Well, it was gratifying, in a way--they died of old age. But die they did. It took three days to show an effect, but when it came, it was dramatic. These were young adult mice, in the full flush of their mousehood, but when these new demons got to work on them, they suddenly developed a frowsy, decrepit appearance that made them look like Bowery bums over whom Cinderella's good fairy had waved her wand in reverse. And two days later they were dead. "I think we've got something," said Greco thoughtfully; but I didn't think so, and I was right. Dead was dead. We could kill the animals by making them too young. We could kill the animals by making them too old. But keep them alive, once the demons were in them, we could not. Greco evolved a plan: Mix the two breeds of demons! Take an animal with the young-age demons already in it, then add a batch that worked in the other direction! * * * * * For a while, it seemed to work--but only for a while. After a couple of weeks, one breed or the other would gain the upper hand. And the animals died. It was fast in mice, slow in humans. Minnie stayed alive. But the nose grew longer and facial hair reappeared; simultaneously her complexion cleared, her posture straightened. And then, for the first time, we began to read the papers. STRANGE PLAGUE STRIKES ELGIN bawled the Chicago _Tribune_, and went on to tell how the suburbs around Elgin, Illinois, were heavily infested with a curious new malady, the symptoms of which were--youth. OAKLAND "BABY-SKIN" TOLL PASSES 10,000 blared the San Francisco _Examiner_. The New York _News_ found thousands of cases in Brooklyn. A whole hospital in Dallas was evacuated to make room for victims of the new plague. And more. We looked at each other. "They're out in force," said Theobald Greco soberly. "And we don't have the cure." IV The world was topsy-turvy, and in the middle of it Minnie disappeared, talking hysterically about reporting us to the authorities. I don't mind admitting that I was worried. And the experiments were not progressing. The trouble seemed to be that the two varieties of demons--the aging and the youthing--were not compatible; if one took up residence in a given section of an organism, the other moved out. The more numerous destroyed the weaker; there was no balance. We tested it again and again in the mice and there was no doubt of it. So far, only the youthing demons were free. But when Minnie left us, it was only a matter of time. Our carriers--from Grand Rapids and from the hotel--had spread to California and the East Coast, to the North and to the South, throughout the country, perhaps by now through the world. It would be slower with the aging demons--there was only one of Minnie--but it would be equally sure. Greco began drinking heavily. "It's the end," he brooded. "We're licked." "No, Greek! We can't give up!"