A little wisp of tenuous vapor swirled toward the ant, a wisp of the same vapor that had gathered above the whole range of hills as a thin, low cloud. It enveloped the insect--and the ant seemed to be attacked by a strange convulsion. Its legs moved aimlessly. It threw itself desperately about. If it had been an animal, Burl would have watched with wondering eyes while it coughed and gasped, but it was an insect breathing through air-holes in its abdomen. It writhed upon the spongy fungus growth across which it had been moving. Burl, lying in an exhausted, panting heap upon the purple mass of fungus, was conscious of a strange sensation. His body felt strangely warm. He knew nothing of fire or the heat of the sun, and the only sensation of warmth he had ever known was that caused when the members of his tribe had huddled together in their hiding place when the damp chill of the night had touched their soft-skinned bodies. Then the heat of their breaths and their bodies had kept out the chill. This heat that Burl now felt was a hotter, fiercer heat. He moved his body with a tremendous effort, and for a moment the fungus was cool and soft beneath him. Then, slowly, the sensation of heat began again, and increased until Burl's skin was red and inflamed from the irritation. The thin and tenuous vapor, too, made Burl's lungs smart and his eyes water. He was breathing in great, choking gasps, but the period of rest--short as it was--had enabled him to rise and stagger on. He crawled painfully to the top of the slope, and looked back. The hill-crest on which he stood was higher than any of those he had passed in his painful run, and he could see clearly the whole of the purple range. Where he was, he was near the farther edge of the range, which was here perhaps half a mile wide. It was a ceaseless, undulating mass of hills and hollows, ridges and spurs, all of them colored, purple and brown and golden-yellow, deepest black and dingy white. And from the tips of most of the pointed hills little wisps of vapor rose up. A thin, dark cloud had gathered overhead. Burl could look to the right and left, and see the hills fading into the distance, growing fainter as the haze above them seemed to grow thicker. He saw, too, the advancing cohorts of the army ants, creeping over the tangled mass of fungus growth. They seemed to be feeding as they went, upon the fungus that had gathered into these incredible monstrosities. The hills were living. They were not upheavals of the ground, they were festering heaps of insanely growing, festering mushrooms and fungus. Upon most of them a purple mould had spread itself so that they seemed a range of purple hills, but here and there patches of other vivid colors showed, and there was a large hill whose whole side was a brilliant golden hue. Another had tiny bright red spots of a strange and malignant mushroom whose properties Burl did not know, scattered all over the purple with which it was covered.