It did not occur to him that the affair was not his business because he hadn't been assigned to it. He belonged to the Med Service, and the physical well-being of humans everywhere was the concern of that service. If people lived by choice in an inhospitable environment, that was not a Med man's problem, but anything which led to preventable deaths was. And in a Crusoe colony there were plenty of preventable deaths! He cooked a meal to have something to occupy his mind. Murgatroyd sat on his haunches and sniffed blissfully. Presently Calhoun ate, and again presently darkness fell on this part of the world. There were new noises--small ones. He went to look. The pasture inside the landing grid was faintly lighted by the glowing ribbon in the sky. It looked like a many-times-brighter Milky Way. The girders of the landing grid looked very black against it. He saw a dark figure plodding away until he vanished. Then he reappeared as a deeper black against the snow beyond the pasture. He went on and on until he disappeared again. A long time later another figure appeared where he'd gone out of sight. It plodded back toward the grid. It was a different individual. Calhoun had watched a changing of sentries. Suspicion. Hostility. The least attractive qualities of the human race, brought out by isolation. There could not be a large population here, since such suspicions existed. And it was divided into--most likely--three again-isolated communities. This one had the landing grid, which meant power, and a spacephone but no vision screen attached to it. The fact that there were hostile separate communities made the situation much more difficult, from a medical point of view. It multiplied the possible ghastly features which could exist. Murgatroyd ate until his furry belly was round as a ball, and settled to stuffed slumber with his tail curled around his nose. Calhoun tried to read. But he was restless. His own time-cycle on the ship did not in the least agree with the time of daylight on this planet. He was wakeful when there was utter quiet outside. Once one of the cattle made a dismal lowing noise. Twice or three times he heard cracking sounds, like sharp detonations, from the mountains. They would be stirrings in the glaciers. He tried to study, but painstaking analysis of the methods by which human brains defeated their own ends and came up with wrong answers was not appealing. He grew horribly restless. * * * * * It had been dark for hours when he heard rustling noises on the ground outside--through the microphones, of course. He turned up the amplification and made sure that a small party of men moved toward the Med Ship. From time to time they paused, as if in caution. "Murgatroyd," he said dryly, "we're going to have visitors. They didn't give notice by spacephone, so they're unauthorized."