THE INSTABILITY OF THE HOMOGENEOUS. 441 



upon it. The resultant force exercised by the aggregate on 

 each unit, being in no two cases alike in both amount and 

 direction, and usually not in either, any incident force, even 

 if uniform in amount and direction, cannot produce like ef- 

 fects on the units. And the various positions of the parts in 

 relation to any incident force, preventing them from receiv- 

 ing it in uniform amounts and directions, a further differ- 

 ence in the effects wrought on them is inevitably produced. 

 One further remark is needed. To the conclusion that 

 the changes with which Evolution commences, are thus ne- 

 cessitated, remains to be added the conclusion that these 

 changes must continue. The absolutely homogeneous must 

 lose its equilibrium; and the relatively homogeneous must 

 lapse into the relatively less homogeneous. That which 

 is true of any total mass, is true of the parts into which 

 it segregates. The uniformity of each such part must as 

 inevitably be lost in multiformity, as was that of the orig- 

 inal whole; and for like reasons. And thus the continued 

 changes which characterize Evolution, in so far as they are 

 constituted by the lapse of the homogeneous into the hetero- 

 geneous, and of the less heterogeneous into the more hetero- 

 geneous, are necessary consequences of the persistence of 

 force. 



30 



