CONTROL OF HEREDITY: EUGENICS 395 



probably arise as new combinations of factors 

 or parts of factors previously present. In short 

 as modern science regards all types of organ- 

 isms as having evolved by the transformation 

 of previously existing organisms, so it must re- 

 gard all types of hereditary factors as hav- 

 ing existed from the beginning or as having 

 evolved by transformations of preexisting fac- 

 tors; as it regards all types of chemical com- 

 pounds as having arisen by various combina- 

 tions of chemical elements, so it must regard 

 all "new" elements as having existed from the 

 beginning or as having evolved by the associa- 

 tion or dissociation of still smaller particles, the 

 negative and positive electrons. Nowhere in 

 the entire process is there any evidence that 

 factors or elements or electrons are created de 

 novo. The whole process is one of evolution, 

 that is of new combinations of existing units, 

 having new qualities which are the result of 

 these new combinations. 



If these changes in the germ plasm may be 

 induced by extrinsic conditions, then a real 

 experimental evolution will be possible ; if they 

 cannot be so induced but are like the changes 



