Page:Popular Science Monthly Volume 77.djvu/440

434 of the Blake under Alexander Agassiz's scientific direction. It is but just to add that these notable achievements would have been impossible had it not been for the inventive genius and intelligent interest of Captain Sigsbee in devising sounding apparatus and trawls.

We now come to the closing period of Alexander Agassiz's scientific life—his long years of exploration of the coral reefs of the world, for during the winter of 1885 he visited the Hawaiian Islands, studying the reefs of Oahu, Maui and Hawaii.

For twenty-five years this study of the mode of formation of coral islands was to engage his rapt attention, and he was destined to wander farther and to see more coral reefs than has any man of science of the present or the past. His boyish joy upon the sight of some rare creature of the sea was something not altogether his own, for he inherited it from his father. The years of toil and care were all forgotten when he drifted in the mirrored waters above the reef and gazed downward into its world of subtle color where contrasts of olives, browns and greens were accentuated by a butterfly-like flash of brilliancy as some fish of the coral world glided outward from the depths of the shaded cavern.

He saw more coral reefs than has any living man and this very virtue of his exploration is its chief fault, for the study of coral reefs is a complex problem and it can not be solved by a superficial inspection such as he was forced to make. No one realized this more fully than he did himself, but he believed that the subject should be approached by a superficial survey of all of the reefs of the world, and thus he might hope to discover places where the problem might afterwards be studied with decisive results. He aimed to point out only the broad aspects of the problem, leaving the elucidation of details to those who might follow him.

I believe that science will come to see that he succeeded in showing that Darwin's simple explanation of the formation of atolls does not hold in any part of the world. Darwin, it will be remembered, assumed that wherever we find a volcanic mountain projecting above the sea in the tropical regions corals will grow upon its submerged slopes and form a ring around it. If then the mountain slowly sinks beneath the sea the corals will as constantly grow upward toward the surface, so that after the mountain has disappeared the atoll-ring of coral reefs will still remain.

Alexander Agassiz maintains, however, that atolls are formed in a variety of ways, and may develop where there has been neither marked elevation nor subsidence in modern times, as at the Great Barrier Reef of Australia, or under stationary conditions after a past period of elevation, as in the Fiji Islands, or by the dissolving away of the inner parts of an elevated limestone island as at Bermuda, or Fulangia in