While Leighton and Raoul were discussing the old problem of what became of the Chibcha Empire's far-famed treasure, the others had wandered away from the Black Magnet and were examining some of the strange objects in its immediate vicinity. The more familiar they became with this portion of the cave, the more signs they saw in it of human occupation. For one thing, the place was honeycombed with paths, most of them radiating from the shaft that sank to the bottom of Lake Guatavita. These paths led in different directions; but there was no way of telling whether any or all of them had been recently used. This question was of more immediate interest than the one connecting the cave with the fate of the ancient Chibchas. If this cave was inhabited to-day--if it was the hiding place of a lawless gang of Bogotanos, for example--it was well for the explorers to be on their guard. Herran was particularly alive to this possibility, and he was quick to heed, therefore, Mrs. Quayle's terrified exclamation, which she repeated-- "Good heavens! What is that?" It was at the head of one of the paths, running behind the close ranks of stalactites before which they had found their way from the large open cave beyond, that Mrs. Quayle stood, her eyes round with excitement, pointing vaguely at something in front of her. But the others could see nothing. Indeed, it was hard to tell whether she had really seen anything worth serious investigation, her chronic nervousness had such an uncomfortable habit of discovering specters--that did not exist--in every dark corner. Then, too, clusters of stalactites had a way of taking on odd, fantastic shapes that might easily seem to be alive even to the cool-headed. But this time there really was substance to Mrs. Quayle's fancies. She continued to point down the pathway of stalactites, crying repeatedly-- "What is that?" "Well, what is it?" demanded Leighton. "The man in the toga! The man in the toga!" she cried breathlessly. The others crowded about her. "It is nothing!" said Miranda incredulously. "It is! It is!" whispered Una. "I just caught the flash of white drapery at the bend in that farthest corridor." Raoul laughed. "You are mistaken," he said. "Nothing is there now, that's certain." They stood silently watching the dark green-and-white figures that stretched away in closely huddled ranks before them. But they could detect nothing that answered to Mrs. Quayle's description. There was nothing that moved, nothing human, in all that glittering array of grotesque forms. Then, there was a sharp, clinking sound, as if the brittle point of a stalactite had been broken off and had fallen to the ground. "We are watched," said Leighton in a low voice. "Whoever they are, these people have some reason for following us--and keeping out of the way." "Time to be on our guard," said Herran in Spanish to Miranda, who assented vehemently. "Nonsense!" exclaimed Raoul.