generated in whirling wheels. Apparently these cars, or chariots, were
universally used.

The explorers returned to the cube, where they found that Smith,
happening to look out a window, had spied a pond not far off. The three
visited it and found, on its banks, the first green stuff they had seen;
a tiny, flowerless salt grass, very scarce. It bordered a slimy, bluish
pool of absolutely still fluid. Nobody would call it water. They took a
few samples of it and went back.

And within a few minutes the doctor slid a small glass slide into his
microscope, and examined the object with much satisfaction. What he saw
was a tiny, gelatinlike globule; among scientists it is known as the
amoeba. It is the simplest known form of life--the so-called "single
cell." It had been the first thing to live on that planet, and
apparently it was also the last.



V

THE CLOSED DOOR


As they neared Jackson's pet "mansion" each man paid close attention to
the intervening blocks. For the most part these were simply shapeless
ruins; heaps of what had once been, perhaps, brick or stone. Once they
allowed the cube to rest on the top of one of these mounds; but the sky-
car's great weight merely sank it into the mass. There was nothing under
it save that same sandy dust.