Carnivores of Light and Darkness by Alan Dean Foster

arcing vines, the struggling rain-forest plants and saplings. Heard the musical chorusing of the canopy creatures, smelled the pungent odors of decaying vegetation, inhaled the oxygen-rich air, and fainted.
    Ehomba was never sure whether the man slid back over the wall or was pulled back, perhaps by his companion. Regardless, he did not reappear. Letting loose the haft of his tooth-lined sword, the herdsman turned away and resumed his hike along the wall. A couple of times he looked back uneasily, but there was no sign of his former pursuers.
    No wonder he was traveling in what were known as the Unstable Lands, he reflected. Crossing the wall had seen him, for a few brief, unpleasant moments, stranded in another country. No, he corrected himself. In another world. One that, while superficially fascinating, he had no desire ever to revisit.
    He eyed the wall, a constant companion on his left. If he jumped it again would he once more find himself in that same choking, clangorous place? It was a conundrum he had no desire to resolve. As for the hapless inhabitants of that world, none of them sprang forth to confront him again. Perhaps the wall, or the section of it that was easily crossed, was more readily accessed from Ehomba’s side.
    When the wall finally disappeared, leaving him free to turn in any direction, it did not sink into the soil or rise magically into the sky. It simply stopped. Frowning at the abruptness of it, he cautiously examined the terminus. Long, ribbed bars of metal as thick around as his thumb protruded from the end, giving it an unfinished look. Perhaps that was its status in that other world—incomplete. Mischievously, he plucked a large toadstool from the fallen log on which it was growing nearby and placed the beige-hued fungal disk carefully between two of the metal bars. That should give the inhabitants of that other world something to think about, he resolved with a grin.
    Leaving the jagged terminus of the wall behind, he continued on his way. From now on, until he left the Unstable Lands, he would be careful what artifacts he handled, what doors he entered, and what walls he leaped.
    The rain forest grew denser, packing in tight around him, the trees pressing together, impenetrable undergrowth more prevalent. Clouds gathered, turning the visible sky the color of wet soot. Without the setting sun to guide him, it became more difficult to maintain his bearings.
    Unsheathing the sky-metal sword, he hacked a large arrow into the bark of a nearby tree. With its thin, greenish outer covering thus distinctively incised, the much paler inner wood was revealed. Yellowish white, it would be visible from a distance. Letting the blade hang at his side, he strode on.
    He was preparing to blaze another tree when a glimpse of pale not far in front of him made him hesitate. Hurrying forward, he found himself staring at the same arrow mark he had incised only moments ago. The edges of the cut were still fresh. Turning a slow circle, he studied the intense verdure that engulfed him on all sides. It was impossible to tell one growth from another. Angles blended together, and one bush looked much the same as its neighbor. Amidst all the greenery, only the blaze mark on the tree stood out distinctively.
    He would have bet a whole steer that he had hewed to a straight line through the forest, but the marked tree gave lie to that claim. There was no questioning it: Somehow, he had become turned around and walked in a circle. He was back where he had been not long before.
    Even though he had seen no one for days, he took the precaution of adding a straight line beneath the arrow. Sheathing the blade, he walked forward. Every few seconds he paused to look back, until the blazed tree was no longer in sight. Satisfied, he continued onward, marking his progress carefully. If not in a perfectly straight line, he was certainly walking north.
    A flash of diminishing light illuminated a trunk and his eyes widened. He did not