62 WHAT EVOLUTION IS 



the evidence in favor of evolution 

 seemed persuasive, that which can be 

 brought forward now would have been 

 overpowering. It is this strength of 

 the modern position that has placed 

 every biologist of any standing what- 

 soever on the side of evolution. In 

 other w^ords, practically all biologists 

 to-day accept without any reserva- 

 tions descent with modification as a 

 process of nature. They no longer 

 question this view. This statement 

 cannot be emphasized too strongly. 



At the same time that these biolo- 

 gists accept descent with modification 

 as an actual occurrence in nature, they 

 are most skeptical and reserved about 

 what may be called the driving force 

 behind descent. What is there in 

 nature that has kept in motion this 

 incredible capacity to produce new 

 species? How is it that from age to 

 age large and ever larger floods of 



