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
composit , 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 rudimentary for its proper function of giving
buoyancy, but has become converted into a nascent breathing organ or
lung. Other similar instances could be given.
Rudimentary organs in the individuals of the same species are very
liable to vary in degree of development and in other respects.
Moreover, in closely allied species, the degree to which the same organ
has been rendered rudimentary occasionally differs much. This latter
fact is well exemplified in the state of the wings of the female moths
in certain groups. Rudimentary organs may be utterly aborted; and this
implies, that we find in an animal or plant no trace of an organ, which
analogy would lead us to expect to find, and which is occasionally
found in monstrous individuals of the species. Thus in the snapdragon
(antirrhinum) we generally do not find a rudiment of a fifth stamen;
but this may sometimes be seen. In tracing the homologies of the same
part in different members of a class, nothing is more common, or more
necessary, than the use and discovery of rudiments. This is well shown
in the drawings given by Owen of the bones of the leg of the horse, ox,
and rhinoceros.
It is an important fact that rudimentary organs, such as teeth in the
upper jaws of whales and ruminants, can often be detected in the
embryo, but afterwards wholly disappear. It is also, I believe, a
universal
rule, that a rudimentary part or organ is of greater size relatively to
the adjoining parts in the embryo, than in the adult; so that the organ
at this early age is less rudimentary, or even cannot be said to be in
any degree rudimentary. Hence, also, a rudimentary organ in the adult,
is often said to have retained its embryonic condition.
I have now given the leading facts with respect to rudimentary organs.
In reflecting on them, every one must be struck with astonishment: for
the same reasoning power which tells us plainly that most parts and
organs are exquisitely adapted for certain purposes, tells us with
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