Page:Popular Science Monthly Volume 32.djvu/256

244 ocean. Such seeds again find lodgment among the broken corals, and among the decaying pumice. Under tropical heat and moisture, they soon spring to life. The moment a palm-tree rears its fronds, it is visited by birds—especially by fruit-eating pigeons—bringing with them other seeds, which are deposited with convenient guano. These in turn take root and live. Each new accession to the incipient forest attracts more and more numerous winged messengers from interminable archipelagoes, until the result is attained which so excites our admiration and our wonder, in the atoll-islands of the Pacific. All this is simple. But here as elsewhere it is the first step that costs. Are all atolls nothing more than the cup-like rings of volcanic vents? And if they are, can a like explanation be given for the barrier-reefs which lie off continental coasts, and where the crater-like lagoon of an atoll is represented only by a vast linear expanse of included and protected sea?

Here were problems eminently attractive to such a mind as that of Darwin. Vast in the regions they affect, complicated in the results which are presented, most beautiful and most valuable to man in the products which are concerned, the facts do nevertheless suggest some physical cause which would be simple if only it could be discovered. All his faculties were set to work. Analysis must begin every work of reason. Its function is to destroy—to pull to pieces. Darwin had to deal with some theories already formed. With some of these he had no difficulty. "The earlier voyagers fancied that the coral-building animals instinctively built up these great circles to afford themselves protection in the inner parts." To this Darwin's answer was complete. So far is this explanation from being true, that it is founded on an assumption which is the reverse of the truth. These massive kinds of coral which build up reefs, so far from wanting the shelter of a lagoon, are unable to live within it. They can only live and thrive fronting the open ocean, and in the highly aerated foam of its resisted billows. Moreover, on this view, many species of distinct genera and families are supposed instinctively to combine for one end; and of such a combination Darwin declares "not a single instance can be found in the whole of Nature." This is rather a sweeping assertion. In the sense in which Darwin meant it, and in the case to which he applied it, the assertion is probably, if not certainly, true. The weapon of analysis, however, if employed upon it, would limit and curtail it much. We can not, indeed, suppose that any of the lower animals, even those much higher than the coral-builders, have any consciousness of the ends or purposes which they or their work subserve in the great plan of Nature. But Darwin has himself shown us, in later years, how all their toil is co-operant to ends, and how not only different species and families, but creatures belonging to different kingdoms, work together most directly, however unconsciously, to results on which their common life and propagation