Page:Popular Science Monthly Volume 51.djvu/845

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THE influence which the lower animals have had upon mankind has never been appreciated; had it been, they would have received more consideration at our hands. They not only provide us with food, raiment, and a vast array of industries, but they have been factors in the physical and intellectual development of mankind. The beauty of the birds and insects, the splendid coloring of the fishes and reptiles, the quiet harmonies of Nature and the problems they suggest, have insensibly had a refining effect, and aided in the evolution of the higher and aesthetic senses. In a word, the so-called lower animals have been important factors in producing the high civilization which marks the Caucasian race of to-day.

In glancing at the many forms which pay tribute to our wants and requirements, the larger animals naturally attract the attention; yet the greatest works, the most enduring monuments, are those produced by the smallest and most insignificant creatures. Such are the rhizopods—minute marine forms almost invisible, among the very lowest in the scale of life; literal drops of jelly, yet endowed by Nature with the power to secrete shells of rare and beautiful shapes. So vast are their numbers that it has been estimated that if they are as numerous down to a depth of six hundred feet as they are near the surface, there are more than sixteen tons of calcareous shells suspended in the uppermost one hundred fathoms of every square mile of the ocean.

These countless millions are constantly dying, and their shells when released slowly sink to the bottom in a never-ending rain, filling up the inequalities of the ocean bed, and forming a deposit of ooze at a depth of not over twenty-four hundred fathoms several feet in thickness, beneath which are layers of shells of an unknown depth pressed into a solid mass. A prolific source of this ocean rain is a rich spiked atom which has given its name to the globigerina ooze that is almost universal in the deep sea at a depth within the limitations given.

The tendency of the rain of shells is to fill up ocean beds, cap submarine hills and mountains, building them up until they enter the zone of the reef-building corals. In this way these insignificant creatures have aided in the growth of the globe, and, when the deposits by heat or exposure to air are hardened, they become girders of the crust.

The ooze so deposited either fills up the ocean, or by some upheaval is lifted into the air and in time becomes covered with a forest growth; ages pass, and, by a depression of the crust, the