170 J. D. Dana — Origin of Coral Reefs and Islands. 



I. Darwin's insufficient knowledge of the facts. 



In the Address referred to in the opening page of this article, 

 Dr. Greikie, speaking of Darwin, observes : " It should be borne 

 in mind that, compared with more recent explorers, he did not 

 enjoy large opportunities for investigating coral reefs." " He 

 appears to have examined one atoll, ti>e Keeling Reef, and one 

 barrier-reef, that of Tahiti." "By a gradually widening circle 

 of observations a series of facts has been established which were 

 either not known, or only partially known, to Darwin." — The 

 authors appealed to for the views that are presented as a substi- 

 tute for Darwin's are Prof. Karl Semper, who has examined and 

 described reefs of the Pelew and Philippine Islands ; Dr. J. J. 

 Rein, who has published on the physical geography of the Ber- 

 mudas; Prof. Alexander Agassiz, who has written on the 

 Florida reefs and others in that vicinity ; and Mr. John Murray 

 of the Challenger Expedition, whose investigations were made 

 at Tahiti : all able men in science whether more learned or not 

 than Darwin on the special subject under discussion. The facts 

 from " a widening circle of observations" referred to comprise 

 the physical and biological results of deep-sea exploration. 

 The writer is mentioned as one of the "competent observers" 

 who had given " independent testimony" in favor of Darwin's 

 views after "at least equal opportunities of studying the sub- 

 ject," and as he has, in these later years, looked into the new facts, 

 he has at least a claim to a hearing. 



As to Darwin's knowledge, it appears to the writer that the 

 apology offered in the above citations was not needed. In his 

 detailed investigation of Keeling atoll — a good example of 

 atolls and like all the rest in its principal features — and in his 

 examination of the Tahitian reefs, followed up by a careful 

 study of other atolls and reefs of the ocean through the maps 

 and descriptions of former surveying expeditions, he had a 

 broad basis for judgment and right conclusions. When the 

 second edition of his work was published in 1874, many of the 

 important facts from deep-sea exploration were already known ; 

 and later he learned of the more recent results ; and he did not 

 recant. A letter of his, of October 2nd, 1879, published by 

 Mr. Semper, while admitting with characteristic fairness the 

 interest of the facts collected by the latter, expresses his con- 

 tinued adherence to the opinion " that the atolls and barrier 

 reefs in the middle of the Pacific and Indian oceans indicate 

 subsidence." 



The writer, as his expositor, may be excused for adding here 

 that his own " independent testimony" was based on observa- 

 tions among coral reefs and islands in the Pacific during parts 

 of three years, 1839, 1840 and 1841 ; that, besides working 



