252 THE POPULAR SCIB^'Ci: MONTHLY. 



ogy which might have helped Darwin, as it is much needed to help 

 us even now, to conceive it. It is the old doctrine of the science 

 long ago formulated by Hutton, that the work of erosion and of den- 

 udation must be equal to the work of deposition. Rocks have been 

 formed out of the ruins of older rocks, and those older rocks must 

 have been worn down and carried off to an equivalent amount. So it 

 is here, with another kind of erosion and another kind of deposition. 

 The coral-building animals can only get their materials from the sea, 

 and the sea can only get its materials by dissolving it from calcareous 

 rocks of some kind. The dead corals are among its greatest quarries. 

 The inconceivable and immeasurable quantities which have been dis- 

 solved out of the lagoons and sheltered seas of the Pacific and of the 

 Indian Ocean are not greater than the immeasurable quantities which 

 are again used up in the vast new reefs of growing coral, and in the 

 calcareous covering of an inconceivable number of other marine ani- 

 mals. 



Here, then, was a generalization as magnificent as that of Darwin's 

 theory. It might not present a conception so imposing as that of a 

 whole continent gradually subsiding, of its long coasts marked by bar- 

 rier-reefs, of its various hills and irregularities of surface, marked by 

 islands of corresponding size, and finally of the atolls which are the 

 buoys, indicating where its highest peaks finally disappeared beneath 

 the sea. But, on the other hand, the new explanation was more like 

 the analogies of Nature — more closely correlated wath the wealth of 

 her resources, with those curious reciprocities of service, which all her 

 agencies render to each other, and which indicate so strongly the ul- 

 timate unity of her designs. This grand explanation we owe to JMr. 

 John Murray, one of the naturalists of the Challenger expedition, 

 a man whose enthusiasm for science, whose sagacity and candor of 

 mind, are not inferior to those of Darwin, and whose literary ability 

 is testified by the splendid volumes of *' Reports " now in course of 

 publication under his editorial care. Mr. Murray's new explanation 

 of the structure and origin of coral reefs and islands was communi- 

 cated to the Royal Society of Edinburgh in 1880,* and supported with 

 such a weight of facts, and such a close texture of reasoning, that no 

 serious rejjly has ever been attempted. At the same time, the reluc- 

 tance to admit such an error in the great Idol of the scientific world, 

 the necessity of suddenly disbelieving all that had been believed and 

 repeated in every form, for upward of forty years — of canceling 

 what had been taught to the young of more than a whole generation 

 — has led to a slow and sulky acquiescence, rather than to that joy 

 which every true votary of science ought to feel in the discovery of a 

 new truth and — not less — in the exposure of a long-accepted error. 

 Darwin himself had lived to hear of the new solution, and with that 

 splendid candor which was eminent in him, his mind, though now 

 * " rroccedings of the Royal Society of Edinturgh," vol. x, pp. 506-518. 



