ADAPTATION 191 



IV. OEIGIN OF ADAPTATIONS 



A. The Problem. The question of the ori- 

 gin of the adaptations themselves is much more 

 difficult. If comparatively few or no new adap- 

 tations have arisen in any one neighborhood, 

 nevertheless all these modifications must have 

 arisen somewhere and should be accounted for. 

 Many explanations have been offered. The sup- 

 porters of some of the explanations adhere to 

 them with the fanaticism of religious behef . But 

 it is necessary to have been reared in the faith 

 to see all that is claimed for them. 



Hereditary succession may follow a horizontal 

 line or one that swerves up or down. In other 

 words, successive generations may be alike, in 

 which case the species remain in statu quo, or 

 subsequent generations may deviate from their 

 parents in one or more points. 



All deviations from the horizontal must start 

 in the germ, or must become located in the germ. 

 The question of the origin of adaptive deviations 

 is the question of how and why adaptive ger- 

 minal modifications arise, or how adaptive so- 

 matic modifications are transferred to the germ. 

 In either case it is the question of how the straight 

 line of exact hereditary repetition may be caused 

 to swerve in a definite direction to reach an 

 adaptive point. This is the question of the pres- 

 ent generation, perhaps of the entire twentieth 

 century. 



