CHAP. XIV.] AND ABORTED ORGANS. 373 



when grown up have not a tooth in their heads; or the teeth, 

 which never cut through the gums, in the upper jaws of unborn 

 calves ? 



Rudimentary organs plainly declare their origin and meaning 

 in various ways. There are beetles belonging to closely allied 

 species, or even to the same identical species, which have either 

 full-sized and perfect wings, or mere rudiments of membrane, 

 which not rarely lie under wing-covers firmly soldered together ; 

 and in these cases it is impossible to doubt, that the rudiments 

 represent wings. Rudimentary organs sometimes retain their 

 potentiality: this occasionally occurs with the mammae of male 

 mammals, which have been known to become well developed and 

 to secrete milk. So again in the udders in the genus Bos, there 

 are normally four developed and two rudimentary teats ; but the 

 latter in our domestic cows sometimes become well developed 

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

 rudimentary, and sometimes well -developed in the individuals of 

 the same species. In certain plants having separated sexes 

 Kolreuter found tha by crossing a species, in which the male 

 flowers included a rudiment of a pistil, with an hermaphrodite 

 secies, having 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 tadpoles inside her with ex- 

 'quisitely feathered gills; and when placed in water they swim 

 'about like the tadpoles of the water-newt. Obviously this 

 'aquatic organisation 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 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 Composite, 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 U 



