Slipping and sliding over loose rocks and gravel, we at last emerged from behind the line of tumbled boulders and reached level ground. We didn't see Sandley at once. He had obviously moved from where we had left him. Then I noticed a small cloud of butterfly-creatures hovering over something on the ground about a hundred yards or so down the boulder line. An outstretched leg, all that was visible to us from where we stood, provided identification. It was Sandley. Heedless of danger, Pearce and I rushed forward. When we reached Sandley, the last of what must originally have been a horde of butterfly-creatures was leaving his motionless form. We were too late. Our terrible knowledge hadn't come soon enough. In an abrupt, overwhelming fury, I pointed my machine-pistol at the fluttering demons and sent a stream of pellets into their midst. The force of the barrage would have cut a man in two, but the things didn't seem to be affected in the slightest way. The pellets went through them as though they were no more solid than shadows. * * * * * The things made no move toward Pearce and myself, but continued to circle aimlessly overhead. They seemed too sated from whatever ghastly feast they had made upon Sandley to be interested in us just then. Having made certain of this, Pearce and I performed a quick examination of Sandley, which confirmed what we already knew--that he was dead. And there wasn't a mark upon him. Keeping a close watch upon the butterfly things, Pearce and I gave Sandley a hasty burial. Then I wrapped his belongings in my shirt, and together Pearce and I ran back to the ship. It wasn't until the port had been shut behind us that I felt safe. I prepared a light meal, which Pearce and I ate in brooding silence. Finally Pearce said, "What I can't understand is why the butterfly things should have attacked Sandley. It isn't logical for the life forms of one world to prey upon the life forms of another. There are too many differences." "I've been thinking about that myself," I answered. "The solution seems to be that the butterfly-creatures feed upon something common to all life forms--the mysterious electrical force that gives matter the peculiar property of being alive." Pearce shrugged, and after a moment his face brightened. "Anyway, we now have one less to divide with." He reached into a pocket, placing upon the table seven of the large crimson gems. I added the four that I had found, and for some seconds we gazed dreamily at our hoard. "People on Earth are going to fight like mad to own one of these gems," Pearce said softly. "By selling the gems slowly, playing one buyer against another, our profits will be plenty big." I nodded. "It won't make us very popular, but the end justifies the means." "I wish we had some means of protection against those butterfly things, so that we could look for more of the gems," Pearce said. "They're dangerous, and we don't seem to be able to harm them."