They sprinted to their ship with spears and knives singing around them, reached it safely and bolted the port. "Too close," Carver said, panting for breath, leaning against the dogged port. "Have you got the serum?" "I got it," said Fred, rubbing his arm. "Damn!" "What's wrong?" "My arm. It feels numb." * * * * * Carver examined the wound, pursed his lips thoughtfully, but made no comment. "It's numb," Fred said. "I wonder if they poison those spears." "It's quite possible," Professor Carver admitted. "They did!" Fred shouted. "Look, the cut is changing color already!" The edges of the wound had a blackened, septic look. "Sulfa," Carver said. "Penicillin, too. I wouldn't worry much about it, Fred. Modern Terran drugs--" "--might not even touch this stuff. Open one of those tubes!" "But, Fred," Carver objected, "we have so little of it. Besides--" "To hell with that," Fred said. He took one of the tubes and uncorked it with his teeth. "Wait, Fred!" "Wait, nothing!" Fred drained the contents of the tube and flung it down. Carver said testily, "I was merely going to point out that the serum should be tested before an Earthman uses it. We don't know how it'll react on a human. It was for your own good." "Sure it was," Fred said mockingly. "Just look at how the stuff is reacting." The blackened wound had turned flesh-colored again and was sealing. Soon there was a line of white scar tissue. Then even that was gone, leaving firm pink flesh beneath. "Pretty good, huh?" Fred gloated, with a slight touch of hysteria. "It works, Professor, it works! Drink one yourself, pal, live another sixty years. Do you suppose we can synthesize this stuff? Worth a million, worth ten million, worth a billion. And if we can't, there's always good old Loray. We can drop back every fifty years or so for a refill. The stuff even tastes good, Professor. Tastes like--what's wrong?" Professor Carver was staring at Fred, his eyes wide with astonishment. "What's the matter?" Fred asked, grinning. "Ain't my seams straight? What you staring at?" Carver didn't answer. His mouth trembled. Slowly he backed away. "What the hell is wrong!" Fred glared at Carver. Then he ran to the spaceship's head and looked in the mirror. "_What's happened to me?_" Carver tried to speak, but no words came. He watched as Fred's features slowly altered, smoothed, became blank, rudimentary, as though nature had drawn there a preliminary sketch of intelligent life. Strange knobs were coming out on Fred's head. His complexion was changing slowly from pink to gray. * * * * * "I told you to wait," Carver sighed. "_What's happening?_" asked Fred in a frightened whimper.