Gridley saw the vast number of animals that had been slaughtered and most of them uselessly, since there was more flesh there than the surviving tigers could consume before it reached a stage of putrefaction that would render it unpalatable even to one of the great cats. And this fact suggested the conviction that the cunning of the tigers had reached a plane where it might reasonably be expected to react upon themselves and eventually cause their extinction, for in their savage fury and lust for flesh they had slaughtered indiscriminately males and females, young and old. If this slaughter went on unchecked for ages, the natural prey of the tigers must become extinct and then, goaded by starvation, they would fall upon one another. The last stage of the ascendancy of the great cats upon the outer crust must have been short and terrible and so eventually it would prove here in Pellucidar. And just as the great cats may have reached a point where their mental development had spelled their own doom, so in the preceding era the gigantic, carnivorous dinosaurs of the Jurassic may similarly have caused the extinction of their own contemporaries and then of themselves. Nor did Jason Gridley find it difficult to apply the same line of reasoning to the evolution of man upon the outer crust and to his own possible extinction in the not far remote future. In fact, he recalled quite definitely that statisticians had shown that within two hundred years or less the human race would have so greatly increased and the natural resources of the outer world would have been so depleted that the last generation must either starve to death or turn to cannibalism to prolong its hateful existence for another short period. Perhaps, thought Gridley, in nature's laboratory each type that had at some era dominated all others represented an experiment in the eternal search for perfection. The invertebrate had given way to fishes, the fishes to the reptiles, the reptiles to the birds and mammals, and these, in turn, had been forced to bow to the greater intelligence of man. What would be next? Gridley was sure that there would be something after man, who is unquestionably the Creator's greatest blunder, combining as he does all the vices of preceding types from invertebrates to mammals, while possessing few of their virtues. As such thoughts were forced upon his mind by the scene below him they were accompanied by others of more immediate importance, first of which was concern for his fellows. Nowhere about the clearing did he see any sign of a human being alive or dead. He called aloud several times but received no reply, though he realized that it was possible that above the roaring and the growling of the feeding beasts his voice might not carry to any great distance. He began to have hopes that his companions had all escaped, but he was still greatly worried over the fate of Von Horst.