Instinct or experience must have imparted this useful truth to the lurker in the sumac patch, for as the great dog drew near the man incontinently wheeled and broke cover. At the same instant Lad charged. The man had a ten-foot start. This vantage he utilized by flinging himself bodily at a low-forked hickory tree directly in his path. Up the rough trunk to the crotch he shinned with the speed of a chased cat. Lad arrived at the tree bole barely in time to collect a mouthful of cloth from the climber's left trouser ankle. After which, since he was not of the sort to clamor noisily for what lurked beyond his reach, the dog yawned and lay down to keep guard on his arboreal prisoner. For half an hour he lay thus, varying his vigil once or twice by sniffing thoughtfully at a ragged scrap of trouser cloth between his little white forepaws. He sniffed the thing as though trying to commit its scent to memory. The man did not seek help by shouting. Instead, he seemed oddly willing that no other human should intrude on his sorry plight. A single loud yell would have brought aid from the stables or from the house or even from the lodge up by the gate. Yet, though the man must have guessed this, he did not yell. Instead, he cursed whisperingly at intervals and snarled at his captor. At last, his nerve going, the prisoner drew out a jackknife, opened a blade at each end of it and hurled the ugly missile with all his force at the dog. As the man had shifted his position to get at the knife, Lad had risen expectantly to his feet with some hope that his captive might be going to descend. It was lucky for Lad that he was standing when the knife was thrown for the aim was not bad, and a dog lying down cannot easily dodge. A dog standing on all fours is different, especially if he is a collie. Lad sprang to one side instinctively as the thrower's arm went back. The knife whizzed, harmless, into the sumac patch. Lad's teeth bared themselves in something that looked like a smile and was not. Then he lay down again on guard. A minute later he was up with a jump. From the direction of the house came a shrill whistle followed by a shout of "Lad! _La-ad!_" It was the Master calling him. The summons could not be ignored. Usually it was obeyed with eager gladness, but now--Lad looked worriedly up into the tree. Then, coming to a decision, he galloped away at top speed. In ten seconds he was at the veranda where the Master stood talking with a newly arrived guest. Before the Master could speak to the dog, Lad rushed up to him, whimpering in stark appeal, then ran a few steps toward the stables, paused, looked back and whimpered again. "What's the matter with him?" loudly demanded the guest--an obese and elderly man, right sportily attired. "What ails the silly dog?" "He's found something," said the Master. "Something he wants me to come and see--and he wants me to come in a hurry." "How do you know?" asked the guest.