TRAITS NOT TRANSMISSIBLE 99 



can not be entailed ; that is bad news for me. But 

 I see also that actual impiety is not always he- 

 reditary; that is good news for my son." 



The idea that acquired qualities are transmit- 

 ted to succeeding generations lends itself readily 

 to the imagination and passes from one speaker 

 to another to adorn many a theory. It has be- 

 come very current in connection with popular con- 

 ceptions of evolutionary theories to account for 

 the mutations of species in successive generations. 

 It has been oft repeated as a self-evident truth 

 that "the giraffe has attained its long neck by 

 stretching it for many generations; swimming 

 birds have got webbed feet because they stretched 

 their toes in the water ; wading birds have got long 

 legs because they stretched them; the mole has 

 very small eyes because it has ceased to use them ; 

 the whalebone whale has no functional teeth be- 

 cause it has acquired the habit of swallowing its 

 food without mastication." This sounds much 

 like evolution, and evolution is a victorious theory ; 

 therefore this must be taken for granted. Yet 

 it is not believed that the long neck of the giraffe 

 is due to the stretching; but rather that the 

 stretching is due to the long neck. That is, a new 

 species of animals had a start in the leaf-eating 

 direction by the modification of an animal born 

 with a neck longer than usual, from some cause 

 to us untraceable a cause certainly not traceable 

 to the acquirement of its ancestor. The start was 

 not due to environment, but to the selection of ger- 



