With the instinct born of generations, each leaped independently toward the nearest tree, and, with the unconscious strength and celerity which comes to even wild animals with the dread of death at hand, each clambered to a treetop before a word was spoken. Scarcely had either left the ground before there was a rush into the open glade of a huge brown hairy form, and this was instantly followed by another. As Ab and Lightfoot climbed far amid the branches and looked down, they saw upreared at the base of each tree the figure of one of the monsters whose hungry exclamations they knew so well. They had been careless, these two lovers, especially the man. He had known well, but for the moment had forgotten how beast-infested was the immediate area about his new home, and now had come the consequence of his thoughtlessness. He and his wife had been driven to the treetops within a few yards of their own hearthstone, leaving their weapons inside their cave! Alarmed and panting, after settling down to a firm seat far aloft, each looked about to see what had become of the other. Each was at once reassured as to the present, and each became much perplexed as to the future. The cave bear, like his weaker and degenerate descendant, the grizzly of to-day, had the quality of persistence well developed, and both Ab and Lightfoot knew that the siege of their enemies would be something more than for the moment. The trees in which they perched were very close to the wood, but not so close that the forest could be reached by passing from branch to branch. Their two trees were not far from each other, but their branches did not intermingle. There was a distinct opening between them. The tree up which Lightfoot had scrambled was a great fir towering high above the strong beech in which Ab had found his safety. Branches of the fir hung down until between their ends and Ab's less lofty covert there were but a few yards of space. Still, one trying to reach the beech from the lofty fir would find an unpleasantly wide gap.