me to understand its routine? The difficulty is
not an insuperable one. The flights, undertaken seemingly for no
particular purpose, are often of short duration and are completed before
the strain of observation becomes too great; moreover an individual
sometimes possesses a special mark or characteristic which serves to
make it conspicuous. For example, there is a well-marked variety of the
Common Guillemot, the Ringed or Bridled Guillemot of science,
distinguished by an unusual development of white round the eye and along
the furrow behind it. One such individual I was fortunate in discovering
upon a crowded cliff, and, as in the case of the Lapwing with the broken
leg or the Yellow Bunting with the injured foot, the identity of the
bird was beyond dispute, and one could observe that it appropriated to
itself a particular position upon a particular ledge.

Guillemots and Razorbills return at intervals to the breeding stations
early in the season, and these visits are repeated with growing
frequency until the birds are finally established. I have witnessed
these periodic returns during March in the south of England, and during
April in the north-west of Ireland, and I am informed that in the latter
district such visits may occur as early as February. Gaetke, who had
ample opportunity of observing the birds in Heligoland, puts their
return at an even earlier date. "They visit their breeding places," he
says, "in flocks of thousands at the New Year, often even as early as
December, as though they wanted to make sure of their former haunts
being well preserved and ready for their reception." Such visits,
however, are irregular in occurrence; the birds arrive, and, after
spending a short time upon the ledges, disappear. And since there is not
the same evidence in their coming and going of that method which we
observe in the periodical returns of the Bunting or the Finch, it may be
thought that needless importance is being attached to an episode in
their lives which is quite intelligible in terms of a feeble response
determined by a dawning organic change. While it may be quite
intelligible in such terms it is not thereby explained; for every
response must have as its antecedent an inherited connection in the
nervous system determined on biological grounds. Besides, these early
periodic returns conform in general to the type of behaviour displayed
by other species, the males of which return to their breeding grounds
many we