ggle
for existence. So that, in a case of this description, the supply of
food and the comparative scarcity of breeding stations have been factors
of like importance in the evolution of the territory.

Finally we were led to inquire as to how it comes about that the extent
of the area occupied by each individual is adapted to the circumstances
in which the individual finds itself; and we came to the conclusion that
the movements of the bird, subsequent to the initial act of establishing
itself in a position, are regulated and defined by the law of habit
formation. For example, the Warbler, in response to its inherited
nature, takes up a position in an appropriate situation. It then
proceeds to search for food; it makes short journeys first in this
direction and then in that; it repeats these journeys, and gradually
forms a habit which compels it to remain within more or less
well-defined boundaries. But the actual distance that it traverses on
the occasion of its first attempt must be determined by the relative
abundance or scarcity of the particular kind of insect life which it
requires. So that, although habit defines and in some measure helps to
determine the boundaries of the territory, it is clear that in the last
resort they must depend upon the nature of the conditions in the
external environment.

We have, then, the congenital basis which leads to the occupation of a
position, and to the enmity shown by the owner of the position towards
other individuals; and this congenital basis is found alike in many
widely divergent forms, living under equally widely divergent
conditions; we have acquired accommodation; and we have relationships in
the organic and inorganic world--and the outcome of it all is a system
of behaviour which we, who can perceive the end to which such behaviour
is tending, are justified in speaking of as "a disposition to secure a
territory." In the development of this system a primary value must be
ascribed to the conditions in the external environment, for they
determine the direction of the variations of instinctive procedure and
of acquired habit which work towards the same goal--that of adjustment
to the conditions of life.

NOTE

The following are the experiments referred to on page 181:--

On the 14th May 1915, a nest of Blackbirds approximately four days old
was removed at 6.45 A.M. The temperature was considerably below the
normal, and snow lay on all the high ground in th