invariably pearls within
them. The oyster, to defend itself from the worm, covers the hole with
a substance which becomes as hard as the shell, and brilliant as
mother-of-pearl."

A breeze springing up towards evening, we proceeded on our voyage,
followed by the boats, which also shaped a course for the Aru Islands.
In the course of the next day we came in sight of a small rocky island
with high cliffs, off which we espied a couple of Chinese junks at
anchor. As the island was not much out of our course, we stood towards
it, keeping the lead going for fear of reefs. The water, however, was
deep close up to the rocks. The cliffs completely overhung the sea, and
we observed within them numerous hollows and caverns. On getting
nearer, we saw that several boats belonging to the junks were lying
directly under the cliffs. As the wind fell, we came to an anchor, for
the sea over which we were now sailing was so shallow, that we could
anchor in calm weather in almost any part of it.

A boat was lowered, and Mr Hooker invited us to accompany him. As we
passed near the Chinese junk the crew hailed us, and Mr Hooker, who
understood a little Chinese, remarked that they seemed very angry with
us.

"They think, probably, that we have come to search for edible birds'
nests, which they themselves are now collecting," he observed.

"Edible birds' nests?" exclaimed Emily and Grace together. "Do you mean
to say, Mr Hooker, by that, that there are birds' nests fit to eat?"

"The Chinese not only think them fit to eat, but esteem them great
delicacies," observed Mr Hooker. "These junks have come all the way
from China to collect them, and if they manage to get back without being
plundered by pirates, or sent to the bottom by storms, they will make an
enormous profit by the voyage."

Mr Hooker hailed the junk in return, and told the men that they need
not be alarmed; that we did not come to interfere with them, but only
prompted by curiosity to see what they were about. As we got nearer we
saw the entrance to a cavern, into which we pulled. A far from pleasant
odour issued from it, while ahead there was an inky darkness, which the
keenest eye could not penetrate. As we proceeded, however, we observed
a bright light coming from the interior, which showed us a boat with a
couple of Chinese in her, one of whom was holding a torch; while another
man, by means of a ladder, was mounting up a narrow ledge of rock on the
side. O