stroyed
and buried under a thick covering of glowing stones." Now, it is "again
covered with a mantle of green, the growth being in places so
luxuriant that it is necessary to cut one's way laboriously through the
vegetation." (Op. cit. page 4.) Ernst traces minutely how this has been
brought about by the combined action of wind, birds and sea currents,
as means of transport. The process will continue, and he concludes:--"At
last after a long interval the vegetation on the desolated island will
again acquire that wealth of variety and luxuriance which we see in the
fullest development which Nature has reached in the primaeval forest
in the tropics." (Op. cit. page 72.) The possibility of such a result
revealed itself to the insight of Darwin with little encouragement or
support from contemporary opinion.

One of the most remarkable facts established by Ernst is that this has
not been accomplished by the transport of seeds alone. "Tree stems and
branches played an important part in the colonisation of Krakatau by
plants and animals. Large piles of floating trees, stems, branches and
bamboos are met with everywhere on the beach above high-water mark and
often carried a considerable distance inland. Some of the animals on the
island, such as the fat Iguana (Varanus salvator) which suns itself in
the beds of streams, may have travelled on floating wood, possibly also
the ancestors of the numerous ants, but certainly plants." (Op. cit.
page 56.) Darwin actually had a prevision of this. Writing to Hooker he
says:--"Would it not be a prodigy if an unstocked island did not in the
course of ages receive colonists from coasts whence the currents flow,
trees are drifted and birds are driven by gales?" ("More Letters", I.
page 483.) And ten years earlier:--"I must believe in the... whole
plant or branch being washed into the sea; with floods and slips and
earthquakes; this must continually be happening." ("Life and Letters",
II. pages 56, 57.) If we give to "continually" a cosmic measure, can the
fact be doubted? All this, in the light of our present knowledge, is too
obvious to us to admit of discussion. But it seems to me nothing less
than pathetic to see how in the teeth of the obsession as to continental
extension, Darwin fought single-handed for what we now know to be the
truth.

Guppy's heart failed him when he had to deal with the isolated case of
Agathis which alone seemed inexplicable by known means of transport. But
whe