University of Virginia Library

Chapter 17
The Law of Evolution concluded

§139. The conception of Evolution elaborated in the foregoing chapters, is still incomplete. True though it is, it is not the whole truth. The transformations which all things undergo during the ascending phases of their existence, we have contemplated under three aspects; and by uniting these three aspects as simultaneously presented, we have formed an approximate idea of the transformations. But there are concomitant changes about which nothing has yet been said, and which, though less conspicuous, are no less essential.

For thus far we have attended only to the re-distribution of Matter, neglecting the accompanying redistribution of Motion. Distinct or tacit reference has, indeed, repeatedly been made to the dissipation of Motion, that goes on along with the concentration of Matter; and were all Evolution absolutely simple, the total fact would be contained in the proposition that as Motion dissipates Matter concentrates. But while we have recognized the ultimate re-distribution of the Motion, we have passed over its proximate re-distribution. Though something has from time to time been said about the escaping motion, nothing has been said about the motion which does not escape. In proportion as Evolution becomes compound — in proportion as an aggregate retains, for a considerable time, such quantity of motion as permits secondary re-distributions of its component matter, there necessarily arise secondary redistributions of its retained motion. As fast as the parts are transformed, there goes on a transformation of the sensible or insensible motions possessed by the parts. They cannot become more integrated, either individually or as a combination, without their motions, individual or combined, becoming more integrated. There cannot arise among them heterogeneities of size, of form, of quality, without there also arising heterogeneities in the amounts and directions of their motions, or the motions of their molecules. And increasing definiteness of the parts implies increasing definiteness of their motions. In short, the rhythmical actions going on in each aggregate, must differentiate and integrate at the same time that the structures do so.

§139a. The general theory of this re-distribution of the retained motion, must here be briefly stated. Properly to supplement our conception of Evolution under its material aspect by a conception of Evolution under its dynamical aspect, we have to recognize the source of the integrated motions that arise, and to see how their increased multiformity and definiteness are necessitated.

If Evolution is passage from a diffused state to an aggregated state, then the motions of the celestial bodies must have resulted from the uncancelled motions of their once dispersed components. Along with the molecular motions everywhere active, there were molar motions of those vast streams of nebulous matter which were generated during the process of concentration — molar motions of which large portions were gradually dissipated as heat, leaving undissipated portions. But since the molar motions of these nebulous streams were constituted from the motions of multitudinous incoherent gaseous parts severally moving more or less independently it follows that when aggregation into a liquid and finally solid celestial mass was reached, these partially independent motions of the incoherent parts became merged into the motion of the whole: or, in other words, unintegrated motions became an integrated motion.

While we must leave in the shape of hypothesis the belief that the celestial motions have thus originated, we may see, as a matter of fact, that the integration of insensible motions originates all sensible motions on the Earth's surface. As all know, the denudation of lands and deposit of new strata, are effected by water while descending to the sea, or during the arrest of those undullations produced on it by winds; and, as before said, the elevation of water to the height whence it fell, is due to solar heat, as is also the genesis of those aerial currents which drift it about when evaporated and agitate its surface when condensed. That is to say, the molecular motion of the ethereal medium is transformed into the motion of gases, thence into the motion of liquids, and thence into the motion of solids: stages in each of which a certain amount of molecular motion is lost and an equivalent motion of masses gained. It is the same with organic movements. Certain rays issuing from the Sun, enable the plant to reduce special elements existing in gaseous combinations around it, to solid forms — enable the plant, that is, to grow and carry on its functional changes. And since growth, equally with circulation of sap, is a mode of sensible motion, while those rays which have been expended in generating both consist of insensible motions, we have here, too a transformation of the kind alleged Animals, derived as their forces are, directly or indirectly, from plants, carry this transformation a step further. The automatic movements of the viscera, together with the voluntary movements of the limbs and body at large, arise at the expense of certain molecular movements throughout the nervous and muscular tissues; and these originally arose at the expense of certain other molecular movements propagated by the Sun to the Earth; so that both the structural and functional motions which organic Evolution displays, are motions of aggregates generated by the arrested motions of units. Even with the aggregates of these aggregates the same rule holds. For among associated men the progress is ever towards a merging of individual actions in the actions of corporate bodies. In militant life this is seen in the advance from the independent fighting of separate warriors to the combined fighting of regiments, and in industrial life in the advance from the activities of separate workers to the combined activities of factory hands. So is it, too, when instead of acting alone citizens act in bodies — companies, unions, associations, etc. While, then, during Evolution the escaping motion becomes, by widening dispersion, more disintegrated, the motion that is for a time retained, becomes more integrated; and so, considered dynamically, Evolution is a decrease in the relative movements of parts and an increase in the relative movements of wholes — using the words parts and wholes in their most general senses. The advance is from the motions of simple molecules to the motions of compound molecules; from molecular motions to the motions of masses; and from the motions of smaller masses to the motions of larger masses.

The accompanying change towards greater multiformity among the retained motions, takes place under the form of an increased variety of rhythms. A multiplication of rhythms must accompany a multiplication in the degrees and modes of aggregation, and in the relations of the aggregated masses to incident forces. The degree or mode of aggregation will not, indeed, affect the rate or extent of rhythm where the incident force increases as the aggregate increases, which is the case with gravitation: here the only cause of variation in rhythm is difference of relation to the incident force; as we see in a pendulum which, though unaffected in its movements by a change in the weight of the bob, alters its rate of oscillation when its length is altered or when, otherwise unchanged, it is taken to the equator. But in all cases where the incident forces do not vary as the masses, every new order of aggregation initiates a new order of rhythm: witness the conclusion drawn from the recent researches into radiant heat and light, that the molecules of different gases have different rates of undulation. So that increased multiformity in the arrangement of matter necessarily generates increased multiformity of rhythm; both through increased variety in the sizes and forms of aggregates, and through increased variety in their relations to the forces which move them. That these motions, as they become more integrated and more heterogeneous, must become more definite, is a proposition that need not detain us. In proportion as any part of an evolving whole segregates and consolidates, and in so doing loses the relative mobility of its components, its aggregate motion must obviously acquire distinctness.

Here, then, to complete our conception of Evolution, we must contemplate throughout the Cosmos, these metamorphoses of retained motion which accompany the metamorphoses of component matter. We may do this with comparative brevity: the reader having now become so familiar with the mode of looking at the facts, that less illustration will suffice. To save space, it will be convenient to deal with the several aspects of the metamorphoses at the same time.

§140. Masses of diffused matter moving towards a common centre, from many points at many distances with many degrees of indirectness, must carry into the nebulous mass eventually formed, numerous momenta unlike in their amounts and directions. As the integration progresses, such parts of these momenta as conflict are mutually neutralized, and dissipated as heat. Unless the original distribution is quite symmetrical, which is infinitely improbable, rotation will result. The mass having at first unlike angular velocities at the periphery and at various distances from the centre will have its differences of angular velocity gradually reduced; advancing towards a final state, now nearly reached by the Sun in which the angular velocity of the whole mass is the same — in which the motion is integrated. So, too, with each planet and satellite. Progress from the motion of a nebulous ring, incoherent and admitting of much relative motion within its mass, to the motion of a dense spheroid, is progress to a motion that is completely integrated. The rotation, and the translation through space, severally become one and indivisible. Meanwhile, there has been established that further integration displayed by the motions of the Solar System as a whole. Locally in each planet and its satellites, and generally in the Sun and the planets, we have a system of simple and compound rhythms, with periodic and secular variations, forming together an integrated set of movements.

Along with advancing integration of the motions there has gone advance in the multiformity and distinctness of them. The matter which, in its original diffused state, had movements that were confused, indeterminate, or without sharply-marked distinctions, has, during the evolution of the Solar System, acquired definitely heterogeneous movements. The periods of revolution of all the planets and satellites are unlike; as are also their times of rotation. Out of these definitely heterogeneous motions of a simple kind, arise others that are complex, but still definite; — as those produced by the revolutions of satellites compounded with the revolutions of their primaries; as those of which precession is the result; and as those which are known as perturbations. Each additional complexity of structure has caused additional complexity of movements; but still, a definite complexity, as is shown by having calculable results.

§141. While the Earth's surface was molten, the currents in the voluminous atmosphere surrounding it, mainly of ascending heated gases and of descending precipitated liquids, must have been local, numerous, indefinite, and but little distinguished from one another. But when after a vast period the surface, now solidified, had so far cooled that solar radiation began to cause appreciable differences of temperature between the equatorial and polar regions, an atmospheric circulation from poles to equator and from equator to poles, must have slowly established itself: other vast moving masses of air becoming, at last, trade-winds and other such permanent definite currents. These integrated motions, once comparatively homogeneous, were rendered heterogeneous as great islands and continents arose, to complicate them by periodic winds, caused by the varied heating of wide tracts of land at different seasons. Rhythmical motions of a constant and simple kind, were, by increasing multiformity of the Earth's surface, differentiated into an involved combination of constant and recurrent rhythmical motions, joined with smaller motions that are irregular.

Parallel changes must have taken place in the motions of water. On a thin crust, admitting of but small elevations and depressions, and therefore of but small lakes and seas, none beyond small local circulations were possible. But along with the formation of continents and oceans, came the vast movements of water from warm latitudes to cold and from cold to warm — movements increasing in amount, in definiteness, and in variety of distribution, as the features of the Earth's surface became larger and more contrasted. The like holds with drainage waters. The tricklings of insignificant streams over small tracts of land, were once alone possible; but as fast as wide areas came into existence, the motions of many tributaries became massed into the motions of great rivers; and instead of motions very much alike, there arose motions considerably varied.

Nor can we well doubt that the changes in the Earth's crust itself, have presented an analogous progress. Small, numerous, local, and like one another, while the crust was thin, the movements of elevation and subsidence must, as the crust thickened, have extended over larger areas, must have continued for longer eras in the same directions, and must have been made more unlike in different regions by local differences of structure.

§142. In organisms the advance towards a more integrated, heterogeneous, and definite distribution of the retained motion, which accompanies the advance towards a more integrated, heterogeneous, and definite distribution of the component matter, is mainly what we understand as the development of functions. All active functions are either sensible movements, as those produced by contractile organs; or such insensible movements as those propagated through nerves; or such insensible movements as those by which, in secreting organs, molecular re-arrangements are effected, and new combinations of matter produced. And during evolution functions, like structures, become more consolidated individually, as well as more combined with one another, at the same time that they become more multiform and more distinct.

The nutritive juices in animals of low types move hither and thither through the tissues quite irregularly, as local strains and pressures determine: in the absence of a true blood and a distinct vascular system, there is no definite circulation. But along with the structural evolution which establishes a good apparatus for distributing blood, there goes on the functional evolution which establishes large and rapid movements of blood, definite in their courses and definitely distinguished as efferent and afferent, and that are heterogeneous both in their directions and in their characters: being here divided into gushes and there continuous.

Again, accompanying the structural differentiations and integrations of the alimentary canal, there arise differentiations and integrations both of its mechanical movements and its actions of a non-mechanical kind. Along an alimentary canal of a primitive type there pass, almost uniformly from end to end, waves of constriction. But in a well-organized alimentary canal, the waves of constriction are widely unlike at different parts, in their kinds, strengths, and rapidities. In the oesophagus they are propulsive in their office, and travelling with considerable speed, take place at intervals during eating, and then do not take place till the next meal. In the stomach another modification of this originally uniform action occurs: the muscular constrictions are powerful, and continue during the long periods that the stomach contains food. Throughout the upper intestines, again, a further difference shows itself — the waves travel along without cessation but are relatively moderate. Finally, in the rectum this rhythm departs in another way from the common type: quiescence, lasting for many hours, is followed by a series of strong contractions. Meanwhile, the essential actions which these movements aid, have been growing more definitely heterogeneous. Secretion and absorption are no longer carried on in much the same way from end to end of the tube; but the general function divides into various subordinate functions. The solvents and ferments furnished by the coats of the canal and the appended glands, become widely unlike at upper, middle, and lower parts of the canal; implying different kinds of molecular changes. Here the process is mainly secretory there it is mainly absorbent, and in other places, as in the oesophagus, neither secretion nor absorption takes place to any appreciable extent. While these and other internal motions, sensible and insensible, are being rendered more various, and severally more integrated and more distinct, there is advancing the integration by which they are united into local groups of motions and a combined system of motions. While the function of alimentation subdivides, its subdivisions become co-ordinated, so that muscular and secretory actions go on in concert, and so that excitement of one part of the canal sets up excitement of the rest. Moreover, the whole alimentary function, while it supplies matter for the circulatory and respiratory functions, becomes so integrated with them that it cannot for a moment go on without them. And, as evolution advances, all three of these fundamental functions fall into greater subordination to the nervous functions — depend more and more on the due mount of nervous discharge; while at the same time their motions become co-ordinated, or in a sense integrated, with those of the nervo-muscular system, on which they depend for the supply of materials.

When we trace up the functions of motor organs the same truth discloses itself. Microscopic creatures are moved through the water by the oscillations of cilia, here large and single or double, and here smaller and numerous; and various larger forms, as the Turbellaria, progress by ciliary action over solid surfaces. These motions of cilia are, in the first place, severally very minute; in the second place they are homogeneous; and in the third place there is but little definiteness in them individually, or in their joint product, which is mostly a random change of position not directed to any selected point. Contrasting this ciliary action with the action of developed locomotive organs, we see that instead of many small or unintegrated movements there are a few comparatively large or integrated movements; that actions all alike are replaced by actions partially or wholly unlike; and that instead of being very feebly or almost accidentally co-ordinated, their definite co-ordination renders the motions of the body as a whole, precise. A parallel contrast, less extreme but sufficiently decided, is seen when we pass from the lower types of creatures with limbs to the higher types of creatures with limbs. The legs of a Centipede have motions that are numerous, small, and homogeneous; and are so little integrated that when the creature is divided and subdivided, the legs belonging to each part propel that part independently. But in one of the higher Arthropoda: as a Crab, the relatively few limbs have motions which are comparatively large in their amounts, which are considerably unlike one another, and which are integrated into total bodily movements of much definiteness.

§143. The last illustrations introduce us to illustrations of the kind classed as mental. They are the physiological aspects of the simpler among those functions which, under a more special and complex aspect, we distinguish as psychological. The phenomena subjectively known as changes in consciousness, are objectively known as nervous excitations and discharges, which science now interprets into modes of motion. Hence, in following up organic evolution, advance of the retained motion alike in integration, in heterogeneity, and in definiteness, may be expected to show itself both in the visible nervo-muscular actions and in the correlative mental changes. We may conveniently look at the facts as exhibited during individual evolution, before looking at them as exhibited in general evolution.

The progress of a child in speech very clearly displays the transformation. Infantine noises are comparatively homogeneous; alike as being severally long-drawn and nearly uniform from end to end, and as being constantly repeated with but little variation of quality. They are quite un-co-ordinated — there is no integration of them into compound sounds. They are inarticulate, or without those definite beginnings and endings and joinings characterizing words. Progress shows itself first in the multiplication of the inarticulate sounds: the extreme vowels are added to the medium vowels, and the compound to the simple. Presently the movements which form the simpler consonants are achieved, and some of the sounds become sharply cut; but this definiteness is partial, for only initial consonants being used, the sounds end vaguely. While an approach to distinctness thus results, there also results, by combination of different consonants with the same vowels, an increase of heterogeneity; and along with the complete distinctness which terminal consonants give, arises a further great addition to the number of unlike sounds produced. The more difficult consonants and the compound consonants, imperfectly articulated at first, are by-and-by articulated with precision; and hence arises another multitude of different and definite words — words that imply many kinds of vocal movements, severally performed with exactness, as well as perfectly integrated into complex groups. The subsequent advance to dissyllables and polysyllables, and to involved combinations of words, shows the still higher degree of integration and heterogeneity eventually reached by these organic motions.

The acts of consciousness correlated with these nervo-muscular acts, of course go through parallel phases; and the advance from childhood to maturity yields daily proof that the changes which, on their physical side are nervous processes, and on their mental side are processes of thought, become more various, more defined, more coherent. At first the intellectual functions are much alike in kind — recognitions and classifications of simple impressions alone go on; but in course of time these functions become multiform. Reasoning grows distinguishable, and eventually we have conscious induction and deduction; deliberate recollection and deliberate imagination are added to simple unguided association of ides; more special modes of mental action, as those which result in mathematics, music, poetry, arise; and within each of these divisions the mental movements are ever being further differentiated. In definiteness it is the same. At first the infant makes its observations so inaccurately that it fails to distinguish individuals. The child errs continually in its spelling, its grammar, its arithmetic. The youth forms incorrect judgments on the affairs of life. Only with maturity comes that precise co-ordination of data which is implied by a good adjustment of thoughts to things. Lastly, with the integration by which simple mental acts are combined into complex mental acts, we see the like. In the nursery you cannot obtain continuous attention — there is inability to form a coherent series of impressions; and there is a parallel inability to unite many co-existent impressions, even of the same order: witness the way in which a child's remarks on a picture, show that it attends only to the individual objects represented, and never to the picture as a whole. But advancing years bring the ability to understand an involved sentence, to follow long trains of reasoning, to hold in one mental grasp numerous concurrent circumstances. A like progressive integration takes place among the mental changes we distinguish as feelings; which in a child act singly, producing impulsiveness, but in an adult act more in concert, producing a comparatively balanced conduct.

After these illustrations supplied by individual evolution, we may deal briefly with those supplied by general evolution, which are analogous to them. A creature of very low intelligence, when aware of some large object in motion near it, makes a spasmodic movement, causing, it may be, a leap or a dart. The perceptions implied are relatively simple, homogeneous, and indefinite: the moving objects are not distinguished in their kinds as injurious or otherwise, as advancing or receding. The actions of escape, too, are all of one kind, have no adjustments of direction, and may bring the creature nearer the source of peril instead of further off. At a higher stage the dart or the leap is away from danger: the nervous changes are so far specialized that there results distinction of direction; indicating a greater variety among them, a greater co-ordination or integration of them in each process, and a greater definiteness. In still higher animals, able to discriminate between enemies and not-enemies, as a bird which flies from a man but not from a cow, the acts of perception have severally become united into more complex wholes, since cognition of certain differential attributes is implied; they have also become more multiform, since each additional component impression adds to the number of possible compounds; and they have, by consequence, become more specific in their correspondences with objects — more definite. And then in animals so intelligent that they identify by sight not species only but individuals of a species, the mental changes are yet further distinguished in the same three ways. In the course of human evolution the law is equally manifested. The thoughts of the savage are nothing like so heterogeneous in their kinds as those of the civilized man, whose complex environment presents a multiplicity of new phenomena. His mental acts, too are much less involved — he has no words for abstract ideas, and is found to be incapable of integrating the elements of such ideas. And in all but simple matters there is none of that precision in his thinking, and that grasping of many linked conceptions, which, among civilized men, leads to the exact conclusions of science.

§144. How in societies the movements or functions produced by the confluence of individual actions, increase in their amounts, their multiformities, their precision, and their combination, scarcely needs insisting upon after what has been potted out in foregoing chapters. For the sake of symmetry of statement, however, a typical example or two may be set down.

At first the military activities, undifferentiated from the rest (all men in primitive societies being warriors) are relatively homogeneous, ill-combined, and indefinite: savages making a joint attack severally fight independently; in similar ways, and without order. But as societies evolve the movements of the thousands of soldiers which replace the tens of warriors, are divided and re-divided in their kinds of movements: here are gunners, there infantry and elsewhere cavalry. Within each of the differentiated functions of these bodies there come others: there are distinct actions of privates, sergeants, captains, colonels, generals, as also of those who constitute the commissariat and those who attend to the wounded. The clustered motions that have thus become comparatively heterogeneous in general and in detail, have simultaneously increased in precision; so that in battle, men and the regiments formed of them, are made to take definite positions and perform definite acts at definite times. Once more, there has gone on that integration by which the multiform actions of an army are directed to a single end. By a co-ordinating apparatus having the commander-in-chief for its centre, the charges, and halts, and retreats are duly concerted; and a hundred thousand individual motions are united under one will.

Again on comparing the rule of a savage chief with that of a civilized government, aided by its subordinate local governments and their officers, down to the police, we see how, as men have advanced from tribes of hundreds to nations of millions, the regulative action has grown large in amount; how, guided by written laws, it has passed from vagueness and irregularity to comparative precision; and how it has subdivided into processes increasingly multiform. Or after observing how the barter that goes on among barbarians differs from our own commercial processes, by which a million's worth of commodities is distributed daily; by which the relative values of articles immensely varied in kinds and qualities are exactly measured, and the supplies adjusted to the demands; and by which industrial activities of all orders are so combined that each depends on the rest and aids the rest; we see that the kind of movement which constitutes trade, has become progressively more vast, more varied, more definite, and more integrated.

§145. A finished conception of Evolution thus includes the re-distribution of the retained motion, as well as that of the component matter. This added element of the conception is scarcely, if at all, less important than the other. The movements of the Solar System have a significance equal to that which the sizes, forms, and relative distances of its members possess. The Earth's geographical and geological structure are not more important elements in the order of Nature than are the motions, regular and irregular, of the water and the air clothing it. And of the phenomena presented by an organism, it must be admitted that the combined sensible and insensible actions we call its life, do not yield in interest to its structural traits. Leaving out, however, all implied reference to the way in which these two orders of facts concern us, it is clear that with each redistribution of matter there necessarily goes a re-distribution of motion; and that the unified knowledge constituting Philosophy, must comprehend both aspects of the transformation.

Our formula, therefore, needs an additional clause. To combine this satisfactorily with the clauses as they stand in the last chapter, is scarcely practicable; and for convenience of expression it will be best to change their order. On doing this, and making the requisite addition, the formula finally stands thus: — Evolution is an integration of matter and concomitant dissipation of motion; during which the matter passes from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity and during which the retained motion undergoes a parallel transformation.

[Note. Only at the last moment, when this sheet is ready for press and all the rest of the volume is standing in type, so that new matter cannot be introduced without changing the "making up" throughout 150 pages, have I perceived that the above formula should be slightly modified. Hence my only practicable course is to indicate here the alteration to be made, and to set forth the reasons for it in Appendix A.

The definition of Evolution needs qualifying by introduction of the word "relatively" before each of its antithetical clauses. The statement should be that "the matter passes from a relatively indefinite, incoherent homogeneity to a relatively definite, coherent heterogeneity." Already this qualification has been indicated in a note to §116 (page 295 [p.302, 1909]), but, more effectually to exclude misapprehensions, it must be incorporated in the definition. In Appendix A are named the circumstances which led to inadequate recognition of it.]

NOTES