ants, that would not allow the Ecitons to ascend these trees.

Amongst the mammalia the opossums can convey their young out of
danger in their pouches, and the females of many of the tree-rats
and mice have a hard callosity near the teats, to which the young
cling with their milk teeth, and can be dragged away by the mother
to a place of safety.

The eyes in the Ecitons are very small, in some of the species
imperfect, and in others entirely absent; in this they differ
greatly from those ants which hunt singly, and which have the eyes
greatly developed. The imperfection of eyesight in the Ecitons is
an advantage to the community, and to their particular mode of
hunting. It keeps them together, and prevents individual ants from
starting off alone after objects that, if their eyesight were
better, they might discover at a distance. The Ecitons and most
other ants follow each other by scent, and, I believe, they can
communicate the presence of danger, of booty, or other
intelligence, to a distance by the different intensity or qualities
of the odours given off. I one day saw a column of Eciton hamata
running along the foot of a nearly perpendicular tramway cutting,
the side of which was about six feet high. At one point I noticed a
sort of assembly of about a dozen individuals that appeared in
consultation. Suddenly one ant left the conclave, and ran with
great speed up the perpendicular face of the cutting without
stopping. It was followed by others, which, however, did not keep
straight on like the first, but ran a short way, then returned,
then again followed a little further than the first time. They were
evidently scenting the trail of the pioneer, and making it
permanently recognisable. These ants followed the exact line taken