inal reaction of jumping
up on you; and these preparatory reactions were, of course, responses
to the particular trees he had to dodge, and the ditches he had to
jump; but they were at the same time governed by the inner state set
up in him by your {78 } whistle. This inner state favored certain
reactions and excluded others that would have occurred if the dog had
not been in a hurry. He passed another dog on the way without so much
as saying, "How d'ye do?" And he responded to a fence by leaping over
it, instead of trotting around through the gate. That is to say, the
inner state set up in him by your whistle _facilitated_ reactions that
were preparatory to the final reaction, and _inhibited_ reactions that
were not in that line.

A hunting dog following the trail furnishes another good example of a
directive tendency. Give a bloodhound the scent of a particular man
and he will follow that scent persistently, not turning aside to
respond to stimuli that would otherwise influence him, nor even to
follow the scent of another man. Evidently an inner neural adjustment
has been set up in him predisposing him to respond to a certain
stimulus and not to others.

The homing of the carrier pigeon is a good instance of activity
directed in part by an inner adjustment, since, when released at a
distance from home, he is evidently "set" to get back home, and often
persists and reaches home after a very long flight. Or, take the
parallel case of the terns, birds which nest on a little island not
far from Key West. Of ten birds taken from their nests and transported
on shipboard out into the middle of the Gulf of Mexico and released
500 miles from home, eight reappeared at their nests after intervals
varying from four to eight days. How they found their way over the
open sea remains a mystery, but one thing is clear: they persisted in
a certain line of activity until a certain end-result was reached, on
which this line of activity ceased.

One characteristic of tendencies that has not previously been
mentioned comes out in this example. When a tendency has been aroused,
the animal (or man) is tense and {79} restless till the goal has been
reached, and then quiets down. The animal may or may not be clearly
conscious of the goal, but he is restless till the goal has been
attained, and his restlessness then ceases. In terms of behavior, what
we see is a series of actions which continues till a certain result
has been reached and th