oes not abuse the authority which he possesses. Always at the head,
he leaps from branch to branch, and the band follows him. From time to
time he scales a tall tree, and from its heights scrutinises the
neighbourhood. If he discovers nothing suspicious a particular
guttural grunt gives information to his companions. If, on the
contrary, he perceives some danger he warns them by another cry, and
all draw in ready to follow him in his retreat, which he directs in
the same way as he guided the forward march.

Apes are not alone in relying on the experience of one of their
members. Many other animals act in the same way: antelopes, gazelles,
elephants, who advance in troops always conducted by an old male or
female who knows all the forest paths, all the places favourable to
pasture, and all the regions which must be avoided.

[Illustration: FIG. 9.]

Others, more democratic, instead of giving up the care of their safety
to one individual, which cannot be done without abdicating some degree
of individual independence, dispose around the place which they occupy
a certain number of sentinels charged to watch over the common safety.
This custom exists among prairie dogs, moufflons, crows, paroquets,
and a great many other animals. The sentinels of the crows are not
only always on the watch, but they are extremely discriminating; they
do not give a warning at the wrong time. It is certain that these
birds can distinguish a man armed with a gun from another who merely
carries a stick, and they allow the second to approach much nearer than
the first before giving the alarm.

Paroquets of all species live in joyous and noisy bands. After having
passed the night on the same tree they disperse in the neighbourhood,
not without having first posted watchers here and there, and they are
very attentive to their cries and indications.

The great Aras or Macaws, the large and handsome parrots of the Andes,
act with much prudence when circumstances make it advisable, and they
know when they ought to be on their guard. When they are in the depths
of the forest, their own domain, they gather fruits in the midst of a
deafening noise; each one squalls and cries according to his own
humour. But if they have resolved to pillage a field of maize, as
experience has taught them that these joyous manifestations would then
be unseasonable and would not fail to attract the furious proprietor,
they consummate the robbery in perfect silence. Senti