But two hours later he did a thing that Willis had never seen him do before. He threw the team into disorder by coming to an abrupt standstill in mid-trail without any hint of an order from his master. He was sniffing hard at the trail, turning sharply from side to side, his flews in the snow, while his nostrils avidly drank in whatever it was they found there, as a parched dog drinks at a water-hole. "Mush on there, Jan! What ye playin' at?" cried Willis. At the word of command Jan plunged forward mechanically. But in the next moment he had halted again and, nose in the snow, wheeled sharply to the right, almost flinging on its side the dog immediately behind him in the traces. For an instant Jim Willis wondered uncomfortably if his leader had gone mad. He had known sudden and apparently quite inexplicable cases of madness among sled-dogs, and, like most others having any considerable experience of the trail, he had more than once had to shoot a dog upon whom madness had fallen. At all events, before striding forward to the head of his team Willis fumbled under the lashings of the sled and drew out the long-thonged dog-whip which for months now he had ceased to carry on the trail, finding no use for it under Jan's leadership of the team. A glance now showed the cause of Jan's abrupt unordered right turn. Close to the trail Jim saw the fresh remains of a camp-fire beside the deep marks of a sled's runners. "Well, an' what of it?" said he to Jan, sharply. "'Tain't the first time you've struck another man's trail, is it? What 'n the nation ails ye to be so het up about it, anyway?" And then, with his practised trailer's eyes he began to examine these tracks himself. "H'm! Do seem kind o' queer, too," he muttered. "The sled's a middlin'-heavy one, all right, only I don't see but one dog's track here, and that's onusu'l. Mus' be a pretty good husky, Jan, to shift that load on his own--eh? But hold on! I reckon there's two men slep' here. But there's only one man's track on the trail, an' only one dog. Some peculiar, I allow: but this here stoppin' and turnin' an' playin' up is altogether outside the contrac', Jan. Clean contr'y to discipline. Come, mush on there! D'ye hear me? Mush on, the lot o' ye." It may be that, if he had had no reason for haste, Jim Willis would have gone farther in the matter of investigating Jan's peculiar conduct. As it was he saw every reason against delay and no justification for close study of a trail which he was desirous only of putting behind him. As a result he carried his whip for the rest of that day, and used it more often than it had been used in all the months since he first saw Jan. For, contrary to all habit and custom, Jan seemed to-day most singularly indifferent to his master's wishes, and yet not indifferent, either, to these or to anything, but so much preoccupied with other matters as to be neglectful of these.