He called to Kreiss who was digging into a thin stratum of rock. The scientist had a splinter of flint in his hand, and he was gouging at a red outcropping layer. "Old John Q. Neanderthal, himself!" said Chet. "What have you found, silver or gold? Whatever it is, you're forgetting to eat; better come along." But Doctor Kreiss had turned geologist, it was plain. "Cinnabar," he said; "an ore of hydrargyrum!" His tone was excited, but Chet refused to have his mind turned from practical things. "Is it good to eat?" he demanded. "_Nein, nein!_" Kreiss protested. "It is what you call mercury--quicksilver!" "Ladies and gentlemen," said Chet dryly, "I see where this man Kreiss is to be a big help. He has discovered the site for the thermometer factory. He will be organizing a Chamber of Commerce next." He left out a portion of the cooked meat for Kreiss' later attention, and he and Harkness rolled a supply into leaf-wrapped packages and stowed them in the pockets of their coats before they started on. Again the little procession took up the march with Harkness leading. "Leave as little trail as possible," Harkness ordered. "We don't want to shout to Schwartzmann where we have gone." They left the Valley of the Fires to follow the stream-bed in another hollow between great hills. Chet found himself looking back at the familiar flares with regret. Here was the only place on this new world which was not utterly strange to his eyes. He continued to glance behind him, long after the smoky fires were lost to sight; but he would not admit even to himself that it was for another reason. Nineteen seventy-three!--and he was a man of the modern civilization. Yet deep within him there stirred ancient instincts--racial memories, perhaps. And, as he splashed through the little stream and bent to make his way through strange-leafed vines and leprous-spotted trees, a warning voice spoke inaudibly within his own mind--spoke as it might have whispered to some ancestor scores of centuries dead. "You are followed!" it told him. "Listen!--there is one who follows on the trail!" CHAPTER X _A Mysterious Rescuer_ Their way led through tangled growths of trees and vines that were like unreal things of a dream. Unreal they were, too, in their strange degree of livingness, for there were snaky tendrils that drew back as if in fear at their approach and stalks that folded great, thorny leaves protectingly about pulpy centers at the first touch of a hand. The world of vegetation seemed strangely sentient and aware of their approach. Only the leprous-white trees remained motionless; their red-veined trunks towered high in air, and the sun of late afternoon shot slantingly through a leafy roof overhead.