So ARE THE EFFECTS OF USE INHERITED ? 



holds that " natural selection is continually trying 

 to economize every part of the organization/' 

 He says : " If under changed conditions of life 

 a structure, before useful, becomes less useful, its 

 diminution will be favoured, for it will profit the 

 individual not to have its nutriment wasted in 

 building up an useless structure. . . . Thus, as I 

 believe, natural selection will tend in the long 

 run to reduce any 'part of the organization, as 

 soon as it becomes, through changed habits, 

 superfluous." 1 If, as Darwin powerfully urges 

 (and he here ignores his usual explanation), 

 ostriches' wings are insufficient for flight in con- 

 sequence of the economy enforced by natural 

 selection, 2 why may not the reduced wings 

 of the dodo, or the penguin^cr the apteryx, or of 

 the Cursores generally, be wholly attributed to 

 natural selection in favour of economy of material 

 and adaptation of parts to changed conditions ? 



1 Origin of Species, pp. 117, n 8. 2 Ibid. p. 180. 



