which they had come; so at Bob's suggestion they carefully proceeded to walk in a circle—checking the route by notching the trees, and taking wider courses each time a circuit was completed.

But even these means were ineffective. Circle after circle was made, and still the earlier track was undiscovered. All the afternoon was thus occupied, and, when evening came, the boys were footsore and weary—glad to throw themselves down on the first piece of springy grass, too tired even to trouble about preparing food.

The disappointment was beyond words. They had started out in the morning full of cheerful hopes of being able to render aid to their parents who (they felt sure) were in need of assistance. And now, not only was this purpose frustrated, but they themselves were in that terrible plight of being lost in the backwoods—a hundred miles or more from the haunts of white men, with nothing but plucky hearts to help them, and limited ammunition to supply bodily needs.

The sun passed over their heads and sunk somewhere beyond the forest. They could not tell where it vanished, for the camp was amid such dense surroundings that they could hardly see beyond a hundred yards through the branches.

With dusk, and after a sparse meal, it was decided to light a fire, more for the sake of the cheering sight than the need for warmth.

Bob was the first to rise, and as he stood upright he was heard to give vent to a decided—

"Bother it!"

"What's the matter?" grunted Alf, as he also proceeded to rise.

"Matter?" repeated his chum. "Nothing; only I have stuck my head into a cloud of moths—big ones and little ones. There seems to be a regular party going on under this tree."

"It's that luminous patch in the tree that we've been sitting under," said Holden, at the same time drawing his friend's attention to what looked like a patch of light on the trunk of the maple about five feet from the ground.

"That's curious," remarked Bob, bending forward to examine the spot. "I wonder what it can be? It looks like the light on one of those luminous match-boxes that are made so that you can see them in the dark."

"They say that rotten wood sometimes has that effect——"

"But this tree is quite sound. And see! There's another the same on that tree to the right!"

It was certainly strange, and the boys picked up their guns and sauntered over to examine the next trunk, on which they found the same peculiar light attracting an equally numerous lot of moths of many descriptions.

"There's another!" exclaimed Alf, pointing ahead of him.

"And another!"

"And another!"

By this time the boys were quite excited by their discovery, and when Alf suddenly drew attention to the further discovery that the marked trees were almost in a straight line, their excitement was still further stirred.

"It's the strangest thing I ever heard of—in the natural history way," the younger lad said. "To find all these trees marked on the same side, and all in a straight line—why, it would puzzle the brains of anybody to explain it!"

Without any decided plan, and more out of curiosity than from any other motive, the chums proceeded from one tree to another, examining each as they reached it, and marvelling all the time at what they decided as being one of the most remarkable freaks of Nature that they had ever heard about.

Then they became aware of a strange sound that reached them from no great distance through the trees. It was a most remarkable sound—not that of any animal with which they were familiar; indeed, it was not a sound that suggested any beast or bird.

"What on earth is it?" questioned Alf, as the weird wail sighed through the forest.

"It sounds like a harmonium in distress!" replied Bob, with a slight laugh. And even as he spoke the wail was repeated, though this time could be distinctly heard the voice of some person struggling to articulate to some musical accompaniment the words—