The Original Home of Life 1 1 



(p. 502) that "such a trend of evolutionary progress does away 

 entirely with a marine ancestry at any stage in the process." Cham- 

 berlain dC Salisbury (1905) also believe that the first life consisted 

 of plants and animals in "land waters" and that the latter "spread 

 thence to the sea and out upon the land." Gilsen (1947) believes 

 that animals originally invaded land from brackish or fresh-water 

 coasts. Carl Hubbs in a letter says, "changing environment as a 

 stimulus to evolution favors the view that most evolution took 

 place in fresh water." 



The geologic history of the earth and paleontologic history of 

 plants and animals show that climatic changes have been rhythmical. 

 Plants preceded animals on land (Case, 1919) and furnished basic 

 food supplies. Land plants appear to have come from green algae 

 (Bower, 1929) , probably by direct migration from the ocean 

 (Church, 1919, 1921, 1926). At first algae were probably pelagic, 

 then sessile, and finally terrestrial. The reproductive organs of 

 specialized plants did not come from those of bryophytes but from 

 algae (Church, 1926). Pollen permitted fertilization out of water 

 (Bower, 1929; Campbell, 1930) , and seeds furnished nutritious, 

 concentrated food (Berry, 1920). At the beginnings and ends of 

 epochs there were striking changes in climate which preceded 

 marked readjustments and evolutionary changes in animals. Defor- 

 mation of the earth's crust, volcanic dust, and variations in the 

 amount of carbon dioxide in the atmosphere were important factors 

 in producing climatic changes (Case, 1919). A monotonous envi- 

 ronment may permit many individuals to exist but limits the num- 

 ber of types; whereas a changing environment is associated with 

 variety and the evolution of new types (Clark, 1925) . "Nothing is 

 better established, amidst all the confusion of the discussions as to 

 method of evolution, than the fact that the environment changes 

 before changes appear in organic forms" (Case, 1926) . On the 

 other hand some animals are preadapted for certain new habitats 



