Ch. XV.] CORAL REEFS, 1881. 283 



not accumulate in the open ocean. Certainly, shells, &c, were 

 in several cases completely rotten, and crumbled into mud 

 between my fingers ; but you will know well whether this is in 

 any degree common. I have expressly said that a bank at the 

 proper depth would give rise to an atoll, which could not be 

 distinguished from one formed during subsidence. I can, 

 however, hardly believe in the former presence of as many 

 banks (there having been no subsidence) as there are atolls in 

 the great oceans, within a reasonable depth, on which minute 

 oceanic organisms could have accumulated to the thickness of 

 many hundred feet. 



" 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 that 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 subsi- 

 dence. 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 Dar- 

 winian 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. 



4i 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 introduced. Those who desire it, 

 will find clear and impartial statements of the varied and often 



