ping of wings
succeed in separating the weakest and killing it.[23]

[23] Bendire, _Life Histories of North American Birds_,
1892, p. 319.

Dr. J. Lowe has recently called attention to a very curious method of
attracting prey adopted by the Blackcap (_Sylvia atricapilla_) at
Orotava, Teneriffe.[24] This bird has discovered that the juice exuded
by certain flowers (_Hibiscus Rosa sinensis_ and _Abutilon frondosum_)
is attractive to the insects upon which he preys; he therefore
punctures the petals of these flowers in order to promote the
exudation of this viscid secretion.

[24] Linnaean Society, 1st June 1893.

Many of us in our schooldays have admired the intelligence of Jackdaws
having their nests in some old tower or belfry. They are able to
distinguish according to the hour the significance of the various
school bells. Most of these clangs do not move them, and they continue
to attend to their affairs without paying attention. Their attention
is only attracted by the ringing which marks the beginning and the end
of recreation time. At the sound of the first they all flee and
abandon the courts before even a single pupil has yet appeared. The
bell, on the contrary, which marks the end of recreation time invites
them to descend in a band to collect the crumbs of lunch. They arrive
in a hurry, so as to be the first to profit by the repast, not waiting
even until the place is abandoned; they know very well that the young
people still there are not to be feared, having no time now to be
occupied with them.

In this class of facts, there are a certain number which may be
considered as more marked by custom and perhaps less marked by
spontaneous reflection. Such, for example, is the custom of Sharks and
Seagulls to follow ships.

In the seas where Dog-fish are abundant, one or more of them become
attached to a ship, and quit it neither night nor day. One may believe
sometimes that they are not there; but if any object is thrown into
the sea, the fin of one of these monsters appears at the surface;
everything which is thrown overboard disappears in their large
jaws--kitchen refuse, bottles, etc. When a dead body is thrown into
the sea it is soon seized by the shark, while living men who fall into
the water have great difficulty in escaping, and are often drawn up
horribly mutilated and half dead.

Sea-gulls also follow vessels when they approach the coast. It is a
pleasant sight to see the noisy band