The slayer had been a deft hand at the job. No sound had escaped the Missourian, from the moment the stranglingly tight left arm had been thrown around his throat from behind until, a second later, he fell bleeding and lifeless. In twenty leaping strides, Bruce came up to the slain sentinel and bent over him. Dog-instinct told the collie his friend had been done to death. And the dog's power of scent told him it was a German who had done the killing. For many months, Bruce had been familiar with the scent of German soldiers, so different from that of the army in which he toiled. And he had learned to hate it, even as a dog hates the vague "crushed cucumber" smell of a pitviper. But while every dog dreads the viper-smell as much as he loathes it, Bruce had no fear at all of the boche odor. Instead, it always awoke in him a blood-lust, as fierce as any that had burned in his wolf-ancestors. This same fury swept him now, as he stood, quivering, above the body of the kindly man who so lately had petted him; this and a craving to revenge the murder of his human friend. For the briefest time, Bruce stood there, his dark eyes abrim with unhappiness and bewilderment, as he gazed down on the huddled form in the wet grass. Then an electric change came over him. The softness fled from his eyes, leaving them bloodshot and blazing. His great tawny ruff bristled like an angry cat's. The lazy gracefulness departed from his mighty body. It became tense and terrible. In the growing moonlight his teeth gleamed whitely from under his upcurled lip. In a flash he turned and set off at a loping run, nose close to ground, his long stride deceptively swift. The zest of the man-hunt had obsessed him, as completely as, that day, it had spurred the advance of the "Here-We-Comes." The trail of the slayer was fresh, even over such broken ground. Fast as the German had fled, Bruce was flying faster. Despite the murderer's long start, the dog speedily cut down the distance between his quarry and himself. Not trusting to sight, but solely to his unerring sense of smell. Bruce sped on. Then, in a moment or two, his hearing re-enforced his scent. He could catch the pad-pad-pad of running feet. And the increasing of the sound told him he was gaining fast. But in another bound his ears told him something else--something he would have heard much sooner, had not the night wind been setting so strongly in the other direction. He heard not only the pounding of his prey's heavy-shod feet, but the soft thud of hundreds--perhaps thousands--of other army shoes. And now, despite the adverse wind, the odor of innumerable soldiers came to his fiercely sniffing nostrils. Not only was it the scent of soldiers, but of German soldiers. For the first time, Bruce lifted his head from the ground, as he ran, and peered in front of him. The moon had risen above the low-lying horizon vapors into a clear sky, and the reach of country was sharply visible.