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 .
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 adaptive changes; for I cannot quite remember the point, and others will perhaps be in the same predicament. I think I always saw that the larva and the adult might be separately modified to any extent. Bearing in mind what strange changes of function parts undergo, with the intermediate state of use (244/3. This slightly obscure phrase may be paraphrased, "the gradational stages being of service to the organism."), it seems to me that you speak rather too boldly on the impossibility of a mandibulate insect being converted into a sucking insect (244/4. "There are, however, peculiar difficulties in those cases in which, as among the lepidoptera, the same species is mandibulate as a larva and suctorial as an embryo" (Lubbock, "Origin of Insects," page 423).); not that I in the least doubt the value of your explanation.
Cirripedes passing through what I have called a pupal state (244/5. "Hence, the larva in this, its last stage, cannot eat; it may be called a "locomotive Pupa;" its whole organisation is apparently adapted for the one great end of finding a proper site for its attachment and final metamorphosis." ("A Monograph on the Sub-Class Cirripedia." By Charles Darwin. London, Ray Soc., 1851.)) so far as their mouths are concerned, rather supports what you say at page 52.
At page 40 your remarks on the Argus pheasant (244/6. There is no mention of the Argus pheasant in the published paper.) (though I have not the least objection to them) do not seem to me very appropriate as being related to the mental faculties. If you can spare me these proof-sheets when done with, I shall be obliged, as I shall be correcting a new edition of the "Origin" when I return home, though this subject is too large for me to enter on. I thank you sincerely for the great interest which your discussion has given me.
(245/1. The following letter refers to Mivart's "Genesis of Species.")
I am preparing a new and cheap edition of the "Origin," and shall introduce a new chapter on gradation, and on the uses of initial commencements of useful structures; for this, I observe, has produced the greatest effect on most persons. Every one of his [Mivart's] cases, as it seems to me, can be answered in a fairly satisfactory manner. He is very unfair, and never says what he must have known could be said on my side. He ignores the effect of use, and what I have said in all my later books and editions on the direct effects of the conditions of life and so-called spontaneous variation. I send you by this post a very clever, but ill-written review from N. America by a friend of Asa Gray, which I have republished. (245/2. Chauncey Wright in the "North American Review," Volume CXIII., reprinted by Darwin and published as a pamphlet (see "Life and Letters," III., page 145).)