Although the two physicians were deeply interested in the question of toxicology they could not forget their situation and its perils. The craft had nearly completed its half mile to the mouth of the tributary which it was intended to ascend, when the polemen, pausing for a moment's rest, whispered that they heard the sound of paddles again.

"There they are!"

It was Jack Everson who uttered the exclamation, loud enough for all to hear. He pointed down stream as he spoke, and every one perceived the dreaded boat returning.

Although nearer at hand than before, it seemed to be following the course of the river, and there was hope that it would again pass without discovering the shrinking ones so near land.

When first observed the other boat was fifty yards out and not quite so far down stream. Moving against the current its progress was slower than before, but its advance was plainly perceptible. The craft of the white people had lost the momentum imparted by the poling, and was now controlled only by the current, which was so sluggish close to the land that the motion was hardly noticeable.

The hopes of our friends steadily rose until the other boat was almost directly abreast. It would seem that if the occupants intended attacking they would have veered inward before this, but there could be no assurance so long as they remained visible.

Every one started when the gaunt, sloping figure suddenly became upright at the prow of the boat and stood motionless. He had ceased u............