In front, the wall of leaves and branches still hung, seemingly impenetrable. The chief difference between this spot and any on either side, was that the mangrove boughs had apparently been trained to hang so low that the roots were invisible. Tentatively, Brice drew aside an armful of branches, just above the waiting dog. And, as though he had pulled back a curtain, he found himself facing a well-defined path, cut through the tangled thicket of root and trunk and bough--a path that wound out of sight in the dark recesses of the swamps. Roots had been cleared away and patches of water filled with them and with earth. Here and there a plank bridge spanned a gap of deeper water. Altogether--so far as Brice could judge in the fading light--the path was an excellent bit of rustic engineering. And it was hidden as cunningly from casual eyes as ever was a hermit thrush's nest. Some one had been at much pains and at more expense, to lay out and develop that secret trail. For it is no easy or cheap task to build a sure path through such a swamp. From a distance, forests of mangrove seemed to be massed on rising ground, and to group themselves about the sides and the crests of knolls. As a matter of fact, the presence of a mangrove forest is a sign of the very lowest ground, ground covered for the most part by salt tidewater. The lowest pine barren is higher than the loftiest mangrove wilderness. Gavin Brice's aspect of lassitude dropped from him like an outworn garment. For hours--except during his brief encounter with the beach comber--he had been steadily on the move, and had covered a good bit of ground. Yet, any one, seeing him as he traversed the miles from the Royal Palm Park at Miami, would have supposed from his gait that he was on some aimless ramble. Now, alert, quick-stepping, eager, he made his swift way along the windings of the secret path. Light as were his steps, they creaked lamentably at times on the boards of a bridge-span. More than once, he heard slitherings, in the water and marsh to either side, as some serpent or other slimy swamp-dweller wriggled away, at his passing. The collie trotted gravely along, just in front of him, pausing once in a while, as if to make certain the man was following. The silence and gloom and sinister solemnity of the place had had a dampening effect on the dog's gay spirits. The backward glances at his self-chosen master were for reassuring himself, rather than for guidance. Surroundings have quicker and stronger effect on collies than on almost any other kind of dog. And these surroundings, very evidently, were not to the collie's taste. Several times, when the path's width permitted, he dropped back to Gavin's side, to receive a word of friendly encouragement or a pat on the head.