Darwin's concluding words in the same letter written within a year of his
death, are a striking proof of the candour and openness of mind which he
preserved so well to the end, in this as in other controversies.

"If I am wrong, the sooner I am knocked on the head and annihilated so much
the better. It still seems to me a marvellous thing that there should not
have been much, and long-continued, subsidence in the beds of the great
oceans. I wish some doubly rich millionaire would take it into his head to
have borings made in some of the Pacific and Indian atolls, and bring home
cores for slicing from a depth of 500 or 600 feet."

It is noteworthy that the objections to Darwin's theory have for the most
part proceeded from zoologists, while those who have fully appreciated the
geological aspect of the question, have been the staunchest supporters of
the theory of subsidence. The desirability of such boring operations in
atolls has been insisted upon by several geologists, and it may be hoped
that before many years have passed away, Darwin's hopes may be realised,
either with or without the intervention of the "doubly rich millionaire."

Three years after the death of Darwin, the veteran Professor Dana
re-entered the lists and contributed a powerful defence of the theory of
subsidence in the form of a reply to an essay written by the ablest
exponent of the anti-Darwinian views on this subject, Dr. A. Geikie. While
pointing out that the Darwinian position had been to a great extent
misunderstood by its opponents, he showed that the rival theory presented
even greater difficulties than those which it professed to remove.

During the last five years, the whole question of the origin of coral-reefs
and islands has been re-opened, and a controversy has arisen, into which,
unfortunately, acrimonious elements have been very unnecessarily