"Be sure you take the smaller male body," she warned again. "Unless that's the female. You found evolution different in these creatures once," he reminded her. For a moment, she was silent. Then there was a mental shrug, and almost amusement as she answered. "Matching sex isn't logically necessary. It might even be an interesting amusement. But I must have the larger body." She began shifting at once. The silth gasped and tried to thresh about in death as Ptarra released control. Arnek sighed to himself and began to follow. It was worse than he remembered. After the centuries, the cells hated to give up their fixed form. The agony of the silth fed back to him, until his withdrawal stopped its heart. But slowly the nuclear matter flowed from the cells and up the pathways to their egress, taking the minimum of nutrient fluid with them. It took nearly an hour, and he could see the thin film of Ptarra already lying over the sleeping human. He began hurrying now, remembering her warning that the humans would not stay here once they wakened to find the two abandoned silths dead. He forced himself over the hateful dryness of the floor, up to the open mouth. Beyond lay the lungs, the circulatory system, and then the strange nerve bundle in the skull. Some of it was ugly, and some was hard. But the last stage was almost pleasant. He had forgotten how unsatisfactory the nerves of the last silth had been. These were like coming home to a friendly world, in a universe that had died too long ago and far away. For a time, he was almost glad that he had not died with it. Then the first allergic reactions began, and he had to relapse into instinct, to let his being fight to save both himself and his host cells from the reaction. He set the first stage up, however. This time he managed with no help from Ptarra. Then he relapsed into unconsciousness, making no effort to control his new silth yet. He'd have to revise when the silth awoke, he told himself. But it was only a dream order, half completed.... * * * * * It was a sudden painful pressure of acceleration that finally brought him out of his torpor. He felt half sick, and he could vaguely sense that the new silth was fevered and uncomfortable. But, amazingly, it was sitting up. And around it was a room bigger than the whole ship had seemed, and controls under its hands, and fantastic equipment. "It's about time," Ptarra's thoughts reached him. They were weak now, since it was hard to transmit in a partial stage, but they were cold and sure. "I've been aware for hours, while the silths reached the ship and took off. We've been off planet for at least an hour. Long enough to study their body controls and to learn how the ship operates." Arnek sighed to himself, while the pressure of tension refused to leave. "Are you sure?"