112 THE STRUCTURE OF EVOLUTIONARY THEORY
from the oddities and imperfections of modern objects. (This arrangement of the
last part struck me with particular force, as I reread the Origin before writing this
book, and realized that the introductory paragraph for almost every new subject—
from geographic variation to rudimentary organs—explicitly restates the general
argument for method four.) Of course, the rest of the Origin also abounds with
cases of method four, beginning as usual with examples from domestication.
(Darwin argues that the chicks of wildfowl hide in grass and bushes to give their
mother an opportunity for escape by flight. Domesticated chickens retain this habit,
which no longer makes sense "for the mother-hen has almost lost by disuse the
power of flight"—p. 216.)
Of subjects treated in this final part of the Origin's trilogy, rudimentary or-
gans represent, almost by definition, the "holotype" of method four. Darwin's
definition, in the first sentence of his discussion, emphasizes this theme— "organs
or parts in this strange condition, bearing the stamp of inutility" (p. 450). Nature
tries to give us a history lesson, Darwin argues in some frustration, but we resist
the message as inconsistent with received wisdom about natural harmony: "On the
view of each organic being and each separate organ having been specially created,
how utterly inexplicable it is that parts, like the teeth in the embryonic calf or like
the shrivelled wings under the soldered wing-covers of some beetles, should thus
so frequently bear the plain stamp of inutility! Nature may be said to have taken
pains to reveal, by rudimentary organs and by homologous structures, her scheme
of modification, which it seems that we wilfully will not understand" (p. 480).
What else but imprints of history can explain rudimentary organs? Darwin
ridicules the special pleading of creationist accounts as fancy ways of saying
nothing at all. "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 seems to me no explanation, merely a restatement of the fact.
Would it be thought sufficient to say that because planets revolve in elliptic
courses round the sun, satellites follow the same course round the planets, for the
sake of symmetry, and to complete the scheme of nature?" (p. 453). Always
searching for analogies with a short-term human history that we cannot deny,
Darwin compares rudimentary organs with silent letters, once sounded, in the
orthography of words: "Rudimentary organs may be compared with the letters in a
word, still retained in the spelling, but become useless in the pronunciation, but
which serve as a clue in seeking for its derivation" (p. 455).
Darwin continues the same argument as an underpinning for all discussions
on other aspects of organic form. He introduces morphology as "the most
interesting department of natural history, [which] may be said to be its very soul"
(p. 434) and continues immediately with an example of method four: "What can be
more curious than that the hand of a man, formed for grasping, that of a mole for
digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat,
should all be constructed on the same pattern, and should include the same bones,
in the same relative positions" (p. 434).
Similarly, the section on embryology begins with an example of method