d wings, and another mere rudiments of membrane; and here it is
impossible to doubt, that the {451} rudiments represent wings. Rudimentary
organs sometimes retain their potentiality, and are merely not developed:
this seems to be the case with the mammae of male mammals, for many
instances are on record of these organs having become well developed in
full-grown males, and having secreted milk. So again there are normally
four developed and two rudimentary teats in the udders of the genus Bos,
but in our domestic cows the two sometimes become developed and give milk.
In plants of the same species the petals sometimes occur as mere rudiments,
and sometimes in a well-developed state. In plants with separated sexes,
the male flowers often have a rudiment of a pistil; and Koelreuter found
that by crossing such male plants with an hermaphrodite species, the
rudiment of the pistil in the hybrid offspring was much increased in size;
and this shows that the rudiment and the perfect pistil are essentially
alike in nature.

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 protected in the ovarium at its
base. The pistil consists of a stigma supported on the style; but in some
Compositae, the male florets, which of course cannot be fecundated, have a
pistil, which is in a rudimentary state, for it is not crowned with a
stigma; but the style remains well developed, and is clothed with hairs as
in other compositae, for the purpose of brushing the pollen out of the
surrounding anthers. Again, an organ may become rudimentary for its proper
purpose, and be used for a distinct object: in certain fish the
swim-bladder seems to be nearly rudimentary for its proper function of
giving buoyancy, but has become converted into a {452} nascent breathing
organ or lung. Other similar instances could be given.

Organs, however little developed, if of use, should not be called
rudimentary; they cannot properly be said to be in an atrophied condition;
they may be called nascent, and may hereafter be developed to any extent by
natural selection. Rudimentary organs, on the other hand, are essentially
useless, as teeth which never cut through the gums; in a still less
developed condition, they would be of still less use. They cannot,
therefore, under