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Show 14 TilE PRESENT CONDITION soon begins to draw into itself from the earth and the surrounding air matters which in themselves contain no vital properties whatever; it absorbs into its own substance water, an inorganic body; it draws into its substance carbonicacid, au inorganic matter; and ammonia., another inorganic matter, found in the air; and then_, by some wonderful chemical process, the details of which chemists do not yet understand, though they are near foreshadowing them, it combines them into one substance, which is known to us as 'Protein,' a complex compound of carbon, hydrogen, oxygen, and nitrogen, which alone possesses the property of rnanifes~ ing vitality and of permanently supporting animal life. So that, you see, the waste products of the animal economy, the effete materials which are continually being thrown off by all living beings, in the form of organic matters, are constantly replaced by supplies of the necessary repairing and rebuilding materials drawn from the plants, which in their turn manufacture them, so to speak, by a mysterious combination of those same inorganic materials. Let us trace out the history of the I-Iorse in anothe1• direction. After a certain time, as the result of sickness or disease, the effect of accident, or the consequence of old age, sooner or later, the animal dies. The nlultitudinous operations of this beautiful mechanism flao· in their p.e rformance' the Horse loses I·ts v·igoubr, an d after passing through the curious .series of chanO'es comprised in its formation and preservation, it fin~~ly dec~ys, and ends its life by. going back into that inol:ganlc world from which all but an inappreciable fraction of its substance was derived. Its bones become OF ORGANIC NATURE. 15 mere carbonate and phosphate of lime; the matter of its flesh, and of its other parts, becomes, in the long run, converted into carbonic acid, into water, and into ammonia. You will now, perhaps, understand the curious relation of the animal with the plant, of the organic with the inorganic world, which IS shown in this diagram. INORGANIC WORLD. Carbonic Acid. VEGETABLE WORLD. (FIG. 3.) ANIMAL WORLD. The plant gathers these inorganic rnaterials together ~nd makes them up into its own substance. The animal eats the plant and appropriates the r..utritious portions to its own sustenance, rejects and gets rid of the useless matters; and, finally, the animal itself dies, and its whole body is decomposed and returned into the inorganic world. There is thus a constant circulation from one to the other, a continual formation of organic life from inorganic matters, and as constant a return of living bodies to the inorganic world; so that the materials of which our bodies are composed are largely, in all probability, the substances which constituted the matter of long extinct creations, but which l1ave in the interval constituted a part of the inorganic world. |