"Reproduction, man, reproduction," he said. "Their race, just as any other, would come to a quick end if they didn't propagate." He pointed to five B.D.s whose fur was slowly turning yellow and falling from their bodies in brittle patches. "In exactly half an hour, those creatures will be dead, and from these seeds will come new B.D.s to fill the gaps. By actual count, we know there are approximately five hundred of these beings on Titan. At noon and midnight, half of them reproduce, and the half that has already reproduced dies. Thus there are at all times exactly five hundred of the creatures, no more and no less. The disease germs that all of them carry, though fatal to the Squeakers, don't seem to have any ill effects on them. If they are injured, their bodies heal, no matter how deep the wound. So a B.D. lives his full half-day, Titan-reckoning, regardless of accidents and diseases. I would like to remain here and watch these seeds develop into full-grown B.D.s, but we must be getting on to the mine. We shall remain there a week, Sergeant, returning to the garrison at the end of that time for fresh supplies and equipment. Four or five grav-trucks and cranes would make the work much easier, but all of my requisitions to the government for these have been rejected on the grounds the Squeakers might stage an uprising and gain possession of valuable equipment. As I said, we'll have to struggle along as best we can until we can catch the Squeakers in a false move and blast them out of existence. Carry on, Sergeant." Hallihan snapped to attention as the captain whirled on his heel and returned to his grav-car. Only fifteen minutes rest. Damn! Under the direction of Hallihan's acid tongue, the men heaved reluctantly to their feet and fell into line, whispering curses as the sergeant roared out the hated, "F'r'ard, harch! Hut! Twuh, hree, foar." "Ungh! Ungh, ungh ungh. Ungh! Ungh, ungh--" The B.D.s quickly appointed a new sergeant and took up the march with an eagerness that brought grunts of disgust from the begrimed men. Hallihan glanced back over his shoulder to fix an icy stare on this new nemesis, and his eyes widened with amazement as he caught sight of a disheveled man stumbling along behind them, his arms waving frantically and his lips moving in a soundless yell. The sergeant called a quick halt and waited for the man to overtake them. It was a soldier from the garrison. Blood trickled from his lips and one arm hung in a queer position at his side. The skin was hideously burnt and blackened where a heat-ray had caught him full in the face. Hallihan knew the man was dying as he collapsed in his arms, insanely babbling: "Managed to 'scape ... got all rest, but managed to 'scape ... must tell you, Serg'nt ... must tell you ... all rest dead...." * * * * *