ii ON ANIMAL LIFE 45 



RUDIMENTARY ORGANS 



Such modifications may be called adaptive, 

 but there are others of a different origin 

 that have reference to the changes which 

 the race has passed through in bygone ages. 

 In fact the great majority of animals do go 

 through metamorphoses (many of them as 

 remarkable, though not so familiar as those 

 of insects), but in many cases they are passed 

 through within the egg and thus escape 

 popular observation. Naturalists who accept 

 the theory of evolution, consider that the 

 development of each individual represents to 

 a certain extent that which the species has 

 itself gone through in the lapse of ages ; that 

 every individual contains within itself, so to 

 say, a history of the race. Thus the rudi- 

 mentary teeth of Cows, Sheep, Whales, etc. 

 (which never emerge from their sockets), the 

 rudimentary toes of many mammals, the hind 

 legs of Whales and of the Boa-constrictor, 

 which are imbedded in the flesh, the rudi- 

 mentary collar-bone of the Dog, etc., are in- 



