Having learned many facts vital to the defense of Valeron and knowing that his return homeward would now be unopposed, Radnor put on full touring acceleration and drove toward his native world. Motionless at his controls, face grim and hard, he devoted his entire mind to the problem of how Valeron could best wage the inevitable war of extinction against the implacable denizens of the monstrous, interloping planet Chlora. XIX. As has been said, Radnor's reply to Siblin's message was unheard, for his ultraphones were not upon his person, but were lying disregarded in a corner of the room in which their owner had undergone examination by his captors. They still lay there as the Valeronian in his cage was wafted lightly back into the space ship from which he had been taken such a short time before; lay there as that vehicle of vacuous space lifted itself from its dock and darted away toward distant Valeron. During the earlier part of that voyage Radnor was also in the ether, traveling from Valeron to Chlora. The two vessels did not meet, however, even though each was making for the planet which the other had left and though each pilot was following the path for him the most economical of time and of power. In fact, due to the orbits, velocities, and distances involved, they were separated by such a vast distance at the time of their closest approach to each other that neither ship even affected the ultrasensitive electro-magnetic detector screens of the other. Not until the Chloran vessel was within Valeron's atmosphere did her commander deign again to notice his prisoner. "As I told you when last I spoke to you, I am about to land you in one of your inhabited cities," the amœbus informed Siblin then. "Get in touch with your Bardyle at once and convey our instructions to him. You have the sample and you know what you are to do. No excuses for nonperformance will be accepted. If, however, you anticipate having any difficulty in convincing your fellow savages that we mean precisely what we say, I will take time now to destroy one or two more of your cities." "It will not be necessary--my people will believe what I tell them," Siblin thought back. Then, deciding to make one more effort, hopeless although it probably would be, to reason with that highly intelligent but monstrously callous creature, he went on: "I wish to repeat, however, that your demand is entirely beyond reason. That ore is rare, and in the time you have allowed us I really fear that it will be impossible for us to mine the required amount of it. And surely, even from your own point of view, it would be more logical to grant us a reasonable extension of time than to kill us without further hearing simply because we have failed to perform a task that was from the very first impossible. You must bear it in mind that a dead humanity cannot work your mines at all."