netrate a
preoccupied mind.

Wallace (222/2. Wallace, "Westminster Review," July, 1867. The
article begins: "There is no more convincing proof of the truth of a
comprehensive theory, than its power of absorbing and finding a place
for new facts, and its capability of interpreting phenomena, which had
been previously looked upon as unaccountable anomalies..." Mr. Wallace
illustrates his statement that "a false theory will never stand this
test," by Edward Forbes' "polarity" speculations (see page 84 of
the present volume) and Macleay's "Circular" and "Quinarian System"
published in his "Horae Entomologicae," 1821, and developed by Swainson
in the natural history volumes of "Lardner's Cabinet Cyclopaedia."
Mr. Wallace says that a "considerable number of well-known naturalists
either spoke approvingly of it, or advocated similar principles, and for
a good many years it was decidedly in the ascendant...yet it quite died
out in a few short years, its very existence is now a matter of history,
and so rapid was its fall that...Swainson, perhaps, lived to be the last
man who believed in it. Such is the course of a false theory. That of
a true one is very different, as may be well seen by the progress of
opinion on the subject of Natural Selection."

Here, (page 3) follows a passage on the overwhelming importance of
Natural Selection, underlined with apparent approval in Mr. Darwin's
copy of the review.), in the "Westminster Review," in an article on
Protection has a good passage, contrasting the success of Natural
Selection and its growth with the comprehension of new classes of facts
(222/3. This rather obscure phrase may be rendered: "its power of growth
by the absorption of new facts."), with false theories, such as the
Quinarian Theory, and that of Polarity, by poor Forbes, both of
which were promulgated with high advantages and the first temporarily
accepted.

LETTER 223. TO G.H. LEWES.

(223/1. The following is printed from a draft letter inscribed by Mr.
Darwin "Against organs having been formed by direct action of medium in
distinct organisms. Chiefly luminous and electric organs and thorns."
The draft is carelessly written, and all but illegible.)

August 7th, 1868.

If you mean that in distinct animals, parts or organs, such for instance
as the luminous organs of insects or the electric organs of fishes, are
wholly the result of the external and internal conditions to which the
organs have been subjected, in