434 THE POPULAR SCIENCE MONTHLY 
plorations 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 in- 
terest 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 in- 
herited it from his father. The years of toil and care were all for- 
gotten 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 bril- 
liancy 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 inspec- 
tion 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 ap- 
proached by a superficial survey of all of the reefs of the world, and 
thus he might hope to discover places where the problem might after- 
wards 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, as- 
sumed 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 ele- 
vation, 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 
