ariously employed in breaking down branches, tearing up
long grass, and otherwise clearing ground for an encampment.

"How could insects make an island?" asked Polly, sitting down on a bank
to rest.

"Don't you know, Poll?" said Edwin; "why, I thought your father taught
you about almost everything."

"Oh no," replied Polly, with an innocent smile, "not everything yet, you
know, but I daresay he will in the course of time. Tell me about the
insects."

"Well, let me see, how shall I begin?" said Jack, leaning against the
bank, and crossing his arms on his breast. "The coral insects, Polly,
are very small, some of them not larger than a pin's head. They are
great builders. There is lime in sea-water. The insects, which are
called corallines, have the power of attracting this lime to them;
drawing it away from the water, so to speak, and fixing it round their
own bodies, which is called secreting the lime. Thus they form shells,
or houses, to themselves, which they fix at the bottom of the sea.
Having laid the basements of their houses close together, they proceed
to add upper storeys, and thus they add storey to storey, until they
reach the surface of the sea. They work in such innumerable millions
that, in course of time, they form reefs and islands, as you see."

"But I _don't_ see!" said Polly, looking round; "at least, I don't see
corallines working."

"Ah, good," said Baldwin, with a nod of approval to the child, as if to
say, "You have him there!"

"True," returned the philosopher, "because the corallines can only work
under water. The moment they reach the surface they die; but those that
remain continue their labours on the sides of the reef or island, and
thus widen it. Then the waves break off masses of coral, and cast them,
with drifting sea-weed and other things, up on the reef, which makes it
higher; then sea-birds come to rest on it. The winds carry seeds of
various plants to it, which take root, grow up, die; and thus thicken
the soil by slow degrees, till at last, after a long, long time, the
island becomes a pretty large and fertile one like this."

"Wonderful!" exclaimed Polly; "what a clever insect!"

"Clever indeed," returned Edwin; "especially when we consider that it
has got no brains."

"No brains!" echoed Baldwin.

"No, it has little more than a stomach."

"Oh! come now," remonstrated Baldwin; "we can't believe that, can we,
Miss Polly? Even a house-builder must think, much