pressed, and presently we
learned why.

It seemed that he had gone straight to that section of the forest
where he had hitherto always found signs of the transparent and
invisible creatures which he had determined to capture, and he had not
found a single trace of them.

"It alarms me," he said, gravely. "If they have deserted this region,
it might take a lifetime to locate them again in this wilderness."

Then, very quietly, sinking her voice instinctively, as though the
unseen might be at our very elbows listening, Miss Barrison recounted
the curious adventure which had befallen the dog and the first batch
of apple-pies.

With visible and increasing excitement the professor listened until
the very end. Then he struck the table with clinched fist--a
resounding blow which set the concentrated soup dancing in the bowls
and scattered the biscuits and the industrious red ants in every
direction.

"Eureka!" he whispered. "Miss Barrison, your deduction was not only
perfectly reasonable, but brilliant. You are right; the pies are for
that very purpose. I conceived the idea when I first came here. Again
and again the pies that my guide made out of dried apples disappeared
in a most astonishing and mysterious manner when left to cool. At
length I determined to watch them every second; and did so, with the
result that late one afternoon I was amazed to see a pie slowly rise
from the table and move swiftly away through the air about four feet
above the ground, finally disappearing into a tangle of jasmine and
grape-vine.

"The apparently automatic flight of that pie solved the problem; these
transparent creatures cannot resist that delicacy. Therefore I decided
to bait the cage for them this very night--Look! What's the matter
with that dog?"

The dog suddenly bounded into the air, alighted on all fours, ears,
eyes, and muzzle concentrated on a point directly behind us.

"Good gracious! The pies!" faltered Miss Barrison, half rising from
her seat; but the dog rushed madly into her skirts, scrambling for
protection, and she fell back almost into my arms.

Clasping her tightly, I looked over my shoulder; the last pie was
snatched from the table before my eyes and I saw it borne swiftly away
by something unseen, straight into the deepening shadows of the
forest.

The professor was singularly calm, even slightly ironical, as he
turned to me, saying:

"Perhaps if you relinquish Miss Barrison she may be able to free
he