_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.