Suppose, as you are walking home from school to-day, you are about to
cross the street when you see an automobile coming very fast. What do
you do? You stop, of course; wait for it to go by, and then start on
again. Why do you stop? "Why," you say, "if I didn't, the automobile
might run over me." Something of that sort would just flash through
your mind, wouldn't it, in the very same second that you first saw the
automobile coming. Now, as you know, you think with your brain. But
what was it this time that set your brain to thinking? "Nothing," you
say, "I just saw the automobile coming." And that is true in a way:
you didn't need anything more than your eyes to tell you.
But how did your eyes get the message to your brain, and how did your
brain tell your legs to stop walking? We must have in our bodies a
kind of telephone system. And that is, in fact, just what we have. Our
_brain_ is our "central office"; and our _nerves_ are the wires,
running from all parts of our body to the brain, carrying messages
back and forth.
An old man and an old woman lived out on the very edge of a little
town. One day their house caught fire and was blazing away before they
noticed it. They rushed to their neighbor's telephone and rang up
"Central" to tell her to "phone" for the firemen and hose cart. _Kling
a-ling-a-ling!_ went their bell, but no "Central" answered; and while
a man was running to town to get the firemen, the fire got such a good
start that the house burned down.
You can see from this why we need a central office in good working
order, when we use the "phone." All the wires run into the one
building, and there must be some one there to receive calls and see
that they are sent out to their proper places. In this case, you see,
"Central" should have been at her post to see that the message went on
to the engine house, and then the fire would have been put out
"double-quick."
The "central office" of our Body Telephone System is just as important
and just as necessary to keep in good working order. It would be very
little use to have even the keenest of eyes and the sharpest of ears,
with the readiest of nerve wires to carry their messages into the
center of the body, unless we had some _organ_, or headquarters, there
for switching the messages over to the nerves running to the right
muscles to tell them what to do. If the brain-"Central" should fail in
its duty, or get out of order, then the body would be in serious
trouble at once.
Every day we read in the papers of accidents because somebody didn't
think, as well as see or hear. People see cars and automobiles coming,
but don't give them a thought and so are run down and hurt. They hear
the whistle of the engine at the crossing, but drive on just the same,
without seeming to have heard it at all. They are absent-minded; the
operator in the "central office" seems to be off duty, or busy about
something else. But if we are going to get on in this world of cars
and automobiles and all sorts of unexpected things, we must always
"have our wits about us," as the saying goes, ready to send the
messages out to the muscles in our legs and arms and fingers just as
soon as any one of our "Five Senses" "rings up" the "Central" in our
brain.
Our body wires do not look at all like telephone wires; and the brain,
if you could see it, would never suggest to you a central office.
The nerves are fine white cords, the smallest ones finer than a hair,
and the largest so big and strong that you could lift the body by it;
and their branches run all over the body, to the muscles and the blood
tubes and the skin and all the other parts, as the picture shows. You
have already read how the skin can tell you when you feel warm and
when you feel cold and when something hurts you.
The brain is a soft wrinkled mass, partly gray and partly white. It is
in the head; and because it is very soft and easily hurt, Mother
Nature has put around it a strong wall, or shell, of bone--the
_skull_, or brain box. Feel your head and see how very hard this bone
is. Solomon, the Hebrew poet-king, called it the "golden bowl." I
suppose he called it a "bowl" because it is round like one, and
"golden" because it is so precious. People do not often grow well
again if the "golden bowl" is broken or even cracked.
[Illustration: THE NERVOUS SYSTEM--OUR BODY TELEPHONE
The picture shows the brain, or "Central," and the thick nerve
cord that runs down through the backbone, and the principal
nerves of the back and the arms.]
The big _nerve cable_, called the _spinal cord_, that connects the
brain with the rest of the body, and carries all the messages backward
and forward, runs down the back and is protected by the backbone, or
_spine_, which is hollow, so that the cord can run down through it.
This backbone is jointed together so beautifully, too, that you can
bend your back about and stoop over, and carry heavy weights on your
back, and yet the bony tube still protects the cord inside. Solomon
calls this the "silver cord," because it is so white and shiny that it
looks like silver. You see, our bodies are full of beautiful as well
as wonderful things.
Probably sometime when your teacher has asked you to recite a poem you
have all learned, someone in the class has answered, "I don't remember
it," or has stood up and recited the first few lines and then stopped,
and thought, and finally had to say, "I can't go on."
Now what is the matter with this boy, or girl? He looks bright enough,
and you will probably remember that he was in the class when you
learned the poem. "Oh," you say, "the poem didn't stay in his head."
No, it didn't "stick" in his memory; but why didn't it?
Some of the messages that the Five Senses carry to the brain are
answered at once, as when we move away from danger, or reach out our
hands and help ourselves to butter, or take off a shoe to shake out a
pebble. But there are other messages that do not call for an immediate
reply, and are just stored away for future use in the big "central
office" of our Body Telephone, in what we call our _memory_. And
later, when the proper message is sent in by our eyes or ears, or
other sense organs, which reminds us of this message which they sent
before, perhaps several weeks, months, or even years ago, it wakes up
the old message stored away in the memory, and we say we "remember"
what happened to us, or what we learned at that time.
So, when your teacher asks you to recite a certain poem, and your ears
hear the title or the first line, you recall the rest of the verses
and the lesson about it. How many things does the word "Christmas"
wake up out of your memory? or the sight of soldiers marching? or the
first taste of strawberries in May?
You think about a great many things that you never _do_. Really you
are thinking almost all the time you are awake. And besides the
messages that "Central" just stores away for future use, there are a
great many messages being carried back and forth along the "telephone
system" all the time, that you don't keep track of at all--the
messages that keep the stomach and the heart and the lungs and
everything in your body working together properly.
How are we to take care of the telephone lines and "Central" of our
_nervous system_? Whatever you do to build up and help the other parts
of the body will help your brain to _feel_ and _think_ and _remember_;
and will help your muscles and nerves to answer promptly and truly
whatever the message may be. Plenty of good food, plenty of sleep and
fresh air, plenty of play, will keep your nerves and brain healthy and
growing.
"ABSENT TO-DAY?"