general effect. Further, the characters themselves, which in early fictions play their respective parts without showing how their minds are modified by one another or by the events, are now presented to us as held together by complex moral relations, and as acting and re-acting upon one another's natures.

§ 115. Evolution then, under its primary aspect, is a change from a less coherent form to a more coherent form, consequent on the dissipation of motion and integration of matter. This is the universal process through which sensible existences, individually and as a whole, pass during the ascending halves of their histories. This proves to be a character displayed equally in those earliest changes which the Universe at large is supposed to have undergone, and in those latest changes which we trace in society and the products of social life. And throughout, the unification proceeds in several ways simultaneously.

Alike during the evolution of the Solar System, of a planet, of an organism, of a nation, there is progressive aggregation of the entire mass. This may be shown by the increasing density of the matter already contained in it; or by the drawing into it of matter that was before separate; or by both. But in any case it implies a loss of relative motion. At the same time, the parts into which the mass has divided, severally consolidate in like manner. We see this in that formation of planets and satellites which has gone on along with the concentration of the nebula out of which the Solar System originated; we see it in the growth of separate organs that advances, pari passu, with the growth of each organism; we see it in that rise of special industrial centres and special masses of population, which is associated with the rise of each society. Always more or less of local integration accompanies the general integration. And then, beyond the increased closeness of juxta-position among the compo

nents of the whole, and among the components of each part, there is increased closeness of combination among the parts, producing mutual dependence of them. Dimly foreshadowed as this mutual dependence is in inorganic existences, both celestial and terrestrial, it becomes distinct in organic and super-organic existences. From the lowest living forms upwards, the degree of development is marked by the degree in which the several parts constitute a cooperative assemblage. The advance from those creatures which live on in each part when cut to pieces, up to those creatures which cannot lose any considerable part without death, nor any inconsiderable part without great constitutional disturbance, is an advance to creatures which, while more integrated in respect to their solidification, are also more integrated as consisting of organs that live for and by each other. The like contrast between undeveloped and developed societies, need not be shown in detail: the ever-increasing co-ordination of parts, is conspicuous to all. And it must suffice just to indicate that the same thing holds true of social products: as, for instance, of Science; which has become highly integrated not only in the sense that each division is made up of mutually-dependent propositions, but in the sense that the several divisions are mutually dependent-cannot carry on their respective investigations without aid from one another.

CHAPTER XV.

THE LAW OF EVOLUTION CONTINUED.

§ 116. Changes great in their amounts and various in their kinds, which accompany those dealt with in the last. chapter, have thus far been wholly ignored-or, if tacitly recognized, have not been avowedly recognized. Integration of each whole has been described as taking place simultaneously with integration of each of the parts into which the whole divides itself. But how comes each whole to divide itself into parts? This is a transformation more remarkable than the passage of the whole from an incoherent to a coherent state; and a formula which says nothing about it omits more than half the phenomena to be formulated.

This larger half of the phenomena we have now to treat. In this chapter we are concerned with those secondary redistributions of matter and motion that go on along with the primary re-distribution. We saw that while in very incoherent aggregates, secondary re-distributions produce but evanescent results, in aggregates that reach and maintain a certain medium state, neither very incoherent nor very coherent, results of a relatively persistent character are produced-structural modifications. And our next inquiry must be-What is the universal expression for these structural modifications?

Already an implied answer has been given by the titleCompound Evolution. Already in distinguishing as simple Evolution, that integration of matter and dissipation of mo

tion which is unaccompanied by secondary re-distributions, it has been tacitly asserted that where secondary re-distributions occur, complexity arises. Obviously if, while there has gone on a transformation of the incoherent into the coherent, there have gone on other transformations, the mass, instead of remaining uniform, must have become multiform. The proposition is an identical one. To say that the primary re-distribution is accompanied by secondary re-distributions, is to say that along with the change from a diffused to a concentrated state, there goes on a change from a homogeneous state to a heterogeneous stato. The components of the mass while they become integrated also become differentiated.*

This, then, is the second aspect under which we have to study Evolution. As, in the last chapter, we contemplated existences of all orders as displaying progressive integration; so, in this chapter, we have to contemplate them as displaying progressive differentiation.

§ 117. A growing variety of structure throughout our Sidereal System, is implied by the contrasts that indicate an aggregative process throughout it. We have nebulæ that are diffused and irregular, and others that are spiral, annular, spherical, &c. We have groups of stars the members of which are scattered, and groups concentrated in all degrees down to closely-packed globular clusters. We have these groups differing in the numbers of their members, from those containing several thousand stars to those con

The terms here used must be understood in relative senses. Since we know of no such thing as absoute diffusion or absolute concentration, the change can never be anything but a change from a more diffused to a less diffused state-from smaller coherence to greater coherence; and, similarly, as no concrete existences present us with absolute simplicity -as nothing is perfectly uniform -as we nowhere find complete homogeneity-the transformation is literally always towards greater complexity, or increased multiformity, or further heterogeneity. This qualification the reader must habitually bear in mind.

taining but two. Among individual stars there are great contrasts, real as well as apparent, of size; and from their unlike colours, as well as from their unlike spectra, numerous contrasts among their physical states are inferable. Beyond which heterogeneities in detail there are general heterogeneities. Nebulæ are abundant in some regions of the heavens, while in others there are only stars. Here the celestial spaces are almost void of objects; and there we see dense aggregations, nebular and stellar together.

The matter of our Solar System during its concentration has become more multiform. The aggregating gaseous spheroid, dissipating its motion, acquiring more marked unlikenesses of density and temperature between interior and exterior, and leaving behind from time to time annular portions of its mass, underwent differentiations that increased in number and degree, until there was evolved the existing organized group of sun, planets, and satellites. The heterogeneity of this is variously displayed. There are the immense contrasts between the sun and the planets, in bulk and in weight; as well as the subordinate contrasts of like kind between one planet and another, and between the planets and their satellites. There is the further contrast between the sun and the planets in respect of temperature; and there is reason to suppose that the planets and satellites differ from one another in their proper heats, as well as in the heats which they receive from the sun. Bearing in mind that they also differ in the inclinations of their orbits, the inclinations of their axes, in their specific gravitics and in their physical constitutions, we see how decided is the complexity wrought in the Solar System by those secondary re-distributions that have accompanied the primary re-distribution.

§ 118. Passing from this hypothetical illustration, which must be taken for what it is worth, without prejudice to the general argument, let us descend to an order of evidence less open to objection.