470 RUDIMENTARY, ATROPHIED, 



the case; it is more probably a reduced organ, modified 

 for a new function: the wing of the Apter3^x, on the other 

 liand, is quite useless, and is truly rudimentary. Owen 

 considers the simple filamentary limbs of the Lepidosiren 

 as the "beginnings of organs which attain full functional 

 development in higher vertebrates; " but, according to tlie 

 view lately advocated by Dr. Giinther, they are probably 

 remnants, consisting of the persistent axis of a fin, with 

 the lateral rays or branches aborted. The mammary glands 

 of the Ornithorhynchus may be considered, in comparison 

 with the udders of a cow, as in a nascent condition. The 

 ovigerous frena of certain cirripedes, which have ceased to 

 give attachment to the ova and are feebly developed, are 

 nascent branchiae. 



Rudimentary organs in the individuals of the same 

 species are very liable to vary in the degree of their devel- 

 opment and in other respects. In closely allied s^Decies, 

 also, the extent to which the same organ has been reduced 

 occasionally differs much. This latter fact is well exem- 

 plified in the state of the wings of female 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 occasion- 

 ally 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 rudi- 

 ment 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 

 understand the relations of the parts, more useful than the 

 discovery of rudiments. This is well shown in the draw- 

 ings 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 afterward wholly disappear. 

 It is also, I believe, a universal rule, that a rudimentary 

 part is of greater size in the embryo relatively to the ad- 

 joining parts, than in the adult; so that the organ at this 



