All who had come into contact with the terrible substance had been destroyed. Hundreds, perhaps thousands, must have been employed in hauling the countless masses of stones to the spot, in painting the lacquered designs upon their surfaces, in placing the stones in the corrosive clay, in withdrawing the stones after they had been etched, in handling and cleaning them. And all of these men who had touched the incredibly powerful material, had succumbed to its effects. I shuddered as I thought of what agonies they must have suffered, of how their flesh and bones must have been eaten away as if by fire. Perhaps even the emanations of the material were deadly, and I hurriedly retreated at the thought. Azcopil had said that in the past the valley had been almost depopulated by the “gods who carved the stones.” As I recalled his words, I remembered the prophecy as related by old Katchilcan--“The people shall wither and die. Those who carved the stones and placed the images shall vanish.” Here was the explanation, the solution of the mystery of the disappearance of the Mayas! They had been destroyed, wiped out by the very means they had employed to produce their greatest monuments! I felt sure of it, convinced of it. If the horrible stuff existed here, if the people had used it for etching the stones, it must have existed elsewhere, must have been used in other places. That no one had hitherto discovered it, meant nothing. Perhaps, during the centuries, it had disintegrated, disappeared. Perhaps it still existed in some remote, hidden localities. But that it had been the prime factor in the destruction of the civilization, I felt assured. Here in Mictolan the segregated survivors of the people had come close to utter annihilation by it. They had only escaped extermination by the wise old priest, Tutul Hunac, who put an end to etching the stones. No doubt, elsewhere, the people had gone blindly on, believing superstitiously that the gods demanded human lives in return for carving the stones, until the race had been decimated, reduced to a handful of survivors. But what could the material be? What mineral could possess such powers? A wild idea occurred to me. Was it, could it contain radium? Was the black mineral exuding from the mountain side pitchblende? It had all the earmarks of that wonderful ore. And there was that strange fluorescent light. Had these people harnessed the mysterious powers of radium? Had they a knowledge of forces of which we had not dreamed? Was I on the verge of discoveries even more remarkable, more incredible than any I had yet made? For a space, my brain whirled, my thoughts ran wild, I gave my imagination full rein. But I was soon to learn that the actuality was far beyond my wildest dreams. * * * * *