This order of precedence in time in some of these cases is
believed to hold good; but I think our evidence is so exceedingly
incomplete regarding the number and kinds of organisms which have
existed during all, especially the earlier, periods of the earth's
history, that I should put no stress on this accordance, even if it held
truer than it probably does in our present state of knowledge.

{485} _Origin_, Ed. i. p. 449, vi. p. 618.

CHAPTER IX

ABORTIVE OR RUDIMENTARY ORGANS

_The abortive organs of naturalists._

Parts of structure are said to be "abortive," or when in a still lower
state of development "rudimentary{486}," when the same reasoning power,
which convinces us that in some cases similar parts are beautifully
adapted to certain ends, declares that in others they are absolutely
useless. Thus the rhinoceros, the whale{487}, etc., have, when young,
small but properly formed teeth, which never protrude from the jaws;
certain bones, and even the entire extremities are represented by mere
little cylinders or points of bone, often soldered to other bones: many
beetles have exceedingly minute but regularly formed wings lying under
their wing-cases{488}, which latter are united never to be opened: many
plants have, instead of stamens, mere filaments or little knobs; petals
are reduced to scales, and whole flowers to buds, which (as in the
feather hyacinth) never expand. Similar instances are almost
innumerable, and are justly considered wonderful: probably not one
organic being exists in which some part does not bear the stamp of
inutility; for what can be clearer{489}, as far as our reasoning powers
can reach, than that teeth are for eating, extremities for locomotion,
wings for flight, stamens and the entire flower for reproduction; yet
for these clear ends the parts in question are manifestly unfit.
Abortive organs are often said to be mere representatives (a
metaphorical expression) of similar parts in other organic beings; but
in some cases they are more than representatives, for they seem to be
the actual organ not fully grown or developed; thus the existence of
mammae in the male vertebrata is one of the oftenest adduced cases of
abortion; but we know that these organs in man (and in the bull) have
performed their proper function and secreted milk: the cow has normally
four mammae and two abortive ones, but these latter in some instances are
largely developed and even (??) give milk{490}.