condition of their efficiency is absolute indifference to their own
security. Probably the majority of the ants that actually lay hold on
a foe suffer death in consequence; certainly they not merely run the
risk of but eagerly invite death.

The following day we descended the Sao Lourenco to its junction with
the Paraguay, and once more began the ascent of the latter. At one
cattle-ranch where we stopped, the troupials, or big black and yellow
orioles, had built a large colony of their nests on a dead tree near
the primitive little ranch-house. The birds were breeding; the old
ones were feeding the young. In this neighborhood the naturalists
found many birds that were new to them, including a tiny woodpecker no
bigger than a ruby-crowned kinglet. They had collected two night
monkeys--nocturnal monkeys, not as agile as the ordinary monkey; these
two were found at dawn, having stayed out too late.

The early morning was always lovely on these rivers, and at that hour
many birds and beasts were to be seen. One morning we saw a fine marsh
buck, holding his head aloft as he stared at us, his red coat vivid
against the green marsh. Another of these marsh-deer swam the river
ahead of us; I shot at it as it landed, and ought to have got it, but
did not. As always with these marsh-deer--and as with so many other
deer--I was struck by the revealing or advertising quality of its red
coloration; there was nothing in its normal surroundings with which
this coloration harmonized; so far as it had any effect whatever it
was always a revealing and not a concealing effect. When the animal
fled the black of the erect tail was an additional revealing mark,
although not of such startlingly advertising quality as the flag of
the whitetail. The whitetail, in one of its forms, and with the
ordinary whitetail custom of displaying the white flag as it runs, is