Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: ON CORALS. In reflecting on the physical structure of the earth, and on its repeated alterations of level, the mind is prone to be more impressed by the Infinitely Great forces of nature, the earthquakes, volcanoes, iind floods, than by the Infinitely Small agencies which are nevertheless unceasingly at work, and do more to alter the physical geography of the globe, than the most furious convulsions of nature. Invisible diatoms, of which 100 thousand occupy only a square inch, form beds of hundreds of miles in extent, in fact the entire sea bottom is largely composed of the remains of dead foramenifera, while the white chalk cliffs of England, which are continued across the channel, and form ranges of hundreds of miles through Europe, are almost entirely composed of the remains of the same microscopic animalcules. Nearly the whole of the limestone rocks from the Laurentiau epoch, though formerly supposed to belong to a period before life in any form existed on the earth, are now known to owe their origin to minute organic remains. -The entire city of Paris i re-built with a limestone largely consisting of dead miliolae (little shells the size of a millet seed) and the gigantic pyramids and sphinx are built of stone made of the bodies of the naummulites, a small disc-like mollusc about as large as a lentil. Someof these smaller organisms exist in such countless myriads, that the mind refuses to take cognizance of their number; thus Schleiden has calculated that the tripoli, which we use for polishing steel articles, and which forms beds of twenty-five or thirty miles square in Bohemia, contains as many as 41 millions of infusoria in a cubic inch. Since the commencement of life on the earth, these ' creatures have been multiplying by millions of millions daily, and their...