Polaris snapped himself to his feet and bounded across the hall on the balls of his feet, almost as noiselessly as the shadow which had departed. And it had departed. Along the wall and behind the pillars Polaris glanced quickly. There was nothing there. Back of the pillar where he had seen the white shape was the closed door of a chamber. He tried the door and found it fast. He listened. From the darkness beyond the closed door, he thought he heard the ghost of a thin chuckle. Immediately his attention was drawn to another quarter. Close behind him arose a deep growl, which had nothing ghostly in its quality, but was most material. Polaris spun upon his heels. Some ten feet from him, and beside one of the pillars, from the foot of which it evidently had arisen, stood a huge dog. It was the first animal of its kind which the son of the snows had seen in Maeronica, and the largest he ever had set eyes on in his life; larger by far even than gray old Marcus, his friend and comrade that he'd left behind in Boston town. This brute was neither Great Dane nor mastiff, though in points it resembled both of those breeds. Its jaws were square, and its head and neck were massive. The tips of its powerful shoulders were a long yard up from the stone floor where it stood. It was smooth of coat and of a glossy, blue-black color, except on its breast, where was a triangular patch of tawny yellow. Its ears had been clipped and stood erect and pointed. As it regarded the man, its big eyes glittered in the dim light. Its lips were writhed back from formidable teeth. Another low growl rumbled from its deep chest. Instinctively, dogs trusted Polaris. He had had much experience with their kind, and never had he seen one that in the end he could not make his friend. Unhesitatingly he extended his hand and crossed the floor to where the big beast stood. He guessed that it must have come in with the old man whom he had glimpsed, and had been left behind when the silent visitor had made his hurried departure. As he drew nearer, Polaris saw that the animal wore a broad leather collar, bossed with gold. Unhurriedly, the son of the snows approached the brute until there was not the space of a yard between them. There he paused. The dog neither shrank nor cowered, but waited with muscles tensed and teeth exposed. Polaris was very watchful. "Good fellow," he said. At the sound of the man's voice, the dog shifted his position slightly. His head swayed. From Polaris's face he glanced to the outstretched hand. The bristling hackles at his neck subsided. He took a stiff step forward, then another. The tip of his cold muzzle touched the man's fingers. He sniffed. A long, red tongue crept forth and licked Polaris's hand. Another step, and the brute rubbed his great head against the man's thigh.