84 THE BEGINNINGS OF LIFE. 



how these re-distributions of Matter and Motion which 

 constitute Evolution, structural and functional, imply 

 motions in the units that are redistributed ; we shall 

 see a probable meaning in the fact that organic bodies 

 which exhibit the phenomena of Evolution in so high 

 a degree, are mainly composed of ultimate units having 

 extreme mobility.' When such mobile units enter 

 into various combinations, this initial property though 

 masked is still potentially present, and must have its 

 influence upon the molecular mobility of the com- 

 pounds into which they enter. Hence Mr. Spencer 

 adds, c We may infer some relation between the gaseous 

 form of three out of the four chief organic elements, 

 and that comparative readiness to undergo those changes 

 in the arrangement of parts which we call development, 

 and those transformations of motion which we call 



function One more fact that is here of great 



interest for us must be set down. These four elements 

 of which organisms are almost wholly composed, pre- 

 sent us with certain extreme antitheses. While be- 

 tween two of them we have an unsurpassed contrast 

 in chemical activity; between one of them and the 

 other three we have an unsurpassed contrast in mole- 

 cular mobility. While carbon by successfully resisting 

 fusion and volatilization at the highest temperatures 

 that can be produced, shows us a degree of atomic 

 cohesion greater than that of any other known element, 



the succeeding chapters of Mr. Spencer's work should be read by all 

 who wish fully to understand this part of the subject. 



