ll the peace and soothing of
quiet Nature lay in that dark curtain of vegetation, but away from
behind there came ever the one message from our fellow-man. "We will
kill you if we can," said the men in the east. "We will kill you if we
can," said the men in the north.

All day the drums rumbled and whispered, while their menace reflected
itself in the faces of our colored companions. Even the hardy,
swaggering half-breed seemed cowed. I learned, however, that day once
for all that both Summerlee and Challenger possessed that highest type
of bravery, the bravery of the scientific mind. Theirs was the spirit
which upheld Darwin among the gauchos of the Argentine or Wallace among
the head-hunters of Malaya. It is decreed by a merciful Nature that
the human brain cannot think of two things simultaneously, so that if
it be steeped in curiosity as to science it has no room for merely
personal considerations. All day amid that incessant and mysterious
menace our two Professors watched every bird upon the wing, and every
shrub upon the bank, with many a sharp wordy contention, when the snarl
of Summerlee came quick upon the deep growl of Challenger, but with no
more sense of danger and no more reference to drum-beating Indians than
if they were seated together in the smoking-room of the Royal Society's
Club in St. James's Street. Once only did they condescend to discuss
them.

"Miranha or Amajuaca cannibals," said Challenger, jerking his thumb
towards the reverberating wood.

"No doubt, sir," Summerlee answered. "Like all such tribes, I shall
expect to find them of poly-synthetic speech and of Mongolian type."

"Polysynthetic certainly," said Challenger, indulgently. "I am not
aware that any other type of language exists in this continent, and I
have notes of more than a hundred. The Mongolian theory I regard with
deep suspicion."

"I should have thought that even a limited knowledge of comparative
anatomy would have helped to verify it," said Summerlee, bitterly.

Challenger thrust out his aggressive chin until he was all beard and
hat-rim. "No doubt, sir, a limited knowledge would have that effect.
When one's knowledge is exhaustive, one comes to other conclusions."
They glared at each other in mutual defiance, while all round rose the
distant whisper, "We will kill you--we will kill you if we can."

That night we moored our canoes with heavy stones for anchors in the
center of the stream, and made every