With a visible diminishing of his first eager excitement, but with submissive haste, the big dog stepped out on to the veranda and began to cast about in the drifts at the porch edge.
Immediately, he struck Cyril's shuffling trail.

And, immediately, he trotted off along the course.
The task was less simple than ordinarily.

For, the snow was coming down in hard-driven sheets; blotting out scent almost as effectively as sight.

But not for naught had a thousand generations of Lad's thoroughbred ancestors traced lost sheep through snowstorms on the Scottish moors.

To their grand descendant they had transmitted their weird trailing power, to the full.