The efficiency of their herding was perfect. At each side entrance along the way stood one of the ghastly soldiers, jaws clashing with monotonous deadliness. Now and again several of the monsters appeared straight ahead, barring the avenue, and leaving no choice but to turn to right or left into off-branching tunnels. Small chance here of missing the path! And always behind them marched their two particular guards, closing off their retreat. "How do you suppose they sense our approach?" wondered Jim, who had noticed that the menacing jaw-clashing began while they were still fairly far from whatever side entrance was being barred to them. And again: "You're _sure_ they can't see?" "There isn't an eye in the lot of them," said Denny. "They must sense our coming by the vibration of our footsteps." But when they tried tiptoeing, on noiseless bare feet, the result was the same. Surely the things could not hear them for more than a few feet; yet with no sound to guide them, the blind guards commenced automatically opening and closing those invulnerable jaws with the distant approach of the two men just the same. They could only ascribe it to the same force that seemed able to follow them, step by step and thought by thought, though it was far away and out of sight--the ruling brain of the termite tribe. * * * * * Ever hotter it grew as they descended, till at length a blast of heat like a draft from a furnace met them as they rounded a corner and stepped into a corridor that no longer led downward. They knew that they were very near the ruler's lair now, on the lowest level, deep in the foundations of the vast pile. Dennis wiped perspiration, caused as much by emotion as by heat, from his face. He alone of all students on earth was going to penetrate the very heart of the termite mystery. He alone was going to have at least a glimpse of the baffling intelligence that science had guessed about for so many decades He ... alone. For it was hardly likely that he would ever get back up to the surface of earth to share his knowledge. How different was this adventure from what he had hoped it might be! He had thought that the two of them might simply enter the termitary, mingle--perilously, but with at least a margin of safety--with the blind race it housed, and walk out again whenever they pleased. But from the moment of entering they'd had no chance. They had been hopelessly in the clutch of the insects; played with, indulged, and finally trapped, to be led at last like dogs on a leash to the lair of the ruling power.