108 THE DATA OF BIOLOGY. 



reached the conclusion that a fore 3 falling on any aggregate 

 is divided into several forces; that when the aggregate con- 

 sists of parts that are unlike, each part becomes a centre of 

 unlike differentiations of the incident force; and that thus 

 the multiplicity of such differentiations must increase with 

 the multiplicity of the unlike parts. Consequently organic 

 aggregates, which as a class are distinguished from inorganic 

 aggregates by the greater number of their unlike parts, must 

 be also distinguished from them by the greater number of 

 simultaneous changes they display; and, further, that the 

 higher organic aggregates, having more numerous unlike 

 parts than the lower, must undergo more numerous simul- 

 taneous changes. We next found that the changes 

 occurring in living bodies are contrasted with those occurring 

 in other bodies, as being much more heterogeneous; and that 

 the changes occurring in the superior living bodies are 

 similarly contrasted with those occurring in inferior ones. 

 Well, heterogeneity of function is the correlate of hetero- 

 geneity of structure; and heterogeneity of structure is the 

 leading distinction between organic and inorganic aggre- 

 gates, as well as between the more highly organized and the 

 more lowly organized. By reaction, an incident force must 

 be rendered multiform in proportion to the multiformity of 

 the aggregate on which it falls ; and hence those most multi- 

 form aggregates which display in the highest degree the 

 phenomena of Evolution structurally considered, must also 

 display in the highest degree the multiform actions which 

 constitute Evolution functionally considered. These 

 heterogeneous changes, exhibited simultaneously and in suc- 

 cession by a living organism, prove, on further inquiry, to be 

 distinguished by their combination from certain non-vital 

 changes which simulate them. Here, too, the parallelism is 

 maintained. It was shown in Fii^st Principles, Chap. XIY, 

 that an essential characteristic of Evolution is the integration 

 of parts, which accompanies their differentiation — an integra- 

 tion shown both in the consolidation of each part, and in the 



