374 RUDIMENTARY, ATROPHIED, [CHAP. XIV 



brush the pollen out of the surrounding and conjoined anthers. 

 Again, an organ may become rudimentary for its proper purpose, 

 and be used for a distinct one : in certain fishes the swim-bladder 

 seems to be rudimentary for its proper function of giving 

 buoyancy, but has become converted into a nascent breathing 

 organ or lung. Many similar instances could be given. 



Useful organs, however little they may be developed, unless we 

 have reason to suppose that they were formerly more highly 

 developed, ought not to be considered as rudimentary. They may 

 be in a nascent condition, and in progress towards further develop- 

 ment. Kudimentary organs, on the other hand, are either quite 

 useless, such as teeth which never cut through the gums, or almost 

 useless, such as the wings of an ostrich, which serve merely as 

 sails. As organs in this condition would formerly, when still less 

 developed, have been of even less use than at present, they cannot 

 formerly have been produced through variation and natural 

 selection, which acts solely by the preservation of useful modifica- 

 tions. They have been partially retained by the power of inheri- 

 tance, and relate to a former state of things. It is, however, often 

 difficult to distinguish between rudimentary and nascent organs ; 

 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 

 consequently 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 probably 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 Omithorhynchus 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 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 



