Based on the essay which was awarded the Society's Singer Prize for 1980.

¹ Wright, S., ‘Genic and organismic selection’, Evolution, 1980, 34, 825–43CrossRefGoogle ScholarPubMed, quote from p. 826. We may suppose that Wright's estimate of the relative importance of different arguments against natural selection is a little biased by his own research interests!

² Rudwick, M. J. S., The meaning of fossils, London, 1972, ch. 3.Google Scholar Rudwick points oui that Cuvier relied more on his wide empirical knowledge of skeletons of living species than on his theoretical principle in reconstructing fossil species. Coleman, W., Georges Cuvier zoologist, Cambridge, Mass., 1964, p. 172.CrossRefGoogle Scholar

³ Darwin, C., The origin of species (ed. Burrow, J.), Harmondsworth, 1969, p. 219.Google Scholar Also, from the ‘B’ notebook, p. 175: ‘We never may be able to trace the steps by which the organization of the eye passed from simpler stages to more perfect preserving its relation. … This really perhaps greatest difficulty to whole theory.’ transcribed in Sirde Beer, Gavin, ‘Darwin's notebooks on transmutation of species Part II. Second notebook (February to July 1838)’, Bulletin of the British Museum (Natural History) Historical Series, 1960, 2, 77–117, quoted from p. 103.Google Scholar

⁴ Darwin, , op. cit. (3), p. 217.Google Scholar Similarly Darwin's letters to Lyell in Darwin, F. (ed.), Life and Letters of Charles Darwin, London, 1887, vol. ii, pp. 273, 289, 304.Google Scholar

⁵ Wright, , op. cit. (1), p. 827.Google Scholar

⁶ Hull, D., Darwin and his critics, Cambridge, Mass., 1973, p. 301Google Scholar writes ‘Earlier reviews in this anthology tended to ignore in their criticisms the role that ‘chance’ played in evolutionary theory. For example, Owen never mentions it. In later years it was to become one of the main objections to Darwin's theory.' Of the reviews anthologized by Hull, Hutton (pp. 299–300) and von Baer (p. 426) onlv objected to chance in Darwin's theory.

⁷ Gillespie, N. C., Charles Darwin and the problem of creation, Chicago, 1979, ch. 2Google Scholar, gives plenty of examples of a lack of interest in secondary causes shown by natural theologians.

⁸ Bowler, P. J., ‘Darwin and the argument from design: suggestions for a reevaluation’, Journal of the history of biology, 1976, 10, 29–43.CrossRefGoogle ScholarOspovat, D., ‘Perfect adaptation and teleological explanation: approaches to the problem of life in the mid-nineteenth century’, Studies in history of biology, 1978, 2, 35–9.Google ScholarPubMedYeo, R., ‘William Whewell, natural theology and the philosophy of science in mid nineteenth century Britain’, Annals of science, 1979, 36, 507–9.CrossRefGoogle Scholar

⁹ Carpenter, W. B., ‘The argument from design in the organic world’, The modern review, 1884, 5, 698–9.Google Scholar The article was reprinted in Carpenter, W. B., Nature and man, London, 1888.Google Scholar

¹⁰ Gillespie, , op. cit. (7)Google Scholar, discusses this and refers to previous historians. Chs v–vi are especially relevant to this paper.

¹¹ Carpenter, , op. cit. (9), p. 681.Google Scholar

¹² I took the quote from Murphy's Belfast address from Darwin, C., The variation of animals and plants under domestication, London, 1868, vol. ii, p. 222.Google Scholar I have not seen the original in the Belfast northern wig cited by Darwin. Darwin said that ‘Mr. Murphy here follows the line of argument against my views previously and more cautiously given by the Rev. C. Pritchard, Pres. Royal Astronomical Soc., in his sermon (Appendix, p. 33) preached before the British Association at Nottingham, 1866.’ I have not found anything published by Pritchard on coadaptation, nor is there any mention of his sermon in the 1866 Report of the British Ass. Murphy, J. J., Habit and intelligence, London, 1869, pp. 317–27Google Scholar, clearly follows Spencer, not Pritchard. Murphy omitted the section from his 2nd edn (London, 1879) though he worked it in elscwhere: ‘A variation may be injurious if not accompanied by other variations’ (pp. 192–3).

¹³ Mivart, G., On the genesis of species, London, 1871, pp. 58–60, also pp. 32, 117.CrossRefGoogle Scholar On Mivart's idealism see Gruber, J., A conscience in conflict, New York, 1960, pp. 18–21.Google Scholar

¹⁴ Owen, R., On the anatomy of vertebrates, London, 1866–1868, quoted from vol. iii, pp. 808, 809.Google Scholar The Duke of Argyll used other arguments against natural selection (see Gillespie, , op. cit. (7), p. 97)Google Scholar. There was a strong connexion between idealistic morphology and the use of coadaptation against natural selection among German writers. See Russell, E. S., Form and function, London, 1916, p. 242Google Scholar (von Baer and A. Wigand), p. 244 (von Haartman), and Montgomery, W. M., ‘Germany’, in Glick, T. F. (ed.), The comparative reception of Darwinism, Texas, 1972, pp. 90, 94, 96 (eye), 99, 101.Google Scholar

¹⁵ Dupree, A. H., Asa Gray, Cambridge, Mass., 1959.Google ScholarBowler, , op. cit. (8)Google Scholar, treats Gray as a paragon adherent of the utilitarian argument from design.

¹⁶ Darwin to Gray in Darwin, F. & Seward, A. C. (eds), More letters of Charles Darwin, London, 1903, vol. i, p. 242.Google Scholar Gray to Darwin in Gray, J. L. (ed.), Letters of Asa Gray, London, 1893, p. 508.Google ScholarDarwin, C., On the various contrivances by which Brilish and foreign orchids are fertilised by insects and on the good effects of intercrossing, London, 1862.Google Scholar

¹⁷ note 10 bis.

¹⁸ Darwin, , op. cit. (4), vol. i, pp. 312–13.Google Scholar Darwin expressed similar sentiments to Gray (ibid., vol. ii, p. 273). For Darwin's views on chance and ideal design, see Schweber, S., ‘The origin of the Origin revisited’, Journal of the history of biology, 1977, 10, 266–71CrossRefGoogle ScholarPubMed, and Manier, E., The young Darwin and his cultural circle, Dordrecht, Holland, 1978, pp. 117–23.CrossRefGoogle Scholar

¹⁹ Duke quoted in Darwin, , op. cit. (4), vol. i, p. 316.Google Scholar

²⁰ The following list is not intended to be exhaustive, only exhausting: Darwin, , op. cit. (3), pp. 399, 404, 415, 416, 430Google Scholar; a passage added to the 4th edn, Peckham, M., The origin of species by Charles Darwin: a variorum text, Philadelphia, 1959, p. 678Google Scholar; the essay of 1844, Darwin, F. (ed. ), The foundatians of the origin of species, Cambridge, 1909, p. 40Google Scholar; Darwin, & Seward, , op. cit. (16), vol. i, pp. 73, 191, 202Google Scholar; Darwin, C., The descent of man, London, 1871, vol. i, p. 32Google Scholar; and the essay on theology, transcribed in Gruber, H. E. and Barrett, P. H., Darwin on man, London, 1974, pp. 416–20.Google Scholar T. H. Huxley thought likewise: Huxley, T. H., ‘The origin of species’, reprinted from the Westminster review (04, 1860)Google Scholar in his book Lay sermons, addresses and reviews, London, 1870, see p. 309.Google Scholar

²¹ Darwin, & Seward, , op. cit. (16), vol. i, p. 191.Google ScholarGillespie, , op. cit. (7)Google Scholar. Darwin's main comments on directed variation are in his correspondence with Gray and in Variation under domestication (op. cit. (12)).

²² Russell, , op. cit. (14), pp. 232–41, quote from p. 241.Google Scholar There is truth in Russell's judgement although I would question whether it was a ‘drawback’ (p. 232) in Darwin's thought.

²³ Young, R. M., Mind, brain and adaptation, London, 1970, pp. 167–9.Google Scholar

²⁴ Spencer, H., ‘Weismannism once more’, Contemporary review, 1894, 66, p. 608.Google Scholar He made a similar statement in the preface to the separately published version of Factors of organic evolution, London, 1887, p. iiiGoogle Scholar (originally published in Nineteenth century, 1886, 19, 570–89 and 749–70). Spencer's contemporaries were well aware of the inter-dependencies within Spencer's System, e.g. Huxley to W. P. Bail in Huxley, L. (ed.), Life and letters of Thomas Henry Huxley, London, 1900, vol. ii, p. 268Google Scholar, and Wallace to Meldola in Marchant, J. (ed.), Alfred Russel Wallace: letters and reminiscences, London, 1916, vol. ii, pp. 55–6.Google Scholar For Spencer's theory of social evolution. Spencer, H., The principles of biology, London, 1864–1867, vol. i, pp. 466–9Google Scholar, and Peel, J. D. Y., Herbert Spencer. The evolution of a sociologist, London, 1971, pp. 138–9.Google Scholar

²⁵ Spencer, , Principles of biology, op. cit. (24), vol. i, pp. 449–57Google Scholar (quotation from p. 538 of 2nd edn, London, 1898, which has similar wording to p. 453 of 1st edn), 424, 192–3.

²⁶ Spencer, , Principles of biology, op. cit. (24), vol. i, pp. 182–3, 239–91.Google Scholar For mechanism of inheritance of acquired characteristics, see 2nd edn (op. cit. (25)), vol. i, p. 371.

²⁷ Spencer, , Principles of biology, op. cit. (24), vol. i, p. 288.Google Scholar

²⁸ ‘As Weismann has pointed out, while Spencer gave an epigenetic Darwin gave an evolutionary account of development.…’ Thus G. C. Bourne, in his 1909 Herbert Spencer lecture at Oxford, Herbert Spencer and animal evolution, Oxford, 1910, p. 13.Google Scholar

²⁹ Darwin, , op. cit. (12), vol. II, pp. 220–3 and 333–5.Google Scholar Quotations from pages 221 and 222.

³⁰ Darwin, C., The descent of man, London, 1871, p. 142–51Google Scholar, quotations from pp. 143, 143–4; in the second passage Darwin changed ‘act and react’ to ‘often co-operate’ in the 2nd edn, London, 1874 (p. 53 of the 1894 edition). For a similar statement see the passage added to the 6th edn of the Origin, Peckham, , op. cit. (20), p. 262.Google Scholar

³¹ Peckham, , op. cit. (20), pp. 242–3.Google Scholar Also Darwin, to Wallace, , 30.i.1871Google Scholar, in Darwin, , op. cit. (4), vol. iii, pp. 135–6.Google Scholar

³² On the extent of variation, further see: Darwin to Lyell, Darwin, , op. cit. (4), vol. ii, p. 388Google Scholar; Rudwick, , op. cit. (2), p. 203Google Scholar: Schweber, S. S., ‘The young Darwin’, Journal of the history of biology, 1979, 12, pp. 185–6.CrossRefGoogle Scholar

³³ Darwin, & Seward, (eds), op. cit. (16), vol. i, p. 145.Google Scholar Darwin here, as elsewhere, is using coadaptation as a synonym of adaptation rather than in the more specific sense of an adaptation in which the parts are necessarily mutually adjusted.

³⁴ Spencer, , Factors, op. cit. (24).Google Scholar

³⁵ Spencer did not mention Weismann in Factors. According to Spencer's biographer, ‘The earliest notice of Dr. Weismann to be found in the correspondence is in a letter to Mr. Henry Collins (26 February, 1890)’, Duncan, D. (ed. ), Life and latters of Herbert Spencer, London, 1908, p. 343.Google Scholar See also G.J. Romanes to his wife, 21.iii.1893, in Romanes, E. (ed.), Life and letters of George John Romanes, London, 1896, p. 301.Google Scholar

³⁶ Romanes, G. J., ‘The factors of organic evolution’, Nature, 1887, 36, 401–7CrossRefGoogle Scholar, quotation from p. 406.

³⁷ Turner, F. M., Between science and religion, New Haven, 1974, pp. 134–63Google Scholar on Romanes, quotations from p. 142. ‘Physicus’ [Romanes, G. J.], A candid examination of theism, London, 1878; p. 171Google Scholar illustrates splendidly Romanes' beliefs about the relation of morality and evolution.

³⁸ Wallace, A. R., Darwinism, London, 1889, p. 127Google Scholar for covariation, p. 418 for quote; Wallace, A. R., ‘The origin of species controversy’, Nature, 1869, 105–7 and 132–3CrossRefGoogle Scholar, for gradual evolution of eye see p. 106, for artificial selection analogy pp. 106–7. Also see Wallace to Darwin quoted in Hull, , op. cit. (6), p. 302Google Scholar and Darwin, to Wallace, , op. cit. in (31).Google Scholar

³⁹ For Wallace's non-use of the analogy in his original discovery, see Limoges, C., La sélection naturelle, Paris, 1970, pp. 96–9Google Scholar and Bowler, P. J., ‘Alfred Russel Wallace's concepts of variation’, Journal of the history of medicine, 1976, 31, p. 24.Google ScholarPubMed Quote from Wallace, A. R., ‘On the tendency of varieties to depart indefinitely from the original type’, Journal of the proceedings of the Linnean Society, 1859, 3, p. 61.Google Scholar For other examples see Young, R. M., ‘Darwin's metaphor: Does nature select?’, The monist, 1971, 55, pp. 471–3CrossRefGoogle Scholar and Wallace, , Darwinism, op. cit. (38), p. vi.Google Scholar

⁴⁰ Romanes, G. J., ‘Mr. Wallace on Darwinism’, Contemporary review, 1889, 56, 244–58Google Scholar, quotation from p. 256.

⁴¹ A point that is further illustrated by the exchange on coadaptation between Raphael Meldola and Romanes in Nature in 1891. Meldola argued that coadaptations evolve in small stages; Romanes accepted this as the only way of reconciling natural selection with coadaptation. The exchange was prolonged by Romanes’ curious conceit (which he cannot have read) that Meldola was repeating Wallace's artificial selection analogy. The letters, mainly entitled ‘Coadaptation’, were in Nature, 1891, 43, 409–12, 489–90, 557–8, 582–3, 44, 7, 28–9, 55.Google Scholar See also Wallace to Meldola in Marchant, , op. cit. (24), vol. ii, pp. 50–1.Google Scholar Meldola, a professor of chemistry and expert on dyes, was also an entomologist, President of the Royal Entomological Society, and translator of Weismann. He held similar views on evolution to Wallace and Weismann. He was passed over by DSB and DNB; the best biographical source is Marchant, J. (ed.), Raphael Meldola, London, 1916.Google Scholar At about this time, Ball, W. P., Are the effects of use and disuse inherited?, London, 1890, pp. 19–20Google Scholar, discussed Spencer on coadaptation and concluded that coadaptations could be built up in small stages by natural selection.

⁴² Spencer, H., ‘The inadequacy of “natural selection”’, Contemporary review, 1893, 63, 153–66 and 439–56, see pp. 159–60.Google Scholar (This and his subsequent papers in the controversy were republished as separate pamphlets and also in the 2nd edn of Principles of biology, London, 1898, vol. i, pp. 602–91.Google Scholar) Wallace, A. R., ‘Are individually acquired characters inherited?’, Fortnightly review, 1893, 59 (O.S., 53 N.S.), p. 659Google Scholar (original italics), 660, 660–1 (original italics). Wallace introduced this paper as being jointly inspired by Weismann's The germ plasm, Spencer's ‘Inadequacy of “natural selection”’ and a work by the American neo-Lamarckian, C. A. Keeler (who Wallace quotes as approving of Spencer's coadaptation argument).

⁴³ Churchill, F. B., ‘The Weismann–Spencer controversy over the inheritance of acquired characters’, in Forbes, E. G. (ed.), Human implications of scientific advance (Proceedings of the XVth International Congress of the History of Science), Edinburgh, 1978, pp. 451–68Google Scholar; Blacher, L. J., ‘Die Diskussion zwischen Spencer und Weismann über die Bedeutung der natürlichen Zuchtwahl and der drekten Anpassung für die Evolution’, NTM-Schriftenreihe Geschichle, 1973, 2, 50–8.Google Scholar

⁴⁴ Weismann, A., ‘Botanisches Beweise für eine Vererbung erworbener Eigenschaften’, Biologisches Centralblatt, 1888, 8, p. 67.Google Scholar

⁴⁵ Weismann, A., ‘The all-sufficiency of natural selection’, Contemporary review, 1893, 64, 309–38 and 596–610.Google Scholar

⁴⁶ Weismann, , op. cit. (45), p. 314.Google Scholar

⁴⁷ Darwin, , for example op. cit. (3), pp. 235–6.Google Scholar

⁴⁸ Ball, W. P., ‘Natural selection and Lamarckism’, Natural science, 1893, 2, p. 347Google Scholar; this paper was another of the replies to Spencer's ‘Inadequacy’.

⁴⁹ Weismann, , op. cit. (45), p. 328Google Scholar (original italics).

⁵⁰ Spencer, H., ‘A rejoinder to Professor Weismann’, Contemporary review, 1893, 64, 893–912Google Scholar; Ball, W. P., ‘Neuter insects and Darwinism’, Natural science, 1894, 4, 281–9Google Scholar; Weismann, A., The effect of external influences on development, London, 1894, p. 68Google Scholar; Spencer, , ‘Weismannism’, op. cit. (24), pp. 597–9, 603Google Scholar; Weismann, A., ‘Heredity once more’, Contemporary review, 1895, 68, p. 445.Google Scholar

⁵¹ Published as Weismann, , Effect, op. cit. (50)Google Scholar. G. J. Romanes founded the lecture in 1892, the selection of lecturers to be ‘determined with reference either (a) to general eminence in art, literature, or science, or (b) to special claims for discussing any particular subject of high interest at the time.’ (Founder's Preface). The 1893 lecture was Huxley's classic Evolution and ethics. Romanes died soon after Weismann delivered his lecture. The lecture is now given annually by someone from the posher echelons of the artistic establishment.

⁵² Roux, W., Der Kampf der Theile im Organismus, Leipzig, 1881.Google Scholar Roux sent Darwin a copy, of which Darwin wrote to Romanes: ‘As far as I can imperfectly judge, it is the most important book on Evolution which has appeared for some time. I believe that G. H. Lewes hinted at the same fundamental idea.…’ (Darwin, , op. cit. (4), vol. iii, p. 244Google Scholar, also see Darwin to Huxley in ibid, p. 119). Lewes was one of Spencer's closer friends, and they discussed the inheritance of acquired characters (Duncan, , op. cit. (35), p. 541).Google Scholar

⁵³ Weismann, , Effect, op. cit. (50), pp. 17, 18, 18–19 (italics original).Google Scholar

⁵⁴ Spencer, , ‘Weismannism’, op. cit. (24), p. 597.Google Scholar

⁵⁵ Weismann, A., Neue Gedanken zur Vererbungsfrage, Jena, 1894Google Scholar; ‘On germinal selection’, The monist, 1896, 6, 250–93Google Scholar reprinted as a pamphlet (Chicago, 1896). Germinal selection is a precise application of intra-selection to the germ plasm, a possibility vaguely noted but not much explored in the Romanes lecture (Weismann, , Effect, op. cit. (50), pp. 20–1).Google Scholar

⁵⁶ Weismann, , ‘Heredity’, op. cit. (50), p. 430.Google Scholar

⁵⁷ Weismann, , ‘on germinal selection’, op. cit. (55), p. 264.Google Scholar The second passage was italicized in the original; it is a remarkable statement, Weismann not having admitted this before even as a possibility.

⁵⁸ Weismann later accommodated the possibility of non-adaptive orthogenesis in a modified theory of germinal selection, on which see Bowler, P. J., ‘Thomas Eimer and orthogenesis: evolution by ‘definitely directed variations’, Journal of the history of medicine, 1979, 34, 40–73, especially pp. 55–8.Google Scholar Bowler tends to treat germinal selection as if it were solely a response to the debate on orthogenesis (e.g. p. 45), though it was also stimulated by the claim that natural selection could not explain useful structures. The precursor of germinal selection, intra-selection, was first proposed as a direct answer to the problem of coadaptation, in the 1894 Romanes lecture.

⁵⁹ Spencer, H., Facts and comments, London, 1902, pp. 92–6CrossRefGoogle Scholar; and a short note, ‘Heredity once more’, Contemporary review, 1895, 68, p. 608.Google ScholarWeismann, A., Tne evolution theory, London, 1904, vol. ii, pp. 81–7Google Scholar, and, ‘The selection theory’ in Seward, A. C. (ed.), Darwin and modern science, Cambridge, 1909, pp. 32–42.Google Scholar

⁶⁰ Robinson, G., ‘Weismann, August Friedrich Leopold’, in Gillespie, C. C. (ed.), Dictionary of scientific biography, New York, 1976, vol. xiv, p. 237.Google Scholar William James, by contrast, praised Spencer: ‘I may say that Spencer's controversy over use-inheritance with Weismann, entered into after he was sixty, seems to me in point of quality better than any other part of his work. It is genuine labor over a puzzle, genuine research.’ (‘Herbert Spencer’, The Atlantic monthly, 1904, 94, p. 107Google Scholar; reprinted in James, W., Memories and studies, London, 1911.)Google Scholar

⁶¹ Anonymous, ‘Weismann and Spencer’, Natural science, 1895, 7, p. 233.Google Scholar

⁶² Simpson, G. G., ‘The Baldwin effect’, Evolution, 1953, 7, 110–17CrossRefGoogle Scholar is an authoritative christening. The idea was first and most clearly stated by Spalding, D. A., ‘Instinet with original observations on young animals’, Macmillan's magazine, 1873, 27, 282–93Google Scholar, which was reprinted in the British journal of animal behaviour, 1954, 2, 2–11Google Scholar, with an introduction by J. B. S. Haldane (p. 1 ) drawing attention to Spalding's priority. See the passage about Robinson Crusoe's parrot on p. 11 of the reprint. Wallace, A. R., ‘Lamarck versus Darwin’, Nature, 1889, 40, p. 619CrossRefGoogle Scholar, also independently published the same idea. Neither Spalding nor Wallace applied the idea to the problem of coadaptation, and none of the authors that did seemed aware of Spalding's or Wallace's papers.

⁶³ Morgan, C. L., Animal life and intelligence, London, 1891, p. 213.CrossRefGoogle Scholar In Morgan, C. L., ‘Factors in the evolution of the Mammalia’, Natural science, 1892, 1, pp. 100–1Google Scholar, he seems to be groping towards (if you'll pardon the anachronism) the Baldwin effect. Morgan, C. L., Habit and Instinet, London, 1896, ch. xiv.CrossRefGoogle ScholarRichards, R. J., ‘Lloyd Morgan's theory of Instinet: from Darwinism to neo-Darwinism’, Journal of the history of the behavioral sciences, 1977, 13, 12–323.0.CO;2-E>CrossRefGoogle ScholarPubMed, documents Lloyd Morgan's close knowledge of Spalding's work (p. 22) and his gradual conversion to Weismannism (pp. 26–30).

⁶⁴ Wallace, A. R., ‘The problem of Instinct’, Natural science, 1897, 10, p. 168.Google Scholar

⁶⁵ Baldwin mentioned the idea in various publications in 1895, and he collected the relevant quotations in Baldwin, J. M., ‘A new factor in evolution’, American naturalist, 1896, 30, 441–51 and 536–53CrossRefGoogle Scholar (I have quoted from p. 449). This paper along with all the previous ones was collected in Baldwin, J. M., Development and Evolution, New York, 1902Google Scholar, dedicated to Lloyd Morgan, Osborn and E. B. Poulton. Baldwin's contemporaries found him verbose and obsessively self-important. See Mueller, R. H., ‘A chapter in the history of the relationship between psychology and sociology in America: James Mark Baldwin’, Journal of the history of the behavioral sciences, 1976, 12, p. 2503.0.CO;2-H>CrossRefGoogle ScholarPubMed, where Cooley's advice to Baldwin is quoted: ‘If you wish to produce anything of lasting value, you must see to it that the subject matter, the truth, is the first interest of your mind, not your books, your essay, yourself as discoverer and Communicator of the truth.’ (original italics).

⁶⁶ Osborn, H. F., ‘[A mode of evolution requiring neither natural selection nor the inheritance of acquired characters]’ Transactions of the New York academy of sciences, 1896, 15, 141–3 and 148Google Scholar; and ‘The limits of organic selection’, American naturalist, 1897, 31, 944–51, especially p. 950.Google Scholar ‘Across the flyleaf he [Osborn] wrote in his large and elegant hand: To George Gaylord Simpson with the appreciation and best wishes of Henry Fairfield Osborn. As this was in heavy, flowing black ink, I reached for a blotter, but he stayed my hand and said, “Never blot the signature of a great man.”’ (Simpson, G. G., Concession to the improbable, New Haven, 1978, p. 40.)Google Scholar

⁶⁷ Osborn, , ‘Limits’, op. cit. (66), p. 950.Google Scholar

⁶⁸ Baldwin, , ‘New factor’, op. cit. (65), p. 549.Google Scholar

⁶⁹ For yet more authors on coadaptation, see Ellegård, A., Darwin and the general reader, Göteborg (Göteborgs Universitets Arskrift, Ixiv, no. 7), 1958, ch. 6 and pp. 247–50.Google Scholar