258 KUDIMENTABY, ATKOPHIED, [Chap. XIV. 



for we can judge only by analogy whether a part is 

 capable of further development, in which case alone it 

 deserves to be called nascent. Organs in this condition 

 will always be somewhat rare ; for beings thus provided 

 will commonly have been supplanted by their successors 

 with the same organ in a more perfect state, and conse- 

 quently will have become long ago extinct. The wing 

 of the penguin is of high service, acting as a fin; it 

 may, therefore, represent the nascent state of the wing : 

 not that I believe this to be the case ; it is more pro- 

 bably a reduced organ, modified for a new function : the 

 wing of the Apteryx, on the other hand, 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 the 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 adders 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 branchia}. 



Rudimentary organs in the individuals of the same 

 species are very liable to vary in the degree of their 

 development and in other respects. In closely allied 

 species, also, the extent to which the same organ has 

 been reduced occasionally differs much. This latter fact 

 is well exemplified 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 



