Now that the hexan threat that had so long oppressed the humanity of the _Sirius_ was lifted, that dull gray football of armor steel was filled with relief and rejoicing as the pilot laid his course for Europa. Lounges and saloons resounded with noise as police, passengers, and such of the crew as were at liberty made merry. The control room, in which were grouped the leaders of the expedition and the scientists, was orderly enough, but a noticeable undertone of gladness had replaced the tense air it had known so long. "Hi, men!" Nadia Stevens and Verna Pickering, arms around each other's waists, entered the room and saluted the group gaily before they became a part of it. "'Smatter, girls--tired of dancing already?" asked Brandon. "Oh, no--we could dance from now on," Verna assured him. "But you see, Nadia hadn't seen that husband of hers for fifteen minutes, and was getting lonesome. Being afraid of all you men, she wanted me to come along for moral support. The real reason I came, though," and she narrowed her expressive eyes and lowered her voice mysteriously, "is that you two physicists are here. I want to study my chosen victims a little longer before I decide over which of you to cast the spell of my fatal charm." "But you can't do that," he objected, vigorously. "Quince and I are going to settle that ourselves some day--by shooting dice, or maybe each other, or...." he broke off, listening to an animated conversation going on behind them. "... just simply outrageous!" Nadia was exclaiming. "Here we saved his life, and I fed him a lot of my candy, and we went to all the trouble of bringing their ship back here almost to Jupiter for them, and then they simply dashed off without a word of thanks or anything! And he always acted as though he never wanted to see or hear of any of us again, ever! Why, they don't _think_ straight--as Norman would say it, they're _full_ of little red _ants_! Why, they aren't even _human_!" "Sure not." Brandon turned to the flushed speaker. "They couldn't be, hardly, with their make-up. But is it absolutely necessary that all intelligent beings should possess such an emotion as gratitude? Such a being without it does seem funny to us, but I can't see that its lack necessarily implies anything particularly important. Keep still a minute," he went on, as Nadia tried to interrupt him, "and listen to some real wisdom. Quince, _you_ tell 'em." "They are, of course, very highly developed and extremely intelligent; but it should not be surprising that intelligence should manifest itself in ways quite baffling to us human beings, whose minds work so differently. They are, however ... well, peculiar." "I _won't_ keep still!" Nadia burst out, at the first opportunity. "I don't want to talk about those hideous things any more, anyway. Come on, Steve, let's go up and dance!" Crowninshield turned to Verna, with the obvious intention of leading her away, but Brandon interposed.