Plant matter

“ Animals, however simple, do eat and digest their food, plants take various mineral substances from the earth or air or water in the form of inorganic matter such as oxygen, carbon, nitrogen, and all the food materials found in the soil, and transform them, with the aid of sunshine, into the structure that characterizes each particular form. Plants, then, may be defined as any living organism that, with minor exceptions, has the power to assimilate inorganic substances and transform them into organic matter. Nothing else in all the realm of nature has this power. ”

“ But the whole plant, often many feet in length, consists only of single gigantic cells. A tough skin incloses its juices, which flow in a continuous stream through the stem, leaves, and roots of the curious growth, here taking up through the skin and assimilating mineral substances, there producing and transforming organic matter, and at the same time advancing the growth and increase of the whole. Not less peculiar than the inner structure and appearance of the stem is the form of the leaves of water plants. Their service to the organism is the same with that of the leaves of other plants. ”

“ It has been already observed that the life of the plant consists chiefly in the formation of its organs; whence it follows, that its most essential and fundamental activity manifests itself in the process of assimilation and secretion, as well as in the circulation of the sap, which is nothing but a repetition of the chemical attraction and repulsion observed in unorganized matter. ”

“ Under the light of the sun, acting upon green parts or foliage, that is, upon the chlorophyll, or upon what answers to chlorophyll, which these parts contain. The sun in some way supplies a power which enables the living plant to originate these peculiar chemical combinations,—to organize matter into forms which are alone capable of being endowed with life. ”

“ The Simplest Plants.—We have seen that perhaps the simplest plant would be exemplified by one of the tiny bacteria we have just read about. A typical one-celled plant, however, would contain green coloring matter or chlorophyll, and would have the power to manufacture its own food under conditions giving it a moderate temperature, a supply of water, oxygen, carbon dioxide, and sunlight. ”

“ Or if there be any the less necessary and essential Corpuscles wanting, there will be some failure in the Plant; 'twill be defective in Taste, in Smell, in Colour, or some other way. But though a Tract of Land may happen not to contain Matter proper for the Constitution of some one peculiar kind of Plant; yet it may for several others, and those much differing among themselves. The Vegetative Particles are commix'd and blended in the Earth, with all the diversity and variety, as well as all the uncertainty, conceivable. ”

“ All living organisms are dependent for existence upon inorganic matter, and sooner or later return these elements to the sources whence they came. Thus, a plant extracts from the earth and air certain inorganic compounds which are converted by the activity of the plant into a part of its own substance, becoming thus incorporated into a living organism. After the plant dies, however, it undergoes decomposition, and the elements are returned again to the earth and atmosphere from which they were taken. ”

“ As the student will learn early in his botanical reading, the typical plant has, in its green colouring matter, chlorophyll, a trap to catch the radiating energy of the sun, and to accomplish, by the absorption of that energy, the synthesis (building up) of those organic compounds which the animal destroys. ”

“ A continuity of response having been established between the responses of inorganic matter on the one hand and living plants on the other, inquiry was continued to find out whether the fundamental physiological mechanisms were similar in plant and in animal life. The plant world affords an unique opportunity for studying the changes by which a simple and primitive organ becomes gradually transformed into one of greater complexity. ”

“ The latter, when duly fertilized by being brought into contact with the "pollen" of the stamens, become "seeds," and are capable of growing up, when planted, into new plants. Now, the botanist will inform us that it is a matter of common experience to find some individual plants of a species with well-developed petals or blossoms, and other individuals of the same species with petals in a rudimentary condition, thus proving that the production of imperfect parts in flowers occurs as an ordinary event under our own eyes, and under the common conditions of plant-life. ”

“ Plant-life is all directly or indirectly dependant on the heat and light of the sun—directly dependant in the immense majority of plants, and indirectly dependant in plants which, as the fungi, flourish in the dark: since these, growing as they do at the expense of decaying organic matter, mediately draw their forces from the same original source. ”

“ What root hairs take out of soil. Plant needs mineral matter to make living matter. Why? Nitrogen necessary. Sources of nitrogen, the nitrogen-fixing bacteria. Relation of this to man. Rotation of crops.
Tenth week. How Green Plants make Food. Passage of liquids up stem. Demonstration. Structure of a green leaf. Cellular structure demonstrated. Microscopic demonstration of cells, stoma, air spaces, chlorophyll bodies. Evaporation of water from green leaf, regulation of transpiration.
Eleventh week. Midterm Examinations. Sun a source of energy. Effect of light on green plants. ”

“ From the compound substances, described in the preceding chapter, plants derive the greater portion of the carbon, hydrogen, oxygen, and nitrogen, of which their organic part consists. The living plant possesses the power of absorbing these compound bodies, of decomposing them in the interior of its several vessels, and of recompounding their elements in a different way, so as to produce new substances,—the ordinary products of vegetable life. Let us briefly consider the general structure of plants, and their mode of growth. ”

“ When we reflect that the constant removal of water in the leaf, both as such, and as the only carrier of food supplies from the roots, depends in such large measure upon the functioning of these guard cells, then we come to some realization of their importance to the plant. ”

“ We do not aspire to a treatise on botany, but stop to consider only certain facts which are essential to this argument; a consideration of the higher plants will serve our purpose. Certain phytons are modified to become roots, which are the organs devoted to the absorption from the earth of the materials which are to be woven into the plant; other phytons become the stem for support; others the branches for expansion; others the leaves for respiration; others pistils and stamens for reproduction, while others become floral envelopes for their protection. ”

“ The very simplest plants (if such may specifically be called plants rather than animals, or one may say, the simplest living things) are mere particles, or pellets, or threads, or even indefinite masses of protoplasm of vague form, which possess powers of motion or of changing their shape, of imbibing water, air, and even other matters, and of assimilating these into plant-stuff for their own growth and multiplication. Their growth is increase in substance by incorporation of that which they take in and assimilate. ”

“ These factors are physical, or chemical, or biological, and affect the plant mainly through the agency of the soil, the atmosphere, or living organisms.
“The living plant is a synthetic machine.” Under proper working conditions of heat, moisture, and light it builds up its body by absorption of inorganic{99} material, liquid and gaseous, through its roots and leaves. ”

“ Receiving the water from the soil with such materials as it brings thence in solution, and absorbing carbonic dioxide and ammonia from the air, the living protoplasm of the leaf-cells has the power of chemically changing all these substances, and of producing from them those complicated and otherwise inimitable organic compounds of which the tissues of the plant are built up. ”

“ But when we attempt to consider how the particular secretions of different species and tribes of plants are formed; how the same soil, the same atmosphere, should in a leaf of the vine or sorrel produce a wholesome acid, and in that of a spurge or manchineel a most virulent poison; how sweet and nutritious herbage should grow among the acrid crowfoot and aconite, we find ourselves totally unable to comprehend the existence of such wonderful powers in so small and seemingly simple an organ as the leaf of a plant. ”

“ All insight not only into the chemical processes in the nutrition of plants, but also into the mechanical laws of the movement of the sap, and generally into the whole internal economy of plants, depends on a knowledge of the fact, that it is only the cells which contain chlorophyll, and therefore in the higher plants the leaves chiefly as consisting largely of such cells, which have the power of converting the gaseous food supplied by the atmosphere into the substance of the plant with the aid of the materials taken up from the soil. ”

“ Living plants were pictured as a multitude of units competing for food, light, air, and room for growth, and struggling against unfavorable environments. The classification of tissues was begun, and the phenomena of absorption of water and salts, the ascent of sap, the absorption of minerals and nitrogen, and metabolism and growth were elucidated. Investigations were made into the nature and functions of chlorophyll and other plant substances. These studies resulted in suggesting means for improving crops by artificial selection, as shown in the work of Luther Burbank. ”

“ Actually what are ordinarily thought of as plants make up only a fraction of the great plant world. The fact that our familiar roadside and garden plants produce blossoms followed by a fruit and seed, such as peas and beans and all the ordinary flora of any region, separates them at once from that other large group of plants that do not. Common examples of the latter class are the green scum on the ponds, moss, seaweed, the rust on wheat, yeast, disease-causing bacteria, the smallest of all known plants, and many others. ”

“ They breathe when the leaf mouths take from the air the oxygen, and give back to it carbonic-acid gas.
The veins and veinlets, of which you see so many running through a leaf, act in something the same way as the water pipes of a city; for through these veins the watery food, the earth broth, is carried to the different cells.
When one knows all that we know even now about a plant, one looks at a tree covered with leaves with a good deal of admiration. ”

“ In the main, these agencies are external to the plant and are either physical, such as changes of temperature, amount of light received, etc.; or chemical, such as variations in the salts received from the soil, or common anæsthetics applied to the plants by man. A plant grows normally under certain conditions to which it has become adjusted by hereditary acquirements. When these conditions are altered, the effect upon the functioning of the plant protoplasm may be either stimulating or depressing. ”

“ And on the plant as it grows, and as a perfect whole, chemistry expends entire and most gifted intellectual lives. Of what the plant consists, whence it draws its subsistence, how it takes it in—in what form, in what quantity, at what period of the day—how the air feeds it, how the soil sustains it, why it grows well here and badly there—what are the nature, composition, action, and special influences of manures—where and when, and of what kind, they should be applied to the plant—how this or that effect is to be produced by them, and this or that defect remedied. ”

“ It is of the essence of the grain of plants, to be impregnated by the pollen or seed of the stygma of the flower; in this state of copulation they in consequence develope themselves in the bowels of the earth; expand by the aid of water; shoot forth by the accession of heat; attract analogous particles to corroborate their system: thus by degrees they form a plant, a shrub, a tree, susceptible of that life, filled with that motion, capable of that action which is suitable to vegetable existence. ”

“ The mineral and nitrogenous constituents of plants are taken up by their roots from the soil, which is almost, if not quite, the exclusive source of these elements of plant-growth, while all of the carbon is elaborated by the leaves from the supplies in the atmosphere. ”

“ Without recourse to the evidence afforded by the plants of past ages, we must always admit that our existing classification of the vegetable kingdom is an expression of real gaps which separate the several classes of plants from one another. On the other hand our recently acquired and more accurate knowledge of such genera as have been alluded to, has made us acquainted with types of plant structure which enable us to fill in some of the lacunae in our existing classification. ”

“ We have considered the various chemical changes which take place within the growing plant, during the formation of its woody stem, the blossoming of its flower, and the ripening of its seed or fruit,—and have traced the further changes it undergoes, when, the functions of its short life being discharged, it hastens to serve other purposes, by mingling with the soil, and supplying food to new races. ”