eds, so that the movements of the bird can be
followed without much difficulty. Under favourable conditions
manifestations of the developing situation become visible at a
comparatively early date in the season--the middle or the latter part of
February--and these manifestations resemble those of other species. But
the Moor-Hen passes summer and winter alike in the same situation, and
being therefore in a position to respond at once to internal
stimulation, however vague, the change from the one state to the other
is gradual. This, however, is a matter of detail; the main consideration
lies in the fact that the impulse to retire to a definite position, to
avoid companions, and to live in seclusion, is strongly marked, and
produces a type of behaviour similar on the whole to that of the
Lapwing. First of all there is the appropriation of a certain position,
the limits of which are fixed according to the law of habit formation,
and according to the pressure exerted by neighbouring individuals; then
there is the neutral ground over which the birds wander amicably in
search of food; and finally there is the contrast between the pugnacity
of the male whilst in its territory, and its comparative friendliness
when upon neutral ground.

Evidence of similar behaviour is to be found in the life of the Black
Grouse, a bird which has always excited the curiosity of naturalists on
account of the special meeting places to which both sexes resort in the
spring. Mr. Edmund Selous watched these birds in Scandinavia, where he
kept a daily record at one of the meeting places. In various passages he
refers to the appropriation of particular positions by particular males,
and concludes thus: "It would seem from this that, like the Ruffs, each
male Blackcock has its particular domain on the assembly ground, though
the size of this is in proportion to the much greater space of the
whole. On the other mornings, too, the same birds, as I now make no
doubt they are, have flown down into approximately the same areas."

The cliff-breeding species--Guillemots, Razorbills, and Puffins--are
difficult to investigate because individuals vary so little, and the
sexes resemble one another so closely; yet, despite these difficulties,
we can gain some idea of the general purport of their activities. But
when the ledges are crowded and the air is filled with countless
multitudes, how is it possible to keep a single bird in view for a
sufficient length of ti