Near the center of each of the giant crystals there was visible through the semi-transparent wall a large inner nucleus of sullen opalescence that ceaselessly swirled and eddied. Their powers of movement were apparently limited to a slow, ponderous, half-rocking, half-rolling progress on their heavy rounded bases. They were now grouped in a rough semicircle just under the edge of the rocky projection that extended out over the pit. The opalescent nucleus in every silvery faceted form seemed to be "watching" with frightening intensity the figures on the pit's edge above them. * * * * * There was no mistaking the meaning of the scene. The giant carnivorous crystals had obviously been lured from their normal habitat in Arret's red vegetation, and established there in the big pit by the rat-men to act as principals in their primitive religious ceremonies. Those Devil Crystals waiting down there on the pit's floor were waiting to be fed--and the small group of captives, rat-men and human beings, were to be the feast! Utterly sick at heart, Powell wondered if they would at least be given the boon of a merciful death before being hurled over the brink to those lurking shapes. He was not left long in doubt. At a shrill command from the rat-king the guards closed in upon the captives and herded two of the bound rat-men from among them. A guard placed to the lips of each of the captive brutes a small cup containing a faintly cloudy white liquid. Apparently resigned to their fate, the creatures docilely drained the cups. The drugged drinks acted with startling rapidity. Scarcely a minute passed before the rodents' eyes clouded dully, their jaws dropped slackly open, and their bodies stiffened in almost complete rigidity. The bonds were quickly stripped from the two stupefied creatures. The ceremonial rites apparently required that the victims go to their doom unbound and of their own volition. The guards maneuvered the two over to the rocky projection that jutted out over the pit. Moving with the stiffly wooden steps of automatons, the two victims started out along the narrow projection, leaving the guards behind. On they marched, straight for the end of the rocky strip--and then, without a second's hesitation, they plunged on and over. Their bodies crashed to the pit's floor squarely among the group of waiting crystals. One of the rat-men lay motionless. The other dazedly tried to struggle to his feet--but was too late. * * * * * From the side of the nearest Devil Crystal, some fifteen feet away from the dazed rat-man, a cone-shaped projection budded with startling swiftness. A fraction of a second more and the projection had lengthened into a long slender arm of crystalline silver that streaked across the intervening space with the swiftness of a spear.