Chap. XIV.] AND ABORTED ORGANS. 259 



analogy would lead us to expect to find in them, and 

 which are occasionally found in monstrous individuals. 

 Thus in most of the Scrophulariaceae the fifth stamen 

 is utterly aborted; yet we may conclude that a fifth 

 stamen once existed, for a rudiment of it is found in 

 many species of the family, and this rudiment occasion- 

 ally becomes perfectly developed, as may sometimes 

 be seen in the common snap-dragon. In tracing the 

 homologies of any part in different members of the same 

 class, nothing is more common, or, in order fully to UU' 

 derstand the relations of the parts, more useful than 

 the discovery of rudiments. This is well shown in the 

 drawings given by Owen of the leg-bones of the horse, 

 ox, and rhinoceros. • 



It is an important fact that rudimentary organs, such 

 as teeth in the upper jaws of whales and ruminants, can 

 often be detected in the embryo, but afterwards wholly 

 disappear. It is also, I believe, a universal rule, that 

 a rudimentary part is of greater size in the embryo rela- 

 tively to the adjoining parts, than in the adult; so that 

 the organ at this early age is less rudimentary, or even 

 cannot be said to be in any degree rudimentary. Hence 

 rudimentary organs in the adult are often said to have 

 retained their embryonic condition. 



I have now given the leading facts with respect to 

 rudimentary organs. In reflecting on them, every one 

 must be struck with astonishment; for the same reason- 

 ing power which tells us that most parts and organs are 

 exquisitely adapted for certain purposes, tells us with 

 equal plainness that these rudimentary or atrophied 

 organs are imperfect and useless. In works on natural 

 history, rudimentary organs are generally said to have 

 been created "for the sake of symmetry," or in order 

 42 



