He woke with the sun's warmth on his body and the realization of something amiss trickling through his head. It was a little while before he recognized the wrongness, and when he did he sat bolt upright. The sun was already up, and the monster should have begun once more its steady, ravenous march to the east. But there was no motion; the great living expanse lay still around him. He wondered wildly if it was dead. Presently, though, he felt a faint shuddering and lift beneath his feet, and heard far stifled mutterings and sighs. Westover's mind was beginning to function again; it was as though the cessation of the rock and sway had exorcised the lethargy that had lain upon him. He knew now that he had been almost insane for the time he had passed here, touched by the madness that takes hermits and men lost in deserts or oceans. And his was a stranger solitude than any of those. Now he listened strainingly to the portentous sounds of change in the monster's vitals, and in a flash of insight knew them for what they were. The scientists had found, in the burst bodies of the Titans that had been killed by atomic bombs, the answer to the riddle of these creatures' crossing of space: great vacuoles, pockets of gas that in the living animal could be under exceedingly high pressures, and that could be expelled to drive the monster in flight like a reaction engine. Rocket propulsion, of course, was nothing new to zoology; it was developed ages before man, by the squids and by those odd degenerate relatives of the vertebrates that are called tunicates because of their gaudy cellulose-plastic armor.... The monster on which Westover had been living as a parasite was generating gases within itself, preparing to leave the ravished Earth. That was the meaning of its gargantuan belly rumblings. And they meant further that he must finally leave it--now or never--or be borne aloft to die gasping in the stratosphere. Hurriedly the man scrambled to the highest eminence of the back and stood looking about; and what he saw brought him to the brink of despair. For all around lay blue water, waves dancing and glinting in the fresh breeze; and sniffing the air he recognized the salt tang of the sea. While he slept the monster had crept beyond the coast line, and lay now in what to it was shallow water--fifty or a hundred fathoms. Back the way it had come, a headland was visible, mockingly, hopelessly distant. Of course--the great beast would crawl into the sea, which would float its bloated bulk and enable it to accelerate and take flight. It would never have been able to lift itself into the air from the dry land.