President's Address. 7 



bank. Not only was this explanation self-consistent, but it 

 harmonised well with the conclusion, derived from totally 

 different evidence, that there may have been wide-spread 

 and long-continued subsidence over the ocean-basins. It 

 was, moreover, supported by the independent testimony of 

 competent observers, who, with at least equal opportunities 

 of studying the subject, had espoused Darwin's views. Of 

 these witnesses, the most important was undoubtedly Professor 

 Dana, who accompanied the Wilkes' Exploring Expedition of 

 1838-42.^ Another powerful ally was found in Mr Couthouy, 

 who had studied coral-growths in the Pacific and in the West 

 Indian Seas.^ But even without the concurrent testimony of 

 eye-witnesses, the theory proposed by Darwin fitted so ad- 

 mirably into the geological theory of the day that it came itself 

 to be used as one of the most cogent proofs of vast oceanic 

 depression. And such is still the position which it holds. 



By a gradually widening circle of observations, however, a 

 series of facts has been established, which were either not 

 known, or only partially known, to Darwin. It should be 

 borne in mind that, compared with more recent explorers, he 

 did not enjoy large opportunities of investigating coral-reefs. 

 So far as can be judged from his published works, he appears 

 to have examined only one atoll — the Keeling Eeef; and 

 one barrier-reef — that of Tahiti. The Admiralty charts, the 

 work of previous voyagers, and unpublished information 

 communicated to him, enabled him to extend his generalisa- 

 tion over the whole of the rest of the coral regions which he 

 had not personally explored. The deep-sea expeditions of 

 recent years have now brought so much new light to bear 

 upon the whole question, that we are in a far better posi- 

 tion to discuss it than he was nearly half a century ago. Of 

 a few of the more important investigations, a brief resiome 

 may here be given, and their bearing upon Darwin's theory 

 of coral-reefs will then be discussed. 



As far back as the year 1851, the late L. Agassiz stated 



1 The narrative, containing Professor Dana's observations on Coral-Reefs, 

 appeared among the Reports of the Expedition. In 1872 he published a 

 volume on Coral and Coral-Reefs, where he again gave the weight of his 

 authority to the theory of subsidence. 



- Boston Jour. Nat. Hist., iv., 1843-44, p. 137. 



