Page:Popular Science Monthly Volume 30.djvu/707

Rh accepted that Réaumur, in the Academy of Sciences, did not disclose the name of Peysonnell, a physician of Marseilles, who first declared them to be animals, for fear of his being ridiculed. For what Aristotle, the founder of the descriptive natural sciences, had written more than two thousand years ago, had passed into oblivion.

And how much greater is the resemblance which is borne to plants by those little animals that build the immense coral reefs; which turn again into rock that which the solvent power of the waters had at one time extracted from the cliffs! Very early in the history of the world, these little builders entered into the thoughts of man. Mythology attributed their origin to plants, which were said to have been thus transformed, as is related in the following legend: When Perseus had released the beautiful Andromeda from the terrible monster, he placed the head of the Medusa, whose frightful aspect turned to stone everything that beheld it, on some plants which he had taken from the ocean. But lo! these plants were immediately turned to stone. The water-nymphs soon came to satisfy their curiosity, and to marvel at the wonder. Playfully they scattered the seeds of these stone-plants into the ocean, and behold, the corals were created!

Not unfrequently hidden coral reefs prove a source of great danger to navigation. Two hundred and fifty years ago only thirty coral islands had been located in the strait between New Holland and New Guinea; now they number over one hundred and fifty, and soon, perhaps, this channel will become impassable. But is it not probable that other forces, besides the growth of the corals, are here actively at work? One of the most changeable parts of the globe is the neighborhood of that wonderful island, Australia. Numerous are the islets which there slowly arise from beneath the waters; numerous those which gradually disappear. Darwin was the first to show how sure a proof of geological changes such coral reefs are. The polyps which build them die at a depth of thirty metres, and the contact with the atmosphere is fatal to them. Hence, very deep coral structures denote a sinking, those above the water, on the contrary, an upheaval of the earth's crust.

And as the Jura, a part of the Alps and the Carpathian Mountains, display marks of such animal structures, it is a proof that all those mountain-ranges have, in the past ages, arisen from the ocean. They must have risen from a warm ocean, warmer than the climate of those regions is to-day, for the tropics only are the home of the reef-building coral-polyps. And how enormously they multiply under favorable circumstances is shown by the barrier-reef, four hundred miles in length, near the northern shore of Australia. Between it and the mainland there is a channel, over six miles in width, the water of which is calm, and always affords to vessels a refuge from the wildest storms.

And when we turn our gaze on the fauna existing between the