o,
but afterwards wholly disappear. It is also, I believe, a universal
rule, that a rudimentary part is of greater size in the embryo
relatively to the adjoining parts, 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 rudimentary organs in the adult are often
said to have retained their 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 that most parts and organs are
exquisitely adapted for certain purposes, tells us with equal plainness
that these rudimentary or atrophied organs are imperfect and useless. In
works on natural history, rudimentary organs are generally said to have
been created "for the sake of symmetry," or in order "to complete the
scheme of nature." But this is not an explanation, merely a restatement
of the fact. Nor is it consistent with itself: thus the boa-constrictor
has rudiments of hind limbs and of a pelvis, and if it be said that
these bones have been retained "to complete the scheme of nature," why,
as Professor Weismann asks, have they not been retained by other snakes,
which do not possess even a vestige of these same bones? What would be
thought of an astronomer who maintained that the satellites revolve in
elliptic courses round their planets "for the sake of symmetry," because
the planets thus revolve round the sun? An eminent physiologist accounts
for the presence of rudimentary organs, by supposing that they serve to
excrete matter in excess, or matter injurious to the system; but can we
suppose that the minute papilla, which often represents the pistil in
male flowers, and which is formed of mere cellular tissue, can thus act?
Can we suppose that rudimentary teeth, which are subsequently absorbed,
are beneficial to the rapidly growing embryonic calf by removing
matter so precious as phosphate of lime? When a man's fingers have been
amputated, imperfect nails have been known to appear on the stumps, and
I could as soon believe that these vestiges of nails are developed in
order to excrete horny matter, as that the rudimentary nails on the fin
of the manatee have been developed for this same purpose.

On the view of descent with modification, the origin of rudimentary
organs is comparatively simple; and we can understand to a large extent
the laws