it they would change their minds, for they
were not ordinarily lacking in courage--but so long as they ran both had
the feeling of being pursued by malignant entities which were always
just a step behind, but gaining.

They slipped on the smooth surface face and fell sprawling. Each felt,
when he fell, that he must rise at once, with all his speed, lest
something grasp him and hold him down forever. It was a horrible trapped
feeling, and yet....

They had but to look at each other to see that they were free. Nothing
gripped their feet to hold them back. Of course the way was slippery,
but no more so than an icy surface which one essays in ordinary shoes.
What then caused their fear?

* * * * *

The plane, so plainly visible there ahead and above, was like a haven of
refuge to them. They panted inside their helmets and their breath misted
the glass of their masks. But they stumbled on, making the best speed
they could under the circumstances.

Perhaps if they took, off, and regained their courage, returned to
normal in surroundings they knew and understood, they could come back
and try again, after having heard each other's voices. The silence, the
sign manual, the odd, awesome sensations, all combined to rob them of
courage. They must get it back if they were to succeed. And they had
been away from the plane for almost an hour. Hadley would be waiting for
some news.

The plane was twenty yards away--and almost at the same time Eyer and
Jeter saw something queer about it. At first it was hard to say just
what it was.

They rushed on. They were within ten yards of the plane when a wail of
anguish was born--and died--in two soundproof helmets. There was no
questioning the fact that the plane had settled into the surface of the
field.

The plane was invisible below the tops of the landing wheels, as though
the plane were sinking into invisibility, slowly dissolving from the
bottom.

"Understand?" Jeter's fingers almost shouted. "Understand why we felt
the desire to keep moving? This field is alive, Eyer, and if we stand
still it will swallow us just as it is swallowing our plane! Let's get
in fast; maybe we can still pull free from the stuff and take off."

They were racing against time and in the heart of each was the feeling
that whatever they did, their efforts would be hopeless. Still, the
spinning propeller of their plane gave them strength to hope.

They went through the