large, shapeless body half-floating in the lashing
water that covered their rocky shelf to a depth of several feet, the
upper part spectral and gray. It was a giant amoeba, fully six feet in
diameter in its present spheroid form, but capable of assuming any
shape that would be useful. It had an envelope of tough, transparent
matter, and was filled with a fluid that was now cloudy and then
clear. Near the center there was a mass of darker matter, and this was
undoubtedly the seat of its intelligence.

The Earth man recoiled in horror! A single cell with a brain! It was
unthinkable. It was a biological nightmare. Never before had he seen
one--had, in fact, dismissed the stories of the Inranian natives as a
bit of primitive superstition, had laughed at these gentle, stupid
amphibians with whom he traded when they, in their imperfect language,
tried to tell him of it.

They had called it the Ul-lul. Well, let it be so. It was an amoeba,
and it was watching him. It floated in the downpour and watched him.
With what? It had no eyes. No matter, it was watching him. And then it
suddenly flowed outward until it became a disc rocking on the waves.
Again its fluid form changed, and by a series of elongations and
contractions it flowed through the water at an incredible speed. It
came straight for the window, struck the thick, unbreakable glass with
a shock that could be felt by the men inside. It flowed over the glass
and over the building. It was trying to eat them, building and all!
The part of its body over the port became so thin that it was almost
invisible. At last, its absolute limit reached, it dropped away,
baffled, vanishing amid the glare of the lightning and the frothing
waters like the shadows of a nightmare.

* * * * *

The heat was intolerable and the air was bad.

"Haw, we have to open vent'lator, Boss!" gasped the Martian.

Forepaugh nodded grimly. It wouldn't do to smother either. Though to
open the ventilator would be to invite another invasion by the black
mold, not to mention the amoebae and other fabulous monsters that had
up to now been kept at a safe distance by the repeller zone, a simple
adaptation of a very old discovery. A zone of mechanical vibrations,
of a frequency of 500,000 cycles per second, was created by a large
quartz crystal in the water, which was electrically operated. Without
power, the protective zone had vanished.

"We watch?" asked Gunga.

"You b