its treads spinning crazily as
the earth collapsed underneath it, where Alan had dug, then it fell with
a heavy splash into the mud, ten feet from where Alan stood.

Without hesitation Alan threw himself across the blaster housing,
frantically locking his arms around the barrel as the robot's treads
churned furiously in the sticky mud, causing it to buck and plunge like
a Brahma bull. The treads stopped and the blaster jerked upwards
wrenching Alan's arms, then slammed down. Then the whole housing whirled
around and around, tilting alternately up and down like a steel-skinned
water monster trying to dislodge a tenacious crab, while Alan, arms and
legs wrapped tightly around the blaster barrel and housing, pressed
fiercely against the robot's metal skin.

Slowly, trying to anticipate and shift his weight with the spinning
plunges, Alan worked his hand down to his right hip. He fumbled for the
sheath clipped to his belt, found it, and extracted a stubby hunting
knife. Sweat and blood in his eyes, hardly able to move on the wildly
swinging turret, he felt down the sides to the thin crack between the
revolving housing and the stationary portion of the robot. With a quick
prayer he jammed in the knife blade--and was whipped headlong into the
mud as the turret literally snapped to a stop.

The earth, jungle and moons spun in a pinwheeled blur, slowed, and
settled to their proper places. Standing in the sticky, sweet-smelling
ooze, Alan eyed the robot apprehensively. Half buried in mud, it stood
quiet in the shadowy light except for an occasional, almost spasmodic
jerk of its blaster barrel. For the first time that night Alan allowed
himself a slight smile. "A blade in the old gear box, eh? How does that
feel, boy?"

He turned. "Well, I'd better get out of here before the knife slips or
the monster cooks up some more tricks with whatever it's got for a
brain." Digging little footholds in the soft bank, he climbed up and
stood once again in the rustling jungle darkness.

"I wonder," he thought, "how Pete could cram enough brain into one of
those things to make it hunt and track so perfectly." He tried to
visualize the computing circuits needed for the operation of its
tracking mechanism alone. "There just isn't room for the electronics.
You'd need a computer as big as the one at camp headquarters."

* * * * *

In the distance the sky blazed as a blaster roared in the jungle. Then
Alan hea