SUMMARY OP PHYSIOLOGICAL DEVELOPMENT. 395 



among other parts that are modified, molecularly or other- 

 wise, must be those which cast off the germs of new organ- 

 isms. The molecules of their produced germs must tend 

 ever to conform the motions of their components, and there- 

 fore the arrangements of their components, to the molecular 

 forces of the organism as a whole; and if this aggregate 

 of molecular forces be modified in its distribution by a local 

 change of structure, the molecules of the germs must be 

 gradually changed in the motions and arrangements of their 

 components, until they are re-adjusted to the aggregate of 

 molecular forces. 



