But the time came when he could walk no farther. He tried repeatedly and failed, and meanwhile the earth spun even more rapidly, threatening to whirl him off into space. It was a terrible sensation; he lay down and hugged the ground, clinging to roots and sobbing weakly. Rosa, he knew, was just around the next bend in the trail; he called to her, but she did not answer, and he dared not attempt to creep forward because his grip was failing. He could feel his fingers slipping--slipping. It was agony. He summoned his last atom of determination, but to no avail. He gave up finally, and felt himself propelled dizzily outward into immeasurable voids. His last thought, as he went whirling end over end through space, was of his sister. She would never know how hard he had tried to reach her.