new to enlarge the shaft.
Even the blood grows, the watery portion coming from the food we eat
and the water we drink; but the red and white corpuscles which float
in the watery part, are made in special factories in the body (some
of them in the marrow of the bones) and turned loose in the blood
stream.
Growing, you see, tho easy to do, is by no means so simple as it
appears.
IX
How We Grow Up
Ten years from now, you who are reading these sentences will be
grown up. Once you were little pink and white babies, all soft and
sweet and clean. And because you were soft and unresisting, you grew
at a tremendous rate. At first you probably doubled your weight in
six months. Then it took three years; then six or eight. By the time
you are twelve, you probably will be half as heavy as you ever will
be. In all the rest of your lives, you will do no more growing than
you did in the first 180 days of them.
You will grow, too, as you have grown, by fits and starts. Sometimes
you will shoot up like sunflower stalks. Sometimes, again, you will
stop growing large, and begin growing hard. You will not seem to be
getting bigger; but you will be getting stronger. Then, when you
start growing again, you will perhaps find that you really can’t do
so much as you could when you were a year younger, nor do it so
well.
So you will keep on, sometimes growing large and sometimes growing
hard, but almost never both at once, until you come to the full
stature of men and women, and your soft baby flesh that couldn’t
lift its head from the pillow has changed to tough muscle and hard
bone. That is, of course, supposing that you have taken care of
yourselves. If you haven’t—why then it may be different.
This growing up is so common an affair, so many of us do it, puppies
and calves and kittens and little rabbits and baby birds, that we
usually forget how wonderful a matter it is. Wonderful indeed it is;
yet hardly less strange is it that after we have grown a while, then
we stop. Yet our hair, as we know, doesn’t stop, nor the skin, nor
the nails. Sometimes parts of the body which have hardly grown at
all in youth, start up and grow in middle life. But the parts of the
body which count, the parts which if they did grow would make us
larger, these somehow know enough to stop.
It is not so with some other living creatures. A tree does not stop
growing so long as it lives; nor does a fish. The big oak or the big
trout may have grown faster than the little one; most likely it has
simply been growing longer. We call any creature adult when it is
large enough to have children of its own. But the oak bears acorns
and the trout lays eggs, and then keeps on growing till it is ten,
twenty, fifty times bigger than it was when it first had little
ones. It is as if the cat, when her kittens were growing up, kept on
growing along with them; and next year when there were more kittens
kept on growing nearly as fast as they; and kept on year after year
as long as it lived until it got to be as large as an elephant. And
still its kittens would be just kittens, no larger than before.
Many animals manage their growing this way. The star-fish egg, you
remember, is for size like a minute grain of dust, and the baby star
when he first hatches out is hardly bigger. After that, he eats all
he can get and grows as fast as he can, like any other kind of baby.
But suppose the little star-fish, as large say as a pin head,
doesn’t find enough to eat. Does he then starve? Not a bit. He
simply doesn’t grow. The eggs hatch out in the late spring within a
few weeks of one another, and the little stars which do not happen
upon a good boarding place, go practically without food all summer
long. They remain perfectly healthy; but they scarcely grow at all,
so that at the end of the summer they are still the pin heads that
they were six months before.
On the other hand, when a star-fish happens to be born where he can
find plenty of barnacles or small clams or mussels, he doesn’t do
much but eat, and grows to match. It may happen, then, that of two
stars, hatched on the same day, the one which has been well fed will
be no less than five thousand times larger than the other which has
gone hungry. Now a grown man is only about fifteen times as large as
a new-born babe. But this is as if two babies, each six months old,
should be, one no heavier than at birth, while the other weighed
twenty-five tons and was as large as a whale.
So you can’t judge by appearances. The star-fish that you pick up at
the shore may be a very young animal which has been well fed, or a
very old one which has gone on short rations, while a young star,
still growing, may be twenty times larger than his own great-grandfather.
X
How We Grow Old
After we grow up, we grow old. People say that we first grow up to
men and women; then we continue adults; then we grow old. Really,
however, we begin to grow old the day we are born; while we shall
never again grow old so fast as we did when we were babes in arms.
For growing old is simply growing hard. We begin life as squashy
little babies. Our bones are like green sticks. Our flesh is like
dough, only the softest cloth must touch our skins, and Nurse has to
hold her hand under our poor backs to keep our heads from dropping
off. Children are not squashy, but they are still soft. You can
pinch children. Sometimes you do. But you can’t pinch a grown man,
any more than you can pinch a board. Children are of course, much
harder than babies. All the same, if you put your fingers in your
mouths, or stand too much on one leg or slouch over your books or
shrug your shoulders up beside your ears when you play first base,
or sit on one foot when you curl up in the big chair in the library,
or do any other of the forty-leven things that somebody has to tell
you forty-leven times a day not to do, then you will pull your bones
all out of shape as if they were so much India rubber; and when you
grow up and your bones and muscles set, then you can’t get back into
shape again—tho you’ll wish you could.
For get hard you will. Then you will be grown up. When you are just
hard enough, you will be in the prime of life, able to work as
easily as you now play, and liking it, I hope, even better. But
still you will keep on getting hard; and when you get too hard, then
you are old.
So growing old is growing hard. And since the younger you are, the
faster you grow, you never grew old so fast as when you were a tiny
baby, and you never again will grow old so fast as you are growing
old now.
And the moral is, as the Duchess used to tell Alice, that since we
stay young and soft only a very short while, and grown-up and hard
most of our days, we’d better, as much as we possibly can, make the
short end of our lives help out the long one.
What I mean is this. While we are young, we are soft and plastic and
teachable. As we grow older, not only do our bodies harden, but our
minds also. We can do a great deal more after we are grown up than
we can while we are children; and I think we are, if less
light-hearted, on the whole quite as happy. But we shall be a great
deal less able to take up anything new. Let us, therefore, practice
while we are young those things which will bring us most happiness,
after we are too old to change.
For example, suppose a boy is fond of out-door games, as every
normal and healthy boy ought to be. He plays baseball all the
spring, tennis all summer, football thruout the autumn, and what
there is left of the year goes into ice hockey. He plays expertly,
has a glorious time; and he grows up manly and strong. This is as it
should be—so far.
But suppose the same boy, thru school and college and at work. There
is no more football for him, and no more ice hockey. For a few years
he may get an occasional game of baseball; if he is very lucky he
will get a little tennis. But tell me, boy who is reading this page,
how many of your father’s friends and associates ever play at all
the games at which you spend your spare time?
Now while we are supposing, let us suppose that this boy of ours,
instead of spending all his spare time at games, spent only half.
The other half he shall devote to sports which are not games. He
shall learn to ride a horse, to fish, to handle a sail boat, to
swim, row, paddle, to climb mountains, to take care of himself in
the woods, and above all to walk thru level country and enjoy the
sight of all he sees. By and by, this boy will grow up. In the
natural course of things, he will put away bat and ball and hockey
stick before he is thirty, but rod and saddle and oar will bring him
happiness and health almost to the end of his days.
There is a difference too in games. One plays football thru school
and perhaps in college—eight years at the outside. But one world’s
champion tennis player was well by forty; he must have played thirty
years. A golfer gets forty or fifty years of pleasure for the
trouble of learning his game. You may think you will learn the boy’s
game now, and the man’s game later. But you won’t. You will learn
the man’s game now along with the boy’s, or else you won’t learn it
at all. You will be too old to learn, and go gameless to your grave.
Or suppose a girl is fond of music, and learns to play, very nicely,
the banjo. It will be charming enough, summer evenings on the
porch—so long as one is young and has only a girl’s soul to express
in music. But by and by she will grow up to be a woman, and have
little children of her own. Will she get out her banjo Sunday
evenings and play for them hymns and solemn songs, or tinkle coon
melodies for them when they are sick? Indeed she will not. She will
put that banjo on the top shelf of the spare bed room closet, and
wish she had spent her effort learning some other instrument more
worth while.
So it is with everything else. If, while we are young, we train our
ears to enjoy good music, and our eyes to love good pictures and
good furniture, cloudy landscapes and great trees, and our minds to
care for the important things of life, literature and religion and
art and science and politics and history, we shall still possess
growing sources of happiness longer after we have ceased to care to
read stories or to be able to play ball. A wise child will study the
happiest adults whom he knows, and learn to like and to do whatever
most helps to make them blessed.
However, I meant to tell about how we grow old, rather than how we
can best get ready to be so.
Oddly enough, most living creatures do not grow old. They simply
live along till some other creature comes along and eats them up, or
till the cold weather comes on and they freeze. A fresh egg is so
soft that it hardly holds together; a young chicken is as tender as
you please; while an old hen has to be boiled for days in order to
be eaten at all. But an old fish isn’t tough; neither is an old
lobster. Who ever heard a cook asking for little oysters, for the
sake of getting them tender and juicy, or a fisherman preferring
small fish? We like these the better, the older and larger they are.
All animals, before they hatch out of the egg, are very soft.
Afterwards they all grow larger and harder. But some stop growing
big and continue to grow hard; and some stop growing hard and
continue to grow big. The first sort grow old; the second do not.
Now when you come to think of it, about the only animals that grow
old are the four-footed beasts, ourselves, and the birds. But the
rate at which these various creatures grow old may be very different
indeed.
Let us take a new-born human baby, and a new-born puppy, and a
new-born mouse. All these are helpless little babies; and all three
start immediately growing up and growing old. But while it takes six
months for the human baby to grow to be twice as large as it was at
birth, the puppy doubles its weight in nine days; while the little
mouse, in the first twenty-four hours doubles its weight twice, so
that at the end of its first day of life it is already four times as
large as at the beginning.
At six months, the human baby, if he is very much up and coming, as
you no doubt, my reader, were, can just begin to sit up without a
pillow at its floppy back; it cannot walk a step, and it hasn’t a
tooth in its head. But a six months puppy is a wiggly little beast,
who runs away miles when he gets lost, chews up the family
overshoes, and is well on the way toward losing his milk teeth.
Meanwhile the mouse has grown up to be as large as he ever will be,
has children of his own and probably grandchildren.
At five years the mouse is dying of old age. The puppy has become a
sedate and middle-aged dog; but the baby is still a little child,
just beginning to go to school, and still some years from losing its
first tooth. At ten years, the child is young, the dog is old, and
the mouse has become ancient history.
You musn’t think that the larger animals live longest. A horse is as
large as six or eight men, but it is old long before a man first
votes, and the birds, which are in general much smaller than the
beasts, also in general live three, four, and five times as long.
Even the elephant, thought to be longest lived of all beasts, lives
no longer than we. But fish and turtles and crocodiles and
shell-fish and the like, which are neither beasts nor birds and grow
big without growing old, may outlive even parrots, elephants and
men.