river may have been the cause. The upper waters of the Xingu are
remarkably clear and pure, a fact which rendered the first theory most
probable.

The explorers had landed in a dangerous region, as they were destined
to learn very soon, and the experience of the couples who took routes
at right angles to each other was of the most thrilling character.

It has been stated that the progress of the canoe had been checked, as
was often the case before, by the rapids of the Xingu, which could be
passed only by carrying the canoe and luggage to the smoother waters
above. It was apparent that the river frequently overflowed its banks,
for immense quantities of driftwood lined both shores, while the
vegetation had been swept away to that extent that a space of a dozen
feet from the margin of the stream was comparatively free from it.
Thus both parties found the travelling easy.

The rapids were a hundred yards wide, more or less, and, with such a
steep incline, that the foamy waves dashed hither and thither and
against each other with the utmost fury, sending the spray high in air
and sweeping forward with such impetuosity that it seemed impossible
for the strongest craft under the most skilful guidance to shoot them.
The explorers studied them with great interest as they ascended the
left bank.

It was inevitable that in a country with such excessive vegetable
growth, every part of the Xingu should show much floating timber. The
logs which plunged through the rapids played all manner of antics.
Sometimes they leaped high out of the waters, like immense sea
monsters, the out-spreading limbs showing a startling resemblance to