It was filled with great, transparent cases, ranged in long, regular rows, extending from flickering blue-light wall to wall of the vast hall. In those cases there were shapes and figures, rigid and unmoving, that had apparently once been living things, and that were of a strangeness inconceivable. In hundreds, in thousands, they were grouped there in the protecting cases, beasts and beings all but indescribable in appearance, so strange were they even to our eyes, which had seen all the countless forms of life of our own galaxy. There was, in a case near us, a vast flat thing of white flesh, disk-like and scores of feet in diameter, with a single staring eye at its center. In another case was a great, many-legged cylinder of flesh without discernible features whatever. In still another, just before us, a black, powerful-looking insect-shape that was apparently double-headed, with two sets of black, beady eyes. All down the great hall's length stretched the rows of cases, filled with beings of which the sight of some alone was a creeping horror, and as we gazed at that incredible collection of alien forms in amazement, its significance rushed upon me. "It's a museum!" I exclaimed. "A great collection of the living forms that have existed in this dying universe--preserved here for countless ages, perhaps, out of the past!" As I spoke, though, there were coming down toward us from the far end of the great hall two serpent-creatures who seemed the custodians of this strange collection. Our guards addressed to them a few hissing commands, and the two turned, seemed to survey the cases about them, while we stared in perplexity. Then one turned toward a niche inset in the wall, in which rested two transparent containers or tubes of liquid, one of bright red and the other of green, and a long, slender metal needle that was apparently a hypodermic of some sort. Thrusting the needle into the red liquid, the serpent-creature holding it advanced to the case nearest us, which contained only the double-headed insect-creature. He swung the side of the case open, and then, with a swift jab, inserted the needle in the body of the thing inside.