Merciful in its mercilessness, the hard-driven right front wheel smote the silky golden head with a force that left no terrible instant of fear or of agony. More lucky by far than the myriad innocent and friendly dogs that are left daily to scream out their lives writhingly in the wake of speeding motor-cars, Lady was killed at a single stroke. The fluffy golden body was hurled far in front of its slayer; and the wheels struck it a second time. The force of the impact caused the runabout to skid, perilously; and the youthful driver brought it to a jarring and belated halt. Springing to the ground, he rolled the dead collie's impeding body into the shallow wayside ditch, clear of his wheels. Then, scrambling aboard again, he jammed down the accelerator. Lad had made a flying leap over the door of the Master's car. He struck ground with a force which crumpled his healing right shoulder under him. Heedless of the pain, he hurled himself forward, on three legs, at an incredible speed; straight for the runabout. His great head low, his formidable teeth agleam beneath drawn-back lips, his soft eyes a-smolder with red flame, Lad charged. But, for all his burst of speed, he was too late to avenge; even as he had been too late to save. By the time he could reach the spot where Lady lay crumpled and moveless in the ditch, the runabout had gathered full speed and was disappearing down the bend of the highway. After it flew Lad, silent, terrible,--not stopping to realize that the fleetest dog,--even with all four of his legs in commission,--cannot hope to overhaul a motor-car driven at fifty miles an hour. But, at the end of a furious quarter-mile, his wise brain took charge once more of his vengeance-craving heart. He halted, snarled hideously after the vanished car, and limped miserably back to the scene of the tragedy. There, he found the Mistress sitting in the roadside dust, Lady's head in her lap. She was smoothing lovingly the soft rumpled fur; and was trying hard not to cry over the inert warm mass of gold-and-white fluffiness which, two minutes earlier, had been a beautiful thoroughbred collie, vibrant with life and fun and lovableness. The Master had risen from his brief inspection of his pet's fatal injuries. Scowling down the road, he yearned to kick himself for his stupidity in failing to note the Juggernaut's number. Head and tail a-droop, Lad toiled back to where Lady was lying. A queer low sound, strangely like a human sob, pulsed in his shaggy throat, as he bent down and touched his dead mate's muzzle with his own. Then, huddling close beside her, he reverted all at once to a trait of his ancestors, a thousand generations back.