EVOLUTION BY HYBRIDIZATION 565 



Astronomy and Geology this idea of a dynamic universe finds little 

 opposition. In the biological sciences the conclusions are more 

 recent and less widely acknowledged. Organic evolution is regarded 

 by biologists as established, because it explains, in a reasonable 

 manner, innumerable facts that have no other scientific explana- 

 tion. The course and causes of organic evolution are less certain 

 than those of the inorganic evolution described in Geology, but 

 organic evolution as the historic fact seems attested by overwhelm- 

 ing evidence. 



