Chapter 6

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

[1] It appears exceptional for the crystal line configuration to stand higher in the scale of energy than the amorphous.

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a more than compensatory increase of potential molecular energy.

Thus, between growth in the living world and growth in the dead world, the energy relations with the environment reveal a marked contrast. Again, in the phenomena of combustion, there are certain superficial resemblances which have led to comparison between the two. Here again, however, the attitudes towards the energy of the environment stand very much as + and -. The life absorbs, stores, and spends with economy. The flame only recklessly spends. The property of storage by the organism calls out a further distinction between the course of the two processes. It secures that the chemical activity of the organism can be propagated in a medium in which the supply of energy is discontinuous or localised. The chemical activity of the combustion can, strictly speaking, only be propagated among contiguous particles. I need not dwell on the latter fact; an example of the former is seen in the action of the roots of plants, which will often traverse a barren place or circumvent an obstacle in their search for energy. In this manner roots will find out spots of rich nutriment.

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

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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

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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,

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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.[1] 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

[1] I find a similar conclusion arrived at in Semper's _Animal Life_, p. 52.

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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.

EVOLUTION AND ACCELERATION OF ACTIVITY

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._

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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

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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.

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THE PERIODICITY OF THE ORGANISM AND THE LAW OF PROGRESSIVE ACTIVITY

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

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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,"[1] 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.

[1] See his _Biological Memoirs._ Oxford, 1888.

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Weismann contends against the transmission of acquired characters as being unproved.[1] 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,

[1] Biological Memoirs, p. 142.

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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." [1]

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)[2]--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

[1] Loc. cit., p. 159

[2] Geddes and Thomson, The Evolution of Sex, chap. xviii.

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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

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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.

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On this diagram reproduction, on the part of the organism, is represented by a line which repeats the curvature of the parent organism originating at such a point as P in the path of the latter, when the rate of consumption of energy has become constant. The organism A has now ceased to act as a unit. The products of fission each carry on the vital development of

{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.

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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

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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

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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]

THE LENGTH OF LIFE

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