394 THE LAW OF EVOLUTION CONCLUDED. 



before shown (§ 69), the denudation of lands and deposit 

 of new strata, are effected by water in the course of its de- 

 scent to the sea, or during the arrest of those undulations 

 produced on it by winds; and, as before shown, the eleva- 

 tion 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 

 etherial medium is transformed into the motion of gases, 

 thence into the motion of liquids, and thence into the mo- 

 tion 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 combination 

 around it, to a solid form — 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 sen- 

 sible motion, while those rays which have been expended 

 in generating it 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 au- 

 tomatic movements of the viscera, together with the 

 voluntary movements of the limbs and body at large, arise 

 at the expense of certain molecular movements through- 

 out 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 arrest- 

 ed 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 ac- 

 tions in the actions of corporate bodies. While, then, dur- 

 ing Evolution, the escaping motion becomes, by perpetual- 



