Chap. XII. 
OCEA:t^IC ISLANDS. 
398 
successfully competing in stature with a fully deve¬ 
loped tree, when established on an island and having 
to compete with herbaceous plants alone, might readily 
gain an advantage by growing taller and taller and 
overtopping the other plants. If so, natural selection 
would often tend to add to the stature of herbaceous 
plants when growing on an oceanic island, to whatever 
order they belonged, and thus convert them first into 
bushes and ultimately into trees. 
With respect to the absence of whole orders on 
oceanic islands, Bory St. Vincent long ago remarked 
that Batrachians (frogs, toads, newts) have never been 
found on any of the many islands with which the great 
oceans are studded. I have taken pains to verify this 
assertion, and I have found it strictly true. I have, 
however, been assured that a frog exists on the moun¬ 
tains of the great island of New Zealand; but I suspect 
that this exception (if the information be correct) may 
be explained through glacial agency. This general 
absence of frogs, toads, and newts on so many oceanic 
islands cannot be accounted for by their physical con¬ 
ditions ; indeed it seems that islands are peculiarly well 
fitted for these animals; for frogs have been introduced 
into Madeira, the Azores, and Mauritius, and have 
multiplied so as to become a nuisance. But as these 
animals and their spawn are known to be immediately 
killed by sea-water, on my view we can see that 
there would be great difficulty in their transportal 
across the sea, and therefore why they do not exist on 
any oceanic island. But why, on the theory of creation, 
they should not have been created there, it would be 
very difficult to explain. 
Mammals offer another and similar case. I have 
carefully searched the oldest voyages, but have not 
finished my search; as yet I have not found a single 
s 3 
