uggestion for Orkins' benefit. The
cave probably would never be finished. One deep enough to offer a
refuge for five men could hardly be dug in a practical length of
time.

Dawn was not far off and the spheres were drifting over the town.
Already streets were filled with panic-stricken people. The
appearance of the strange balls of fire brought residents from
their homes in the middle of the night. Some fled in terror,
believing a new type of raider had been invented by the enemy.
Others stood watching.

The spheres circled. Taylor watched them, realizing he could do
nothing to stop what would happen. There was no way to warn these
helpless people that the spheres dealt death in a most sudden and
violent form.

Something nagged at Taylor's mind. Why had the sphere gone out
when he crept into the tunnel? What had caused it to die? Had the
sphere been grounded, trying to reach him under the surface of
the earth? Not likely, otherwise the creatures would not be able
to attack a man standing on the ground. The bolt, besides, was
not electricity, like lightning, but heat, which is not grounded
easily.

Where had the spheres come from? They surely were not of this
world. On the basis of biological evolution they could not be the
children of any life known to science. Had they evolved suddenly,
by accident? Some scientists thought all life had grown by
accident; the right combination of circumstances had occurred and
a chemical action had followed. Had the right combination for the
spheres come about as the result of the war and the releasing of
untold amounts of energy?

But even if life had begun on earth by accident, all other types
had taken ages to develop. These spheres, thinking creatures,
could not have evolved overnight.

These seemingly invincible creatures could not have come from
this world. Biological development comes through struggle and
survival. An invincible creature does not have to worry about its
existence--in fact, struggle was necessary to develop an
invincible being. These spheres must be from another world.
Refugees, perhaps, from another, even more powerful race; or
maybe they were seeking a new world to conquer.

One was circling overhead again. The leaves rustled. Taylor
thought he heard a choked-off scream. Orkins. He gritted his
teeth grimly.

There was only one link of hope in Taylor's chain of thought.
There must always be a check to every form of life. Terrestrial
plagues of inse