CHAPTER XII. 



THE DIRECTION OP DEVELOPMENT. 



Highest A S we have already seen, all development is from the 



mTnt?'' "^ simple to the complex : all organisms have their origin 



greatest, in perfectly simple germs, and their development goes on 



plS'ity to constantly increasing complexity. -Consequently, the 



highest development is the greatest complexity; the highest 



organisms are those of most complex structure. 



and But when we say that the most complex organisms are the 



distiiTct- iiiost highly organized, we do not mean that high organiza- 



ness of tion consists in mere mtdtitude of parts. The multitude of 



parts. leaves on a tree is no mark of high organization. What 



constitutes high organization is not multitude of similar 



parts, but, what is quite different, distinctness of dissimilar 



parts. In man, or any other of the highest organisms, 



there are no two parts exactly alike, except those which 



correspond with each other on the opposite sides of the 



body. 



In the chapter on the Dynamics of Life it has been 

 stated that all organisms are constantly acquiring matter 

 by assimilation, and parting with it by waste ; and that 

 they are also constantly storing energy, and parting with it 

 again — transforming it, usually, into either motion or heat : 

 and, moreover, all organisms propagate their kind, whether 

 by spontaneous division into parts, or in some other less 

 simple manner. All organisms whatever, consequently, 

 even those which are so simple as to be without structure, 

 have a considerable complication of functions : and pro- 

 gressive organic development consists in the fitting of 



