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An essay by John Joly |
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The Abundance Of Life |
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Title: The Abundance Of Life Author: John Joly [More Titles by Joly] WE had reached the Pass of Tre Croci and from a point a little below the summit, looked eastward over the glorious Val Buona. The pines which clothed the floor and lower slopes of the valley, extended their multitudes into the furthest distance, among the many recesses of the mountains, and into the confluent Val di Misurina. In the sunshine the Alpine butterflies flitted from stone to stone. The ground at our feet and everywhere throughout the forests teamed with the countless millions of the small black ants. It was a magnificent display of vitality; of the aggressiveness of vitality, assailing the barren heights of the limestone, wringing a subsistence from dead things. And the question suggested itself with new force: why the abundance of life and its unending activity? In trying to answer this question, the present sketch originated. I propose to refer for an answer to dynamic considerations. It is apparent that natural selection can only be concerned in a secondary way. Natural selection defines a certain course of development for the organism; but very evidently some property of inherent progressiveness in the organism must be involved. The mineral is not affected by natural selection to enter on a course of continual variation and multiplication. The dynamic relations of the organism with the environment are evidently very different from those of inanimate nature.
It is necessary, in the first place, to refer briefly to the phenomena attending the transfer of energy within and into inanimate material systems. It is not assumed here that these phenomena are restricted in their sphere of action to inanimate nature. It is, in fact, very certain that they are not; but while they confer on dead nature its own dynamic tendencies, it will appear that their effects are by various means evaded in living nature. We, therefore, treat of them as characteristic of inanimate actions. We accept as fundamental to all the considerations which follow the truth of the principle of the Conservation of Energy.[1] [1] "The principle of the Conservation of Energy has acquired so much scientific weight during the last twenty years that no physiologist would feel any confidence in an experiment which showed a considerable difference between the work done by the animal and the balance of the account of Energy received and spent."--Clerk Maxwell, _Nature_, vol. xix., p. 142. See also Helmholtz _On the Conservation of Force._ Whatever speculations may be made as to the course of events very distant from us in space, it appears certain that dissipation of energy is at present actively progressing throughout our sphere of observation in inanimate nature. It follows, in fact, from the second law of thermodynamics, that whenever work is derived from heat, a certain quantity of heat falls in potential without doing work or, in short, is dissipated. On the other hand, work may be entirely converted into heat. The result is the heat-tendency of the universe. Heat, being an undirected form of energy, seeks, as it were, its own level, so that the result of this heat-tendency is continual approach to uniformity of potential. The heat-tendency of the universe is also revealed in the far-reaching "law of maximum work," which defines that chemical change, accomplished without the intervention of external energy, tends to the production of the body, or system of bodies, which disengage the greatest quantity of heat. And, again, vast numbers of actions going on throughout nature are attended by dissipatory thermal effects, as those arising from the motions of proximate molecules (friction, viscosity), and from the fall of electrical potential. Thus, on all sides, the energy which was once most probably existent in the form of gravitational potential, is being dissipated into unavailable forms. We must recognize dissipation as an inevitable attendant on inanimate transfer of energy. But when we come to consider inanimate actions in relation to time, or time-rate of change, we find a new feature in the phenomena attending transfer of energy; a feature which is really involved in general statements as to the laws of physical interactions. It is seen, that the attitude of inanimate material systems is very generally, if not in all cases, retardative of change--opposing it by effects generated by the primary action, which may be called "secondary" for convenience. Further, it will be seen that these secondary effects are those concerned in bringing about the inevitable dissipation. As example, let us endeavour to transfer gravitational potential energy contained in a mass raised above the surface of the Earth into an elastic body, which we can put into compression by resting the weight upon it. In this way work is done against elastic force and stored as elastic potential energy. We may deal with a metal spring, or with a mass of gas contained in a cylinder fitted with a piston upon which the weight may be placed. In either case we find the effect of compression is to raise the temperature of the substance, thus causing its expansion or increased resistance to the descent of the weight. And this resistance continues, with diminishing intensity, till all the heat generated is dissipated into the surrounding medium. The secondary effect thus delays the final transfer of energy. Again, if we suppose the gas in the cylinder replaced by a vapour in a state of saturation, the effect of increased pressure, as of a weight placed upon the piston, is to reduce the vapour to a liquid, thereby bringing about a great diminution of volume and proportional loss of gravitational potential by the weight. But this change will by no means be brought about instantaneously. When a little of the vapour is condensed, this portion parts with latent heat of vaporisation, increasing the tension of the remainder, or raising its point of saturation, so that before the weight descends any further, this heat has to escape from the cylinder. Many more such cases might be cited. The heating of india-rubber when expanded, its cooling when compressed, is a remarkable one; for at first sight it appears as if this must render it exceptional to the general law, most substances exhibiting the opposite thermal effects when stressed. However, here, too, the action of the stress is opposed by the secondary effects developed in the substance; for it is found that this substance contracts when heated, expands when cooled. Again, ice being a substance which contracts in melting, the effect of pressure is to facilitate melting, lowering its freezing point. But so soon as a little melting occurs, the resulting liquid calls on the residual ice for an amount of heat equivalent to the latent heat of liquefaction, and so by cooling the whole, retards the change. Such particular cases illustrate a principle controlling the interaction of matter and energy which seems universal in application save when evaded, as we shall see, by the ingenuity of life. This principle is not only revealed in the researches of the laboratory; it is manifest in the history of worlds and solar systems. Thus, consider the effects arising from the aggregation of matter in space under the influence of the mutual attraction of the particles. The tendency here is loss of gravitational potential. The final approach is however retarded by the temperature, or vis viva of the parts attending collision and compression. From this cause the great suns of space radiate for ages before the final loss of potential is attained. Clerk Maxwell observes on the general principle that less force is required to produce a change in a body when the change is unopposed by constraints than when it is subjected to such. From this if we assume the external forces acting upon a system not to rise above a certain potential (which is the order of nature), the constraints of secondary actions may, under certain circumstances, lead to final rejection of some of the energy, or, in any case, to retardation of change in the system--dissipation of energy being the result.[1] As such constraints seem inherently present in the properties of matter, we may summarise as follows: _The transfer of energy into any inanimate material system is attended by effects retardative to the transfer and conducive to dissipation._ Was this the only possible dynamic order ruling in material systems it is quite certain the myriads of ants and pines never could have been, except all generated by creative act at vast primary expenditure of energy. Growth and reproduction would have been impossible in systems which retarded change at every step and never proceeded in any direction but in that of dissipation. Once created, indeed, it is conceivable that, as heat engines, they might have dragged out an existence of alternate life and death; life in the hours of sunshine, death in hours of darkness: no final death, however, their lot, till their parts were simply worn out by long use, never made good by repair. But the sustained and increasing activity of organized nature is a fact; therefore some other order of events must be possible. [1] The law of Least Action, which has been applied, not alone in optics, but in many mechanical systems, appears physically based upon the restraint and retardation opposing the transfer of energy in material systems.
What is the actual dynamic attitude of the primary organic engine--the vegetable organism? We consider, here, in the first place, not intervening, but resulting phenomena. The young leaf exposed to solar radiation is small at first, and the quantity of radiant energy it receives in unit of time cannot exceed that which falls upon its surface. But what is the effect of this energy? Not to produce a retardative reaction, but an accelerative response: for, in the enlarging of the leaf by growth, the plant opens for itself new channels of supply. If we refer to "the living protoplasm which, with its unknown molecular arrangement, is the only absolute test of the cell and of the organism in general,[1] we find a similar attitude towards external sources of available energy. In the act of growth increased rate of assimilation is involved, so that there is an acceleration of change till a bulk of maximum activity is attained. The surface, finally, becomes too small for the absorption of energy adequate to sustain further increase of mass (Spencer[2]), and the acceleration ceases. The waste going on in the central parts is then just balanced by the renewal at the surface. By division, by spreading of the mass, by [1] Claus, _Zoology_, p. 13. [2] Geddes and Thomson, _The Evolution of Sex_, p. 220.
The encystment of the protoplasm (occurring under conditions upon which naturalists do not seem agreed) is to all appearance protective from an unfavourable environment, but it is often a period of internal change as well, resulting in a segregation within the mass of numerous small units, followed by a breakup of the whole into these units. It is thus an extension of the basis of supply, and in an impoverished medium, where unit of surface is less active, is evidently the best means of preserving a condition of progress. Thus, in the organism which forms the basis of all modes of life, a definite law of action is obeyed under various circumstances of reaction with the available energy of its environment. Similarly, in the case of the more complex leaf, we see, not only in the phenomenon of growth, but in its extension in a flattened form, and in the orientation of greatest surface towards the source of energy, an attitude towards available energy causative of accelerated transfer. There is seemingly a principle at work, leading to the increase of organic activity. Many other examples might be adduced. The gastrula stage in the development of embryos, where by invagination such an arrangement of the multiplying cells is secured as to offer the greatest possible surface consistent with a first division of labour; the provision of cilia for drawing upon the energy supplies of the medium; and more generally the specialisation of organs in the higher developments of life, may alike be regarded as efforts of the organism directed to the absorption of energy. When any particular organ becomes unavailing in the obtainment of supplies, the organ in the course of time becomes aborted or disappears. On the other hand, when a too ready and liberal supply renders exertion and specialisation unnecessary, a similar abortion of functionless organs takes place. This is seen in the degraded members of certain parasites. During certain epochs of geological history, the vegetable world developed enormously; in response probably to liberal supplies of carbon dioxide. A structural adaptation to the rich atmosphere occurred, such as was calculated to cooperate in rapidly consuming the supplies, and to this obedience to a law of progressive transfer of energy we owe the vast stores of energy now accumulated in our coal fields. And when, further, we reflect that this store of energy had long since been dissipated into space but for the intervention of the organism, we see definitely another factor in organic transfer of energy--a factor acting conservatively of energy, or antagonistically to dissipation. The tendency of organized nature in the presence of unlimited supplies is to "run riot." This seems so universal a relation, that we are safe in seeing here cause and effect, and in drawing our conclusions as to the attitude of the organism towards available energy. New species, when they come on the field of geological history, armed with fresh adaptations, irresistible till the slow defences of the subjected organisms are completed, attain enormous sizes under the stimulus of abundant supply, till finally, the environment, living and dead, reacts upon them with restraining influence. The exuberance of the organism in presence of energy is often so abundant as to lead by deprivation to its self-destruction. Thus the growth of bacteria is often controlled by their own waste products. A moment's consideration shows that such progressive activity denotes an accelerative attitude on the part of the organism towards the transfer of energy into the organic material system. Finally, we are conscious in ourselves how, by use, our faculties are developed; and it is apparent that all such progressive developments must rest on actions which respond to supplies with fresh demands. Possibly in the present and ever increasing consumption of inanimate power by civilised races, we see revealed the dynamic attitude of the organism working through thought-processes. Whether this be so or not, we find generally in organised nature causes at work which in some way lead to a progressive transfer of energy into the organic system. And we notice, too, that all is not spent, but both immediately in the growth of the individual, and ultimately in the multiplication of the species, there are actions associated with vitality which retard the dissipation of energy. We proceed to state the dynamical principles involved in these manifestations, which appear characteristic of the organism, as follows:-- _The transfer of energy into any animate material system is attended by effects conducive to the transfer, and retardative of dissipation._ This statement is, I think, perfectly general. It has been in part advanced before, but from the organic more than the physical point of view. Thus, "hunger is an essential characteristic of living matter"; and again, "hunger is a dominant characteristic of living matter,"[1] are, in part, expressions of the statement. If it be objected against the generality of the statement, that there are periods in the life of individuals when stagnation and decay make their appearance, we may answer, that
That the final end of all will be general non-availability there seems little reason to doubt, and the organism, itself dependent upon differences of potential, cannot hope to carry on aggregation of energy beyond the period when differences of potential are not. The organism is not accountable for this. It is being affected by events external to it, by the actions going on through inanimate agents. And although there be only a part of the received energy preserved, there is a part preserved, and this amount is continually on the increase. To see this it is only necessary to reflect that the sum of animate energy--capability of doing work in any way through animate means--at present upon the Earth, is the result, although a small one, of energy reaching the Earth since a remote period, and which otherwise had been dissipated in space. In inanimate actions throughout nature, as we know it, the availability is continually diminishing. The change is all the one way. As, however, the supply of available energy in the universe is (probably) limited in amount, we must look upon the two as simply effecting the final dissipation of potential in very different ways. The animate system is aggressive on the energy available to it, spends with economy, and invests at interest till death finally deprives it of all. It has heirs, indeed, who inherit some of its gains, but they, too, must die, and ultimately there will be no successors, and the greater part must melt away as if it had never been. The inanimate system responds to the forces imposed upon it by sluggish changes; of that which is thrust upon it, it squanders uselessly. The path of the energy is very different in the two cases. While it is true generally that both systems ultimately result in the dissipation of energy to uniform potential, the organism can, as we have seen, under particular circumstances evade the final doom altogether. It can lay up a store of potential energy which may be permanent. Thus, so long as there is free oxygen in the universe, our coalfields might, at any time in the remote future, generate light and heat in the universal grave. It is necessary to observe on the fundamental distinction between the growth of the protoplasm and the growth of the crystal. It is common to draw comparison between the two, and to point to metabolism as the chief distinction. But while this is the most obvious distinction the more fundamental one remains in the energy relations of the two with the environment.[1] The growth of the crystal is the result of loss of energy; that of the organism the result of gain of energy. The crystal represents a last position of stable equilibrium assumed by molecules upon a certain loss of kinetic energy, and the formation of the crystal by evaporation and concentration of a liquid does not, in its dynamic aspect, differ much from the precipitation of an amorphous sediment. The organism, on the other hand, represents a more or less unstable condition formed and maintained by inflow of energy; its formation, indeed, often attended with a loss of kinetic energy (fixation of carbon in plants), but, if so, accompanied by a more than compensatory increase of potential molecular energy.
Thus there is a dynamic distinction between the progress of the organism and the progress of the combustion, or of the chemical reaction generally. And although there be unstable chemical systems which absorb energy during reaction, these are (dynamically) no more than the expansion of the compressed gas. There is a certain initial capacity in the system for a given quantity of energy; this satisfied, progress ceases. The progress of the organism in time is continual, and goes on from less to greater so long as its development is unconstrained and the supply of energy is unlimited. We must regard the organism as a configuration which is so contrived as to evade the tendency of the universal laws of nature. Except we are prepared to believe that a violation of the second law of thermodynamics occurs in the organism, that a "sorting demon" is at work within it, we must, I think, assume that the interactions going on among its molecules are accompanied by retardation and dissipation like the rest of nature. That such conditions are not incompatible with the definition of the dynamic attitude of the organism, can be shown by analogy with our inanimate machines which, by aid of hypotheses in keeping with the second law of thermodynamics, may be supposed to fulfil the energy-functions of the plant or animal, and, in fact, in all apparent respects conform to the definition of the organism. We may assume this accomplished by a contrivance of the nature of a steam-engine, driven by solar energy. It has a boiler, which we may suppose fed by the action of the engine. It has piston, cranks, and other movable parts, all subject to resistance from friction, etc. Now there is no reason why this engine should not expend its surplus energy in shaping, fitting, and starting into action other engines:--in fact, in reproductive sacrifice. All these other engines represent a multiplied absorption of energy as the effects of the energy received by the parent engine, and may in time be supposed to reproduce themselves. Further, we may suppose the parent engine to be small and capable of developing very little power, but the whole series as increasing in power at each generation. Thus the primary energy relations of the vegetable organism are represented in these engines, and no violation of the second law of thermodynamics involved. We might extend the analogy, and assuming these engines to spend a portion of their surplus energy in doing work against chemical forces--as, for example, by decomposing water through the intervention of a dynamo--suppose them to lay up in this way a store of potential energy capable of heating the boilers of a second order of engines, representing the graminivorous animal. It is obvious without proceeding to a tertiary or carnivorous order, that the condition of energy in the animal world may be supposed fulfilled in these successive series of engines, and no violation of the principles governing the actions going on in our machines assumed. Organisms evolving on similar principles would experience loss at every transfer. Thus only a portion of the radiant energy absorbed by the leaf would be expended in actual work, chemical and gravitational, etc. It is very certain that this is, in fact, what takes place. It is, perhaps, worth passing observation that, from the nutritive dependence of the animal upon the vegetable, and the fact that a conversion of the energy of the one to the purposes of the other cannot occur without loss, the mean energy absorbed daily by the vegetable for the purpose of growth must greatly exceed that used in animal growth; so that the chemical potential energy of vegetation upon the earth is much greater than the energy of all kinds represented in the animal configurations. It appears, too, that in the power possessed by the vegetable of remaining comparatively inactive, of surviving hard times by the expenditure and absorption of but little, the vegetable constitutes a veritable reservoir for the uniform supply of the more unstable and active animal. Finally, on the question of the manner of origin of organic systems, it is to be observed that, while the life of the present is very surely the survival of the fittest of the tendencies and chances of the past, yet, in the initiation of the organised world, a single chance may have decided a whole course of events: for, once originated, its own law secures its increase, although within the new order of actions, the law of the fittest must assert itself. That such a progressive material system as an organism was possible, and at some remote period was initiated, is matter of knowledge; whether or not the initiatory living configuration was rare and fortuitous, or the probable result of the general action of physical laws acting among innumerable chances, must remain matter of speculation. In the event of the former being the truth, it is evidently possible, in spite of a large finite number of habitable worlds, that life is non-existent elsewhere. If the latter is the truth, it is almost certain that there is life in all, or many of those worlds.
The primary factor in evolution is the "struggle for existence." This involves a "natural selection" among the many variations of the organism. If we seek the underlying causes of the struggle, we find that the necessity of food and (in a lesser degree) the desire for a mate are the principal causes of contention. The former is much the more important factor, and, accordingly, we find the greater degree of specialisation based upon it. The present view assumes a dynamic necessity for its demands involved in the nature of the organism as such. This assumption is based on observation of the outcome of its unconstrained growth, reproduction, and life-acts. We have the same right to assert this of the organism as we have to assert that retardation and degradation attend the actions of inanimate machines, which assertion, also, is based on observation of results. Thus we pass from the superficial statements that organisms require food in order to live, or that organisms desire food, to the more fundamental one that: _The organism is a configuration of matter which absorbs energy acceleratively, without limit, when unconstrained._ This is the dynamic basis for a "struggle for existence." The organism being a material system responding to accession of energy with fresh demands, and energy being limited in amount, the struggle follows as a necessity. Thus, evolution guiding' the steps of the energy-seeking organism, must presuppose and find its origin in that inherent property of the organism which determines its attitude in presence of available energy. Turning to the factor, "adaptation," we find that this also must presuppose, in order to be explicable, some quality of aggressiveness on the part of the organism. For adaptation in this or that direction is the result of repulse or victory, and, therefore, we must presuppose an attack. The attack is made by the organism in obedience to its law of demand; we see in the adaptation of the organism but the accumulated wisdom derived from past defeats and victories. Where the environment is active, that is living, adaptation occurs on both sides. Improved means of defence or improved means of attack, both presuppose activity. Thus the reactions to the environment, animate and inanimate, are at once the outcome of the eternal aggressiveness of the organism, and the source of fresh aggressiveness upon the resources of the medium. As concerns the "survival of the fittest" (or "natural selection"), we can, I think, at once conclude that the organism which best fulfils the organic law under the circumstances of supply is the "fittest," _ipso facto._ In many cases this is contained in the commonsense consideration, that to be strong, consistent with concealment from enemies which are stronger, is best, as giving the organism mastery over foes which are weaker, and generally renders it better able to secure supplies. Weismann points out that natural selection favours early and abundant reproduction. But whether the qualifications of the "fittest" be strength, fertility, cunning, fleetness, imitation, or concealment, we are safe in concluding that growth and reproduction must be the primary qualities which at once determine selection and are fostered by it. Inherent in the nature of the organism is accelerated absorption of energy, but the qualifications of the "fittest" are various, for the supply of energy is limited, and there are many competitors for it. To secure that none be wasted is ultimately the object of natural selection, deciding among the eager competitors what is best for each. In short, the facts and generalisations concerning evolution must presuppose an organism endowed with the quality of progressive absorption of energy, and retentive of it. The continuity of organic activity in a world where supplies are intermittent is evidently only possible upon the latter condition. Thus it appears that the dynamic attitude of the organism, considered in these pages, occupies a fundamental position regarding its evolution. We turn to the consideration of old age and death, endeavouring to discover in what relation they stand to the innate progressiveness of the organism.
The organic system is essentially unstable. Its aggressive attitude is involved in the phenomenon of growth, and in reproduction which is a form of growth. But the energy absorbed is not only spent in growth. It partly goes, also, to make good the decay which arises from the instability of the organic unit. The cell is molecularly perishable. It possesses its entity much as a top keeps erect, by the continual inflow of energy. Metabolism is always taking place within it. Any other condition would, probably, involve the difficulties of perpetual motion. The phenomenon of old age is not evident in the case of the unicellular organism reproducing by fission. At any stage of its history all the individuals are of the same age: all contain a like portion of the original cell, so far as this can be regarded as persisting where there is continual flux of matter and energy. In the higher organisms death is universally evident. Why is this? The question is one of great complexity. Considered from the more fundamental molecular point of view we should perhaps look to failure of the power of cell division as the condition of mortality. For it is to this phenomenon--that of cell division--that the continued life of the protozoon is to be ascribed, as we have already seen. Reproduction is, in fact, the saving factor here. As we do not know the source or nature of the stimulus responsible for cell division we cannot give a molecular account of death in the higher organisms. However we shall now see that, philosophically, we are entitled to consider reproduction as a saving factor in this case also; and to regard the death of the individual much as we regard the fall of the leaf from the tree: _i.e._ as the cessation of an outgrowth from a development extending from the past into the future. The phenomena of old age and natural death are, in short, not at variance with the progressive activity of the organism. We perceive this when we come to consider death from the evolutionary point of view. Professor Weismann, in his two essays, "The Duration of Life," and "Life and Death," adopts and defends the view that "death is not a primary necessity but that it has been secondarily acquired by adaptation." The cell was not inherently limited in its number of cell-generations. The low unicellular organisms are potentially immortal, the higher multicellular forms with well-differentiated organs contain the germs of death within themselves. He finds the necessity of death in its utility to the species. Long life is a useless luxury. Early and abundant reproduction is best for the species. An immortal individual would gradually become injured and would be valueless or even harmful to the species by taking the place of those that are sound. Hence natural selection will shorten life. Weismann contends against the transmission of acquired characters as being unproved. He bases the appearance of death on variations in the reproductive cells, encouraged by the ceaseless action of natural selection, which led to a differentiation into perishable somatic cells and immortal reproductive cells. The time-limit of any particular organism ultimately depends upon the number of somatic cell-generations and the duration of each generation. These quantities are "predestined in the germ itself" which gives rise to each individual. "The existence of immortal metazoan organisms is conceivable," but their capacity for existence is influenced by conditions of the external world; this renders necessary the process of adaptation. In fact, in the differentiation of somatic from reproductive cells, material was provided upon which natural selection could operate to shorten or to lengthen the life of the individual in accordance with the needs of the species. The soma is in a sense "a secondary appendage of the real bearer of life--the reproductive cells." The somatic cells probably lost their immortal qualities, on this immortality becoming useless to the species. Their mortality may have been a mere consequence of their differentiation (loc. cit., p. 140), itself due to natural selection. "Natural death was not," in fact, "introduced from absolute intrinsic necessity inherent in the nature of living matter, but on grounds of utility, that is from necessities which sprang up, not from the general conditions of life, but from those special conditions which dominate the life of multicellular organisms." On the inherent immortality of life, Weismann finally states: "Reproduction is, in truth, an essential attribute of living matter, just as the growth which gives rise to it.... Life is continuous, and not periodically interrupted: ever since its first appearance upon the Earth in the lowest organism, it has continued without break; the forms in which it is manifest have alone undergone change. Every individual alive today--even the highest--is to be derived in an unbroken line from the first and lowest forms." At the present day the view is very prevalent that the soma of higher organisms is, in a sense, but the carrier for a period of the immortal reproductive cells (Ray Lankester)--an appendage due to adaptation, concerned in their supply, protection, and transmission. And whether we regard the time-limit of its functions as due to external constraints, recurrently acting till their effects become hereditary, or to variations more directly of internal origin, encouraged by natural selection, we see in old age and death phenomena ultimately brought about in obedience to the action of an environment. These are not inherent in the properties of living matter. But, in spite of its mortality, the body remains a striking manifestation of the progressiveness of the organism, for to this it must be ascribed. To it energy is available which is denied to the protozoon. Ingenious adaptations to environment are more especially its privilege. A higher manifestation, however, was possible, and was found in the development of mind. This, too, is a servant of the cell, as the genii of the lamp. Through it energy is available which is denied to the body. This is the masterpiece of the cell. Its activity dates, as it were, but from yesterday, and today it inherits the most diverse energies of the Earth. Taking this view of organic succession, we may liken the individual to a particle vibrating for a moment and then coming to rest, but sweeping out in its motion one wave in the continuous organic vibration travelling from the past into the future. But as this vibration is one spreading with increased energy from each vibrating particle, its propagation involves a continual accelerated inflow of energy from the surrounding medium, a dynamic condition unknown in periodic effects transmitted by inanimate actions, and, indeed, marking the fundamental difference between the dynamic attitudes of the animate and inanimate. We can trace the periodic succession of individuals on a diagram of activity with some advantage. Considering, first, the case of the unicellular organism reproducing by subdivision and recalling that conditions, definite and inevitable, oppose a limit to the rate of growth, or, for our present purpose, rate of consumption of energy, we proceed as follows: {Fig. 1} Along a horizontal axis units of time are measured; along a vertical axis units of energy. Then the life-history of the amoeba, for example, appears as a line such as A in Fig. 1. During the earlier stages of its growth the rate of absorption of energy is small; so that in the unit interval of time, t, the small quantity of energy, e1, is absorbed. As life advances, the activity of the organism augments, till finally this rate attains a maximum, when e2 units of energy are consumed in the unit of time.[1] [1]Reference to p. 76, where the organic system is treated as purely mechanical, may help readers to understand what is involved in this curve. The solar engine may, unquestionably, have its activity defined by such a curve. The organism is, indeed, more complex; but neither this fact nor our ignorance of its mechanism, affects the principles which justify the diagram.
{Fig. 2} the species along the curve B, which may be numbered (2), to signify that it represents the activity of two individuals, and so on, the numbering advancing in geometrical progression. The particular curvature adopted in the diagram is, of course, imaginary; but it is not of an indeterminate nature. Its course for any species is a characteristic of fundamental physical importance, regarding the part played in nature by the particular organism. In Fig. 2 is represented the path of a primitive multicellular organism before the effects of competition produced or fostered its mortality. The lettering of Fig. 1 applies; the successive reproductive acts are marked P1, P2; Q1, Q2, etc., in the paths of the successive individuals. {Fig. 3} The next figure (Fig. 3) diagrammatically illustrates death in organic history. The path ever turns more and more from the axis of energy, till at length the point is reached when no more energy is available; a tangent to the curve at this point is at right angles to the axis of energy and parallel to the time axis. The death point is reached, and however great a length we measure along the axis of time, no further consumption of energy is indicated by the path of the organism. Drawing the line beyond the death point is meaningless for our present purpose. It is observable that while the progress of animate nature finds its representation on this diagram by lines sloping _upwards_ from left to right, the course of events in inanimate nature--for example, the history of the organic configuration after death, or {Fig. 4} the changes progressing--let us say, in the solar system, or in the process of a crystallisation, would appear as lines sloping downwards from left to right. Whatever our views on the origin of death may be, we have to recognise a periodicity of functions in the life-history of the successive individuals of the present day; and whether or not we trace this directly or indirectly to a sort of interference with the rising wave of life, imposed by the activity of a series of derived units, each seeking energy, and in virtue of its adaptation each being more fitted to obtain it than its predecessor, or even leave the idea of interference out of account altogether in the origination or perpetuation of death, the truth of the diagram (Fig. 4) holds in so far as it may be supposed to graphically represent the dynamic history of the individual. The point chosen on the curve for the origination of a derived unit is only applicable to certain organisms, many reproducing at the very close of life. A chain of units are supposed here represented.[1]
If we lay out waves as above to a common scale of time for different species, the difference of longevity is shown in the greater or less number of vibrations executed in a given time, _i.e._ in greater or less "frequency." We cannot indeed draw the curvature correctly, for this would necessitate a knowledge which we have not of the activity of the organism at different periods of its life-history, and so neither can we plot the direction of the organic line of propagation with respect to the axes of reference as this involves a knowledge of the mean activity.[1]
[1] In the relative food-supply at various periods of life the curvature is approximately determinable.
The group of curves which follow, relating to typical animals possessing very different activities (Fig. 5), are therefore entirely diagrammatic, except in respect to the approximate {Fig. 5} longevity of the organisms. (1) might represent an animal of the length of life and of the activity of Man; (2), on the same scale of longevity, one of the smaller mammals; and (3), the life-history of a cold blooded animal living to a great age; _e.g._ certain of the reptilia. It is probable, that to conditions of structural development, under the influence of natural selection, the question of longer or shorter life is in a great degree referable. Thus, development along lines of large growth will tend to a slow rate of reproduction from the simple fact that unlimited energy to supply abundant reproduction is not procurable, whatever we may assume as to the strength or cunning exerted by the individual in its efforts to obtain its supplies. On the other hand, development along lines of small growth, in that reproduction is less costly, will probably lead to increased rate of reproduction. It is, in fact, matter of general observation that in the case of larger animals the rate of reproduction is generally slower than in the case of smaller animals. But the rate of reproduction might be expected to have an important influence in determining the particular periodicity of the organism. Were we to depict in the last diagram, on the same time-scale as Man, the vibrations of the smaller and shorter-lived living things, we would see but a straight line, save for secular variations in activity, representing the progress of the species in time: the tiny thrills of its units lost in comparison with the yet brief period of Man. The interdependence of the rate of reproduction and the duration of the individual is, indeed, very probably revealed in the fact that short-lived animals most generally reproduce themselves rapidly and in great abundance, and vice versa. In many cases where this appears contradicted, it will be found that the young are exposed to such dangers that but few survive (_e.g._ many of the reptilia, etc.), and so the rate of reproduction is actually slow. Death through the periodic rigour of the inanimate environment calls forth phenomena very different from death introduced or favoured by competition. A multiplicity of effects simulative of death occur. Organisms will, for example, learn to meet very rigorous conditions if slowly introduced, and not permanent. A transitory period of want can be tided over by contrivance. The lily withdrawing its vital forces into the bulb, protected from the greatest extremity of rigour by seclusion in the Earth; the trance of the hibernating animal; are instances of such contrivances. But there are organisms whose life-wave truly takes up the periodicity of the Earth in its orbit. Thus the smaller animals and plants, possessing less resources in themselves, die at the approach of winter, propagating themselves by units which, whether egg or seed, undergo a period of quiescence during the season of want. In these quiescent units the energy of the organism is potential, and the time-energy function is in abeyance. This condition is, perhaps, foreshadowed in the encystment of the amoeba in resistance to drought. In most cases of hibernation the time-energy function seems maintained at a loss of potential by the organism, a diminished vital consumption of energy being carried on at the expense of the stored energy of the tissues. So, too, even among the largest organisms there will be a diminution of activity periodically inspired by climatological conditions. Thus, wholly or in part, the activity of organisms is recurrently affected by the great energy--tides set up by the Earth's orbital motion. {Fig. 6} Similarly in the phenomenon of sleep the organism responds to the Earth's axial periodicity, for in the interval of night a period of impoverishment has to be endured. Thus the diurnal waves of energy also meet a response in the organism. These tides and waves of activity would appear as larger and smaller ripples on the life-curve of the organism. But in some, in which life and death are encompassed in a day, this would not be so; and for the annual among plants, the seed rest divides the waves with lines of no activity (Fig. 6). Thus, finally, we regard the organism as a dynamic phenomenon passing through periodic variations of intensity. The material systems concerned in the transfer of the energy rise, flourish, and fall in endless succession, like cities of ancient dynasties. At points of similar phase upon the waves the rate of consumption of energy is approximately the same; the functions, too, which demand and expend the energy are of similar nature. That the rhythm of these events is ultimately based on harmony in the configuration and motion of the molecules within the germ seems an unavoidable conclusion. In the life of the individual rhythmic dynamic phenomena reappear which in some cases have no longer a parallel in the external world, or under conditions when the individual is no longer influenced by these external conditions.,, In many cases the periodic phenomena ultimately die out under new influences, like the oscillations of a body in a viscous medium; in others when they seem to be more deeply rooted in physiological conditions they persist. The "length of life is dependent upon the number of generations of somatic cells which can succeed one another in the course of a single life, and furthermore the number as well as the duration of each single cell-generation is predestined in the germ itself." Only in the vague conception of a harmonising or formative structural influence derived from the germ, perishing in each cell from internal causes, but handed from cell to cell till the formative influence itself degrades into molecular discords, does it seem possible to form any physical representation of the successive events of life. The degradation of the molecular formative influence might be supposed involved in its frequent transference according to some such dynamic actions as occur in inanimate nature. Thus, ultimately, to the waste within the cell, to the presence of a force retardative of its perpetual harmonic motions, the death of the individual is to be ascribed. Perhaps in protoplasmic waste the existence of a universal death should be recognised. It is here we seem to touch inanimate nature; and we are led back to a former conclusion that the organism in its unconstrained state is to be regarded as a contrivance for evading the dynamic tendencies of actions in which lifeless matter participates.[1]
[1] In connection with the predestinating power and possible complexity of the germ, it is instructive to reflect on the very great molecular population of even the smallest spores--giving rise to very simple forms. Thus, the spores of the unicellular Schizomycetes are estimated to dimensions as low as 1/10,000 of a millimetre in diameter (Cornil et Babes, _Les Batteries_, 1. 37). From Lord Kelvin's estimate of the number of molecules in water, comprised within the length of a wave-length of yellow light (_The Size of Atoms_, Proc. R. I., vol. x., p. 185) it is probable that such spores contain some 500,000 molecules, while one hundred molecules range along a diameter.
We began by seeking in various manifestations of life a dynamic principle sufficiently comprehensive to embrace its very various phenomena. This, to all appearance, found, we have been led to regard life, to a great extent, as a periodic dynamic phenomenon. Fundamentally, in that characteristic of the contrivance, which leads it to respond favourably to transfer of energy, its enormous extension is due. It is probable that to its instability its numerical abundance is to be traced--for this, necessitating the continual supply of all the parts already formed, renders large, undifferentiated growth, incompatible with the limited supplies of the environment. These are fundamental conditions of abundant life upon the Earth. Although we recognise in the instability of living systems the underlying reason for their numerical abundance, secondary evolutionary causes are at work. The most important of these is the self-favouring nature of the phenomenon of reproduction. Thus there is a tendency not only to favour reproductiveness, but early reproductiveness, in the form of one prolific reproductive act, after which the individual dies. Hence the wavelength of the species diminishes, reproduction is more frequent, and correspondingly greater numbers come and go in an interval of time. Another cause of the numerical abundance of life exists, as already stated, in the conditions of nourishment. Energy is more readily conveyed to the various parts of the smaller mass, and hence the lesser organisms will more actively functionate; and this, as being the urging dynamic attitude, as well as that most generally favourable in the struggle, will multiply and favour such forms of life. On the other hand, however, these forms will have less resource within themselves, and less power of endurance, so that they are only suitable to fairly uniform conditions of supply; they cannot survive the long continued want of winter, and so we have the seasonal abundance of summer. Only the larger and more resistant organisms, whether animal or vegetable, will, in general, populate the Earth from year to year. From this we may conclude that, but for the seasonal energy-tides, the development of life upon the globe had gone along very different lines from those actually followed. It is, indeed, possible that the evolution of the larger organisms would not have occurred; there would have been no vacant place for their development, and a being so endowed as Man could hardly have been evolved. We may, too, apply this reasoning elsewhere, and regard as highly probable, that in worlds which are without seasonal influences, the higher developments of life have not appeared; except they have been evolved under other conditions, when they might for a period persist. We have, indeed, only to picture to ourselves what the consequence of a continuance of summer would be on insect life to arrive at an idea of the antagonistic influences obtaining in such worlds to the survival of larger organisms. It appears that to the dynamic attitude of life in the first place, and secondarily to the environmental conditions limiting undifferentiated growth, as well as to the action of heredity in transmitting the reproductive qualities of the parent to the offspring, the multitudes of the pines, and the hosts of ants, are to be ascribed. Other causes are very certainly at work, but these, I think, must remain primary causes. We well know that the abundance of the ants and pines is not a tithe of the abundance around us visible and invisible. It is a vain endeavour to realise the countless numbers of our fellow-citizens upon the Earth; but, for our purpose, the restless ants, and the pines solemnly quiet in the sunshine, have served as types of animate things. In the pine the gates of the organic have been thrown open that the vivifying river of energy may flow in. The ants and the butterflies sip for a brief moment of its waters, and again vanish into the inorganic: life, love and death encompassed in a day. Whether the organism stands at rest and life comes to it on the material currents of the winds and waters, or in the vibratory energy of the aether; or, again, whether with restless craving it hurries hither and thither in search of it, matters nothing. The one principle--the accelerative law which is the law of the organic--urges all alike onward to development, reproduction and death. But although the individual dies death is not the end; for life is a rhythmic phenomenon. Through the passing ages the waves of life persist: waves which change in their form and in the frequency to which they are attuned from one geologic period to the next, but which still ever persist and still ever increase. And in the end the organism outlasts the generations of the hills. [The end] GO TO TOP OF SCREEN |