Around the cat were rats, twenty or thirty of them, huge by any standards. The cat had fought; the dead animals were headless or disemboweled, unbelievably battered. But the robot had been outnumbered. Biological Survey had said there weren't any rats on Glade. They had also said that about mice. What was the key to their error? [Illustration] The biologist stood up. "What are you going to do about it?" "Build another warehouse, two-foot-thick fused dirt floors, monolithic construction. Transfer all perishables to it." Marin nodded. That would do it. It would take time, of course, and power, all they could draw out of the recently set up atomic generator. All other construction would have to be suspended. No wonder Hafner was disturbed. "Why not build more cats?" Marin suggested. The executive smiled nastily. "You weren't here when we opened the doors. The warehouse was swarming with rats. How many robot cats would we need--five, fifteen? I don't know. Anyway the engineer tells me we have enough parts to build three more cats. The one lying there can't be salvaged." It didn't take an engineer to see that, thought Marin. Hafner continued, "If we need more, we'll have to rob the computer in the spaceship. I refuse to permit that." Obviously he would. The spaceship was the only link with Earth until the next expedition brought more colonists. No exec in his right mind would permit the ship to be crippled. But why had Hafner called him back? Merely to keep him informed of the situation? * * * * * Hafner seemed to guess his thoughts. "At night we'll floodlight the supplies we remove from the warehouse. We'll post a guard armed with decharged rifles until we can move the food into the new warehouse. That'll take about ten days. Meanwhile, our fast crops are ripening. It's my guess the rats will turn to them for food. In order to protect our future food supply, you'll have to activate your animals." The biologist started. "But it's against regulations to loose any animal on a planet until a complete investigation of the possible ill effects is made." "That takes ten or twenty years. This is an emergency and I'll be responsible--in writing, if you want." The biologist was effectively countermanded. Another rabbit-infested Australia or the planet that the snails took over might be in the making, but there was nothing he could do about it. "I hardly think they'll be of any use against rats this size," he protested. "You've got hormones. Apply them." The executive turned and began discussing construction with the engineer. * * * * * Marin had the dead rats gathered up and placed in the freezer for further study.