existences must always be maintained, while matter courses through the eternal circle, becoming each in turn. 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."
It seems reasonable to suppose that certain kinds of vegetation and certain kinds of animals should
