Page:Popular Science Monthly Volume 4.djvu/612

594 progeny; twin-brother life, to her, with that of animals. The perfect balance between plant existences and animal existences must always be maintained, while "matter" courses through the eternal circle, becoming each in turn.

To state this more intelligibly by illustration: If an animal be resolved into its ultimate constituents in a period according to the surrounding circumstances, say, of four hours, of four months, of four years, or even of four thousand years—for it is impossible to deny that there may be instances of all these periods during which the process has continued—those elements which assume the gaseous form mingle at once with the atmosphere, and are taken up from it without delay by the ever-open mouths of vegetable life. By a thousand pores in every leaf the carbonic acid which renders the atmosphere unfit for animal life is absorbed, the carbon being separated and assimilated to form the vegetable fibre, which, as wood, makes and furnishes our houses and ships, is burned for our warmth, or is stored up under pressure for coal. All this carbon has played its part, "and many parts," in its time, as animal existences from monad up to man. Our mahogany of to-day has been many negroes in its turn, and before the African existed was integral portions of many a generation of extinct species. And, when the table, which has borne so well some twenty thousand dinners, shall be broken up from pure debility and consigned to the fire, thence it will issue into the atmosphere once more as carbonic acid, again to be devoured by the nearest troop of hungry vegetables—green peas or cabbages in a London market-garden, say—to be daintily served on the table which now stands in that other table's place, and where they will speedily go to the making of "lords of the creation." And so on, again and again, as long as the world lasts.

Thus it is that an even balance is kept—demonstrable to the very last grain if we could only collect the data—between the total amounts of animal and of vegetable life existing together at any instant on our globe. There must be an unvarying relation between the decay of animal life and the food produced by that process for the elder twin, the vegetable world. Vegetables first, consumed by animals either directly or indirectly, as when they eat the flesh of animals who live on vegetables. Secondly, these animals daily casting off effete matters, and by decay after death providing the staple food for vegetation of every description. One the necessary complement of the other. The atmosphere, polluted by every animal whose breath is poison to every other animal, being every instant purified by plants, which, taking out the deadly carbonic acid and assimilating carbon, restore to the air its oxygen, first necessary of animal existence.

I suppose that these facts are known to most readers, but I require a clear statement of them here as preliminary to my next subject; and in any case it can do no harm to reproduce a brief history of this