160 BIOLOGY FOR BEGINNERS 



2. Specialization. 



Beginning as single cell. 



Increase in number of cells. 



Separation of functions (division of labor). 



Better performance of functions (specialization). 



Development of fitness for functions (adaptation). 



3. Interdependence. 



1. Advance in development means advance in adaptation. 



2. Advance in adaptation means closer contact with sur- 



roundings. 



3. Both of which mean success in the struggle for existence. 



