CHAP. XIV.] AND ABORTED ORGANS. 375 



moths belonging to the same family. Rudimentary organs may 

 be utterly aborted ; and this implies, that in certain animals or 

 plants, parts are entirely absent which analogy would lead us to 

 expect to find in them, and which are occasionally found in 

 monstrous individuals. Thus in most of the Scrophulariacese 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 occasionally 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 under- 

 stand 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 relatively 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 reasoning 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 " to complete the scheme of 

 nature." But this is not an explanation, merely a re-statement 

 of the fact. Nor is it consistent with itself : thus the boa- 

 constrictor has rudiments of hind-limbs and of a pelvis, and if it 

 be said that these bones have been retained "to complete the 

 scheme of nature," why, as Professor Weismann asks, have they 

 not been retained by other snakes, which do not possess even 

 a vestige of these same bones? What would be thought of an 

 astronomer who maintained that the satellites revolve in elliptic 

 courses round their planets " for the sake of symmetry," because 

 the planets thus revolve round the sun ? An eminent physiologist 

 accounts for the presence of rudimentary organs, by supposing 

 that they serve to excrete matter in excess, or matter injurious to 

 the system ; but can we suppose that the minute papilla, which 

 often represents the pistil in male flowers, and which is formed 

 of mere cellular tissue, can thus act? Can we suppose that 



