440 RUDIMENTARY, ATROPHIED, 



full-formed. This animal never lives in the water. Yet if 

 we open a gravid female, we find tadpoles inside her with 

 exquisitely leathered gills ; and when placed in water they 

 swim about like the tadpoles of the water-newt. Obviously 

 this aquatic organization has no reference to the future life 

 of the animal, nor has it any adaptation to its embryonic 

 condition ; it has solely reference to ancestral adaptations, it 

 repeats a phase in the development of its progenitors." 



An organ, serving for two purposes, may become rudi- 

 mentary or utterly aborted for one, even the more important 

 purpose, and remain perfectly efficient for the other. Thus, 

 in plants, the office of the pistil is to allow the pollen tubes 

 %o reach the ovules within the ovarium. The pistil consists 

 of a stigma supported on a style ; but in some Compositae, 

 ^he male rlorets, which of course cannot be fecundated, have 

 r\ rudimentary pistil, for it is not crowned with a stigma; 

 but the style remains well developed and is clothed in the 

 usual manner with hairs, which serve to 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 

 seoms to be rudimentary for its proper function of giving 

 buoyancy, but has become converted into a nascent beathing 

 organ or lung. Many similar instances could be given. 



Tjcefu 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 rudi- 

 mentary. Th6y may be in a nascent condition, and in pro- 

 gress toward further development. Rudimentary 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 modifications. They have been partially retained by 

 the power of inheritance, 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 



