736. Next inquiries. We have now briefly surveyed the mechanism of the plant, both its outward forms and internal structure. We next inquire into the uses of all this wonderful apparatus; what the specific office which each part performs in the economy of the plant? and how do all parts cooperate in the work of living and growing?
737. This is a subject of great extent, and involves many inquiries of deep interest both in science and art, - many inquiries, also, which have never been answered. Our limits confine us to the bare statement of admitted principles, to the exclusion of all speculative discussion.
738. What is life? This inquiry meets us at the beginning - a problem never solved. The spontaneous action of the plant, the self-determined shapes which it assumes, we at once refer to this principle, its vitality; but of the nature of this principle itself we can only say, Is it not a direct emanation from the Supreme Will, the Fountain of all life?
739. Vegetation is doubtless the lowest form of life. It springs directly from inorganic or mineral matter, and is the first step in the organization of mineral matter. Its material is, therefore, mineral matter rendered organic through the vital force.
740. The subordination of the vegetable to the animal kingdom is thus manifest in its being fed and nourished on inorganic matter. It is interposed between these two incompatible extremes, and is ordained to transform the innutritious mineral into the proper and indispensable food of the animal kingdom.
741. Parasitic plants do indeed require the ready organized juices of other plants, just as the carnivora among animals live on flesh. Still the general fact remains, that plants alone feed on inorganic matter, and in turn become themselves the food of the animal kingdom.
742. The process of VEGETATRON consists of imbibing the crude matters of the earth and air, transforming into sap, assimilating to plant juice (latex), and organizing into its own structure according to its own plan. The vital phenomena on which these transformations depend are called absorption, circulation, exhalation, assimilation, secretion, all of which processes take place in the individual cell. Therefore,
743. Cell-life is an epitome of the life of the whole plant. The cell is never a spontaneous production; it is the offspring of a pre-existing cell. So with the plant; it is always the offspring of a pre-existing embryo or cell Nothing but a cell can produce or nourish a cell.
744. Two kinds of organic matter make up the cell. The first protoplasm or protein (C40 H31 O12 N5), the material of the primordial utricle (§ 645), etc., containing nitrogen; 2d, cellulose, (C12 H10 O10), the material of the outer wall or crust, etc., containing no nitrogen. The former more nearly resembles animal matter, and is the seat of the vital force and chemical action.
745. What the cell imbibes. Through the invisible pores of its walls the cell imbibes the fluid in which its food is dissolved, viz., sugar or dextrine, ammonia or some other nitrogenous substance. Such a fluid may be the flowing sap of the plant or any similar artificial mixture in which the cell is bathed, as (in the case of the yeast plant) a syrup with mucilage.
746. The chemical changes. The sugar is thus brought into contact with the protoplasm in the cell, through whose action it is decomposed and its elements transformed into cellulose and water. Thus each atom of (grape) sugar or dextrine becomes
One atom of cellulose, C12 H10 O10 and two atoms of water, H2 O2
C12 H12 O12=grape sugar.
605, Protococcus viridis, the Green snow-plant.
606, Penicillum glau-cum, the Yeast-plant.
The water is exhaled with the rest; the cellulose is retained to incrust a new cell as soon as the primordial utricle shall next divide itself to form one. Or it may be deposited as starch granules for future use.
747. Action of chlorophylle. In the cells of green plants the globules of chlorophylle act an important part. Their formation depends upon the decomposition of carbonic acid (CO2), the retention of the carbon, and the exhalation of the oxygen under the stimulus of the light. If the formation of cellulose continue beyond the present need for cell-formation, the excess is deposited in the form of starch-granules inclosed within the globules of chlorophylle, one in each.
748. Destination of the starch granules. When the starch granules are redissolved, they go to incrust the next new cell or to form a secondary layer in the old cell; or in autumn they go out into the general circulation and are at length stored up in the buds, the cambium, the roots, ready for an early use the following spring,
749. The increase of the protoplasm from the decomposition of the ammonia or other nitrogenous compounds present is a more intricate process, but no less evident, and when in excess, this also is deposited in minute globules of gluten, mucus, legumine, chiefly in seeds (wheat, beans, rice), in aid of germination.
150. The starch and gluten deposits of the wheat kernel are about sixty-eight and seventeen per cent. The former is found in the interior cells, the latter in the exterior, adjoining the pericarp or bran. In " flouring" some of the gluten adheres to the bran, and some constitutes the coarser meal, all of which is separated by the " bolt." Extra flour must, therefore, necessarily be deficient in gluten, the only element of the wheat which adapts it to the formation of muscle. A great error.