THE LAW OF EVOLUTION 



anticipated the essential portion of Mr. Spen- 

 cer's discovery, Von Baer's formula stands in 

 much the same relation to it in which the spec- 

 ulations of Copernicus stood with reference to 

 the discovery of Newton. Just as Copernicus 

 w r as essentially in error in maintaining that the 

 planets revolve in circular orbits, Von Baer was 

 essentially in error in considering the process 

 of differentiation as the fundamental charac- 

 teristic of evolution, as well as in ignoring the 

 process of integration. The whole foregoing 

 exposition has shown, and the entire remainder 

 of the exposition will still further convince us, 

 that the fundamental characteristic of evolution 

 is integration of matter with dissipation of in- 

 ternal motion ; and that the change from homo- 

 geneity to heterogeneity is but the secondary 

 rearrangement which results wherever the re- 

 tained motion is great enough to allow it. 



Still more, in ignoring the process of integra- 

 tion, Von Baer failed to include in his formula 

 that change from indefiniteness and incoherence 

 to definiteness and coherence, which is equally 

 important with the change from homogene- 

 ity to heterogeneity. In the evolution of an 

 organic germ, integration is just as essential a 

 part of the whole process as differentiation. If 

 the latter were alone to take place, the result 

 would simply be a chaotic medley of organs 

 and tissues. Both operations are requisite to 

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