* * * * * Gunga chuckled. "What's the matter?" Forepaugh barked. "Going crazy already?" "Me, haw! Me, haw! Me thinkin'," Gunga rumbled. "Haw! We got, haw! plenty hydr'gen." He pointed to the low metal roof of the trading station. Though it was well insulated against sound, the place continually vibrated to the low murmur of the Inranian rains that fell interminably through the perpetual polar day. It was a rain such as is never seen on Earth, even in the tropics. It came in drops as large as a man's fist. It came in streams. It came in large, shattering masses that broke before they fell and filled the air with spray. There was little wind, but the steady green downpour of water and the brilliant continuous flashing of lightning shamed the dull soggy twilight produced by the large, hot, but hidden sun. "_Your_ idea of a joke!" Forepaugh growled in disgust. He understood what Gunga's grim pleasantry referred to. There was indeed an incalculable quantity of hydrogen at hand. If some means could be found to separate the hydrogen atoms from the oxygen in the world of water around them they would not lack for fuel. He thought of electrolysis, and relaxed with a sigh. There was no power. The generators were dead, the air drier and cooler had ceased its rhythmic pulsing nearly an hour ago. Their lights were gone, and the automatic radio utterly useless. "This is what comes of putting all your eggs in one basket," he thought, and let his mind dwell vindictively on the engineers who had designed the equipment on which his life depended. An exclamation from Gunga startled him. The Martian was pointing to the ventilator opening, the only part of this strange building that was not hermetically sealed against the hostile life of Inra. A dark rim had appeared at its margin, a loathsome, black-green rim that was moving, spreading out. It crept over the metal walls like the low-lying smoke of a fire, yet it was a solid. From it emanated a strong, miasmatic odor. "The giant mold!" Forepaugh cried. He rushed to his desk and took out his flash pistol, quickly set the localizer so as to cover a large area. When he turned he saw, to his horror, Gunga about to smash into the mold with his ax. He sent the man spinning with a blow to the ear. "Want to scatter it and start it growing in a half-dozen places?" he snapped. "Here!" * * * * * He pulled the trigger. There was a light, spiteful "ping" and for an instant a cone of white light stood out in the dim room like a solid thing. Then it was gone, and with it was gone the black mold, leaving a circular area of blistered paint on the wall and an acrid odor in the air. Forepaugh leaped to the ventilating louver and closed it tightly.