Movements were very painful. His lips were cracking and his face had blackened. The injured knee had swollen inside the protective suit; it throbbed and ached. Dazedly, he pulled himself to his feet.
On the rock beside him, spread an inch thick, was the almost-invisible creature he had been forced to circle in order to stop the liquid scorpion. He wondered tiredly if it was dangerous. It lay completely motionless, just as it had when the liquid scorpion had approached. So it was probably more afraid of him than he was of it. He turned away. There appeared to be shade down the valley—perhaps a mile, perhaps three. Too much for him, he knew, but he set out, feeling the sun beat cruelly at him, crying out when the pain in his knee forced him to catch his balance against the sun-heated rock.
He knew without turning that the liquid creature was following him, stopping when he stopped, starting when he started. When he knew he could go no farther and felt his knee give weakly to his weight, he saw it ooze forward and began to flow over his legs. He tried to reach his pistol, but it seemed so far away.
Xen, following the Sting-killer curiously, put together all that he had learned. This creature was different from himself. It needed shade. It had killed his enemy, which was possibly also its own enemy. Now it was trying to reach the shade, but its progress grew steadily slower.
He considered that progress. The only thing he could liken it to was one of his own kind, caught out in the time of cold, trying to reach the heat-retaining sands, slowly congealing into a solid mass and dying. This, then, was the reverse process. Perhaps the Sting-killer would become liquid after a certain degree of heat.
Xen's sense of knowing warned him gently about too much wandering in the open, where countless Stings could be hiding. He drew back, unwilling to stop following this interesting creature. The Sting-killer vibrated the ground and lay still suddenly. Xen waited for a "sense" of death but none came. This might be for the new thing a stage similar to that when one of Xen's own kind became unable to move from the cold, but still lived and feared.
Caught between his own fear and a very strange sensation that he could not interpret, Xen waited a degree of heat. Then he oozed forward and spread himself over the still shape, until it floated within him. When he flowed over one part, the thing struggled pitiably. Xen drew back startedly and the movement ceased. Carefully, he retraced his course, leaving the part free. This time there was no struggling.
Spurred by fear of Stings, Xen began to flow across the land, letting his "Sense" guide him to the coldness. He slithered up slopes, poured over steep drops, always collecting himself in time to catch his burden.
He found a place that would stay cold until the next time of heat and halted in front of it, his anxiety evident in the way he spread and collected himself, back and forth. At last he inched forward, feeling the agony of the cold bite into every cell. Bunching himself behind the Sting-killer, he made it flow along him until it broke free and lay upon the shaded rock. Xen drew back as hurriedly as his already-sluggish mass would allow. He spread thin across the earth and let the heat liquefy his body again....