The mobile plant-men themselves were to be seen by day clustered in the valleys, their foliage spread to the sun. Only by night did we observe them in action, moving over the bare rock or busy with machines and other artificial objects, instruments of their civilization. There were no buildings, no roofed weatherproof enclosures; for there was no weather. But the plateaux and terraces of the rock were crowded with all manner of artifacts unintelligible to us.
