Chap. XIV. Rudimentary Organs. 397 



Rudimentary ', Atrophied, and Aborted Organs. 



Organs or parts in this strange condition, bearing the plain stamp 

 of inutility, are extremely common, or even general, throughout 

 nature. It would be impossible to name one of the higher animals 

 in which some part or other is not in a rudimentary condition. In 

 the mammalia, for instance, the males possess rudimentary mamma? ; 

 in snakes one lobe of the lungs is rudimentary; in birds the 

 " bastard-wing " may safely be considered as a rudimentary digit, 

 and in some species the whole wing is so far rudimentary that it 

 cannot be used for flight. What can be more curious than the 

 presence of teeth in fetal whales, which 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 oc- 

 casionally occurs with the mamma? 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 deve- 

 loped 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 that by crossing a species, in 

 which the male flowers included a rudiment of a pistil, with an 

 hermaphrodite species, 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 es- 

 sentially 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 exquisitely feathered 

 " gills ; and when placed in water they swim about like the tad- 

 " poles of the water-newt. Obviously this aquatic organisation has 



