ACQUIRED CHARACTERS 39 



Generations of giraffes have stretched their necks to 

 reach the foliage of trees, and the neck of the giraffe 

 is grown to a prodigious length. The antelope has been 

 accustomed for centuries to flee from beasts of prey, 

 and has developed hi the direction of extreme 

 speed. 



Lamarck's theory of evolution was to the effect that 

 races were developed by the accumulation of the effects 

 of use and disuse. And certainly it seems the obvious 

 explanation of the dwindling of the whale's hind limbs, 

 to say that they have become gradually smaller through 

 disuse, or to say that the neck of the giraffe has become 

 long through its special use, which involves its being 

 stretched continually. 



But we have no proof whatever that these explana- 

 tions are the correct ones. Moreover, it is possible to 

 explain all the instances given above without assuming 

 the inheritance of modifications. According to Darwin's 

 theory of Natural Selection, the giraffe's neck has be- 

 come long because through generations the longer- 

 necked specimens have been able to reach more leaves 

 than their shorter-necked fellows, and consequently 

 have been able to live through times of scarcity while 

 the others starved. The longer-necked specimens have 

 continually been preserved by nature, and the race has 

 become long-necked. 



Similarly, the fleet antelope escapes from the lion, 

 while his slightly more slow-footed brother is caught 

 and eaten, and the race thereby becomes swifter of 

 foot. 



As regards the dwindling of disused members, the ex- 

 planation of the modern Darwinian is perhaps less con- 

 vincing. But Darwin says that the wings of the ostrich, 

 for instance, became useless when the ostrich took to 

 running. Hence those individuals which wasted least 

 food and energy in wing-building had the more for 

 leg-building. They had thus the advantage over their 

 stronger-winged fellows and tended to be preserved. 



Yet in certain cases such an explanation seems un- 

 deniably far-fetched. Take the case of the eyes of cave 



