406 THE ORIGIN OF SPECIES 



and yield milk. In regard to plants, the petals are sometimes rudi- 

 mentary, and sometimes well developed in the individuals of the 

 same species. In certain plants having separated sexes, Kolreuter 

 found that by crossing a species, in which the male flowers in- 

 cluded a rudiment of a pistil, with an hermaphrodite species, hav- 

 ing of course a well-developed pistil, the rudiment in the hybrid 

 offspring was much increased in size; and this clearly shows that 

 the rudimentary and perfect pistils are essentially alike in nature. 

 An animal may possess various parts in a perfect state, and yet 

 they may in one sense be rudimentary, for they are useless: thus 

 the tadpole of the common salamander or water-newt, as Mr. 

 G. H. Lewes remarks, "has gills, and passes its existence in the 

 water; but the Salamandra atra, which lives high up among the 

 mountains, brings forth its young full-formed. This animal never 

 lives in the water. Yet if we open a gravid female, we find tad- 

 poles inside her with exquisitely feathered 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 re- 

 peats a phase in the development of its progenitors." 



An organ, serving for two purposes, may become rudimentary 

 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 to reach the ovules within 

 the ovarium. The pistil consists of a stigma supported on a style; 

 but in some Compositae, the male florets, which of course cannot 

 be fecundated, have a 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 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 de- 

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

 be in a nascent condition, and In progress toward further develop- 

 ment. 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 



