Tarzan smiled. It was the law of his own jungle--the law of the tribe of Kerchak, the bull ape--the ancient law of primitive man that needed but the refining influences of civilization to introduce the hired dagger and the poison cup. Then his attention was drawn to the outer edge of the vestibule. Above it appeared the shaggy face of one of Es-sat's warriors. Tarzan sprang to intercept the man; but Ta-den was there ahead of him. "Back!" cried the Ho-don to the newcomer. "It is gund-bar." The fellow looked scrutinizingly at the two fighters, then turned his face downward toward his fellows. "Back!" he cried, "it is gund-bar between Es-sat and Om-at." Then he looked back at Ta-den and Tarzan. "Who are you?" he asked. "We are Om-at's friends," replied Ta-den. The fellow nodded. "We will attend to you later," he said and disappeared below the edge of the recess. The battle upon the ledge continued with unabated ferocity, Tarzan and Ta-den having difficulty in keeping out of the way of the contestants who tore and beat at each other with hands and feet and lashing tails. Es-sat was unarmed--Pan-at-lee had seen to that--but at Om-at's side swung a sheathed knife which he made no effort to draw. That would have been contrary to their savage and primitive code for the chief-battle must be fought with nature's weapons. Sometimes they separated for an instant only to rush upon each other again with all the ferocity and nearly the strength of mad bulls. Presently one of them tripped the other but in that viselike embrace one could not fall alone--Es-sat dragged Om-at with him, toppling upon the brink of the niche. Even Tarzan held his breath. There they surged to and fro perilously for a moment and then the inevitable happened--the two, locked in murderous embrace, rolled over the edge and disappeared from the ape-man's view.