He was oppressed with a sense of calamity happening, if it were not calamity already happened; and as he crossed the last watershed and dropped down into the valley toward camp, he proceeded with greater caution.
Three miles away he came upon a fresh trail that sent his neck hair rippling and bristling, It led straight toward camp and John Thornton.
Buck hurried on, swiftly and stealthily, every nerve straining and tense, alert to the multitudinous details which told a story--all but the end.

His nose gave him a varying description of the passage of the life on the heels of which he was travelling.

He remarked the pregnant silence of the forest.

The bird life had flitted.

The squirrels were in hiding.