Burl sobbed for breath in a little hollow, his sharp-toothed club still clasped in his hands. Something huge, with wings like sails, soared in silhouette against the sunset. Burl lay motionless, breathing in great gasps, his limbs refusing to lift him.

The sound of the army ants continued. At last, above the crest of the last hillock he had surmounted, two tiny glistening antennae appeared, then the small, deadly shape of an army ant. The forerunner of its horde, it moved deliberately forward, waving its antennae ceaselessly. It made its way toward Burl, tiny clickings coming from its limbs.

A little wisp of vapor swirled toward the ant. It was the vapor that had gathered over the whole range of hills as a thin, low cloud. It enveloped the ant which seemed to be thrown into a strange convulsion, throwing itself about, legs moving aimlessly. If it had been an animal instead of an insect, it would have choked and gasped. But ants breathe through air-holes in their abdomens. It writhed helplessly on the spongy stuff across which it had been moving.

Burl was conscious of a strange sensation. His body felt remarkably warm. It felt hot. It was an unparalleled sensation, because Burl had no experience of fire or the heat of the sun. The only warmth he had ever known was when huddling together with his tribesmen in some hiding-place to avoid the damp chill of the night.

Then, the heat of their breath and flesh helped to combat discomfort. But this was a fiercer heat. It was intolerable. Burl moved his body with a tremendous effort and for a moment the fungus soil was cool beneath him. Then the sensation of hotness began again and increased until Burl's skin was reddened and inflamed.

The tenuous vapor, too, seemed to swirl his way. It made his lungs smart and his eyes water. He still breathed in painful gasps, but even that short period of rest had done him some good. But it was the heat that drove him to his feet again. He crawled painfully to the crest of the next hill. He looked back.

This was the highest hill he had come upon and he could see most of the purple range in the deep, deep dusk. Now he was more than halfway through the hills. He had barely a quarter-mile to go, northward. But east and west the range of purple hills was a ceaseless, undulating mass of lifts and hollows, of ridges and spurs of all imaginable colorings.

And at the tips of most of them were wisps of curling gray.

From his position he could see a long stretch of the hills not hidden by the surrounding darkness. Back along the way he had come, the army ants now swept up into the range of hills. Scouts and advance-guard parties scurried here and there. They stopped to devour the creatures inhabiting the surface layers. But the main body moved on inexorably.

The hills, though, were alive, not upheavals of the ground but festering heaps of insanely growing fungus, hollowed out in many places by tunnels, hiding-places, and lurking-places. These the ants invaded. They swept on, devouring everything....