It seemed insane that such creatures, even in miniature, should painstakingly be brought across light-years of space to the new worlds men settled on. But it had been found to be necessary. The ecological system in which human beings belonged had turned out to be infinitely complicated. It had turned out, in fact, to be the ecological system of Earth, and unless all parts of the complex were present, the total was subtly or glaringly wrong. So mankind distastefully ferried pests as well as useful creatures to its new worlds as they were made ready for settlement. Mosquitos throve on the inhabited globes of the Rim Stars. Roaches twitched nervous antennae on the settled planets of the Coal-sack. Dogs on Antares had fleas, and scratched their bites, and humanity spread through the galaxy with an attendant train of insects and annoyances. If they left their pests behind, the total system of checks and balances which make life practical would get lopsided. It would not maintain itself. The vagaries that could result were admirably illustrated in and on the landscape outside the _Nadine_. Something had been left out of the seeding of this planet. The element--which might be a bacterium or a virus or almost anything at all--the element that kept creatures at the size called "normal" was either missing or inoperable here. The results were not desirable. * * * * * Harper drank thirstily. Carol had watched from the control-room. She was still pale. She looked strangely at Moran. "You're sure it didn't get through your suit?" Burleigh asked insistently of Harper. Moran said sourly; "The creatures have changed size. There's no proof they've changed anything else. Beetles live in tunnels they make in fungus growths. The beetles and the tunnels are larger, but that's all. Inchworms travel as they always did. They move yards instead of inches, but that's all. Centipedes--" "It was--" said Carol unsteadily. "It was thirty feet long!" "Centipedes," repeated Moran, "catch prey with their legs. They always did. Some of them trail poison from their feet. We can play a blowtorch over Harper's suit and any poison will be burned away. You can't burn a space-suit!" "We certainly can't leave Moran here!" said Burleigh uneasily. "He kept Harper from being killed!" said Carol. "Your blast-rifles weren't any good. The--creatures are hard to kill." "Very hard to kill," agreed Moran. "But I'm not supposed to kill them. I'm supposed to live with them! I wonder how we can make them understand they're not supposed to kill me either?" "I'll admit," said Burleigh, "that if you'd let Harper get killed, we'd have been forced to let you take his identity and not be marooned, to avoid questions at the space-port on Loris. Not many men would have done what you did." "Oh, I'm a hero," said Moran. "Noble Moran, that's me! What the hell would you want me to do? I didn't think! I won't do it again. I promise!"