"The gas," the scientist replied. "I was working with a rubber latex. I had thought to make a mask, improvise an air-pump and send one of us through the green gas to reach the ship. And there was more that I hoped to do; but, as you say, my work is ended." "Bully for you," said Chet admiringly; "the old bean keeps right on working all the time. Well, you may do it yet; we may come back to the ship. Who can tell? But just now I am more anxious about Towahg. Right now, when we need him the most, he fails to show up." The ape-man was seldom seen by day, but always he came back before nightfall; his chunky figure was a familiar sight as he slipped soundlessly from the jungle where the shadows of approaching night lay first. But now Chet watched in vain at the arched entrance to the leafy tangle. He even ventured, after dark, within the jungle's edge and called and hallooed without response. And this night the hours dragged by where Chet lay awake, watching and listening for some sign of their guide. * * * * * Then dawn, and golden arrows of light that drove the morning mist in lazy whirls above the surface of the lake. But no silent shadow-form came from among the distant trees. And without Towahg--! "Might as well stay here and take it standing," was Chet's verdict, and Harkness nodded assent. "Not a chance," he agreed. "We might make our way through the forest after a fashion, but we would be slow doing it, and the brutes would be after us, of course." They made all possible preparations to withstand a siege. Chet, after a careful, listening reconnaissance, went into the jungle with bow and arrows, and he came back with three of the beasts he had called Moon-pigs. Other trips, with Kreiss as an assistant, resulted in a great heap of fruit that they placed carefully in the shade of a hut. Water they had in unlimited supply. How they would stand off an enemy who fought only with the terrible gleam of their eyes no one of them could have said. But they all worked, and Diane helped, too, to place extra bows at points where they might be needed and to put handfuls of arrows at the firing platforms spaced at regular intervals along the barricade. Chet smiled sardonically as he saw Herr Kreiss laboring mightily and alone to rig a catapult that could be turned to face in all directions. But he helped to bring in a supply of round stones from a distance down the shore, though the picture of this medieval weapon being effective against those broadsides of mental force was not one his mind could easily paint. * * * * * And then Towahg came! Not the silent, swiftly-leaping figure that moved on muscles like coiled steel springs! This was another Towahg who dragged a bruised body through the grass until Harkness and Chet reached him and helped him to the barricade.