LECTURE BY PROFESSOR DAVIS.

Press, Volume L, Issue 14977, 26 May 1914, Page 10

LECTURE BY PROFESSOR DAVIS.

DARWIN'S THEORY REGARDING CORAL REEFS. Professor Evans, president of the Canterbury Philosophical Institute, presided' over a large attendance vi the lecture room of the School of Engineering last night, when Professor Davis gave an address on the "Origin of the Coral Reefs of Fiji."

In briefly introducing Professor Davis. Dr. Evans said that Professor Davis's presence had a special meaning to them as ho was one of a small band, all picked men, who had honoured the Sew Zealand Philosophical Institute by accepting the nignost honour that the Institute had in its power to comer —that of honorary membership. (.Applause.)

Professor Davis, who was with, appiauso, said that he niight reciprocate- t>y saying tliat it. was a particular pleasure to hiia to give nn aduress to an Institute that hau honoured lurh by making mm an honorary member. Tho problem of tuo origin or coral reefs had ■ been closely studied for the past hundied years. Up to twenty or thirty years ago Darwin's tuoory had men wnii gcueral acceptance, but since then it uad lost favour and newer theories had met with a certain, amount of credence .Before loaviug America he had made a oaretul stuuy of all the theories advanced in respect to the origin ot corai rows. He briefly described, with the aid of diagrams, the different classes of coral isiand formations. Kegardiuj; iuo fringing reefs, he ea:d that there was agreement as to their origin. From some already formed reefs the youua (larvm) were carried away; ii tney worjt into coid water they died and many never reached any point of attachment-. In other 'vises the larvje attached themselves fc) somo newly-formed volcanic islet. The corals were of many and beautiful ?orms. Once established tho fringing •■eef grew upward and larger. The problem was how did these fringing reefs bcome barrier reefs. One theory was that the coral had grown up from a great depth from the rim ot some gieafc submerged volcanic crater, but it hed been established that coral could not live at a greater depth than twenty fathoms, and that disposed of thai theory. The lecturer then described tho theories advanced by Sir John Murray, Professor Alexander Agassiz and Charles I>arwin. Murray's idea was that the coral attached itself to the sides of a standing-still volcanic island and built outwards and seawards ; in some cases by the time the reef had extended a mile or so seawards the centre of the island may have been worn down by weathering. Agassiz's idea was somewhat similar, save that he presupposed that sea having formed a shallow rock platform on the sides of the island to which the coral attached itself. Darwin's idea presupposed the subsidence of the eohd core of the island. How was one to select the theory that most satisfactorily extrtained the phenomena? It might seem presumptuous to question the theories of such eminent scientists as those quoted, but science, properly considered, did not rest on authority After outlining his proposed tour of the islands. Professor Davis said that his intention wa s to get a critical ground of discrimination on -which to base an explanation. The theories mentioned could not be- tested by looking at the reefs only, for each of the theories mentioned would explain the reefs provided they accepted the processes that each theory involved It

was impossible to observe tW%L__ tion of these reefs bcause t& time during which they had been Wt^ a had passed. They could, w d ever, note what particular condi tions would bo imposed on■;> som l neighbouring area by the condition* involved in each of the three ;SriS and see if those conditions *are t>wv sent. The explanation would bVfound probably, by a mental of deduction. Professor Davis tlien sub jected the three theories to a Bevere analysis, showing in the cases of jj ur ray's and Agassiz's theories that some conditions ought to exist on the islands as, the result of the formation of the reefs, but which do not exist except in very rare cases. An essential of Darwin's theory of subsidence was that the island of initial corical form, as it jjuq. <=ided, lost its regular shore line, which became an embayed shoro liDe. On visiting the islands this he had found to bo the case. This fact had been ascertained by recent observers in Aus tralia. and by Professor Marshall of I Duuedin, whose handbook on tho'sub- [ jeefc had been very helpful. Ho spoke of the investigations by the American scientific man, Dana, who had confirmed, by observation. Darwin's theory Ho (Professor Davis) had not studied Hio coral formation beoauso that had been fully and abundantly studied, but had concentrated his attention on-tho phase f>o curiously neglected since Dana's time—tho formation and embavment of the const lines. Concluding Professor Davis said that he did not hope, by the publication of a rooori on lines of previous reports, to dispose of the theories of Murray and Agassiz, but An his report he intended to report : quite as emphatically and as clearly >is I hr. possibly _ could on the essential characteristics of the various theories, not only as to reefs, but as to central islands, and he would describo the facLs | and show that they were better ex- I plained by Darwin's theory, and wen? ' not explainable on the still-standing is- ' land theory. Subsidence was the. only theory that could explain tho facts. (Applause.)

Dr. Hilgemlorf, in proposing a voto of thanks, referred to Professor Da vis's address as having been couched in charming language, and as a beautiful exposition of the subject.

Mr Tf. Speight, in seconding, said that_ Professor Da-vis's address was an admirable example of the correct presentation of such a subject.

Professor Davis answered several questions arising out of his address.

The vote of thanks was carried by acclamation.