ow to climb
trees."

When both bears were high in the two trees, Grom and the girl slipped
down by the bending tips of the branches, almost as swiftly as
falling. They snatched up Grom's two spears and A-ya's broken one, and
ran, down along the brook toward the line of the smoking hills. The
bears, descending more slowly, came after them at a terrific,
ponderous gallop.

The girl ran, as she had said, well--so well that Grom who was famous
in the tribe for his running, did not have greatly to slacken his pace
in her favor. Finding that, at first, they gained slightly on their
pursuers, Grom bade her slow down a little till they did no more than
hold their own. Fearing lest she should exhaust herself, he ran always
a pace behind her, admonishing her how to save her strength and her
breath, and ever warily casting his eyes about for a possible refuge.
Warily, too, he chose the smoothest ways, sparing her feet. For he
knew that if she gave out and fell he would stop and fight his last
fight over her body.

For an hour or more the girl ran easily. Then she began to show signs
of distress. Her face grew ashen, the breath came harshly from her
open lips, and once or twice she stumbled. With the first pang of fear
at his heart, Grom closed up beside her, made her lean heavily on his
rigid forearm, and cheered her with words of praise. He pointed to a
spur of broken mountains now close ahead, with a narrow valley
cleaving them midway.

"There will be ledges," he said, "where we can defend ourselves, and
where you can rest."

Skirting a bit of jungle, so dense with massive cane and thorned
creepers that nothing could penetrate it, they came suddenly upon a
space of barren gray plain, and saw, straight ahead, the opening of
the valley. It was not more than a couple of furlongs distant. And its
walls, partly clothed with shrubbery, partly naked, were so seamed and
cleft and creviced that they appeared to promise many convenient
retreats. But across the mouth of the valley extended an appalling
barrier. From an irregular fissure in the parched earth, running on a
slant from one wall to the other, came tongues of red flame, waving
upwards to a height of several feet, sinking back, rising again, and
bowing as if in some enchanted dance.

Grom's heart stood still in awe and amazement, and for a second he
paused. The girl shut her eyes in unspeakable terror, and her knees
gave way beneath her. As she sank, Grom's spirit rose t