ch. xv.] CORAL REEFS, 1881. 299 



only as far as ordinary marine organisms are concerned, for 

 at that time little was known of the multitude of minute 

 oceanic organisms. I rejected this view, as from the few 

 dredgings made in the Beagle, in the south temperate re- 

 gions, I concluded that shells, the smaller corals, &c, de- 

 cayed, and were dissolved, when not protected by the depo- 

 sition of sediment, and sediment could not accumulate in 

 the open ocean. Certainly, shells, &c, were in several cases 

 completely rotten, and crumbled into mud between my fin- 

 gers ; 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 dis- 

 tinguished 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. 



mi 



" Darwin's concluding words in the same letter written 

 within a year of his death, are a striking proof of the can- 

 dour and openness of mind which he preserved so well to 

 the end, in this as in other controversies. 



" 4 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 the- 

 ory of subsidence. The desirability of such boring opera- 

 tions 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 with- 

 out the intervention of the i doubly rich millionaire.' 



" Three years after the death of Darwin, the veteran 

 Professor Dana re-entered the lists and contributed a power- 

 ful defence of the theory of subsidence in the form of a re- 

 ply to an essay written by the ablest exponent of the anti- 

 Darwinian views on this subject, Dr. A. Geikie. While 



