in SIMPLE EXPLANATION 161 



position with the five slender bones of a 

 Bat's wing. In that animal they are 

 used as the supporting framework of a 

 flying membrane, and are wholly useless 

 for any purposes of prehension. The 

 digit which we call our thumb, and 

 which in Man has such essential uses 

 that the hand would hardly be a hand 

 without it, is in the Bat not altogether 

 abolished, but is dwarfed and converted 

 into a mere hook by which the creature 

 catches hold of the surfaces to which, 

 when at rest, it clings. The whole 

 vertebrate creation is full of such ex- 

 amples. Rudimentary organs, therefore, 

 are nothing but a natural and harmonious 

 part of a general principle which is 

 applied in different degrees throughout 

 the animal world. The explanation 

 is, in one sense, very simple. It is 

 that the vertebrate skeleton, with all its 



related tissues, has been what Huxley 

 M 



