Development of aphids; apparent absence of vermiform stage.
I return Linn. Trans. with thanks & I send all the Med. Times with articles on Crustacea.—
If Sir John has the Report Brit. Assoc. for 1839 (Birmingham Meeting) & would
lend it me for a few days, I sh
I have looked carefully at Huxley's Plates of young Aphis but have not read Text to spare my brain.— My impression is that in “germ” Pl. 37 fig. 6. there is nothing that can be called an apodal Vermiform body, but a body already divided into abdomen, thorax with great head. In next plate, in “embryo” we see even proportions indicated in length of antennæ, small Trophi & broad short legs, & other segments not at all developed; so that here there seems to me no Vermiform stage.
I wish you would look at Plates, & if you come to any decision one way or other tell me, but not write otherwise for form sake.— My impression would have been, had you not taken a contrary one, that Aphis was case of insect being developed into its pupa form, as soon as anything could be detected, without passing through the vermiform stage common to other insects.—
Thanks for Wollastons letter, which I have been glad to see. Till one hears how all facts stand on species of Madeira & Canaries, one can form no opinion: I know it would take a powerful deal of evidence to make me believe they had ever been continuously united.— I sent our joint letter to Madeira, & I fear Wollaston will not get it—
Farewell | Yours most truly | C. Darwin
I forgot to ask about Railway to Farnborough.—
P.S | I see I was blundering about homologies of young cirripedes.— The only point I made out at all clearly is that 3 pair of natatory organs in youngest stage are not antennæ: the rest seems all speculative. Proteolepas Cryptophialus are important for homologies of Cirripedes.—
- f1 2419.f1Dated by the relationship to the letters from John Lubbock, 15 March 1859 and to John Lubbock, 16 [March 1859].
- f2 2419.f2Lubbock had evidently lent CD a copy of the most recent issue of the Transactions of the Linnean Society, which included Thomas Henry Huxley's paper on the morphology and reproduction of aphids (T. H. Huxley 1858). Huxley's lectures on general natural history had been published in parts throughout 1856 and 1857 in the Medical Times & Gazette (T. H. Huxley 1856–7). Huxley discussed the Crustacea in detail in his last three lectures (vols. 14 and 15 of the Medical Times & Gazette).
- f3 2419.f3John William Lubbock. CD had attended the Birmingham meeting of the British Association for the Advancement of Science in 1839 (see Correspondence vol. 2).
- f4 2419.f4T. H. Huxley 1858.
- f5 2419.f5In Origin, p. 442, CD stated that aphids do not pass through a worm-like stage of development, citing T. H. Huxley 1858 as his source.
- f6 2419.f6Lubbock sent CD a letter that he had written to Thomas Vernon Wollaston in February, to which CD added a note before posting it to Wollaston in Madeira, where he usually spent the winter (see letter to John Lubbock, [6 February 1859]). For Wollaston's view that the entomology of the Canaries and Madeira seemed to indicate that the two island groups were formerly connected, see Correspondence vol. 6.
- f7 2419.f7See letter to John Lubbock, 8 March .
- f8 2419.f8CD was probably preparing the text of Origin, pp. 440–2, in which he discussed the resemblances and dissimilarities between embryonic and adult organisms, with particular reference to cirripedes. CD placed great emphasis on the position and homologies of cirripede antennae in Living Cirripedia (1851 and 1854). See Correspondence vol. 4, Appendix II.
- f9 2419.f9In Living Cirripedia (1854), CD classified Proteolepas on the basis of homologies with an archetypal crustacean (see Living Cirripedia (1854): 588). Cryptophialus was another extremely aberrant cirripede collected by CD during the Beagle voyage and described in Living Cirripedia (1854). See Correspondence vol. 4.