mparison which gave rise to the passage in the
"Descent of Man" (see Letter 130).)

You know the oak-leaved variety of the common honeysuckle; I could not
persuade a lady that this was not the result of the honeysuckle climbing
up a young oak tree! Is this not like the Viola case?

LETTER 244. TO JOHN LUBBOCK (LORD AVEBURY). Haredene, Albury, Guildford,
August 12th [1871].

I hope the proof-sheets having been sent here will not inconvenience
you. I have read them with infinite satisfaction, and the whole
discussion strikes me as admirable. I have no books here, and wish much
I could see a plate of Campodea. (244/1. "On the Origin of Insects." By
Sir John Lubbock, Bart. "Journ. Linn. Soc. (Zoology)," Volume XI., 1873,
pages 422-6. (Read November 2nd, 1871.) In the concluding paragraph the
author writes, "If these views are correct the genus Campodea [a beetle]
must be regarded as a form of remarkable interest, since it is the
living representative of a primaeval type from which not only the
Collembola and Thysanura, but the other great orders of insects, have
all derived their origin." (See also "Brit. Assoc. Report," 1872, page
125--Address by Sir John Lubbock; and for a figure of Campodea see
"Nature," Volume VII., 1873, page 447.) I never reflected much on the
difficulty which you indicate, and on which you throw so much light.
(244/2. The difficulty alluded to is explained by the first sentence of
Lord Avebury's paper. "The Metamorphoses of this group (Insects) have
always seemed to me one of the greatest difficulties of the Darwinian
theory...I feel great difficulty in conceiving by what natural process
an insect with a suctorial mouth, like that of a gnat or butterfly,
could be developed from a powerfully mandibulate type like the
orthoptera, or even from the neuroptera...A clue to the difficulty
may, I think, be found in the distinction between the developmental and
adaptive changes to which I called the attention of the Society in a
previous memoir."

The distinction between developmental and adaptive changes is mentioned,
but not discussed, in the paper "On the Origin of Insects" (loc. cit.,
page 422); in a former paper, "On the Development of Chloeon (Ephemera)
dimidiatum ("Trans. Linn. Soc." XXV. page 477, 1866), this question is
dealt with at length.) I have only a few trifling remarks to make. At
page 44 I wish you had enlarged a little on what you have said of the
distinction between developmental and