EVOLUTION 503 



plication has been two-fold: (i) simple individuals, 

 whether mountains, rivers, planets, animals, or plants, have 

 become more complex {e.g., compare the structure of 

 Pleurococcus, a simple spherical cell, with that of the fern) ; 

 (2) the relation between living things, and between them 

 and their surroundings has become more complex {e.g., 

 compare a unicellular bacterium, with its relatively simple 

 life relations, with the clover plant, highly organized, 

 and related to water, air, soil, light, temperature, gravity, 

 bacteria (in its roots), and insects (for cross-pollination). 



Most of the steps of evolution have been progressive, 

 toward higher organization, greater perfection of parts, 

 increased efficiency of function, as, for example, from algae 

 to angiosperms; but not all the steps have been in 

 this direction. Some of the steps have been regressive, 

 toward simpler organization, less perfection of parts, 

 decreased efficiency of function, as, for example, from 

 green algae to the alga-like fungi (Phy comycetes) , from 

 independence to parasitism (dodder), or to saprophytism 

 (Indian pipe and bread-mold). 



436. Inorganic Evolution. — The process of evolution is 

 not confined to living things, but, as indicated above, 

 applies to all nature. Even the chemical elements are 

 now believed to have been produced by evolutionary 

 changes, and to be even now in process of evolution. This 

 is one of the results of the recently discovered phenomenon 

 of radioactivity, which is essentially the transformation 

 of the atoms of one chemical element into those of another. 

 Fossil remains of marine animals and plants, found im- 

 bedded in the rocks on mountain summits, indicate, 

 without possibility of reasonable doubt, that what is now 

 mountain top was formerly ocean bottom. The mountain 



