r
example, the largest wing-feather or tail-feather of this Sparrow is
quite like the one I pulled out of its back in texture, only the
back-feather is smaller and not so stiff. But near the roots of these
feathers you notice a fluffy part, where the webs do not hold together
firmly. Some feathers are as fluffy as that in their whole length. Such
are called down-feathers, because they are so downy. Birds that run
about as soon as they are hatched are always clothed in down, like
little chickens, before their other feathers sprout; and some birds,
like Ducks, wear a warm underclothing of down their whole lives. Then
again some feathers do not have any webs at all--only a slender shaft,
as fine as a hair."

"Do feathers keep on growing all the time, like my hair?" asked Dodo.

"No, my dear. They stop growing as soon as they are of the right size;
and you will find your hair will do the same, when it is long
enough--though that won't be for a good many years yet, little girl.
When the blood that has fed the growing feather is all dried up, the
feather ceases to grow. Then after a while longer, when it has become
ragged and worn, it gets loose in the skin and drops out--as I am sorry
to say some of my hair is doing already. That is what we call
_moulting_."

"I know about that," interrupted Nat. "It's when hens shed their
feathers. But I didn't know that it was moulting when people grow bald."

"It is very much the same thing," said the Doctor, "only we don't call
it moulting when people lose their hair. But there is this difference.
Birds wear out their feathers much faster than we do our hair, and need
a new suit at least once a year, sometimes oftener. All young birds get
their first new clothes when the down is worn out. Old birds generally
moult as soon as they have reared their broods, which in this country is
late in summer or early in the fall. Many also moult again the following
spring, when they put on their wedding dress; and one of the curious
things about this change of plumage is, that the new feathers often come
out quite unlike those that were cast off. So a bird may differ much in
appearance at different seasons and ages--in fact, most birds do. The
male also differs in many cases from the female, being more handsomely
dressed than his mate."

"I don't think that's fair," said Dodo. "I shouldn't like Nat to have
nicer clothes than I wear."

"But it is best for Bird People," replied the Doctor, "that