46 A Century of Science 



that is most striking and suggestive. But in 

 studying the inorganic world Mr. Spencer was led 

 to modify . his formula in a way that vastly in- 

 creased its scope. He came to see that the primary 

 feature of evolution is an integration of matter 

 and concomitant dissipation of motion. According 

 to circumstances, this process may or not be at- 

 tended with extensive internal rearrangements and 

 development of organization. The continuous in- 

 ternal rearrangement implied in the development 

 of organization is possible only where there is a 

 medium degree of mobility among the particles, a 

 plasticity such as is secured only by those peculiar 

 chemical combinations which make up what we call 

 organic matter. In the inorganic world, where 

 there is an approach to organization there is an 

 adumbration of the law as realized in the organic 

 world. But in the former, what strikes us most 

 is the concentration of the mass with the reten- 

 tion of but little internal mobility ; in the latter, 

 what strikes us most is the wonderful complication 

 of the transformations wrought by the immense 

 amount of internal mobility retained. These 

 transformations are to us the mark, the distinguish- 

 ing feature, of life. 



Having thus got the nature of the differences 

 between the organic and inorganic worlds into a 



