.

"I could go through all the inside parts of birds, and show you
something like the same parts in people,--stomach and bowels, to take
care of the food they eat and turn it into blood to nourish them; lungs
to breathe with, and keep the blood pure; heart to beat and thus pump
the warm blood into all parts of the body; brain and nerves, which are
what birds think and feel with, just as we do with ours; and all their
bones, which together make what we call the _skeleton_, or framework of
the body, to keep the flesh in shape and support the other organs."

"Dear me!" sighed Dodo; "there must be ever so many more things inside
of birds that we can't see, than there are outside."

"Of course there are!" said the Doctor. "It won't be very hard for you
to remember the outside parts, and learn the names of them all. I have
told you most of them that you need to remember, to understand the
stories I am going to tell you about birds. See here! What do you think
of this?"

[Illustration: Outside parts of a bird.]

So saying, the Doctor unrolled a large sheet of drawing-paper that hung
on the wall. "Here is a picture of the White-throated Sparrow, drawn so
big you can see it almost across the room, with all the outside parts of
which you must learn the names. You see the names are all on the
picture, too; I am going to make it smaller, and put it in the book I
will write for you, so you can look at it whenever you wish.

"It is almost dinner-time now, and you must be very hungry. But now I
must tell you one thing more. You know there are so many, many different
kinds of birds and other animals that nobody could remember them unless
they were classified. To classify is to put things that are most alike
closest together, then next nearest them things that are next most
alike, and to keep furthest apart those things that are least alike. Now
it is true that all beasts, birds, snakes, lizards, frogs, and fishes
have some things alike, though each has some other things different from
all the rest. If they were not all alike in some things, we could not
call them all animals. One of the things in which all the animals I have
named are alike is, that they all have skeletons. One of the things in
which all their skeletons are alike is, that they have backbones.
Backbones are the chains of bones that run along the back from the head
to the tail. Backbones are called by the Wise Men _vertebrae_; animals
that have backbones are name