594 THE POPULAR SCIENCE MONTHLY. 



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, be- 

 coming each in turn. 



To state this more intelligibly by illustration : If an animal be re- 

 solved 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 sepa- 

 rated 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 Lon- 

 don 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 in- 

 stant 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 ani- 

 mals 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 mar- 



