334 THE PRINCIPLES OF HEREDITY 



injured by parental drinking. Notices asking for evidence were inserted 

 in some thirty scientific and other journals. Many letters were received, 

 but no evidence was obtained. 



It is quite indisputable that races adapt themselves to adverse con- 

 ditions, and, short of miracle, no cause for this adaptation is conceivable 

 except Natural Selection. The prevailing medical, or rather alienist 

 belief, then, amounts to this : that during any given epoch injurious 

 influences cause racial deterioration ; but eventually, in some mystical 

 way, this deterioration emerges as racial improvement of an exactly 

 opposite kind. 



