Still wordless, too stirred to speak, they opened the vault-like door and stepped out--into a humid heat which was like that of their own tropical regions, but not so unendurable. In their short stay on the moon, during which they had taken several walks in their insulated suits, they had become somewhat accustomed to the decreased weight of their bodies due to the lesser gravity, so that here, where their weight was even less, they did not make any blunders of stepping twenty feet instead of a yard. Walking warily, glancing alertly in all directions to guard against any strange animals that might rush out to destroy them, they moved toward the nearest stretch of jungle. * * * * * The first thing that arrested their attention was the size of the trees they were approaching. They had got some idea of their hugeness from the shell, but viewed from ground level they loomed even larger. Eight hundred, a thousand feet they reared their mighty tops, with trunks hundreds of feet in circumference; living pyramids whose bases wove together to make an impenetrable ceiling over the jungle floor. The leaves were thick and bloated like cactus growths, and their color was a pronounced lavender. "We must take back several of those leaves," said Wichter, his scientific soul filled with cold excitement. "I wish we could take back some of this air, too." Joyce filled his lungs to capacity. "Isn't it great? Like wine! It almost counteracts the effects of the heat." "There's more oxygen in it than in our own," surmised Wichter. "My God! What's that!" They halted for an instant. From the depths of the lavender jungle had come an ear shattering, screaming hiss, as though some monstrous serpent were in its death agony. They waited to hear if the noise would be repeated. It wasn't. Dubiously they started on again. "We'd better not go in there too far," said Joyce. "If we didn't come out again it would cost Earth a new planet. No one else knows the secret of your water-motor." "Oh, nothing living can stand against these guns of ours," replied Wichter confidently. "And that noise might not have been caused by anything living. It might have been steam escaping from some volcanic crevice." They started cautiously down a well defined, hard packed trail through thorny lavender underbrush. As they went, Joyce blazed marks on various tree trunks marking the direction back to the shell. The tough fibres exuded a bluish liquid from the cuts that bubbled slowly like blood. * * * * * To the right and left of them were cup-shaped bushes that looked like traps; and that their looks were not deceiving was proved by a muffled, bleating cry that rose from the compressed leaves of one of them they passed. Sluggish, blind crawling things like three-foot slugs flowed across their path and among the tree trunks, leaving viscous trails of slime behind them. And there were larger things....