by Grant Allen
A word of explanation is necessary. It may be asked, why will not the organic compounds aggregate at once with the free oxygen, and why do they need the liberating agency of heat or other Energy? The answer is probably analogous to that which we gave in the case of cohesion. Unless the atoms are brought very close to one another they cannot apparently get within the range of their mutual affinities, and mere mechanical juxtaposition is insufficient for this purpose without such atomic vibration as will bring them into close quarters with one another. But the more complex animal compounds, as we shall see hereafter, seem to possess high Kinetic Energy of their own, which can only be kept up in the circumstances of the body: and it is probable that they spontaneously decompose (or split up into simpler and less Energetic compounds) with a liberation of Energy on any direct contact with external agencies.
In the present work no attempt will be made to account for the origin and development of living organisms. That task has been satisfactorily performed in portions by Darwin, Haeckel, Müller, Huxley, Wallace, Hooker, and others, while a more comprehensive and systematic view of the whole process has been given by Mr. Herbert Spencer (whose name I can never pass by without the expression of my deepest intellectual gratitude and veneration). Their results can easily be translated into terms of the theory advocated in this work: and they have not sufficiently direct dynamical bearings to concern us greatly in our present inquiry. It must suffice here to recognise the fact that life owes its origin to the chemically-separative action of ethereal undulations on the cooled surface of the earth, especially carbonic anhydride and water, and that the existing diversity of organic forms is due to the minute interaction of dynamical laws.
It will, however, be desirable to point out that life is essentially separative in its nature, because the identity of Energy with separation is the main point insisted upon in the present treatise, and life is the Mode of Energy with which human beings are most familiar, and from which they form their conception of all its other modes.
Life, then, is shown to be essentially separative, first, because it is a product of solar Energy, acting upon the superficial matter of the earth. This Energy is the locomotive form of the statical separation once existing between the particles of the sun’s mass. When it falls upon the earth, being then in the ethereal form, we know that it is partly absorbed by various loosely aggregated superficial material molecules, in which it sets up separations that overcome the molecular Force of cohesion, and so produces winds, storms, ocean currents, clouds, &c. Now it similarly falls upon certain other molecules, among whose atoms it sets up separations that overcome the atomic Force of Chemical Affinity, and so produces starch, albuminoids, free oxygen, and other like chemically Energetic bodies. The separative nature of this process is obvious. Without the disjunctive solar Energy there could be no life, just as there could be no wind, ocean currents, rain, or clouds. All the stable chemical compounds would remain for ever in the aggregated state, unless the solar Energy came in to separate them. Again, life is seen to be essentially separative by its mechanical position and effects. Trees, plants, and animals stand out for the most part at a visible elevation from the mass of the earth’s solid crust, and when they die, large portions of them fall down and are reaggregated with its substance. The heat which sets up evaporation in leaves causes a capillary circulation in the vessels and cells of the plant, whereby water, holding in solution nitrogenous salts and mineral matters generally, is raised to every part of its surface; and then a large portion of this water is evaporated, while the mineral matters remain in the leaves and fibres. In all this we obviously see separative action opposed to gravitation, as above we saw it opposed to chemical affinity. Still more clear is this point of view in animals, which climb trees, plants, rocks, and mountains; which fly to great heights in the air; and some of which carry about great masses of bone, while others lift stone and brick to conspicuous elevation as houses, towers, and steeples. No one of these separative acts could have been performed without the intervention of solar Energy. But it is especially in its reconversion that organic matter shows its separative nature. As its atoms reaggregate, they give out heat, which obviously causes molecular separation in the surrounding bodies. The animal organism is perpetually in such a heated condition, and is perpetually parting with heat which goes off to swell the volume of ethereal Energy. So that in every way life reveals itself as an effect of the separative action exerted by ethereal Energy on the superficial material particles of our planet.
Succeeding chapters will deal with the phenomena of vegetal and animal life severally, as enforcing and illustrating these principles. For the present we may content ourselves with a brief summary of the results already attained.
Organic life is one of the effects wrought by incident solar Energy on the surface of the earth. It originates mainly in separative actions, whereby atoms are severed from relatively stable chemical combinations, and are either turned loose upon the atmosphere in a free state, or are built up into Energetic Compounds. But through the action of liberating agents, also of solar origin, these free atoms and Energetic Compounds for the most part sooner or later recombine; whereupon the absorbed Energy is once more liberated and turned loose upon the ether. Organic life is thus a transitory result of the general aggregating process during which the Energy liberated by the aggregation of particles in one mass falls upon the aggregated surface of another mass, and there sets up separative actions, which, however, are most often only temporary in their effects, owing to the subsequent incidence of Liberating Energies, whereby the absorbed Energy is once more turned loose upon the ether.
CHAPTER VI.
THE VEGETAL ORGANISM.
Although in the last chapter, where we treated of life generally as a product of incident solar Energy, we made little distinction between the two main forms of life, it must yet be understood that the relation which, as wholes, they bear to the incident Energy is exactly contrary. Vegetal organisms, as a rule, are accumulators of Energy, and not expenders: animal organisms, as a rule, are expenders of Energy and not accumulators. In other words, the vegetal organism is a case where incident Kinetic Energy is setting up separative actions between aggregated atoms, and is being absorbed (or potentialised) in the separation so produced: while the animal organism is a case in which the atoms so separated are being aggregated, and their Energies, Potential or Suppressed, are assuming the Kinetic Mode, either as heat or as visible motion. The energy absorbed and potentialised by the plant, is kineticised and given off by the animal.
These statements must only be accepted as true in the gross, and with certain deductions duly noted hereafter.
The plant is the origin of all the Energy possessed by all living beings. The separation between the atoms of water, carbonic anhydride, and nitrogenous salts, which takes place in its tissues under the influence of sunlight, is the Potential Energy which becomes Kinetic in the growing seed, the expanding flower, and the leaping or flying animal. We may therefore briefly trace the life-history of a plant, as throwing some light upon the dynamical nature of life generally.
Every plant starts as a spore or seed, cast off from a previously existing plant. This first germ contains some small materials for growth for the young plant in the form of Energetic Compounds, whose Potential Energy is to become Kinetic in the act of germination. In order, however, to produce this effect, liberating agents are needed; and these liberating agents are generally three in number, moisture, heat, and light. These, acting upon the materials in the seed, either cause them to aggregate with other matters, or overcome the suppressing Force; and in consequence the materials yield up their Potential or Suppressed Energies in that determinate form imposed by the specific conditions and known as germination. The amount of Energetic materials supplied to the new plant (or the fresh year’s growth) may be very great, as in the potato tuber, the lily bulb, and the wheat grain, or it may be very little, as in fungi, ferns, and cryptogams generally: but in every case, if the p
lant is to continue living, there must be enough Energy to permit of its assuming the shape in which it can begin to be acted upon by the sunlight, and to assimilate fresh matter under the influence of that incident Energy. This stage is reached when leaves are produced. On the surface of these leaves the solar Energy produces evaporation, and this evaporation gives rise to a general capillary action, whereby water is raised into the leaves.
In these leaves the sunlight, acting upon carbonic anhydride sucked in from the atmosphere, frees the carbon atoms from their union with the oxygen, and builds them up with the hydrogen into hydrocarbons — Energetic compounds: while the oxygen is turned out upon the atmosphere in a free state. Nitrogenous salts in solution have also been supplied by the water, and from these and the starch, the plant in some unknown way builds up the protoplasm which forms the moving portion of all living organisms. The starch, sugar, albuminoids, and other organic compounds thus produced are then circulated all over the plant, where they supply the materials for growth, and develop new leaves, which in turn increase the amount of Energetic matter in the plant. Part of the Energy thus absorbed is used up by the plant itself in its own physiological processes. The growth of each cell doubtless involves the expenditure of Energy — that is to say, some Energy previously contained by the protoplasm assumes thereupon the Kinetic Mode, and is in part yielded up to the ether. In the larger physiological processes, such as germination or inflorescence, it is certain that such dissipation of Energy takes place, in the first place because free oxygen is absorbed and carbonic anhydride is evolved, which shows that some of the contained carbon has reaggregated with the oxygen; and in the second place because a rise of temperature can be shown to accompany these processes. Accordingly we may conclude that the motions which take place in plants are due to the reaggregation of certain Energetic particles with the free atoms of their neighbourhood, and that while some of the Energy thereupon liberated has assumed the form of Molar Motion, part of it has been dissipated as heat. But a large portion of the Energy remains dormant in the plant, either in the molar or the atomic species. The leaves and stem as wholes, viewed mechanically, represent the former: the starch, protoplasm, and wood, viewed chemically, represent the latter. When the plant dies or is devoured, on the average of instances the greater part of this Energy is rendered Kinetic, and ultimately yielded up to the ether. Take first the case of a tree which dies a natural death. At the end of each year its leaves fall. Before they do so, they render up their most important chemically Energetic products to the permanent portions of the complex organism; but inasmuch as they will burn, they retain a certain amount of atomic Energy in their cellulose; and inasmuch as they are elevated above the general level, they possess Molar Potential Energy in their position. When the leaves drop off by the weakening of cohesion at their bases (along a pre-arranged line) their Molar Potential Energy becomes Kinetic in the act of falling, and is dissipated as they reach the ground. The dead leaves, lying on the earth, now consist mainly of inorganic earthy matter and cellulose. The action of moisture, heat, and light, as liberating agents, soon sets up decomposition: and the mineral matter lies in situ, while the organic substances combine with the surrounding oxygen. When the whole tree dies the same process is repeated on a larger scale. The actions of moisture, heat, and light, combined with those of fungi, worms, &c., are liberating agencies which cause the trunk to decay and fall, and afterwards produce more or less complete decomposition of the whole tree as it lies. In a few cases, which will be treated of hereafter, the stored-up Energies are long retained in coal, peat, and vegetal débris: but on the average of instances, almost all the Energy absorbed during one year has been yielded up by the next. When the plant is devoured by an animal or burnt by man, it undergoes a somewhat different yet ultimately identical cycle of changes, which will be more fully detailed in our next chapter: for the present it will suffice to say that its Energetic Compounds combine with free oxygen within the animal organism, or the fireplace, and that their Energy is used up in the production of motion and heat, and is thus, as usual, finally transferred to the ethereal medium.
The special case of reproduction requires a few additional remarks. Where this function is carried on by inflorescence, we have a series of leaves produced which are expenders of Energy, instead of being accumulators, growing and unfolding by the employment of Energy stored up in other parts of the plant. Most especially is this the case with the pollen, ovule, and seed. In the protrusion of the pollen-tubes and the growth of the embryo, we see conspicuous instances of the employment and dissipation of previously stored Energy. In the developed seed we sometimes find a store of albumen; and in any case we have in the embryo itself a nitrogenous mass which is able, under the influence of moisture and heat (liberating agents), to aggregate in part with oxygen and produce germination. Somewhat similar in their dynamical nature are those morphologically unlike propagating portions which lay up nutriment for the future growth of the individual or its offspring. Such are the roots and tubers of potatoes and beets, the tubers of the orchis and dahlia, the corms of the saffron, and the bulbs or bulbils of the onion and the tiger-lily. In every case, motion in plants is caused by the aggregation of free oxygen with the Energetic Compounds of the plant, and by the employment of the Energy thus liberated for the production of Molar motion.
It will thus be seen that even those plants which are on the whole accumulators and storers of Energy are themselves to some extent likewise expenders of Energy: and that the broad distinction which we have drawn between the vegetal and the animal organisms, viewed dynamically, must not be pressed too close. In growth, in inflorescence, and in germination, the plant is essentially an animal. It is only in assimilation that it displays the characteristic vegetal function of transferring Energy from ether to material particles mainly by the production of hydrocarbons, plus free oxygen, from carbonic anhydride and water. We may thus say roughly, in reference to our present standpoint, that the assimilating leaf, frond, or thallus, is the only true plant. Nor is this all. Many organisms, classed morphologically as plants, are in their dynamical aspect the analogues of animals: that is to say, their functions are wholly expensive of Energy and not at all accumulative. The leafless parasites (orobanche, cytinus &c.) fasten upon some other plant, and without themselves contributing to the general store of Energy, employ the Energetic Compounds laid up by their host, in the production of their own flowers and seeds. A much larger and more important class is that of fungi, which live upon the roots, stems, seeds, or tubers of other plants, upon the bodies or the dung of animals, or upon the generally diffused undecomposed organic matter of the soil. But whencesoever they derive their materials, they always thrive upon previously-composed Energetic Compounds, whose Energy they liberate with almost explosive power. They are like animals in never accumulating Energy, while expending that which has been previously accumulated by other plants. It is noticeable that all these quasi-animal functions can be carried on in the absence of light, that is, of highpower radiant Energy. Thus, a seed will germinate, a hyacinth will grow from its bulb and produce blossoms, a potato will sprout from its tuber, a flower will open, and a fungus will pass its whole life, under proper conditions of heat and moisture combined with the presence of oxygen, in a perfectly dark cellar: because the Energetic compounds, and the free oxygen whose aggregation liberates their Energy, are all stored up in the plant or its environment beforehand. But no assimilation, no separation of atoms from their stable unions, can take place except under the disjunctive influence of radiant Energy.
So, in spite of these numerous exceptions — these quasi-animal functions of all plants, and these large groups of plants with none but quasi-animal functions — the distinction which we have marked between plants and animals is yet of cardinal importance, and for this reason. Though some plants are quasi-animal, no animal is quasi-vegetal. All the Energetic Compounds which enter into the composition of any living organism are derived, directly or indirectly, from plants.
In the leaf or thallus or body of some plant or protophyte all the organised materials have taken their rise, under the separative influence of radiant Energy.
To sum up, the conclusions at which we have arrived are these. Solar Energy, playing upon certain superficial material particles of our planet, separates their atoms into Energetic Compounds and free elements. The masses immediately built up of these Energetic Compounds, together with certain inorganic (or stably-compounded) substances, are known as plants. They go on continuously assisting (by means of their chlorophyll) in the similar separation of other atoms by solar Energy, some of which (hydrocarbons) swell their mass, while others (oxygen) are turned loose upon the atmosphere. The Energy thus stored in the matter of the plants and the free elements about them, does not remain perpetually connected with the same particles. Partly it is used up in the physiological operations of the plant: partly it is stored away in seed, tubers, &c., for future physiological operations: partly it is dissipated at the death of the plant. In a vast number of instances the plant is eaten by an animal, and in that case the reaggregation of elements and dissipation of Energy takes place within the animal’s body. So that, in the majority of instances, the Energy radiated from the sun into the ether, and temporarily employed on the surface of our planet in the production of vegetal life, is sooner or later cast once more upon the ether, to make its way for ever through the interstellar spaces. Only a small portion remains here, dormant in wood, coal, and peat; and even that small portion, as we shall hereafter see, is finally used up by animals (including man) for some purpose connected with their vital necessities.
