Again, islands often possess
trees or bushes belonging to orders which elsewhere include only herbaceous
species; now trees, as Alph. de Candolle has shown, generally have,
whatever the cause may be, confined ranges. Hence trees would be little
likely to reach distant oceanic islands; and an herbaceous plant, which had
no chance of successfully competing with the many fully developed trees
growing on a continent, might, when established on an island, gain an
advantage over other herbaceous plants by growing taller and taller and
overtopping them. In this case, natural selection would tend to add to the
stature of the plant, to whatever order it belonged, and thus first convert
it into a bush and then into a tree.
ABSENCE OF BATRACHIANS AND TERRESTRIAL MAMMALS ON OCEANIC ISLANDS.
With respect to the absence of whole orders of animals on oceanic islands,
Bory St. Vincent long ago remarked that Batrachians (frogs, toads, newts)
are never found on any of the many islands with which the great oceans are
studded. I have taken pains to verify this assertion, and have found it
true, with the exception of New Zealand, New Caledonia, the Andaman
Islands, and perhaps the Solomon Islands and the Seychelles. But I have
already remarked that it is doubtful whether New Zealand and New Caledonia
ought to be classed as oceanic islands; and this is still more doubtful
with respect to the Andaman and Solomon groups and the Seychelles.
Pages:
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650