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 transformationswhich all things undergo during the ascending phases of their existence,we have contemplated under three aspects; and by uniting these three aspectsas 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, neglectingthe accompanying redistribution of Motion. Distinct or tacit reference has,indeed, repeatedly been made to the dissipation of Motion, that goes on alongwith the concentration of Matter; and were all Evolution absolutely simple,the total fact would be contained in the proposition that as Motion dissipatesMatter concentrates. But while we have recognized the ultimate re-distributionof the Motion, we have passed over its proximate re-distribution. Thoughsomething has from time to time been said about the escaping motion, nothinghas been said about the motion which does not escape. In proportion as Evolutionbecomes compound -- in proportion as an aggregate retains, for a considerabletime, such quantity of motion as permits secondary re-distributions of itscomponent matter, there necessarily arise secondary redistributions of itsretained motion. As fast as the parts are transformed, there goes on a transformationof the sensible or insensible motions possessed by the parts. They cannotbecome more integrated, either individually or as a combination, withouttheir motions, individual or combined, becoming more integrated. There cannotarise among them heterogeneities of size, of form, of quality, without therealso arising heterogeneities in the amounts and directions of their motions,or the motions of their molecules. And increasing definiteness of the partsimplies increasing definiteness of their motions. In short, the rhythmicalactions going on in each aggregate, must differentiate and integrate at thesame time that the structures do so. §139a. The general theory of this re-distribution of the retainedmotion, must here be briefly stated. Properly to supplement our conceptionof Evolution under its material aspect by a conception of Evolution underits dynamical aspect, we have to recognize the source of the integrated motionsthat arise, and to see how their increased multiformity and definitenessare 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 uncancelledmotions of their once dispersed components. Along with the molecular motionseverywhere active, there were molar motions of those vast streams of nebulousmatter which were generated during the process of concentration -- molarmotions of which large portions were gradually dissipated as heat, leavingundissipated portions. But since the molar motions of these nebulous streamswere constituted from the motions of multitudinous incoherent gaseous partsseverally moving more or less independently it follows that when aggregationinto a liquid and finally solid celestial mass was reached, these partiallyindependent motions of the incoherent parts became merged into the motionof the whole: or, in other words, unintegrated motions became an integratedmotion.
While we must leave in the shape of hypothesis the belief that the celestialmotions have thus originated, we may see, as a matter of fact, that the integrationof insensible motions originates all sensible motions on the Earth's surface.
As all know, the denudation of lands and deposit of new strata, are effectedby water while descending to the sea, or during the arrest of those undullationsproduced on it by winds; and, as before said, the elevation of water to theheight whence it fell, is due to solar heat, as is also the genesis of thoseaerial currents which drift it about when evaporated and agitate its surfacewhen condensed. That is to say, the molecular motion of the ethereal mediumis 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 amountof molecular motion is lost and an equivalent motion of masses gained. Itis the same with organic movements. Certain rays issuing from the Sun, enablethe plant to reduce special elements existing in gaseous combinations aroundit, to solid forms -- enable the plant, that is, to grow and carry on itsfunctional changes. And since growth, equally with circulation of sap, isa mode of sensible motion, while those rays which have been expended in generatingboth consist of insensible motions, we have here, too a transformation ofthe kind alleged Animals, derived as their forces are, directly or indirectly,from plants, carry this transformation a step further. The automatic movementsof the viscera, together with the voluntary movements of the limbs and bodyat large, arise at the expense of certain molecular movements throughoutthe nervous and muscular tissues; and these originally arose at the expenseof certain other molecular movements propagated by the Sun to the Earth;so that both the structural and functional motions which organic Evolutiondisplays, are motions of aggregates generated by the arrested motions ofunits. Even with the aggregates of these aggregates the same rule holds.
