EVIDENCES OF EVOLUTION. 113 



scendant, according to the Evolution theory, of some 

 mammoth terrestrial quadruped of which no trace 

 has as yet been discovered. 



Rudimentary Organs. 



It were easy to multiply indefinitely examples 

 of such rudimentary organs as those exhibited by 

 the cetacea. We see them in the tails of birds, in 

 the gill-arches of reptiles, in the dew-claws of a dog's 

 foot, in the splint-bones of the horse, and in the 

 wings of the ostrich and apteryx. Indeed, there is 

 not a single representative of the higher forms of 

 animal life, which does not exhibit one or more 

 parts in an atrophied or rudimentary condition. 



But what is the significance of such aborted and 

 useless organs? What is their origin, and can any 

 reason be assigned for the existence of such func- 

 tionless parts? The only natural explanation which 

 can be offered, the only rational solution of the 

 difficulty which science can give, is that suggested by 

 the theory of Evolution. According to the theory 

 of descent with adaptive modification, rudimentary 

 organs are remnants of "some generalized primal 

 form," in which they were useful, and had a definite 

 function to perform. By reason of changed condi- 

 tions of life of the individual, and corresponding dis- 

 use of certain parts, great modifications in size and 

 form and function ensued, and thus what was useful 

 and necessary in the ancestral form ceased to be of 

 value in its successor. 



" Rudimentary organs," then, to quote from Dar- 

 win, " by whatever steps they may have been 



