These interesting mimicry-rings (trusts), which have much significance for
the theory, have been the subject of numerous and careful investigations,
and at least their essential features are now fully established. Muller
took for granted, without making any investigations, that young birds only
learn by experience to distinguish between different kinds of victims. But
Lloyd Morgan's ("Habit and Instinct", London, 1896.) experiments with young
birds proved that this is really the case, and at the same time furnished
an additional argument against the LAMARCKIAN PRINCIPLE.

In addition to the mimicry-rings first observed in South America, others
have been described from Tropical India by Moore, and by Poulton and Dixey
from Africa, and we may expect to learn many more interesting facts in this
connection. Here again the preliminary postulates of the theory are
satisfied. And how much more that would lead to the same conclusion might
be added!

As in the case of mimicry many species have come to resemble one another
through processes of selection, so we know whole classes of phenomena in
which plants and animals have become adapted to one another, and have thus
been modified to a considerable degree. I refer particularly to the
relation between flowers and insects; but as there is an article on "The
Biology of Flowers" in this volume, I need not discuss the subject, but
will confine myself to pointing out the significance of these remarkable
cases for the theory of selection. Darwin has shown that the originally
inconspicuous blossoms of the phanerogams were transformed into flowers
through the visits of insects, and that, conversely, several large orders
of insects have been gradually modified by their association with flowers,
especially as regards the parts of their body actively concerned. Bees and
butterflies in particular have become what they are through their relation